2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2020
The problem of a networked uncertain Euler-Lagrange systems (followers) to track a virtual dynami... more The problem of a networked uncertain Euler-Lagrange systems (followers) to track a virtual dynamic leader under asymmetric time-varying communication delays is studied in this paper. It is assumed that the network is a directed spanning tree with the virtual leader as the root. Due to highly nonlinear of Euler-Lagrange systems and communication delays, it is challenging to design a control algorithm for followers to track the moving leader. To cope with the problems, we proposed a distributed cascade control framework which decouples an estimate of the leader velocity in the task space and an adaptive controller in the generalized space. It is verified that the network asymptotically achieves task-space consensus. Simulation results of networked Omni-directional mobile robots are provided to demonstrate the efficacy of the proposed control algorithm.
In this paper, we propose a distributed control algorithm for an operator to remotely interact wi... more In this paper, we propose a distributed control algorithm for an operator to remotely interact with a network of multiple robotic systems to exploit the advantage of complementary capabilities of humans and networked robots. A controller that combines adaptive neural network, task-space synchronization, and robust control algorithm, is proposed to account for several practical issues such as uncertain dynamic model, disturbance, and time delays communication. On the basis of Lyapunov technique, the system stability and boundedness of tracking errors are proven. Semi-experiments with a network of heterogeneous robotic systems are carried to verify and demonstrate the efficacy/potency of the proposed control framework.
IEEE Transactions on Control of Network Systems, 2021
In this article, we study the problems of event-based communication and actuation algorithms to m... more In this article, we study the problems of event-based communication and actuation algorithms to mitigate unnecessary network burden and energy consumption, hence increasing the number and work time of robots/agents in a network of multiagent systems. By considering the general dynamic model of networked Euler–Lagrange systems and utilizing the adaptive control algorithm, we propose the following two event-triggered schemes: first, an event-based communication and, second, an event-based controller for a large number of agents to achieve consensus in the task space. Consider that the network connection is a directed spanning tree and the time-varying communication delays are bounded. Theoretical analyses of the proposed control algorithms for both leaderless and leader–follower (static leader) consensus are studied by employing the Lyapunov technique and function analysis. It revealed that the network achieved global stability and asymptotical convergence with avoidance of Zeno behavior. We experimented with a system of four robotic manipulators and performed numerical simulations for a networked mobile manipulator to demonstrate the efficiency and efficacy of the proposed consensus algorithms.
This article proposes a distributed control method for networked manipulators to cooperatively tr... more This article proposes a distributed control method for networked manipulators to cooperatively transport an unmodeled object without force measurement. First, we design an adaptive neural network control algorithm, based on the wavelet neural network, to estimate unknown system dynamics. A novel task-space synchronization control is studied with triggering condition for the network under time-varying communication delays, to improve the cooperative quality while reducing the network burden. The proposed control method ensures uniform ultimate boundedness of velocity/position tracking errors and boundedness of the internal force with the avoidance of Zeno behavior. Moreover, the robustness of networked uncertain manipulators is guaranteed. Finally, a numerical simulation and experiments are carried to demonstrate the performance and efficiency of the proposed control algorithm.
2018 International Automatic Control Conference (CACS), 2018
The use of multiple mobile manipulators (MMs) to perform collaborative object transportation is a... more The use of multiple mobile manipulators (MMs) to perform collaborative object transportation is a promising solution for future industry. However, most existing control laws in this field require sensors to measure interactive force-torque between the transported object and the end-effectors of the robots, which is costly and increasing the system complexity. To overcome this problem, the present study considers the interactive force/torque to be unknown nonlinear functions and estimates them using a wavelet neural network (WNN). In particular, an adaptive-wavelet neural network control law is designed to guarantee trajectory tracking for each robot. Then an output synchronization algorithm is additionally used to coordinate the movement of the network MMs. Stability of the proposed control law is proven theoretically using Lyapunov theorem. Furthermore, the effectiveness of the control law is illustrated by simulations.
2020 59th IEEE Conference on Decision and Control (CDC)
This paper addresses an actuator-fault-tolerant controller for task-space consensus of networked ... more This paper addresses an actuator-fault-tolerant controller for task-space consensus of networked Euler- Lagrange systems under time-varying communication delay and switching topology. To account for the discontinuous signals causing by changing topology, we proposed a taskspace reference acceleration based on the signals interchanged intermittently between agents. The velocity reference, obtaining accordingly, is utilized to design a control law for distributed task-space consensus when the actuators are subject to partial- loss-of-effectiveness. Moreover, the consensus control for Euler- Lagrange systems with actuator saturation fault mode is also studied. The stability and convergence of consensus for the networked Euler-Lagrange systems with actuator faults are addressed by the Lyapunov theory and function analysis technique. Numerical examples verify the proposed control schemes’ effectiveness and performance with a network of 2- DOF manipulators.
2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2020
The problem of a networked uncertain Euler-Lagrange systems (followers) to track a virtual dynami... more The problem of a networked uncertain Euler-Lagrange systems (followers) to track a virtual dynamic leader under asymmetric time-varying communication delays is studied in this paper. It is assumed that the network is a directed spanning tree with the virtual leader as the root. Due to highly nonlinear of Euler-Lagrange systems and communication delays, it is challenging to design a control algorithm for followers to track the moving leader. To cope with the problems, we proposed a distributed cascade control framework which decouples an estimate of the leader velocity in the task space and an adaptive controller in the generalized space. It is verified that the network asymptotically achieves task-space consensus. Simulation results of networked Omni-directional mobile robots are provided to demonstrate the efficacy of the proposed control algorithm.
In this paper, we propose a distributed control algorithm for an operator to remotely interact wi... more In this paper, we propose a distributed control algorithm for an operator to remotely interact with a network of multiple robotic systems to exploit the advantage of complementary capabilities of humans and networked robots. A controller that combines adaptive neural network, task-space synchronization, and robust control algorithm, is proposed to account for several practical issues such as uncertain dynamic model, disturbance, and time delays communication. On the basis of Lyapunov technique, the system stability and boundedness of tracking errors are proven. Semi-experiments with a network of heterogeneous robotic systems are carried to verify and demonstrate the efficacy/potency of the proposed control framework.
IEEE Transactions on Control of Network Systems, 2021
In this article, we study the problems of event-based communication and actuation algorithms to m... more In this article, we study the problems of event-based communication and actuation algorithms to mitigate unnecessary network burden and energy consumption, hence increasing the number and work time of robots/agents in a network of multiagent systems. By considering the general dynamic model of networked Euler–Lagrange systems and utilizing the adaptive control algorithm, we propose the following two event-triggered schemes: first, an event-based communication and, second, an event-based controller for a large number of agents to achieve consensus in the task space. Consider that the network connection is a directed spanning tree and the time-varying communication delays are bounded. Theoretical analyses of the proposed control algorithms for both leaderless and leader–follower (static leader) consensus are studied by employing the Lyapunov technique and function analysis. It revealed that the network achieved global stability and asymptotical convergence with avoidance of Zeno behavior. We experimented with a system of four robotic manipulators and performed numerical simulations for a networked mobile manipulator to demonstrate the efficiency and efficacy of the proposed consensus algorithms.
This article proposes a distributed control method for networked manipulators to cooperatively tr... more This article proposes a distributed control method for networked manipulators to cooperatively transport an unmodeled object without force measurement. First, we design an adaptive neural network control algorithm, based on the wavelet neural network, to estimate unknown system dynamics. A novel task-space synchronization control is studied with triggering condition for the network under time-varying communication delays, to improve the cooperative quality while reducing the network burden. The proposed control method ensures uniform ultimate boundedness of velocity/position tracking errors and boundedness of the internal force with the avoidance of Zeno behavior. Moreover, the robustness of networked uncertain manipulators is guaranteed. Finally, a numerical simulation and experiments are carried to demonstrate the performance and efficiency of the proposed control algorithm.
2018 International Automatic Control Conference (CACS), 2018
The use of multiple mobile manipulators (MMs) to perform collaborative object transportation is a... more The use of multiple mobile manipulators (MMs) to perform collaborative object transportation is a promising solution for future industry. However, most existing control laws in this field require sensors to measure interactive force-torque between the transported object and the end-effectors of the robots, which is costly and increasing the system complexity. To overcome this problem, the present study considers the interactive force/torque to be unknown nonlinear functions and estimates them using a wavelet neural network (WNN). In particular, an adaptive-wavelet neural network control law is designed to guarantee trajectory tracking for each robot. Then an output synchronization algorithm is additionally used to coordinate the movement of the network MMs. Stability of the proposed control law is proven theoretically using Lyapunov theorem. Furthermore, the effectiveness of the control law is illustrated by simulations.
2020 59th IEEE Conference on Decision and Control (CDC)
This paper addresses an actuator-fault-tolerant controller for task-space consensus of networked ... more This paper addresses an actuator-fault-tolerant controller for task-space consensus of networked Euler- Lagrange systems under time-varying communication delay and switching topology. To account for the discontinuous signals causing by changing topology, we proposed a taskspace reference acceleration based on the signals interchanged intermittently between agents. The velocity reference, obtaining accordingly, is utilized to design a control law for distributed task-space consensus when the actuators are subject to partial- loss-of-effectiveness. Moreover, the consensus control for Euler- Lagrange systems with actuator saturation fault mode is also studied. The stability and convergence of consensus for the networked Euler-Lagrange systems with actuator faults are addressed by the Lyapunov theory and function analysis technique. Numerical examples verify the proposed control schemes’ effectiveness and performance with a network of 2- DOF manipulators.
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