A Multi-Task Priority Framework for Redundant Robots with Multiple Kinematic Chains under Hard Joint and Cartesian Constraints

Abstract

This paper introduces an extension of the reverse priority framework for the kinematic control of redundant robots. It integrates, in a unified framework, the treatment of multiple tasks, multiple kinematic chains, different joint priorities and hard constraints. The management of multiple tasks is based on the reverse priority method, that has been modified so that it makes possible the assignment of different priorities to each joint in order to accomplish the tasks. This framework is also suitable for robotic systems with multiple kinematic chains, which could share several joints. Moreover, it can deal with bilateral and unilateral constraints, that can be defined either at joint or cartesian space. Hard constraints are considered at each priority level, instead of treating them separately at the highest priority level. The proposed framework has been evaluated in simulation and in real experiments with a redundant underwater vehicle-manipulator system at sea.