Moray Drive for multijoint manipulators

A new control method for multijoint manipulators, named Moray Drive, is proposed. Moray Drive uses the multijoint manipulator with slider, the sliding mechanism at the arm base, and gives the bending angle command to all joints while shifting the angle commands to the adjacent joints in synchronization with the linear motion of slider. The characteristics of the Moray Drive are: (1) the possibility to use light-weighting joint driving mechanism by subrogating most of the driving power to the slider, (2) simplicity of control in spite of the redundancy of multijoint system, (3) feasibility to make obstacle avoidance motion, and (4) little fluid resistance in operation in a fluid. As to the basic trajectory of the Moray Drive in free space, it is shown that a Clothoid spiral is optimal for minimum time operation in terms of kinematics. It is also shown that the optimum trajectory is closer to linear-like curve than the Clothoid spiral. A comparison made between the Moray Drive and the conventional motion of redundant manipulator without slider both in air and in water environments demonstrates the former is more energy efficient under both environments, especially in water, than the latter.<>