Transactions of the Institute of Measurement and Control

doi: 10.1177/0142331219828273pmid: N/A

Deng, Xiongfeng; Sun, Xiuxia; Liu, Shuguang

doi: 10.1177/0142331218799144pmid: N/A

In this paper, the tracking control problem of nonlinear multi-agent systems with time-varying delays and directed topology is discussed. Each agent of the system is influenced by time-delayed nonlinear terms and disturbances. It is supposed that the global Lipschitz condition is satisfied for nonlinear parts and the norm bounded condition is held for the disturbances. The design of control protocol considers the iterative learning control approach. Then, an improved high-order control scheme is proposed to deal with the consensus tracking, where the tracking trajectory is engendered via a virtual agent. A convergence condition that guarantees that the tracking errors asymptotically converge to an enough small interval is obtained by theoretical analysis. Furthermore, the norms of initial states deviation and disturbances tend towards zero, the norm of tracking errors tend towards zero as well. Finally, some simulation cases are given to clarify the validity of theoretical results.

Xiao, Bing; Shengyuan, Xu; Karimi, Hamid Reza; Yu, Xiang; Zhang, Youmin

doi: 10.1177/0142331219829956pmid: N/A

Liu, Ruixia; Liu, Ming; Liu, Yuan

doi: 10.1177/0142331218773506pmid: N/A

In this paper, the nonlinear optimal control problem is investigated for spacecraft formation flying with collision avoidance. Based on a nonlinear model of formation flying, two optimal tracking control laws are proposed to ensure the formation pattern converges to the predetermined configuration. The first optimal control law which combines Lyapunov optimizing control with a trajectory-following optimization technique is developed to solve the finite-time nonlinear optimal control problem. For the second controller, an extended θ-D method is applied to design a closed-form feedback control scheme for nonlinear control problem of spacecraft formation flying with non-standard cost functions. By taking into account the flying safety, a repulsive control scheme is incorporated in the optimal controller to ensure collision avoidance and minimize the performance index. Finally, a numerical example is performed to demonstrate the effectiveness of the proposed approaches.

Li, Chuang; Yang, Xuebo

doi: 10.1177/0142331218783242pmid: N/A

This paper investigates the problem of adaptive neural output feedback control for a class of switched non-linear systems, and the unknown backlash-like hysteresis of the actuator is also taken into consideration. First, neural networks are used to approximate the uncertain functions in the studied system. Second, a state-observer is proposed to estimate the system states. Finally, an adaptive neural output feedback control algorithm based on a backstepping technique is constructed; in addition, dynamic surface control is applied to eliminate the explosion in complexity caused by the backstepping technique. By using Lyapunov stability theory, it is proved that all the signals of the switched system are bounded under the proposed control scheme. The effectiveness of the proposed approach is further confirmed by simulation experiments.

Ye, Dong; Lu, Wei; Mu, Zhongcheng

doi: 10.1177/0142331218758889pmid: N/A

This paper investigates the coupled position and attitude control problem of an on-orbit servicing spacecraft autonomous docking to a three-axis freely tumbling target in space. A compound control law is presented to guarantee that the docking port of servicing spacecraft is always directing towards the docking port of tumbling target, which is accomplished through the combination of the coupled relative position tracking and relative attitude control. For the purpose of avoiding collision between the two spacecraft, a two-phased approach for the terminal approaching the tumbling target is proposed. Also, the compound control is composed of a nonlinear feedback control law and an integral sliding mode control law. The nonlinear feedback control law is mainly used to track the system command and the integral sliding mode control law is mainly used to deal with the external disturbances and system uncertainties to enhance the robustness of the control system. Furthermore, the control saturation problem is considered. In addition, the characteristic of integral sliding mode under the control constraint and measurement noise is also analyzed. Finally, several numerical simulations are performed to verify the effectiveness and robustness of the compound control law for autonomous docking to a three-axis freely tumbling target.

Lu, Kunfeng; Li, Tianya; Zhang, Lijun

doi: 10.1177/0142331218803410pmid: N/A

This paper describes a novel finite-time attitude tracking control approach for flexible spacecraft. This is achieved by integrating sliding-mode control and the active real-time fault-tolerant reconfiguration method. In this approach, the attitude error dynamics and the kinematics of the flexible spacecraft are first established. Then, a nonsingular terminal sliding-mode surface is designed, based on finite-time control theory. Applying the Chebyshev neural network, the uncertain dynamics induced by external disturbances and uncertain inertia parameters are approximated and estimated. The nominal control law and the compensation control law to obtain the active reconfiguration fault-tolerant controller are finally developed in normal and fault conditions, respectively. The closed-loop tracking system is proved to be uniformly ultimately bounded stable after a finite time. Numerical simulations are presented for a flexible spacecraft to illustrate the efficiency of the proposed controller.

Yu, Chunmei; Xie, Xun

doi: 10.1177/0142331218774393pmid: N/A

This work presents a novel control approach to the attitude stabilisation problem of rigid satellites with external disturbance, control constraint, and angular velocity constraint. The controller is developed in the framework of dynamic sliding mode control. A dynamic sliding mode surface is preliminarily chosen, and then a structure-simple sliding mode control law is synthesised. It is proved that the proposed control law can successfully accomplish the attitude stabilisation manoeuvre. The attitude is exponentially stabilised, and the angular velocity is stabilised with an exponential rate to a ball with a small radius. In comparison with the static sliding mode surface-based controllers, the proposed approach can provide a fast convergence rate. The system convergence time can be shortened by dynamically updating the control parameters in the sliding mode. Simulation results are presented to examine the feasibility of the presented solution.

Zhou, Weidong; Xing, Zejing; Wenbin, Bai; Chengchen, Deng; Xie, Yaen; Wu, Xiande

doi: 10.1177/0142331218785708pmid: N/A

The mission route plays an essential role for the mission security and reliability of an unmanned system. This paper gives a route planning method for autonomous underwater vehicles (AUVs) based on the hybrid of particle swarm optimization (PSO) algorithm and radial basis function (RBF). In the improved PSO algorithm, metropolis criterion is used to prevent the improved PSO algorithm from falling into local optimum and RBF is used to smooth the path planned by PSO algorithm. Compared with classic PSO algorithm, the hybrid algorithm of PSO and RBF can avoid falling into the local optimum effectively and plan an anti-collision route. Moreover, based on the simulation results, it can be seen that the approach presented here is more efficient in convergence performance, and the planned route requires lower performance of AUVs.

Guo, Yanning; Wang, Pengyu; Ma, Guangfu; Wang, Liangyue

doi: 10.1177/0142331218783237pmid: N/A

The problem of steering pyramid control moment gyro (CMG) cluster for fast spacecraft attitude maneuver along eigenaxis is investigated. A novel steering law is proposed to continuously attempt to reduce the difference between the current gimbal angle and the desired one corresponding to the angular momentum envelop of the CMG cluster. The proposed steering law can be decomposed into two parts: the first one is a singularity robust term to keep maneuverability and produce control torque, and the other is a null motion term to rearrange the gimbal angles toward momentum envelope. By involving this steering law, it is expected to possess both rapid angular momentum exchange and singularity avoidance ability. In addition, by introducing a new limit vector on attitude error, classical cascade-saturation control algorithm is revised to guarantee spacecraft eigenaxis rotation. Both open-loop steering law test and closed-loop attitude maneuver simulations are performed to evaluate the efficacy of the proposed methods.