EXPERIMENTAL STUDY OF DYNAMIC STABILITY OF UNDERWATER VEHICLE-MANIPULATOR SYSTEM USING ZERO MOMENT POINT

For manipulative underwater operations, an underwater vehiclemanipulator system (UVMS) has more degrees of freedom than those required to conduct a given mission. To follow the desired end-effector position and velocity accurately, UVMS should be able to generate trajectories of manipulators and the underwater vehicle can maintain dynamic stability of the entire system. In this paper, redundancy resolution is performed to find a solution satisfying the given task among many joint-space solutions. Also, to improve the dynamic stability of the UVMS, zero moment point (ZMP) is adopted such that it requires some constraints. For application of UVMS, a joint limitation is also taken as constraints for UVMS motion. The optimal solution for constraints is obtained through gradient projection method (GPM). To demonstrate the proposed redundancy resolution including ZMP, the UVMS composed of redundant manipulator is developed and tested. Test results show that the end-effector of the manipulator not only keeps track of the desired trajectory but also improves the stability of the UVMS.