Discrete nonsingular terminal sliding mode control for trajectory tracking of space manipulators with mismatched multiple disturbances and noisy measurements

Accurate trajectory tracking is essential for the success of space robotic missions. However, challenges such as modeling uncertainty, measurement noise, and excessive sampling interval can degrade tracking performance and then deteriorate the control safety. In this study, a robust adaptive approach for trajectory tracking of space robotic manipulators is proposed to address the above challenges. The approach integrates the techniques of extended Kalman filter, high-order disturbance observer, and discrete nonsingular terminal sliding control. In particular, by introducing auxiliary variables into the filter, the accuracy of state estimation is significantly improved. In addition, an improved terminal sliding controller is developed based on an equivalent control design philosophy, which ensures both guaranteed tracking stability and mitigation of the adverse effects of long sampling times. Numerical simulation results demonstrate the effectiveness of the proposed techniques and highlight the advantages of the controller in terms of accuracy and robustness.