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Abstract
This thesis presents a study of the optimal design of a class of six degree-of-freedom (DOF) closed-chain manipulators. Dexterity measures based on instantaneous kinematic characteristics of the manipulator are used as the primary objective in isolating optimum designs.
The fully-parallel Stewart platform, which represents a limiting case of a hybrid manipulator where only one joint in each branch is actuated, is first examined. As an initial design step, manipulator configurations optimizing local dexterity are determined. For a platform centred reference location and a given length for scaling purposes, a two-parameter family of optimal configuration is shown to exist. The resulting optimum manipulator architecture is one in which the dimensions of the base are twice those of the platform and the linear actuator attachment points at the base and platform meet in alternating pairs.
Hybrid manipulators are then examined. A novel approach to manipulator configuration optimization for optimal local dexterity objectives is introduced. This new approach involves finding geometric characteristics of manipulator configurations which optimize dexterity and then finding actual manipulator configurations fitting these characteristics. The method is applied to find optimal configurations of hybrid manipulators utilizing the previously identified branch structures. (Abstract shortened by UMI.)
