CONTROL AND SIMULATION FOR A CLOSED-CHAIN DUAL REDUNDANT MANIPULATOR SYSTEM

The two-level hierarchical control scheme is adopted to solve a dual-c hain robotic system formed by two redundant manipulators grasping a co mmon object with hard point contacts. The upper-level coordinator gath ers all the necessary information to resolve the force distribution pr oblem so as to generate all the desired contact forces. With all the d esired contact forces being specified, the dynamics of each chain are decoupled. Therefore, the lower-level local control problem can be tre ated as a general open-chain redundant manipulator problem. Furthermor e, the Compact-Dual LP method is applied to resolve the upper-level co ordination problem; while the Compact QP method associated with the co mputed torque control method is adopted to solve the redundant manipul ator problem. To obtain proper simulation results, the simulated actua l contact forces are formulated and the corresponding simulation probl em of the closed-chain robotic system is also completely solved in the article. Simulation results show that the two-level hierarchical cont rol scheme is an effective and efficient algorithm for resolving the l arge-scale control problem of multiple-chain robotic systems. (C) 1995 John Wiley & Sons, Inc.