Characterization of the Self-Motion Manifolds of 7-DoF Robots

Abstract

Redundant manipulators offer several key advantages when operating in challenging environments and executing complex tasks. Thereby, it may be of interest to resolve the redundancy of a manipulator by globally optimizing a manipulability metric for a given workspace position. However, previous methods have encountered difficulties in achieving a valid configuration space path to a global optimum in the presence of joint limits. Therefore, this thesis aims to solve a pathwise constrained motion planning problem for fixed start and goal configurations for 7 Degrees of Freedom manipulators with a 0-offset 3R-1R-3R arrangement of rotational joints using the example of DLR Lightweight Robot (LWR) III. The analysis of the topological structure of the work and configuration space of the DLR LWR III enables the proposition of a topologically informed method. Thereby, the proposed method is able to efficiently consider the effects of singularities, joint limits as well as obstacles. These abilities are verified in a kinematic simulation of the DLR LWR III including cases with obstacles in the environment of the manipulator.