ADAPTIVE MOTION FORCE CONTROL OF MULTIPLE MANIPULATORS WITH JOINT FLEXIBILITY BASED ON VIRTUAL DECOMPOSITION

Virtual decomposition means that a complex physical system can be virt ually decomposed into several subsystems, in concept, so that the cont rol problem of modeling, controller design, and stability analysis of the original system can be converted into that of each subsystem plus the treatment of the dynamic coupling between these subsystems, In thi s paper, a virtual decomposition-based adaptive motion/force control s cheme is presented to deal with the control problem of coordinated mul tiple manipulators with flexible joints holding a common object in con tact with the environment. The control scheme is essentially a general ized Newton-Euler approach in which the original system is virtually d ecomposed into several subsystems, including the held object, the rigi d links, and the flexible joints, so that the control problem of the o riginal system can be greatly simplified, An interesting result is tha t the dynamic coupling between every two physically connected subsyste ms is completely represented by the so-called virtual power flow (VPF) at the cutting point between them, The VPF takes a very simple form a nd is very easy to handle, Control design of the constraint/internal f orces can be performed with respect to the held object, Asymptotic sta bility of the overall system is ensured in the sense of Lyapunov, The proposed scheme can be extended to treat the control problem of robot manipulators incorporating actuator dynamics, In fact, it is also appl icable to generalized mechanical systems due to the fact that the join t flexibility can be treated separately from the rigid systems, Comput er simulations of two manipulators transporting an object in the plane are given to show the validity of the proposed scheme.