2022 
Hu W, Cheng Y, Chen Z, 'Reset control for consensus of doubleintegrator multiagent systems', Automatica, 136 (2022)
In this paper, we address the consensus problem for doubleintegrator multiagent systems integrated with a novel reset control protocol. It reveals the conditions under which con... [more]
In this paper, we address the consensus problem for doubleintegrator multiagent systems integrated with a novel reset control protocol. It reveals the conditions under which consensus is achieved and the reset function is in action. The proposed reset control essentially provides a dynamically generated higher gain for better transient consensus performance, including faster convergence with less control effort. Compared with a static high gain controller, this dynamic high gain mechanism is more efficient and sophisticated especially in regularly resetting the additional gain to zero during the dynamic evolution.



2021 
Zhang Z, Chen Z, 'Modeling and Control of Robotic Manipulators Based on Symbolic Regression', IEEE Transactions on Neural Networks and Learning Systems, (2021)
Modelbased design is an important method of addressing problems associated with designing complex control systems. For complex dynamic systems in the presence of uncertainties, t... [more]
Modelbased design is an important method of addressing problems associated with designing complex control systems. For complex dynamic systems in the presence of uncertainties, the modeling process from the first principles becomes extremely tedious and simplification in mechanism and parameter measurement may result in model inaccuracy. On the contrary, machine learning has the characteristic of fitting complicated equations, which makes it widely used in the research of model identification. However, it only brings a blackbox model where the design schemes based on an analytical model cannot be applied. In this article, a simple and novel scheme for modeling and control of robotic manipulators is proposed; without prior knowledge, a dynamic model in an analytical form is obtained from artificially excited training data using the symbolic regression technique, and then, a controller is designed based on the dynamic model. Due to the ingenious experimental design, on one hand, the amount of training data is far less than the system identification method by machine learning. On the other hand, a decoupling feature is used in the model that greatly simplifies controller design. The experimental results on twodegree of freedom (DOF) and 6DOF robotic manipulator simulators verify that the scheme is feasible and effective.



2021 
Kou L, Huang Y, Chen Z, He S, Xiang J, 'Cooperative fencing control of multiple secondorder vehicles for a moving target with and without velocity measurements', International Journal of Robust and Nonlinear Control, 31 46024615 (2021)
This article studies the movingtargetfencing problem of multiple secondorder vehicles, where the target moves with an unknown constant velocity. Without a predefined standoff ... [more]
This article studies the movingtargetfencing problem of multiple secondorder vehicles, where the target moves with an unknown constant velocity. Without a predefined standoff distance or formation, two classes of local cooperative controllers are proposed with and without velocity measurements. Specifically, the first controller uses the relative position information from the target and vehicle's neighbors, as well as the vehicle's velocity measurement, while the second controller relaxes the common requirement of velocity measurement of the vehicles. It is proved that both controllers simultaneously assure target fencing, collision avoidance, and velocity convergence. Finally, numerical simulations are provided to verify the efficacy of the proposed controllers.



2021 
Yan Y, Chen Z, Varadharajan V, Hossain MJ, Town GE, 'Distributed ConsensusBased Economic Dispatch in Power Grids Using the Paillier Cryptosystem', IEEE Transactions on Smart Grid, 12 34933502 (2021)
Economic dispatch is a critical problem in operation of power grids. A consensusbased algorithm was recently proposed to solve the economic dispatch problem in a distributed mann... [more]
Economic dispatch is a critical problem in operation of power grids. A consensusbased algorithm was recently proposed to solve the economic dispatch problem in a distributed manner. In this paper, we propose a novel secure scheme for the consensusbased economic dispatch algorithm using the Paillier cryptosystem. This secure scheme ensures that not only the network transmitted information is protected from external malicious party but also the privacy information of each node remains intact. The proposed secure scheme has two features. First, it relies on the solution to the socalled structural consensus problem with timevarying network weights. Second, it contains a strategy for transmitting encrypted information and generating network weights with randomness, as well as treatment of the practical issues like quantization error and computation overflow/underflow. The performance in terms of cost optimization and privacypreserving is verified by rigorous theoretical analysis and numerical simulation.



2021 
Hu Z, Chen Z, Zhang HT, 'Necessary and Sufficient Conditions for Asymptotic Decoupling of Stable Modes in LTV Systems', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 66 45464559 (2021)



2021 
Zhu L, Chen Z, Hill DJ, Du S, 'Eventtriggered controllers based on the supremum norm of samplinginduced error', Automatica, 128 (2021) [C1]
The paper proposes a novel eventtriggered control scheme for nonlinear systems. Specifically, the closedloop system is associated with a pair of auxiliary input and output. The ... [more]
The paper proposes a novel eventtriggered control scheme for nonlinear systems. Specifically, the closedloop system is associated with a pair of auxiliary input and output. The auxiliary output is defined as the derivative of the continuoustime input function, while the auxiliary input is defined as the input disturbance caused by the sampling or equivalently the integral of the auxiliary output over the sampling period. As a result, it forms a cyclic mapping from the input to the output via the system dynamics and back from the output to the input via the integral. The eventtriggered law is constructed to make the mapping contractive such that the stabilization is achieved and an easytocheck Zenofree condition is provided. Within this framework, we develop a theorem for the eventtriggered control of interconnected nonlinear systems which is employed to solve the eventtriggered control for lowertriangular systems with dynamic uncertainties.



2021 
Hu BB, Chen Z, Zhang HT, 'Distributed Moving Target Fencing in a Regular Polygon Formation', IEEE Transactions on Control of Network Systems, (2021)
This paper proposes a distributed controller for a network of agents of secondorder dynamics to fence a moving target of unknown velocity within their convex hull. Moreover, the ... [more]
This paper proposes a distributed controller for a network of agents of secondorder dynamics to fence a moving target of unknown velocity within their convex hull. Moreover, the agents form a regular polygon formation and avoid collision during the entire evolution. In the control scheme, the agents are not necessarily labelled and the nearest angle rules are applied. Each controller is composed of the functionalities of estimation of the target's velocity, regulation of distance between the agents and the target, and angle repulsion among agents resulting in an equal distribution. The latter two also guarantee collision avoidance. The asymptotical behavior of the closedloop system is rigorously analyzed especially subject to the velocity estimation error. The effectiveness of the controller is also demonstrated by numerical simulation.



2021 
Bazaei A, Boudaoud M, Ettefagh MH, Chen Z, Regnier S, 'NonCollocated Displacement Sensing by Semiconductor Strain Gauges in Differentially PiezoDriven Nanopositioners', IEEE Sensors Journal, 21 96909697 (2021) [C1]
We address design, implementation, and characterization of semiconductor strain gauges as stage displacement sensors with small footprint for piezodriven nanopositioners in diffe... [more]
We address design, implementation, and characterization of semiconductor strain gauges as stage displacement sensors with small footprint for piezodriven nanopositioners in differential actuation mode. The strain gauges are not collocated with the stage of the nanopositioner. They are attached to piezo stack actuators in both longitudinal and transverse directions. We address two differential configurations for the displacement sensing. The first configuration uses all strain gauges and provides three output signals. Two of them are proportional to the length variations of the piezo actuators, which are considered as conventional nondifferential sensing method. The last output in the first configuration is the first proposed differential sensor. In the second configuration, we propose an alternative differential sensor using only the longitudinal strain gauges and a simpler readout circuit. The results indicate that in the differential actuation mode, a differential sensing strategy provides much better accuracy than the conventional nondifferential schemes. Using a laser interferometer as an independent collocated sensor for stage displacement, we obtained constant calibration factors both proposed differential sensors and characterized their sensing accuracies.



2021 
Kou L, Chen Z, Xiang J, 'Cooperative Fencing Control of Multiple Vehicles for a Moving Target with an Unknown Velocity', IEEE Transactions on Automatic Control, (2021)
In this paper, we investigate a movingtargetfencing problem for multiple vehicles using nearest neighbor rules where the target moves with an unknown constant velocity. Without ... [more]
In this paper, we investigate a movingtargetfencing problem for multiple vehicles using nearest neighbor rules where the target moves with an unknown constant velocity. Without a predefined standoff distance or formation, two local cooperative controllers are proposed using only the relative position information from the target and its neighbors within its local frame of reference. The controllers consist of three functionalities. The repulsive term between a vehicle and its neighbors is used to avoid collision. The attractive term between a vehicle and the target drives the vehicle towards the target. The adaptive term amounts to estimate the target's velocity. Specifically, with the first controller, the vehicles follow the target's velocity in the average sense resulting in rotation about the target; with the second controller, each vehicle is able to follow the target's velocity resulting in a rigid formation. Furthermore, a decentralized estimator is applied to handle the case where only a portion of vehicles can access the target's position. Both controllers assure targetfencing. The results are proved by rigorous theoretical analysis and verified by extensive numeri



2021 
Fang W, Zamani M, Chen Z, 'Secure and privacy preserving consensus for secondorder systems based on Paillier encryption', Systems and Control Letters, 148 (2021) [C1]
This paper aims at secure and privacypreserving consensus algorithms of networked systems. Due to the technical challenges behind decentralized design of such algorithms, the exi... [more]
This paper aims at secure and privacypreserving consensus algorithms of networked systems. Due to the technical challenges behind decentralized design of such algorithms, the existing results are mainly restricted to a network of systems with simplest firstorder dynamics. Like many other control problems, breakthrough of the gap between firstorder dynamics and higherorder ones demands for more advanced technical developments. In this paper, we explore a Paillier encryption based average consensus algorithm for a network of systems with secondorder dynamics, with randomness added to network weights. The conditions for privacypreserving, especially depending on consensus rate, are thoroughly studied with theoretical analysis and numerical verification.



2021 
Mallick P, Chen Z, Zamani M, 'Reinforcement learning using expectation maximization based guided policy search for stochastic dynamics', Neurocomputing, (2021)
Guided policy search algorithms have been proven to work with incredible accuracy not only for controlling complicated dynamical systems, but also in learning optimal policies fro... [more]
Guided policy search algorithms have been proven to work with incredible accuracy not only for controlling complicated dynamical systems, but also in learning optimal policies from exploration of various unseen instances. This paper deals with a trajectory optimization problem for an unknown dynamical system subject to measurement noise using expectation maximization and extends it to learning (optimal) policies which have less stochasticity in trajectories because of the higher exploitation efficiency. Theoretical and empirical evidence of learned optimal policies for the new approach is depicted in comparison to some well known baselines which are evaluated on an autonomous system with widely used performance metrics.



2021 
Bazaei A, Ettefagh MH, Chen Z, 'Displacement amplification and differential actuation in piezo driven nanopositioners', Mechanical Systems and Signal Processing, 151 (2021) [C1]
We study a novel piezodriven nanopositioning mechanism in the horizontal plane. For each horizontal axis, we employ two externally leverage mechanisms with flexure hinges to prov... [more]
We study a novel piezodriven nanopositioning mechanism in the horizontal plane. For each horizontal axis, we employ two externally leverage mechanisms with flexure hinges to provide bilateral displacement of the output stage as well as amplified displacement with respect to strokes of two piezo stack actuator. The bilateral amplified motion is achieved by differential actuation of the PZT stack pair of each axis. We also designed a housing structure for the nanopositioner with holes and trenches for safe and neat wiring. It also provides proper installation on the optical table and allows incorporation of auxiliary parts to hold and and align capacitive displacement sensors for precise measurements. We designed wedge mechanisms that together with the housing and the nanopositioner structure allow proper alignment of PZT stacks during installation as well as preloading them. Experiments were carried out to identify the ranges of displacements for the output stage as well as the inputs of the leverage mechanism, using LaserDopplerVibrometry and capacitive sensors. We also developed a simple rigidlinkidealhinge kinematic model for the leverage mechanism, which was consistent with the experimental results under no external load conditions. However, due to the external loads and elasticity, large deviations exist between the experimental results and the predicted values by the model. The discrepancy revealed a nonreciprocal property of the individual leverage mechanism and the need to employ more accurate flexure hinge models. Experiments show that the proposed nanopositioner amplifies the input stroke of the PZT stacks by a factor around 12 in the differential actuation mode. Compared to the conventional nondifferential actuation modes, the differential one provides almost twice stroke for the output stage as well as more linear input¿output characteristics. In addition, the proposed structure considerably filters out the offaxis input displacements of the PZT actuators and provides very small parasitic displacements at the output stage. Both channels exhibit almost identical dynamic responses in time and frequency domains, indicating highly symmetric fabrications of the nanopositioner and auxiliary parts for the installation of actuators and sensors.



2021 
Zhang J, Chen Z, Zhang H, Feng T, 'Coupling effect and pole assignment in trajectory regulation of multiagent systems', Automatica, 125 (2021) [C1]
This paper revisits a well studied leaderfollowing consensus problem of linear multiagent systems, while aiming at follower nodes¿ transient performance. Conventionally, when no... [more]
This paper revisits a well studied leaderfollowing consensus problem of linear multiagent systems, while aiming at follower nodes¿ transient performance. Conventionally, when not all follower nodes have access to the leader's state information, distributed observers are designed to estimate the leader's state, and the observers are coupled via communication network. Then each follower node only needs to track its observer's state independently, without interacting with its neighbors. This paper deliberately introduces certain coupling effect among follower nodes, such that the follower nodes tend to converge to each other cooperatively on the way they converge to the leader. Moreover, by suitably designing the control law, the poles of follower nodes can be assigned as desired, and thus transient tracking performance can also be adjusted.



2021 
Zhu L, Chen Z, Chen X, Hill DJ, 'Output Synchronization of Heterogeneous Networked Linear MIMO Systems: Stabilization and H8 Control', IEEE Transactions on Control of Network Systems, 8 147157 (2021) [C1]



2020 
Amin BMR, Taghizadeh S, Rahman MS, Hossain MJ, Varadharajan V, Chen Z, 'Cyber attacks in smart grid  Dynamic impacts, analyses and recommendations', IET CyberPhysical Systems: Theory and Applications, 5 321329 (2020) [C1]
Cyber attacks can cause cascading failures and blackouts in smart grids. Therefore, it is highly necessary to identify the types, impacts and solutions of cyber attacks to ensure ... [more]
Cyber attacks can cause cascading failures and blackouts in smart grids. Therefore, it is highly necessary to identify the types, impacts and solutions of cyber attacks to ensure the secure operation of power systems. As a wellknown practice, steadystate analysis is commonly used to identify cyber attacks and provide effective solutions. However, it cannot fully cover nonlinear behaviours and cascaded blackouts of the system caused by dynamic perturbations, as well as provide a postdisturbance operating point. This study presents a novel approach based on dynamic analysis that excludes the limitations of the steadystate analysis and can be used in the events of various cyber attacks. Four types of common attacks are reviewed, and their dynamic impacts are shown on the IEEE benchmark model of the Western System Coordinating Council system implemented in MATLAB Simulink. Then, recommendations are provided to enhance the security of the future smart power grids from the possible cyber attacks.



2020 
Imran IH, Chen Z, Zhu L, Fu M, 'A distributed adaptive scheme for multiagent systems', ASIAN JOURNAL OF CONTROL, (2020)



2020 
Chen Z, Han QL, Yan Y, Wu ZG, 'How often should one update control and estimation: review of networked triggering techniques', Science China Information Sciences, 63 (2020) [C1]



2020 
Ren GP, Chen Z, Zhang HT, Wu Y, Meng H, Wu D, Ding H, 'Design of Interval Type2 Fuzzy Controllers for Active Magnetic Bearing Systems', IEEEASME TRANSACTIONS ON MECHATRONICS, 25 24492459 (2020) [C1]



2020 
Dehghani Aghbolagh H, Zamani M, Paolini S, Chen Z, 'Balance seeking opinion dynamics model based on social judgment theory', Physica D: Nonlinear Phenomena, 403 (2020) [C1]



2020 
Delgado R, Chen Z, Middleton RH, 'Stepwise Tikhonov Regularisation: Application to the Prediction of HIV1 Drug Resistance', IEEE/ACM Transactions on Computational Biology and Bioinformatics, 17 292301 (2020) [C1]



2020 
Yan Y, Chen Z, Middleton R, 'Autonomous Synchronization of Heterogeneous MultiAgent Systems', IEEE Transactions on Control of Network Systems, (2020)
This paper formulates a new type of synchronization problem for heterogeneous multiagent systems (MASs), called autonomous synchronization. In this problem, neither the synchroni... [more]
This paper formulates a new type of synchronization problem for heterogeneous multiagent systems (MASs), called autonomous synchronization. In this problem, neither the synchronized agent dynamics nor the synchronized states are specified a priori, instead, they are autonomously determined by the inherent properties and the initial states of agents, thus providing an MAS with more degrees of adaptability and higher synchronization efficiency. To achieve autonomous synchronization, a novel dynamics update law and a synchronizing control law are proposed and the sufficient solvability conditions are explicitly revealed. The results are supported by rigorous theoretical analysis and numerical simulation, in both continuoustime and discretetime settings.



2020 
Liu B, Chen Z, Zhang HT, Wang X, Geng T, Su H, Zhao J, 'Collective Dynamics and Control for Multiple Unmanned Surface Vessels', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 28 25402547 (2020) [C1]



2020 
Chen Z, Pasqualetti F, He J, Cheng P, Trentelman HL, Bullo F, 'Guest Editorial: Special Issue on Security and Privacy of Distributed Algorithms and Network Systems', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 65 37253727 (2020)



2020 
Zhang Q, Xu W, Zhang W, Feng J, Chen Z, 'MultiHypothesis SquareRoot Cubature Kalman Particle Filter for Speaker Tracking in Noisy and Reverberant Environments', IEEE/ACM Transactions on Audio Speech and Language Processing, 28 11831197 (2020) [C1]



2020 
Chen Z, Han QL, Wu ZG, Yan Y, 'Special focus on advanced techniques for eventtriggered control and estimation', SCIENCE CHINAINFORMATION SCIENCES, 63 (2020)



2020 
Castro RDS, Flores JV, Salton AT, Chen Z, Coutinho DF, 'A Stabilization Framework for the Output Regulation of Rational Nonlinear Systems', IEEE Transactions on Automatic Control, 65 48604865 (2020) [C1]
A systematic stabilization approach is provided for systems whose regulation error dynamics is subject to rational nonlinearities given prior knowledge of the system zeroerror st... [more]
A systematic stabilization approach is provided for systems whose regulation error dynamics is subject to rational nonlinearities given prior knowledge of the system zeroerror steadystate condition and a proper internal model. The error dynamics is cast in a differentialalgebraic form so as to address the synthesis of controller parameters by a numerical optimization problem subject to bilinear matrix inequality constraints. A particular case is also explored where the resulting constraints are linear matrix inequalities.



2020 
Khan UI, Chen Z, 'Natural Oscillation Gait in Humanoid Biped Locomotion', IEEE Transactions on Control Systems Technology, 28 23092321 (2020) [C1]



2020 
Khan GD, Chen Z, Zhu L, 'A New Approach for EventTriggered Stabilization and Output Regulation of Nonlinear Systems', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 65 35923599 (2020) [C1]



2020 
Sadeghikhorami L, Zamani M, Chen Z, Safavi AA, 'A secure control mechanism for network environments', Journal of the Franklin Institute, 357 1226412280 (2020) [C1]
This paper proposes an encrypted observerbased control paradigm for enhancement of cybersecurity in networked control systems. The proposed paradigm exploits a semihomomorphic e... [more]
This paper proposes an encrypted observerbased control paradigm for enhancement of cybersecurity in networked control systems. The proposed paradigm exploits a semihomomorphic encryption technique which enables the required computation to be done over encrypted data without any need for decryption at controller and observer levels. This improves the privacy of sensitive information such as command and sensor measurement signals. We study the challenges involved with the implementation of the proposed strategy and establish the conditions on system parameters to guarantee the stability of the closedloop system. Some simulations experiments are performed on the TennesseeEastman process to illustrate the effectiveness of the proposed approach.



2019 
Chen Z, 'Nussbaum functions in adaptive control with timevarying unknown control coefficients', Automatica, 102 7279 (2019) [C1]



2019 
Wang J, Sheng A, Xu D, Chen Z, Su Y, 'EventBased Practical Output Regulation for a Class of Multiagent Nonlinear Systems', IEEE TRANSACTIONS ON CYBERNETICS, 49 36893698 (2019) [C1]



2019 
Aghbolagh HD, Zamani M, Chen Z, 'A new bounded confidence model seeking structural balance', IEEE Control Systems Letters, 3 541546 (2019) [C1]



2019 
Khan U, Chen Z, 'Natural gait analysis for a biped robot: jogging vs. walking', Science China Information Sciences, 62 (2019) [C1]



2019 
Chen Z, 'Feedforward design for output synchronization of nonlinear heterogeneous systems with output communication', AUTOMATICA, 104 126133 (2019) [C1]



2019 
Imran IH, Chen Z, Yan Y, Fu M, 'Adaptive Consensus of Nonlinearly Parameterized MultiAgent Systems', IEEE Control Systems Letters, 3 505510 (2019) [C1]



2019 
Yan Y, Chen Z, 'Cooperative output regulation of linear discretetime timedelay multiagent systems by adaptive distributed observers', NEUROCOMPUTING, 331 3339 (2019) [C1]



2019 
Chen Z, Zhang T, 'Motion Mixed Control for Flexiblebase and Flexiblejoint Space Manipulators', Zhongguo Jixie Gongcheng/China Mechanical Engineering, 30 14661473 (2019)
The control problems of a flexiblebase and flexiblejoint space manipulator with uncertainties were addressed, and a mixed control scheme was proposed based on adaptive robust te... [more]
The control problems of a flexiblebase and flexiblejoint space manipulator with uncertainties were addressed, and a mixed control scheme was proposed based on adaptive robust terminal sliding mode control and adaptive optimal vibration control. Firstly, the system was reduced to a slow subsystem and a fast subsystem by singular perturbation method. Secondly, a trajectorytracking adaptive robust terminal sliding mode control scheme, including an equivalent control, a robust control, and an adaptive adjusting algorithm, was presented for the slow subsystems. And then, a vibration optimal control strategy was proposed based on adaptive state observation for the fast subsystems. The simulation results show the validity of the proposed scheme in rigid and flexible motion controls of the system.



2019 
Xiong Q, Lin P, Chen Z, Ren W, Gui W, 'Distributed containment control for firstorder and secondorder multiagent systems with arbitrarily bounded delays', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 29 11221131 (2019) [C1]



2019 
Chen Z, 'A cooperative targetfencing protocol of multiple vehicles', Automatica, 107 591594 (2019) [C1]



2019 
Xiong Q, Lin P, Chen Z, Ren W, Gui W, 'Distributed containment control for firstorder and secondorder multiagent systems with arbitrarily bounded delays (vol 29, 1122, 2019)', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 29 66576657 (2019)



2019 
Khan GD, Chen Z, Meng H, 'Output synchronization of nonlinear heterogeneous multiagent systems with switching networks', Systems and Control Letters, 125 4550 (2019) [C1]



2019 
Bazaei A, Boudaoud M, Ettefagh MH, Chen Z, Regnier S, 'Displacement Sensing by Piezoelectric Transducers in HighSpeed Lateral Nanopositioning', IEEE SENSORS JOURNAL, 19 91569165 (2019) [C1]



2019 
He J, Sheng A, Xu D, Chen Z, Wang D, 'Robust precision attitude tracking of an uncertain rigid spacecraft based on regulation theory (vol 29, pg 3666, 2019)', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 29 52905290 (2019)



2019 
Zhang HT, Sun W, Chen Z, Meng H, Chen G, 'Backwards square completion MPC solution for realtime economic dispatch in power networks', IET CONTROL THEORY AND APPLICATIONS, 13 29402947 (2019) [C1]



2019 
Mo X, Chen Z, Zhang HT, 'Effects of adding a reverse edge across a stem in a directed acyclic graph', Automatica, 103 254260 (2019) [C1]



2019 
Mehrabadi MK, Zamani M, Chen Z, 'Structural Controllability of a Consensus Network With Multiple Leaders', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 64 51015107 (2019) [C1]



2019 
He J, Sheng A, Xu D, Chen Z, Wang D, 'Robust precision attitude tracking of an uncertain rigid spacecraft based on regulation theory', International Journal of Robust and Nonlinear Control, 29 36663683 (2019) [C1]



2018 
Huang T, Zhu L, Du S, Chen Z, Ding H, 'Robust active chatter control in milling processes with variable pitch cutters', Journal of Manufacturing Science and Engineering, Transactions of the ASME, 140 10100511010059 (2018) [C1]



2018 
Wang X, Chen Z, Xu D, 'A Framework for Global Robust Output Regulation of Nonlinear Lower Triangular Systems With Uncertain Exosystems', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 63 894901 (2018) [C1]



2018 
Meng H, Chen Z, Middleton R, 'Consensus of Multiagents in Switching Networks Using InputtoState Stability of Switched Systems', IEEE Transactions on Automatic Control, 63 39643971 (2018) [C1]



2018 
Ponomarev A, Chen Z, Zhang HT, 'DiscreteTime Predictor Feedback for Consensus of Multiagent Systems With Delays', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 63 498504 (2018) [C1]



2018 
Bazaei A, Chen Z, Yong YK, Moheimani SOR, 'A Novel State Transformation Approach to Tracking of Piecewise Linear Trajectories', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 26 128138 (2018) [C1]



2018 
Meng H, Chen Z, 'Inputtostate stability of switched systems with explicit gain functions', Systems and Control Letters, 122 3947 (2018) [C1]



2018 
Zhong C, Wu L, Guo J, Guo Y, Chen Z, 'Robust adaptive attitude manoeuvre control with finitetime convergence for a flexible spacecraft', TRANSACTIONS OF THE INSTITUTE OF MEASUREMENT AND CONTROL, 40 425435 (2018) [C1]



2018 
Chen Z, 'Review and recent development of internal model design', Journal of Control and Decision, 5 94114 (2018) [C1]



2018 
Zhang HT, Hu B, Li L, Chen Z, Wu D, Xu B, et al., 'Distributed Hammerstein Modeling for CrossCoupling Effect of Multiaxis Piezoelectric Micropositioning Stages', IEEEASME TRANSACTIONS ON MECHATRONICS, 23 27942804 (2018) [C1]



2017 
He J, La HJ, Chen Z, Ge SS, 'Guest editorial: special issue on Consensusbased Applications in Networked Systems', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 27 13761378 (2017)



2017 
Chen Z, Zhang H, Zhu L, Knorn S, Cheng Z, 'Advanced Techniques for Networked Systems with Applications', MATHEMATICAL PROBLEMS IN ENGINEERING, 2017 (2017)



2017 
Chen X, Chen Z, 'Robust SampledData Output Synchronization of Nonlinear Heterogeneous MultiAgents', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 62 14581464 (2017) [C1]



2017 
Zhang HT, Wang Q, Chen Z, Wei FL, 'Dynamics and Feedback Control of Electrospinning Processes', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 25 611618 (2017) [C1]



2017 
Zhong C, Chen Z, Guo Y, 'Attitude Control for Flexible Spacecraft With Disturbance Rejection', IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS, 53 101110 (2017) [C1]



2017 
Zhu L, Chen Z, 'Robust inputtooutput stabilization of nonlinear systems with a specified gain*', AUTOMATICA, 84 199204 (2017) [C1]



2017 
Zhu L, Shi X, Chen Z, Zhang HT, Xiong CH, 'Adaptive Servomechanism of Pneumatic Muscle Actuators With Uncertainties', IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, 64 33293337 (2017) [C1]



2017 
Chen Z, Zhang HT, 'A Minimal Control Multiagent for Collision Avoidance and Velocity Alignment', IEEE TRANSACTIONS ON CYBERNETICS, 47 21852192 (2017) [C1]



2017 
Zhang HT, Chen Z, Mo X, 'Effect of Adding Edges to Consensus Networks with Directed Acyclic Graphs', IEEE Transactions on Automatic Control, 62 48914897 (2017) [C1]



2017 
Chen Z, Zheng J, Zhang HT, Ding H, 'Tracking of piezoelectric actuators with hysteresis: A nonlinear robust output regulation approach', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 27 26102626 (2017) [C1]



2017 
Dong Q, Chen L, Li H, Chen Z, 'Force/position control for dualarm space robot capturing object', Xitong Fangzhen Xuebao / Journal of System Simulation, 29 424429 (2017)
The dynamics control and simulation of dualarm space robot capture object was studied. The dynamics model of space robot was derived by the second Lagrange equation, for the obje... [more]
The dynamics control and simulation of dualarm space robot capture object was studied. The dynamics model of space robot was derived by the second Lagrange equation, for the object capture process, the impact influence on space robot base and arm was calculated by momentum theory. For the space robot and object closechain system after capturing, a force/position coordinate control algorithm was designed to control the system motion and object clamp force; the stability, reliability and safety of capture process would be ensured by the control algorithm. The simulation result based on the dynamics model and control algorithm was carried out. The result indicates the validity of above analysis.



2017 
Xu D, Chen Z, Wang X, 'Global robust stabilization of nonlinear cascaded systems with integral ISS dynamic uncertainties', AUTOMATICA, 80 210217 (2017) [C1]



2016 
Salton AT, Chen Z, Zheng J, Fu M, 'Constrained Optimal Preview Control of DualStage Actuators', IEEEASME TRANSACTIONS ON MECHATRONICS, 21 11791184 (2016) [C1]



2016 
Chen X, Chen Z, 'Robust Perturbed Output Regulation and Synchronization of Nonlinear Heterogeneous Multiagents', IEEE TRANSACTIONS ON CYBERNETICS, 46 31113122 (2016) [C1]



2016 
Zhang HT, Chen Z, Chen P, Zhang X, Ding H, 'Saturated Output Regulation Approach for Active Vibration Control of ThinWalled Flexible Workpieces With Voice Coil Actuators', IEEEASME TRANSACTIONS ON MECHATRONICS, 21 266275 (2016) [C1]



2016 
Xu D, Wang X, Chen Z, 'Output regulation of nonlinear output feedback systems with exponential parameter convergence', SYSTEMS & CONTROL LETTERS, 88 8190 (2016) [C1]



2016 
Zhang J, Zhu L, Chen Z, 'Control of Natural Oscillation Gait for Mechanical Locomotors in Three Dimensional Space', ASIAN JOURNAL OF CONTROL, 18 302315 (2016) [C1]



2016 
Chen Z, Xu D, 'OUTPUT REGULATION AND ACTIVE DISTURBANCE REJECTION CONTROL: UNIFIED FORMULATION AND COMPARISON', ASIAN JOURNAL OF CONTROL, 18 16681678 (2016) [C1]



2016 
Zhu L, Chen Z, Middleton RH, 'A General Framework for Robust Output Synchronization of Heterogeneous Nonlinear Networked Systems', IEEE Transactions on Automatic Control, 61 20922107 (2016) [C1]
© 19632012 IEEE.The paper aims to establish a general framework for robust output synchronization of a group of networked agents. The agents under investigation have nonlinear, u... [more]
© 19632012 IEEE.The paper aims to establish a general framework for robust output synchronization of a group of networked agents. The agents under investigation have nonlinear, uncertain and heterogeneous dynamics. Output synchronization denotes that all agents, through collaborative control, achieve output agreement and follow a desired pattern. In particular, the agreed trajectory is not defined by nor known to any agent in advance. Collaborative control is achieved using only output information from neighboring agents. Two concurrent actions are revealed in the proposed synchronization framework. This framework involves design strategies for both perturbed consensus and perturbed regulation problems, subject to a class of small gain conditions. The success of the framework is verified by constructive proof and numerical simulation.



2016 
Meng H, Chen Z, Zhu L, Middleton R, 'Consensus of a class of secondorder nonlinear heterogeneous multiagent systems with uncertainty and communication delay', International Journal of Robust and Nonlinear Control, 26 33113329 (2016) [C1]
In this paper, a consensus problem is studied for a group of secondorder nonlinear heterogeneous agents with nonuniform time delay in communication links and uncertainty in agen... [more]
In this paper, a consensus problem is studied for a group of secondorder nonlinear heterogeneous agents with nonuniform time delay in communication links and uncertainty in agent dynamics. We design a class of novel decentralized control protocols for the consensus problem whose solvability is converted into stability analysis of an associated closedloop system with uncertainty and time delay. Using an explicitly constructed Lyapunov functional, the stability conditions or the solvability conditions of the consensus problem are given in terms of a set of linear matrix inequalities apart from a small number of scalar parameters that appear nonlinearly. Furthermore, the linear matrix inequalities are theoretically verified to be solvable when the communication delay is sufficiently small. The effectiveness of the proposed control protocol is illustrated by numerical examples. Copyright © 2016 John Wiley & Sons, Ltd.



2016 
Lin Z, Wang L, Chen Z, Fu M, Han Z, 'Necessary and sufficient graphical conditions for affine formation control', IEEE Transactions on Automatic Control, 61 28772891 (2016) [C1]
This paper introduces a new multiagent control problem, called an affine formation control problem, with the objective of asymptotically reaching a configuration that preserves c... [more]
This paper introduces a new multiagent control problem, called an affine formation control problem, with the objective of asymptotically reaching a configuration that preserves collinearity and ratios of distances with respect to a target configuration. Suppose each agent updates its own state using a weighted sum of its neighbor's relative states with possibly negative weights. Then the affine control problemcan be solved for either undirected or directed interaction graphs. It is shown in this paper that an affine formation is stabilizable over an undirected graph if and only if the undirected graph is universally rigid,while an affine formation is stabilizable over a directed graph in the ddimensional space if and only if the directed graph is (d + 1)rooted. Rigorous analysis is provided, mainly relying on Laplacian associated with the interaction graph, which contain both positive and negative weights.



2016 
Chen X, Chen Z, Mei C, 'Sampled Measurement Output Feedback Control of MultiAgent Systems With JointlyConnected Topologies', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 61 16701675 (2016) [C1]



2016 
Zhu L, Chen Z, Middleton R, 'Robust asymptotic model matching and its application to output synchronization of heterogeneous multiagent systems', Systems and Control Letters, 94 3745 (2016) [C1]
Output synchronization of heterogeneous multiagent systems has been one of the most interesting cooperative control problems. This paper first gives a brief survey of the researc... [more]
Output synchronization of heterogeneous multiagent systems has been one of the most interesting cooperative control problems. This paper first gives a brief survey of the research on the problem from which we see that the problem can be solved in a twostep manner with the aid of a properly designed local reference for each agent: (i) a controller is designed for each agent to achieve the trajectory regulation of the agent output to its associated reference; (ii) network collaboration is added to achieve consensus among references. In the presence of system uncertainties, the robust trajectory regulation problem in (i) can be solved by an internal model design. In this paper, we formulate a novel robust asymptotic model matching problem which is less conservative than trajectory regulation and can be solved by a static controller not relying on an internal model. Moreover, network collaboration is designed in (ii) within the socalled output communication setting such that consensus among references occurs concurrently with robust asymptotic model matching. As a result, output synchronization of heterogeneous multiagent systems is achieved with a novel approach.



2016 
Chen ZY, Chen L, 'Antitorquewindup control and vibration suppression of flexiblejoint dualarm space robot with an attitudecontrolled base', Gongcheng Lixue/Engineering Mechanics, 33 (2016)
The paper studies the antitorquewindup control and flexible vibration suppression problems on the coordinated positioning of the base attitude and manipulator joints of a freef... [more]
The paper studies the antitorquewindup control and flexible vibration suppression problems on the coordinated positioning of the base attitude and manipulator joints of a freefloating flexiblejoint dualarm space robot. The fullactuated dynamic equations of flexiblejoint dualarm space robot with an attitudecontrolled base are derived by using the linear momentum conservation and Lagrange method. With the flexibility compensating and singular perturbation technology, singular perturbation model of the system is obtained. To suppress the joint flexible vibration of two arms, a torque differential state feedback control strategy is presented for the fast subsystem. Meanwhile, an antitorquewindup control method based on the torque active constraint design is proposed for the slow subsystem to track the desired positions of the base attitude and joints, and then the control saturation problems of the actual base attitude control system and joint motors are avoided. The obtained simulation results show that the proposed control scheme can accurately position the base attitude and two arms' joint, suppress the flexible vibration of joints and limit the output amplitude of the actual control torques effectively.



2016 
Flores JV, Salton AT, Gomes da Silva JM, Neto NB, Chen Z, 'A discretetime framework for proximate timeoptimal performance of damped servomechanisms', MECHATRONICS, 36 2735 (2016) [C1]



2016 
Jin H, Zhu L, Chen Z, 'TRAJECTORY CONTROL OF SNAKELIKE ROBOTS IN NATURAL OSCILLATION', ASIAN JOURNAL OF CONTROL, 18 19081913 (2016) [C1]



2016 
Zhang HT, Chen Z, Fan MC, 'Collaborative Control of Multivehicle Systems in Diverse Motion Patterns', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 24 14881494 (2016) [C1]



2016 
Mei C, Zhu L, Chen Z, 'Robustness analysis of locomotion controllers for mechanical rectifier systems in natural oscillation', IET CONTROL THEORY AND APPLICATIONS, 10 833837 (2016) [C1]



2016 
Cheng Z, Chen Z, Vicsek T, Chen D, Zhang HT, 'Pattern phase transitions of selfpropelled particles: gases, crystals, liquids, and mills', NEW JOURNAL OF PHYSICS, 18 (2016) [C1]



2015 
Huang T, Chen Z, Zhang HT, Ding H, 'Active control of an active magnetic bearings supported spindle for chatter suppression in milling process', Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME, 137 (2015) [C1]
In machining process, chatter is an unstable dynamic phenomenon which causes overcut and quick tool wear, etc. To avoid chatter, traditional methods aim to optimize machining para... [more]
In machining process, chatter is an unstable dynamic phenomenon which causes overcut and quick tool wear, etc. To avoid chatter, traditional methods aim to optimize machining parameters. But they have inherent disadvantage in gaining highly efficient machining. Active magnetic bearing (AMB) is a promising technology for machining on account of low wear and friction, low maintenance cost, and long operating life. The control currents applied to AMBs allow not only to stabilize the supported spindle but also to actively suppress chatter in milling process. This paper, for the first time, studies an integrated control scheme for stability of milling process with a spindle supported by AMBs. First, to eliminate the vibration of an unloaded spindle rotor during acceleration/deceleration, we present an optimal controller with proper compensation for speed variation. Next, the controller is further enhanced by adding an adaptive algorithm based on Fourier series analysis to actively suppress chatter in milling process. Finally, numerical simulations show that the stability lobe diagram (SLD) boundary can be significantly expanded. Also, a practical issue of constraints on controller output is discussed.



2015 
Chen Z, Iwasaki T, Zhu L, 'Feedback Control for Natural Oscillations of Locomotion Systems Under Continuous Interactions With Environment', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 23 12791291 (2015) [C1]



2015 
Han ZM, Lin ZY, Fu MY, Chen ZY, 'Distributed coordination in multiagent systems: a graph Laplacian perspective', FRONTIERS OF INFORMATION TECHNOLOGY & ELECTRONIC ENGINEERING, 16 429448 (2015) [C1]



2015 
Knorn S, Chen Z, Middleton R, 'Overview: Collective control of multiAgent systems', IEEE Transactions on Control of Network Systems, PP (2015)
© 2015 IEEE. Collective control of a multiAgent system is concerned with designing strategies for a group of autonomous agents operating in a networked environment. The aim is to... [more]
© 2015 IEEE. Collective control of a multiAgent system is concerned with designing strategies for a group of autonomous agents operating in a networked environment. The aim is to achieve a global control objective through distributed sensing, communication, computing, and control. It has attracted many researchers from a wide range of disciplines, including the literature of automatic control. The present paper aims to give a general framework that is able to accommodate many of these outcomes. Within this framework, the development on this topic is systematically reviewed and the representative outcomes can be sorted out from four aspects: (i) agent dynamics, (ii) network topologies, (iii) feedback and communication mechanisms, and (iv) collective behaviors. Thus, the stateofTheArt approach and technology is described. Moreover, within this framework, further interesting and promising directions on this research topic are envisioned.



2015 
Meng HF, Kang Y, Chen Z, Zhao YB, Liu GP, 'Stability analysis and stabilization of a class of cutting systems with chatter suppression', IEEE/ASME Transactions on Mechatronics, 20 991996 (2015) [C1]
In this paper, a new method for stability analysis of a single degree of freedom (SDOF) cutting system with sinusoidal spindle speed variation (SSSV) is proposed. Based on the app... [more]
In this paper, a new method for stability analysis of a single degree of freedom (SDOF) cutting system with sinusoidal spindle speed variation (SSSV) is proposed. Based on the approximately periodic property of the time delay in the turning process and the delay decomposition method, novel criteria of stability analysis for an SDOF cutting system are presented. Moreover, a state feedback controller is designed to stabilize the system and improve the steadystate response. Numerical simulation shows the effectiveness of the method.



2015 
Chen Z, 'A novel adaptive control approach for nonlinearly parameterized systems', International Journal of Adaptive Control and Signal Processing, 29 8198 (2015) [C1]
Nonlinearly parameterized systems are commonly encountered in control of practical systems. However, the conventional adaptive estimation and control strategies, based on the esse... [more]
Nonlinearly parameterized systems are commonly encountered in control of practical systems. However, the conventional adaptive estimation and control strategies, based on the essential assumption of linear parameterization, are incapable of dealing with this class of systems. This incapability in turn becomes a bottleneck for prevalent applications of adaptive control. In literature, there have been some attempts to break through this bottleneck by investigating the characteristics of nonlinearities. However, it is still open for an implementable strategy that is powerful for nonlinearly parameterized systems as the certainty equivalence principle for linearly parameterized systems. This paper aims to contribute an attempt to this open problem by proposing a novel adaptive control approach. On the one hand, the controller is conceptually simple, and it does not explicitly rely on the expression of system nonlinearities. On the other hand, the controller is able to achieve system stability and parameter convergence.



2015 
He J, La HJ, Chen Z, Ge SS, 'Call for submissions: Special issue on consensusbased applications in networked systems', International Journal of Robust and Nonlinear Control, (2015)



2015 
Chen Z, Zhang HT, Chen X, Chen D, Zhou T, 'Twolevel leaderfollower organization in pigeon flocks', EPL, 112 (2015) [C1]
The most attractive trait of collective animal behavior is the emergence of highly ordered structures (Cavagna A., Giardina I. and Ginelli F., Phys. Rev. Lett., 110 (2013) 168107)... [more]
The most attractive trait of collective animal behavior is the emergence of highly ordered structures (Cavagna A., Giardina I. and Ginelli F., Phys. Rev. Lett., 110 (2013) 168107). It has been conjectured that the interaction mechanism in pigeon flock dynamics follows a hierarchical leaderfollower influential network (Nagy M., Ákos Z., Biro D. and Vicsek T., Nature, 464 (2010) 890). In this paper, a new observation is reported that shows that pigeon flocks actually adopt a much simpler twolevel interactive network composed of one leader and some followers. By statistically analyzing the same experimental dataset, we show that for a certain period of time a sole leader determines the motion of the flock while the remaining birds are all followers directly copying the leader's direction with specific time delays. This simple twolevel despotic organization is expected to save both motional energy and communication cost, while retaining agility and robustness of the whole group. From an evolutionary perspective, our results suggest that a twolevel organization of group flight may be more efficient than a multilevel topology for small pigeon flocks.



2015 
He WJ, Zhang HT, Chen Z, Lin JL, Tian K, Shan B, Chen R, 'Temperature Control for NanoScale Films by SpatiallySeparated Atomic Layer Deposition Based on Generalized Predictive Control', IEEE Transactions on Nanotechnology, 14 10941103 (2015) [C1]
This paper established a closedloop temperature control system for a spatiallyseparated atomic layer deposition (SALD) reactor using generalized predictive control (GPC) algori... [more]
This paper established a closedloop temperature control system for a spatiallyseparated atomic layer deposition (SALD) reactor using generalized predictive control (GPC) algorithm. The GPCbased closedloop control system rapidly and precisely stabilized the reactor temperature in the presence of thermal field disturbances. Compared with the proportionintegration differentiation (PID) control commonly used for SALD, the closedloop GPC system attenuated reaction temperature oscillations when producing twoelement nanoscale thin films. Furthermore, the proposed GPC system demonstrated the superiority in multielement nanolaminates depositing efficiency by reducing the settling time with a substrate moving between different reactors. Electrical and optical properties of films verified the feasibility of the proposed GPC system. Finally, experimental results presented that the microstructure of the deposited ALD nanometer thin film was improved with the developed GPC system, compared with the PID strategy.



2015 
Chen ZY, Chen L, 'Singular perturbation augmented robust adaptive PD composite control for flexiblejoint dualarm space robot', Zhendong yu Chongji/Journal of Vibration and Shock, 34 7984 (2015)
To solve the joint movement control problem of a flexiblejoint dualarm space robot system with an uncontrolled base under the effects of external disturbances and unknown load p... [more]
To solve the joint movement control problem of a flexiblejoint dualarm space robot system with an uncontrolled base under the effects of external disturbances and unknown load parameters, a singular perturbation augmented robust adaptive PD composite control method was proposed. On the basis of the underactuated robot dynamic subequations and joint motor dynamic subequations, a singular perturbation correction model of robot system was established by using the flexibility compensating singular perturbation technique. Then, a composite control integrating the fast varying state feedback control and the augmented robust adaptive PD slowly varying control were designed for the flexiblejoint dualarm space robot with unknown upper bound external disturbances and unknown load parameters. The simulation results confirm that the influences of the joint flexibility, unknown external disturbances and unknown load parameters can be eliminated effectively by the presented control method, and the desired joint movement of dualarm space robot can be achieved accurately.



2015 
Chen Z, Huang J, 'Global robust adaptive output regulation for nonlinear systems of relative degree up to two', COMMUNICATIONS IN INFORMATION AND SYSTEMS, 15 1533 (2015)



2015 
He WJ, Zhang HT, Chen Z, Chu B, Cao K, Shan B, Chen R, 'Generalized Predictive Control of Temperature on an Atomic Layer Deposition Reactor', IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, 23 24082415 (2015) [C1]



2015 
Chen Z, Fan MC, Zhang HT, 'How Much Control is Enough for Network Connectivity Preservation and Collision Avoidance?', IEEE Transactions on Cybernetics, 45 16471656 (2015) [C1]
© 2013 IEEE. For a multiagent system in free space, the agents are required to generate sufficiently large cohesive force for network connectivity preservation and sufficiently la... [more]
© 2013 IEEE. For a multiagent system in free space, the agents are required to generate sufficiently large cohesive force for network connectivity preservation and sufficiently large repulsive force for collision avoidance. This paper gives an energy function based approach for estimating the control force in a general setting. In particular, the force estimated for network connectivity preservation and collision avoidance is separated from the force for other collective behavior of the agents. Moreover, the estimation approach is applied in three typical collective control scenarios including swarming, flocking, and flocking without velocity measurement.



2014 
Zhang HT, Chen Z, Vicsek T, Feng G, Sun L, Su R, Zhou T, 'Routedependent switch between hierarchical and egalitarian strategies in pigeon flocks', Scientific Reports, 4 (2014) [C1]
The mechanisms that underlie fascinating interindividual interactions among animal groups have attracted increasing attention from biologists, physicists, and system scientists. ... [more]
The mechanisms that underlie fascinating interindividual interactions among animal groups have attracted increasing attention from biologists, physicists, and system scientists. There are two wellknown types of interaction patterns: hierarchical and egalitarian. In the former type, individuals follow their leaders, whereas they follow their neighbors in the latter. Using highresolution spatiotemporal data derived from the free flights of a flock of pigeons, we show that pigeon flocks actually adopt a mode that switches between the two aforementioned strategies. To determine its flight direction, each pigeon tends to follow the average of its neighbors while moving along a smooth trajectory, whereas it switches to follow its leaders when sudden turns or zigzags occur. By contrast, when deciding how fast to fly, each pigeon synthesizes the average velocity of its neighbors. This switching mechanism is promising for possible industrial applications in multirobot system coordination, unmanned vehicle formation control, and other areas.



2014 
Zhang HT, Chen Z, 'Consensus acceleration in a class of predictive networks', IEEE Transactions on Neural Networks and Learning Systems, 25 19211927 (2014) [C1]
A fastest consensus problem of topology fixed networks has been formulated as an optimal linear iteration problem and efficiently solved in the literature. Considering a kind of p... [more]
A fastest consensus problem of topology fixed networks has been formulated as an optimal linear iteration problem and efficiently solved in the literature. Considering a kind of predictive mechanism, we show that the consensus evolution can be further accelerated while physically maintaining the network topology. The underlying mechanism is that an effective prediction is able to induce a network with a virtually denser topology. With this topology, an even faster consensus is expected to occur. The result is motivated by the predictive mechanism widely existing in natural systems.



2014 
Chen Z, Fujioka H, 'Performance Analysis of Nonlinear SampledData Emulated Controllers', IEEE Transactions on Automatic Control, 59 27782783 (2014) [C1]



2014 
Chen Z, 'Pattern Synchronization of Nonlinear Heterogeneous Multiagent Networks With Jointly Connected Topologies', IEEE Transactions on Control of Network Systems, 1 349359 (2014) [C1]



2014 
Colaneri P, Middleton RH, Chen Z, Caporale D, Blanchini F, 'Convexity of the cost functional in an optimal control problem for a class of positive switched systems', AUTOMATICA, 50 12271234 (2014) [C1]



2014 
Zhu L, Chen Z, 'Robust homogenization and consensus of nonlinear multiagent systems', Systems and Control Letters, 65 5055 (2014) [C1]
In this paper, we consider consensus of a group of heterogeneous agents with nonlinear dynamics in the presence of system uncertainties. It requires that all agent states reach an... [more]
In this paper, we consider consensus of a group of heterogeneous agents with nonlinear dynamics in the presence of system uncertainties. It requires that all agent states reach an agreement which is governed by specified reference dynamics. However, the reference dynamics do not generate a specific reference trajectory for feedback regulation for any agent. For this purpose, the proposed controller integrates two fundamental actions, homogenization and consensus, concurrently. On one hand, it asymptotically regulates each individual (heterogeneous, nonlinear, and uncertain) agent dynamics to the common reference dynamics using a robust homogenization technique; on the other hand, it aligns agent trajectories, asymptotically governed by the common reference dynamics, to consensus through network cooperation. The effectiveness of the controller is verified in the rigorous proof and numerical simulation. © 2014 Elsevier B.V. All rights reserved.



2014 
Zhu L, Chen Z, 'Erratum: Robust homogenization and consensus of nonlinear multiagent systems (Systems and Control Letters (2014) 65 (5055))', Systems and Control Letters, 67 71 (2014)



2014 
Chen Z, Huang J, 'Attitude tracking of rigid spacecraft subject to disturbances of unknown frequencies', INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, 24 22312242 (2014) [C1]



2014 
Chen Z, Zhang HT, Zhang X, Ding H, 'Adaptive Active Chatter Control in Milling Processes', Journal of Dynamic Systems, Measurement, and Control, 136 02100710210077 (2014) [C1]



2014 
Chen Z, Guo Y, Chen L, 'Slidingmode neural network control of flexiblejoint dualarm space robot', Xitong Fangzhen Xuebao / Journal of System Simulation, 26 29502956 (2014)
The slidingmode neural network control problem was discussed for a flexiblejoint dualarm space robot under the influences of parametric uncertainty and external disturbance. Th... [more]
The slidingmode neural network control problem was discussed for a flexiblejoint dualarm space robot under the influences of parametric uncertainty and external disturbance. The elastic deformation of joint was described by the linear torsion spring, in terms of the principle of linear and angular momentum and the Lagrange method, the dynamic model of flexiblejoint dualarm space robot was derived. By using of the singular perturbation approach, two subsystems which can be controlled independently were separated from the system with the joint flexible compensation. To realize the accurately trajectory tracking of endeffectors on the effects of two uncertain factors and suppress the elastic vibration of joints, a hybrid control scheme composed by the slidingmode neural network control of rigid motion and the feedback control of flexible motion was put forward. Simulation results show that the presented scheme has stronger ability to resist disturbance and parametric uncertainty, and can control the system to perform the desired circular motions and suppress the elastic vibration of joints.



2014 
Fan MC, Chen Z, Zhang HT, 'SemiGlobal Consensus of Nonlinear SecondOrder MultiAgent Systems With Measurement Output Feedback', IEEE Transactions on Automatic Control, 59 22222227 (2014) [C1]



2014 
Zhu L, Chen Z, 'Robust homogenization and consensus of nonlinear multiagent systems (vol 65, pg 50, 2014)', SYSTEMS & CONTROL LETTERS, 67 7171 (2014)



2014 
Chen Z, Zhang HT, Fan MC, Wang D, Li D, 'Algorithms and Experiments on Flocking of Multiagents in a Bounded Space', IEEE Transactions on Control Systems Technology, 22 15441549 (2014) [C1]



2014 
Islam MN, Chen Z, 'Natural gaits for multilink mechanical systems', IEEE Transactions on Robotics, 30 765771 (2014) [C1]
Typical animal locomotion is achieved by the rhythmical undulation of its body segments while interacting with its environment. It inspires the mechanical design of multilink loco... [more]
Typical animal locomotion is achieved by the rhythmical undulation of its body segments while interacting with its environment. It inspires the mechanical design of multilink locomotors. With different postures, a multilink system may present different locomotion gaits. Recently, a socalled natural oscillation gait was studied for multilink systems, and a class of biologically inspired controllers was designed for the achievement of the gait. In this paper, the theoretical design is experimentally applied on a mechanical multilink testbed of two posture configurations in rayfishlike flappingwing motion and snakelike serpentine motion. The effectiveness of the design is cross examined by theoretical analysis, numerical simulation, and experiments. © 20042012 IEEE.



2013 
Chen Z, Zhang HT, 'A remark on collective circular motion of heterogeneous multiagents', Automatica, 49 12361241 (2013) [C1]



2013 
Chen Z, Iwasaki T, Zhu L, 'Neural control for coordinated natural oscillation patterns', Systems and Control Letters, 62 693698 (2013) [C1]
We consider linear mechanical systems with asymmetric stiffness matrices. The class of systems captures essential body dynamics of animal/robotic locomotion. In particular, rhythm... [more]
We consider linear mechanical systems with asymmetric stiffness matrices. The class of systems captures essential body dynamics of animal/robotic locomotion. In particular, rhythmic body movements similar to those observed in animals can be found as a properly defined natural oscillation of the linear system. The objective is to design a nonlinear feedback controller that achieves the natural oscillation as a stable limit cycle for the closedloop system. The controller structure we employ is inspired by neuronal circuits for animal locomotion. We translate the design requirement into a multivariable harmonic balance condition, and provide characterizations of neural controllers satisfying the condition. © 2013 Elsevier B.V. All rights reserved.



2013 
Zhang HT, Chen Z, Yan L, Yu W, 'Applications of collective circular motion control to multirobot systems', IEEE Transactions on Control Systems Technology, 21 14161422 (2013) [C1]
Collective circular motion is common in both natural systems and engineering applications. Recent theoretical research has intensively studied the fundamental control mechanism. T... [more]
Collective circular motion is common in both natural systems and engineering applications. Recent theoretical research has intensively studied the fundamental control mechanism. This brief aims to pave the way from theoretical design to practical implementation by addressing a set of issues encountered in real applications. As a result, a practically effective control algorithm is successfully implemented and examined for a multirobot system to achieve a desired circular formation. © 19932012 IEEE.



2013 
Zhu L, Chen Z, Iwasaki T, 'Oscillation, orientation, and locomotion of underactuated multilink mechanical systems', IEEE Transactions on Control Systems Technology, 21 15371548 (2013) [C1]



2013 
Peng Z, Wang D, Chen Z, Hu X, Lan W, 'Adaptive dynamic surface control for formations of autonomous surface vehicles with uncertain dynamics', IEEE Transactions on Control Systems Technology, 21 513520 (2013) [C1]



2013 
Chen ZY, Chen L, 'Augmented adaptive control and joint vibration suppression for flexiblejoint space robot with flexibility compensation', Yuhang Xuebao/Journal of Astronautics, 34 15991604 (2013)
The problems of joint motion control and flexible vibration suppression of a flexible joint spacebased robot for manipulating an unknown payload are studied. Based on the system ... [more]
The problems of joint motion control and flexible vibration suppression of a flexible joint spacebased robot for manipulating an unknown payload are studied. Based on the system linear momentum conservation and the Lagrange method, the underactuated dynamics model of the space robot is established. For convenience of the design of its control system, the system is divided into both fast and slow subsystems by using the joint flexibility compensation technique and the singular perturbation theory. A torque differential feedback controller is proposed for the fast subsystem to suppress the joints' flexible vibration, meanwhile an adaptive control scheme based on the augmentation approach is designed for the slow subsystem to realize the joint trajectory asymptotic tracking under the condition of unknown payload parameters. Because of introduction of the flexibility compensation technique, the presented control scheme can equivalently increase the joint stiffness, and it is suitable to control the space robot systems with low joint stiffness. Moreover, the effect of unknown parameters is realtime compensated by its adaptive controller, and then the specified joint motion task is achieved precisely. The effectiveness of the scheme is verified by the corresponding simulation results.



2013 
Chen ZY, Chen L, 'Adaptive backstepping control of flexiblejoint space robot based on neural network', Gongcheng Lixue/Engineering Mechanics, 30 397401 (2013)
The design problem of a joint motion controller for a flexiblejoint space robot with an uncontrolled base is discussed. With the linear and angular momentum conservation of the s... [more]
The design problem of a joint motion controller for a flexiblejoint space robot with an uncontrolled base is discussed. With the linear and angular momentum conservation of the system and a Lagrangian method, the dynamic model of a space robot is established. To realize the control target of joint motion, an adaptive backstepping control scheme for a flexiblejoint space robot is proposed via the function approximation technique of neural network. The presented control scheme need not know the information of system parameters, and avoids the measurements and feedback of the positionrelated variables of the base. Thusly, it is more suitable for practical applications. Numerical simulation results show that the control scheme proposed can obtain the smaller vibration of flexible joints and effectively control the space robot system to accomplish the desired joint motion.



2013 
Chen Z, Zhang HT, 'Analysis of Joint Connectivity Condition for Multiagents With Boundary Constraints', IEEE Transactions on Cybernetics, 43 437444 (2013) [C1]



2012 
Islam MN, Chen Z, 'Natural oscillation control of prototype mechanical rectifiers', IEEE Transactions on Control Systems Technology, 20 15591566 (2012) [C1]



2012 
Salton AT, Chen Z, Fu M, 'Improved control design methods for proximate timeoptimal servomechanisms', IEEEASME Transactions on Mechatronics, 17 10491058 (2012) [C1]



2012 
Chen ZY, Chen L, 'Adaptive variable structure control for flexible space manipulator based on hybrid sliding mode concept', Gongcheng Lixue/Engineering Mechanics, 29 216221 (2012)
The coordinated motion control and flexible vibration suppression problems of flexible space manipulator are studied. With the assumed mode method and the linear momentum conserva... [more]
The coordinated motion control and flexible vibration suppression problems of flexible space manipulator are studied. With the assumed mode method and the linear momentum conservation of the system, the system dynamics model of the space manipulator is derived. Based on the hybrid sliding mode concept, an adaptive variable structure control scheme is proposed for the flexible space manipulator to achieve the coordinated motion between the base's attitude and the arm's joints, which accounts for the uncertainty in inertial parameters. The hybrid sliding mode introduced consists of two parts, the frequency shaped optimal sliding mode and the terminal sliding mode. The former is used to suppress the vibration of flexible link of the system, and the latter is utilized to guarantee the convergence of system tracking errors in finite time. Moreover, the control scheme proposed does not require the foreknowledge of flexible variables in control. Thus, it can effectively avoid the realtime measurements and feedbacks of system flexible variables, and be more suitable for practical applications. Simulation results demonstrate the effectiveness of the proposed control scheme.



2012 
Chen ZY, Chen L, 'Robust control of flexiblejoint space robot via flexibility compensation', Gongcheng Lixue/Engineering Mechanics, 29 5357 (2012)
The robust control problem of a freefloating flexiblejoint space robot with an uncontrolled base to track the desired trajectory in workspace is discussed. With the system linea... [more]
The robust control problem of a freefloating flexiblejoint space robot with an uncontrolled base to track the desired trajectory in workspace is discussed. With the system linear and angular momentum conservation and Lagrangian method, the dynamic equations are derived. In the consideration of the strong joint flexibility of a space robot, a joint flexibility compensation controller is designed to compensate the effects of the joint flexibility to the system control precision. Then by using of the singular perturbation technology, a robust control scheme for the robot system with uncertain inertial parameters to track the desired trajectory in workspace is presented. A planar space robot system with flexible joints is simulated to verify the effectiveness of the proposed control method.



2011 
Chen Z, Zhang HT, 'Nobeacon collective circular motion of jointly connected multiagents', Automatica, 47 19291937 (2011) [C1]



2011 
Zhang HT, Zhai C, Chen Z, 'A general alignment repulsion algorithm for flocking of multiagent systems', IEEE Transactions on Automatic Control, 56 430435 (2011) [C1]



2011 
Liu L, Chen Z, Huang J, 'Global disturbance rejection of lower triangular systems with an unknown linear exosystem', IEEE Transactions on Automatic Control, 56 16901695 (2011) [C1]



2011 
Salton AT, Chen Z, Zheng J, Fu M, 'Preview control of dualstage actuator systems for superfast transition time', IEEE/ASME Transactions on Mechatronics, 16 758763 (2011) [C2]



2011 
Chen Z, Chen L, 'Study on dynamics modeling and singular perturbation control of freefloating space robot with flexible joints', Zhongguo Jixie Gongcheng/China Mechanical Engineering, 22 21512155 (2011)
The dynamic modeling and singular perturbation control problems of freefloating space robot with normal flexible joints and an uncontrolled base were discussed. With the relation... [more]
The dynamic modeling and singular perturbation control problems of freefloating space robot with normal flexible joints and an uncontrolled base were discussed. With the relationship of the system linear and angular momentum conservation, a system dynamics model was established by Lagrangian formulation. To eliminate the limitation of joint flexibility for applications of the traditional singular perturbation control technique in space robot with normal flexible joints, a joint flexibility compensator was introduced, which can level down the equivalent joint flexibility of the system. And then with the help of singular perturbation theory, the singular perturbation control schemes for freefloating space robot with flexible joints to track the desired trajectory in joint space and inertial space were designed successively. The control schemes presented are more suitable for the control of space robot systems with normal flexible joints, because of no joint flexibility limitation. Theoretical analysis and simulation results verify the feasibility of the proposed control schemes.



2011 
Chen ZY, Chen L, 'Augmented adaptive neural network compensation control of spacebased robot', Xitong Fangzhen Xuebao / Journal of System Simulation, 23 27502755 (2011)
The compensation control problems of spacebased robot system with external disturbances were studied. The dynamic equations of the system were given firstly. Then, with the augme... [more]
The compensation control problems of spacebased robot system with external disturbances were studied. The dynamic equations of the system were given firstly. Then, with the augmentation approach, the augmented adaptive neural network compensation control schemes were developed for spacebased robot with unknown inertial parameters and external disturbances to track the desired trajectories in joint space and in inertial space, respectively. The control schemes proposed don't require the measurements and feedback of the position, linear velocity and acceleration of the base. Besides, compared with traditional adaptive control schemes, they can avoid linearly parameterizing the dynamic equations of the system and subsequently reduce tedious computations during the determination of the regression matrix for the system. The simulation results validate the presented control schemes.



2010 
Chen Z, 'On observability of nonlinear steadystate generators', Automatica, 46 17121718 (2010) [C1]



2010 
Chen ZY, Chen L, 'Robustadaptive combined control for dualarm space robot with external disturbances and uncertain parameters', Gongcheng Lixue/Engineering Mechanics, 27 2733 (2010)
The control problem of freefloating space robot system with dualarm is studied. The dynamic equations of the system are formulated by the underactuated form to guarantee that t... [more]
The control problem of freefloating space robot system with dualarm is studied. The dynamic equations of the system are formulated by the underactuated form to guarantee that they can be linearly parameterized. With the augmentation approach, the dynamics of the system is analyzed and the augmented generalized Jacobi matrix of the system can also be linearly dependent on a group of inertial parameters. Based on the results, a robustadaptive combined control scheme is developed for dualarm space robot system with external disturbances and uncertain payload parameters to track the desired trajectories in inertial space. Comparing with the adaptive control, the control scheme proposed can effectively reduce the calculation time, because it can transfer many integral operations into four arithmetic operations. Therefore, it is suitable for realtime and online applications in spacebased robot system. The simulation results verify the proposed control scheme.



2010 
Chen Z, Chen L, 'Online selflearning compensation control for dualarm space robot with external disturbances via neural network', Zhongguo Jixie Gongcheng/China Mechanical Engineering, 21 21142118 (2010)
The compensation control problems of coordinated motion between the base's attitude and two endeffector of a freefloating dualarm space robot with unknown external disturb... [more]
The compensation control problems of coordinated motion between the base's attitude and two endeffector of a freefloating dualarm space robot with unknown external disturbances to track the desired trajectories were discussed. With the linear momentum conservation of the system, the kinematics and dynamics of the system were analyzed, and then the dynamics equations of the system described in workspace were derived. Based on the results, a neural network online selflearning compensation control scheme for coordinated motion of the freefloating dualarm space robot with unknown external disturbances was designed. The control scheme proposed can avoid the measurements of the positionrelated variables of the base, and effectively enhance the robustness and adaptive ability of the system because of the good online selflearning compensation of the neural network for external disturbances. Simulation results validate the feasibility of the presented control scheme.



2010 
Chen Z, Chen L, 'Fuzzy terminal sliding mode control of vibration suppression of flexible space manipulator', Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis, 30 481486 (2010)
A scheme of fuzzy terminal sliding mode control was proposed for vibration suppression of a flexible space manipulator base position of which was not controlled. The dynamical equ... [more]
A scheme of fuzzy terminal sliding mode control was proposed for vibration suppression of a flexible space manipulator base position of which was not controlled. The dynamical equation of the flexible space manipulator was derived by using the assumed mode method, linear momentum conservation of the system and the Lagrange method. To solve the problems of trajectory tracking control and vibration suppression of the flexible space manipulator, the singular perturbation approach was adopted to decompose the manipulator system into a slow subsystem and a fast subsystem. And then, the controller could be designed separately for the subsystems. A fuzzy terminal sliding mode control scheme was designed to control the slow subsystem and the linear quadratic regulator (LQR) based on the reduced order observer was proposed for the fast subsystem. A simulation example of flexible space manipulator demonstrates that the control scheme not only guarantees that the tracking errors of the base's attitudes and arm's joints of the system converge to zero in finite time, but also weakens the chattering of the sliding mode controller and the vibration of the flexible arm effectively.



2010 
Zhang HT, Chen MZQ, Chen Z, 'Nonlinear laguerrevolterra observercontroller and its application to process control', International Journal of Robust and Nonlinear Control, 20 412423 (2010) [C1]



2009 
Guo HF, Chen ZY, Yu CW, '3D numerical simulation of compressible swirling flow induced by means of tangential inlets', International Journal for Numerical Methods in Fluids, 59 12851298 (2009)
The objective of the present work is to predict compressible swirl flow in the nozzle of airjet spinning using the realizable ke turbulence model and discuss the effect of the n... [more]
The objective of the present work is to predict compressible swirl flow in the nozzle of airjet spinning using the realizable ke turbulence model and discuss the effect of the nozzle pressure. The periodic change of flow patterns can be observed. The recirculation zone near the wall of the injectors upstream increases in size and moves gradually upstream, whereas the vortex breakdown in the injector downstream shifts slowly towards the nozzle outlet during the whole period. A low axial velocity in the core region moves gradually away from the centerline, and the magnitude of the center reverse flow and the area occupied by it increase with axial distance due to the vortex breakdown. From the tangential velocity profile, there is a very small freevortex zone. With increasing nozzle pressure, the velocity increases and the location of vortex breakdown is moved slightly downward. However, the increase in the velocity tends to decline at nozzle pressure up to a high level. Copyright © 2008 John Wiley & Sons, Ltd.



2009 
Liu L, Chen Z, Huang J, 'Parameter convergence and minimal internal model with an adaptive output regulation problem', Automatica, 45 13061311 (2009) [C1]



2009 
Chen Z, 'Global stabilization of nonlinear cascaded systems with a Lyapunov function in superposition form', Automatica, 45 20412045 (2009) [C1]



2009 
Chen Z, Huang J, 'Attitude tracking and disturbance rejection of rigid spacecraft by adaptive control', IEEE Transactions on Automatic Control, 54 600605 (2009) [C1]



2009 
Chen Z, 'A remark on sensor disturbance rejection of nonlinear systems', IEEE Transactions on Automatic Control, 54 22062210 (2009) [C1]



2009 
Chen Z, Iwasaki T, 'Matrix perturbation analysis for weakly coupled oscillators', Systems and Control Letters, 58 148154 (2009) [C1]



2008 
Chen Z, Huang J, 'A Lyapunov's direct method for the global robust stabilization of nonlinear cascaded systems', Automatica, 44 745752 (2008) [C1]



2008 
Chen Z, Iwasaki T, 'Circulant synthesis of central pattern generators with application to control of rectifier systems', IEEE Transactions on Automatic Control, 53 273286 (2008) [C1]



2008 
Chen Z, Zheng M, Friesen WO, Iwasaki T, 'Multivariable harmonic balance analysis of the neuronal oscillator for leech swimming', Journal of Computational Neuroscience, 25 583606 (2008) [C1]



2007 
Chen Z, Huang J, 'Global robust servomechanism of a class of nonlinear systems using output feedback', Asian Journal of Control, 9 292305 (2007) [C1]



2006 
Xiao C, Chen Z, Liu L, He Y, 'Ordovician Cephalopod Biofacies of South China and Its Provincialization', Journal of China University of Geosciences, 17 221230 (2006)
The research on biofacies and its provincialization is of important significance not only for the increasing of precision of stratigraphic subdivision and correlation in South Chi... [more]
The research on biofacies and its provincialization is of important significance not only for the increasing of precision of stratigraphic subdivision and correlation in South China, the reconstruction of ancient environment and paleogeography and even the guiding of oil and gas exploration, but also for the study of paleobiogeogrphy and sea level changes of southern China in Ordovician. On the basis of the studies of the ecological characteristics of Ordovician cephalopods from South China, eighteen cephalopod biofacies are recognized and described: (1) Open platform Proterocameroceras biofacies; (2) Restricted platform PseudoectenolitesXiadongoceras biofacies; (3) Open platform RetroclitendocerasPararetroclitendoceras biofacies; (4) Open platform PronajacerasMamagouceras biofacies; (5) Shelf slopebasin Cyclostomiceras biofacies; (6) Open platform CamerocerasCyrtovaginoceras biofacies; (7) Open platform CoreanocerasManchuroceras biofacies; (8) Shelf slopebasin KaipingocerasKyminoceras biofacies; (9) Inner shelf BathmocerasProtocycloceras biofacies; (10) Middle shelf DiderocerasAncistroceras biofacies; (11) Deepwater shelf LituitesCyclolituites biofacies; (12) Stagnant basin LituitetTrilacinoceras biofacies; (13) Deepwater basin ParaendocerasSactorthoceras biofacies; (14) Deepwater shelf SinocerasMichelinocerasDisoceras biofacies; (15) Deepwater shelf BeloitocerasJiangshanoceras biofacies; (16) Deepwater shelfbasin Eurasiaticoceras biofacies; (17) Shelfslope JiangxicerasYushanoceras biofacies; (18) Deepwater basin Michelinoceras biofacies. The cephalopods of these biofacies, their ecological characteristics, and living conditions are elucidated in this article. The association law of cephalopod biofacies in time and space shows that there were three cephalopod biofacies provinces in South China during the Ordovician, i. e., Yangtze biofacies province, East Guizhou ({A figure is presented})West Hunan ({A figure is presented}) biofacies province (mixedtype biofacies province), and Central HunanWest Zhejiang ({A figure is presented}) biofacies province. It is suggested that differentiation of cephalopod biofacies was mainly controlled by sea level changes and tectonic evolution. The differentiation is obvious during lower sea level and not developed during high sea level. © 2006 China University of Geosciences.



2005 
Chen ZY, Huang H, 'A simplified small gain theorem for timevarying nonlinear systems', IEEE TRANSACTIONS ON AUTOMATIC CONTROL, 50 19041908 (2005) [C1]



2005 
Chen Z, Huang J, 'Global robust output regulation for output feedback systems', IEEE Transactions on Automatic Control, 50 117121 (2005) [C1]
The global robust output regulation problem for the class of nonlinear systems in output feedback form has been studied under the assumption that the solution of the regulator equ... [more]
The global robust output regulation problem for the class of nonlinear systems in output feedback form has been studied under the assumption that the solution of the regulator equations is polynomial. This assumption essentially requires these systems contain only polynomial nonlinearity and is due to the failure of finding a nonlinear internal model to account for more complex nonlinearities than polynomials. Recently, it was found that a nonlinear internal model can be constructed under some assumption much milder than the polynomial assumption. In this note, we will apply this type of internal model to solve the global robust output regulation problem for the class of nonlinear systems in output feedback form. © 2005 IEEE.



2005 
Chen Z, Zhao R, Shangguan D, Liu G, 'Preparation and evaluation of uniformsized molecularly imprinted polymer beads used for the separation of sulfamethazine', Biomedical Chromatography, 19 533538 (2005)
Uniformsized molecularly imprinted polymer (MIP) beads were prepared using a onestep swelling and polymerization method. The obtained sulfamethazine (SMZ)imprinted polymer show... [more]
Uniformsized molecularly imprinted polymer (MIP) beads were prepared using a onestep swelling and polymerization method. The obtained sulfamethazine (SMZ)imprinted polymer showed high affinity and selectivity toward SMZ and other structurally related sulfonamides in acetonitrile or wateracetonitrile mobile phases, particularly in high aqueous systems. The column performance of the MIPs for SMZ and its analogues could be improved by elevating the column temperature and optimizing the flow rate. The hydrogenbonding effect plays a significant role in the recognition process of SMZimprinted polymer systems in organic media, while the ionexchange effect, as well as hydrophobic effect, dominantes the retention mechanism in aqueousrich media, in addition to shape recognition. Copyright © 2005 John Wiley & Sons, Ltd.



2005 
Chen Z, Huang J, 'Robust output regulation with nonlinear exosystems', Automatica, 41 14471454 (2005) [C1]
For over a decade, the solvability of the nonlinear robust output regulation problem relies on the assumption that the exosystem is linear and neutrally stable. Thus, the only exo... [more]
For over a decade, the solvability of the nonlinear robust output regulation problem relies on the assumption that the exosystem is linear and neutrally stable. Thus, the only exogenous signal that can be accommodated by the existing theory is a combination of finitely many step functions and sinusoidal functions. In this paper, we will show that it is possible to find controllers that can admit exogenous signals produced by nonlinear exosystems. An example with the well known van der Pol oscillator as the exosystem is given to illustrate our approach. © 2005 Elsevier Ltd. All rights reserved.



2005 
Chen Z, Huang J, 'A general formulation and solvability of the global robust output regulation problem', IEEE Transactions on Automatic Control, 50 448462 (2005) [C1]
While the output regulation problem for linear systems accommodates both bounded and unbounded exogenous signals, the existing formulation of the output regulation problem for non... [more]
While the output regulation problem for linear systems accommodates both bounded and unbounded exogenous signals, the existing formulation of the output regulation problem for nonlinear systems only allows bounded exogenous signals produced by an exosystem with a neutrally stable equilibrium. In particular, when it comes to the robust output regulation problem, the only admissible exogenous signal is a finite combination of step and sinusoidal functions. In this paper, we give a general formulation of the robust output regulation problem that admits unbounded exogenous signals, and contains the previous formulations as special cases when the system is linear or when the exogenous signals are bounded. Then, we give conditions under which the problem can be solved by solving a robust stabilization problem of an augmented system. Finally, we apply our general result to obtain the solvability conditions of the general robust output regulation problem for the class of lower triangular nonlinear systems. © 2005 IEEE.



2005 
Lan W, Chen Z, Huang J, 'Semiglobal robust output regulation for nonlinear systems in normal form using output feedback', Communications in Information and Systems, 5 385400 (2005) [C1] 


2004 
Huang J, Chen Z, 'A general framework for tackling the output regulation problem', IEEE Transactions on Automatic Control, 49 22032218 (2004) [C1]
Output regulation aims to achieve, in addition to closedloop stability, asymptotic tracking and disturbance rejection for a class of reference inputs and disturbances. Thus, it p... [more]
Output regulation aims to achieve, in addition to closedloop stability, asymptotic tracking and disturbance rejection for a class of reference inputs and disturbances. Thus, it poses a more challenging problem than stabilization. For over a decade, the nonlinear output regulation problem has been one of the focuses in nonlinear control research, and active research on this problem has generated many fruitful results. Nevertheless, there are two hurdles that impede the further progress of the research on the output regulation problem. The first one is the assumption that the solution or the partial solution of the regulator equations is polynomial. The second one is the lack of a systematic mechanism to handle the global robust output regulation problem. In this paper, we establish a general framework that systematically converts the robust output regulation problem for a general nonlinear system into a robust stabilization problem for an appropriately augmented system. This general framework, on one hand, relaxes the polynomial assumption, and on the other hand, offers a greater flexibility to incorporate recent new stabilization techniques, thus setting a stage for systematically tackling the robust output regulation with global stability. © 2004 IEEE.



2004 
Chen Z, Huang J, 'Dissipativity, stabilization, and regulation of cascadeconnected systems', IEEE Transactions on Automatic Control, 49 635650 (2004) [C1]
This paper presents a technical framework utilizing the dissipativity mechanism that gives rise to the solution of the global regulation problem of the cascadeconnected systems s... [more]
This paper presents a technical framework utilizing the dissipativity mechanism that gives rise to the solution of the global regulation problem of the cascadeconnected systems subject to both dynamic uncertainty and static uncertainty without knowing the bound of the static uncertainty. Additionally, this paper shows that the nonlinear robust servomechanism problem for the lower triangular systems can be cast into the regulation problem for the cascadeconnected systems, thus leading to a complete solution of the nonlinear robust servomechanism problem for the lower triangular systems for the most general case where both the uncertain parameters and the exogenous signals can be arbitrarily large.



2004 
Chen Z, Huang J, 'Global robust servomechanism problem of lower triangular systems in the general case', Systems and Control Letters, 52 209220 (2004) [C1]
The global robust servomechanism problem (alternatively, global robust output regulation problem) for lower triangular systems has been studied for two special cases. The first ca... [more]
The global robust servomechanism problem (alternatively, global robust output regulation problem) for lower triangular systems has been studied for two special cases. The first case assumes that the systems only contain polynomial nonlinearities, and the second case limits the exogenous signals and the unknown parameters to be within a known bounded set. This paper presents the solvability conditions of the global robust servomechanism problem for the lower triangular systems for the most general case where neither of the above two assumptions is needed. Our approach consists of two steps. In the first step, we convert the problem into a global adaptive regulation problem for lower triangular systems subject to both dynamic and static uncertainties. In the second step, we derive the solvability conditions of the problem by appealing to the recent result on the solvability of the global adaptive regulation problem for lower triangular systems with both dynamic and static uncertainties. © 2003 Elsevier B.V. All rights reserved.



2002 
Chen Z, Huang J, 'Solution of output regulation of singular nonlinear systems by normal output feedback', IEEE Transactions on Automatic Control, 47 803813 (2002) [C1] 


2002 
Chen Z, Huang J, 'Solution of output regulation of singular nonlinear systems by normal output feedback', IEEE Transactions on Automatic Control, 47 808813 (2002)
The output regulation problem of singular nonlinear systems via the normal output feedback control has been a challenging problem. Existing approaches for solving this problem emp... [more]
The output regulation problem of singular nonlinear systems via the normal output feedback control has been a challenging problem. Existing approaches for solving this problem employed techniques similar to those used for linear singular systems. Results from these approaches either rely on a normalizability assumption or are limited to systems with special structures. This note gives a complete solution for this problem by employing a novel approach that is also interesting for linear systems.



2002 
Chen Z, Huang J, 'Global robust stabilization of cascaded polynomial systems', Systems and Control Letters, 47 445453 (2002) [C1]
Global robust stabilization of nonlinear cascaded systems is a challenging problem when the zerodynamics is not exponentially stable. Recently, some recursive procedure has been ... [more]
Global robust stabilization of nonlinear cascaded systems is a challenging problem when the zerodynamics is not exponentially stable. Recently, some recursive procedure has been developed for handling this problem utilizing the small gain theorem. However, the success of the procedure depends on the satisfaction of some conditions which arise at each step of the recursion. In this paper, we will show that, for the important class of cascaded polynomial systems, the solvability conditions can be made satisfied by appropriately implementing the recursive procedure. This result leads to an explicit construction of the control law. © 2002 Elsevier Science B.V. All rights reserved.



2001 
Chen Z, Huang J, 'Robust output regulation of singular nonlinear systems', Communications in Information & Systems, 1 381394 (2001) [C1] 

