Robust control of a space robot based on an optimized adaptive variable structure control method

Space robot has been playing an increasingly important role in on-orbit service missions. Dynamic coupling exists between the space robot arm and the floating base, and an inaccurate dynamic model will deteriorate the control accuracy of space robot motion. This paper proposed an optimized adaptive variable structure control method to realize coordinate motion control of space robot base and its arm. The controller can adapt its gain to match system uncertainties and external disturbances so that the error dynamics converge to the origin following a parabola-like path which is close to the natural behavior of a second-order system. Therefore, the controller will eliminate the chattering phenomenon and reduce the settling time. Further, taking the motion error as the objective function, the gain parameter is optimized by adopting the modified Gaussian barebones differential evolution method. Numerical simulations aimed at verifying the space robot dynamic model and the effectiveness of the controller are carried out based on Simscape Multibody. The results prove that the theoretical dynamic model of the space robot is accurate. In addition, the controller is demonstrated to present reduced settling time and higher control accuracy in comparison with the boundary layer sliding mode control method.