An implementation of a dexterous manipulator for a two-dimensional, low-friction environment

Abstract

Dexterous manipulation can be defined as the set of motions necessary to stably grasp an object in a robot hand and change its position and/or orientation through a series of coordinated motions. This thesis describes the design and implementation of a two-dimensional (planar) robot hand which can perform dexterous manipulation in low friction environments. In order for the hand to be able to perform a successful manipulation, it is necessary to have a coordinated set of joint torques and joint position set points. These can then be fed to the digital control system for each joint. Planning (to produce these trajectories) is done off-line under the assumption that the environment is frictionless. This assumption reduces the computational complexity of the problem, because motion is reversible in the frictionless domain. Also, planning in the frictionless case results in all contacts between objects being sliding contacts and no rolling occurs. While executing such "frictionless" plans in low friction environments, it is necessary to recognize that rolling contacts can occur and steps should be taken to prevent this from happening. The analysis and design of the control systems for each of the joints as well as their implementation are discussed. Experimental results are presented and compared with theoretical results. It is shown that it is possible to execute "frictionless' plans in low-friction environments.