Dynamic control of a flexible macro–micro manipulator based on rigid dynamics with flexible state sensing

Abstract

A macro–micro manipulator system is formed by attaching a small (or micro) manipulator at the end of a conventional large (macro) manipulator. The system can provide high-precision motion of the micro robot for local operation and retain the versatility, speed, and workspace of a larger robot. In this study the macro–micro manipulator approach is intended to enhance the tracking/positioning performance of flexible manipulators. Additional actuation of the micro rigid manipulator is employed to compensate for the deflections due mainly to the link flexibility involved. The manipulator system is firstly modelled based on the rigid dynamics by taking into account the full coupling between the macro and micro manipulators. For accomplishing fast and gross motion of the macro flexible manipulator, the PD controller is employed incorporating a fuzzy adaptive tuner. A control scheme is then proposed for the micro manipulator, where the sensed flexible states are used as feed-forward signals and added to the control command for the rigid-motion control of the micro manipulator, for the purpose of deflection compensation. An integrated laser-optical system is dedicated to sense the tip deflections of the flexible links. The control schemes proposed are verified through simulation experiments.