Trajectory Generation and Sliding-Mode Controller Design of an Underwater Vehicle-Manipulator System with Redundancy

An Underwater Vehicle-Manipulator System (UVMS) can be applied to pick up and carry objects for autonomous manipulation in the water However; it is difficult to control the motion of the whole system because the movement of a manipulator affects the motion of the vehicle and vice versa. Additionally, a lack of information about the object, such as the shape and inertia, makes motion control even more difficult. In the current paper, a motion control algorithm of the UVMS with redundancy was developed to guarantee the stability robustness when the mass information of the objects is not available. In order to generate the joint trajectories of the manipulator, a redundancy resolution was performed to minimize the restoring moments acting on the vehicle. This means the propulsion energy for controlling the vehicle's motion can be reduced. To control the motion of the system with an unknown parameter, a controller based on the sliding mode theory has been designed. Finally, the effectiveness of the proposed method was verified through a series of simulation for a 3DOF vehicle-3DOF manipulator system.