This paper addresses trajectory planning and control for a dual-arm free-floating space robot (FFSR) based on predefinedtime stability. Firstly, a class of general nonsingular terminal sliding mode control strategy is proposed to achieve global predefined-time stability by switching a control parameter in a form of function. Then, a high-precision trajectory planning method is proposed for a FFSR using the proposed predefined-time stability theorem, which can make the end-effector and the base reach the desired pose within a prespecified time, and reduce the adverse effect on planning accuracy resulted from the singularity avoidance algorithm and the obstacle avoidance one. Subsequently, a trajectory tracking control strategy is proposed for a FFSR employing the proposed general nonsingular predefined-time terminal sliding mode, and the tracking errors can converge within a predefined time to an arbitrarily small neighborhood of zero in the presence of persistent disturbances. The proposed trajectory planning method has the advantage of pose feedback, so can be combined with the trajectory tracking controller in the control process to further enhance the control performance for the FFSR. Simulation results validate the effectiveness of the proposed methodologies.

In space mission, the tracking accuracy of robot will be affected by many factors. Fortunately, some errors can be eliminated by trajectory planning without the need for additional fuel, hence, in this paper, a nonsingular error-free trajectory planning method for a dual-arm free-floating space robot(FFSR) will is studied with the large initial measurement errors and non-zero dynamic of base. Firstly, the pose error kinematic equation is deduced by the desired pose command and related kinematics. Then, a predefined-time stability function is used as the pose-feedback control law to converge the error to zero, and the convergence time is bounded. In the end, the motion trajectory of balance arm will be planned by the momentum conservation equations of the system to offset the dynamic coupling. The predefined-time stability theorem will significantly improve the anti-disturbance performance of the traditional pose-feedback based trajectory planning method, and the error can be eliminated within any required task time. Simulation results validate the effectiveness of the proposed methodology.