IEEE/CAA JOURNAL OF AUTOMATICA SINICA, VOL. 7, NO. 5, SEPTEMBER 2020 1417 The Fuzzy Neural Network Control Scheme With H ∞ Tracking Characteristic of Space Robot System With Dual-arm After Capturing a Spin Spacecraft Jing Cheng and Li Chen Abstract—In this paper, the dynamic evolution for a dual- arm space robot capturing a spacecraft is studied, the impact effect and the coordinated stabilization control problem for post- impact closed chain system are discussed. At first, the pre-impact dynamic equations of open chain dual-arm space robot are established by Lagrangian approach, and the dynamic equations of a spacecraft are obtained by Newton-Euler method. Based on the results, with the process of integral and simplify, the response of the dual-arm space robot impacted by the spacecraft is analyzed by momentum conservation law and force transfer law. The closed chain system is formed in the post-impact phase. Closed chain constraint equations are obtained by the constraints of closed-loop geometry and kinematics. With the closed chain constraint equations, the composite system dynamic equations are derived. Secondly, the recurrent fuzzy neural network control scheme is designed for calm motion of unstable closed chain system with uncertain system parameter. In order to overcome the effects of uncertain system inertial parameters, the recurrent fuzzy neural network is used to approximate the unknown part, the control method with H∞ tracking characteristic. According to the Lyapunov theory, the global stability is demonstrated. Meanwhile, the weighted minimum-norm theory is introduced to distribute torques guarantee that cooperative operation between manipulators. At last, numerical examples simulate the response of the collision, and the efficiency of the control scheme is verified by the simulation results. Index Terms—Capturing operation, calm motion control, closed chain system, dual-arm space robot, recurrent fuzzy neural network, H∞ tracking characteristic. I. I NTRODUCTION A S the exploration of space continuously advancing, the space robot has been employing to accomplish more on- orbit service missions [1]. There is harsh operating environ- ment in outer space, space robot system assisted astronauts complete space missions, can protect the astronauts’ life from dangers. Space robotic systems have received a large number of significant attentions [2]−[5] in the past decades. The space robot was employed to accomplish complicated tasks, such as fueling, maintaining of spacecraft in earth orbit, clearing of orbital debris, etc. [6]−[8]. Therefor it is becoming increas- ingly important for space robot system to have the capability This work was supported by the National Natural Science Foundation of China (11372073, 11072061). Recommended by Associate Editor Yuanqing Xia. (Corresponding author: Jing Cheng.) Citation: J. Cheng and L. Chen, “The fuzzy neural network control scheme with H∞ tracking characteristic of space robot system with dual-arm after capturing a spin spacecraft,” IEEE/CAA J. Autom. Sinica, vol. 7, no. 5, pp. 1417-1424, Sept. 2020. J. Cheng is with the School of Aerospace Engineering, Tsinghua University, Beijing 100084, China (e-mail: chengjingf@mail.tsinghua.edu.cn). L. Chen is with the School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350116, China (e-mail: chnle@fzu.edu.cn). Digital Object Identifier 10.1109/JAS.2018.7511180 of capturing a satellite. As space robot system with dual- arm possesses bigger carrying capacity and better structure rigidity, it is more expected to fulfil capturing spacecraft tasks. Since the weightlessness condition in outer space, it makes the dynamics and control problems related to capturing satellite operation by space robot system with dual-arm to be extremely complicated compared with the counterpart of fixed-base robot system and single arm space robot system, and there are some unique characteristics, such as, nonholonomic dynamics restriction, change of system configuration, transfer of linear momentum, angular momentum and energy, topology transfer from open to closed loop system, and the constraints of closed-loop geometry and kinematics during capturing satellite operation. It develops many challenging problems that need to be solved. Space robot system is essentially a coupling, time-varying and nonlinear system [9]−[11], if there is uncertain parameter exists in the system will make control scheme design more difficult [12], [13]. Vafa et al. [14] proposed a concept of virtual manipulator approach for the kinematics and dynamics analysis of space robot. Nakamura et al. [15] proposed a concept of generalized Jacobi matrix, and studied the relation between the velocity of joint space and the velocity of working space for single arm space robot. Huang et al. [16]−[18] studied the application of tethered space robots capturing a target in future on-orbit missions, they analyzed the impact dynamic modeling and proposed coordinated stabilization scheme, adaptive postcapture backstepping control, et al. for tumbling tethered space robot-target combination. Abad et al. [19] predicted the best capturing time and configuration of the target, and found an optimal control solution to guide the robot to reach the predicted location with a minimal attitude disturbance. Rekleitis et al. [20] proposed a planning and control methodology for manipulating passive objects by cooperating orbital free-flying servicers in zero gravity. During the process of capturing operation, the end-effectors of dual-arm space robot will inevitably collide with the captured target. The collision lead to instability and rolling of space robot in the weightlessness environment which is harm for the precise instrument on the servicing spacecraft, even lead to the failure of space missions. Because of the aforementioned challenging problems, the current studies are mostly focus on single arm space robot [21]−[23]. In fact, dual-arm space robot is similar to human arms; it is more suitable for capturing operation. Patolia et al. [24] discussed the coordinated motion planning problems for the dual-arm space robot system. Chen et al. [25] proposed an hybrid posi- tion and force control method based on radial basis function