HYBRID MOTION CONTROL OF A CABLE-DRIVEN HYPER REDUNDANT ROBOT WITH KINEMATIC OPTIMIZATION CONSIDERING CABLE TENSION

Cheng Wei, Haiyu Gu, Shengxin Sun, and Yang Zhao

Keywords

Abstract

Inspired from bionics, cable-driven hyper redundant robots (CHRRs) have superior dexterity, and can be used in narrow and confined workspace. However, each cable generates driving tension on its terminal section and disturbance force on other contacting sections. The disturbance force increasing with close to the base is highly time-varying and nonlinear during the motion, which is difficult to suppress using static state feedback compensation. In this article, a CHRR prototype is designed and described. With transforming the force generated by cables to force screw, the accurate model of cables is established, and then a dynamic model considering the redundancy of joints and tension is derived. Based on multi-solutions of calculating joints motion and tension, an optimization algorithm is derived from the objection functions for avoiding joints angle overrunning and cables overloading. From the optimization algorithm, a control method is proposed to realize dexterous motion with different tension distribution. Finally, the models and control method are validated through simulating motions of the 3D virtual prototype. Simulation results show the robot can track complex desired motion, as well as varying null-space vector of velocity Jacobin matrix and tension Jacobin matrix to optimize velocity and tension.

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