Smooth finite-time coordinated attitude control for a space robot based on adaptive multivariable disturbance compensation

This work investigates a smooth finite-time coordinated attitude control scheme for the space robot with strong system nonlinearities, multiple input torques, coupled uncertainties and unknown disturbances. This paper reformulates the dynamic equations of a space robot by taking reaction wheels into account. An adaptive multivariable generalized super-twisting algorithm based on sliding mode disturbance observer is introduced to estimate the lumped disturbances with unknown bounds in finite time. Utilizing the estimation as feedforward compensation, a multivariable homogenous smooth twisting algorithm based on coordinated controller is designed to ensure the finite-time attitude tracking and generate a smooth input signal. Simulations are provided to demonstrate the effectiveness and robustness of the proposed method.