Singular perturbation-based pose tracking control for rigid-flexible coupled space robot

This paper investigates the pose tracking control problem of a rigid-flexible coupled space robot subject to parameter uncertainties and external disturbances. A novel singular perturbation-based sliding mode-linear quadratic regulator (LQR) composite controller is proposed, which integrates sliding mode control (SMC) and an LQR to achieve robust and precise tracking. The rigid-flexible coupled dynamic model of the space robot, that accounts for both uncertainties and bounded disturbances, is derived using Jourdain’s principle. To simultaneously ensure trajectory tracking accuracy and vibration suppression, the dynamic model is decomposed via SP theory into a slow subsystem governing rigid motion and a fast subsystem describing flexible dynamics. A finite-time convergent adaptive sliding mode controller is developed for the slow subsystem, enhanced with a radial basis function (RBF) neural network for uncertainty estimation, while adaptive compensation is employed to mitigate estimation errors. For the fast subsystem, an LQR-based optimal controller is designed to guarantee rapid stabilization of elastic vibrations. Numerical simulations demonstrate that the designed controller achieves excellent performance in terms of control accuracy, robustness, and vibration suppression, thereby validating the effectiveness of the proposed control method.