| Trussarm is a Variable-Geometry-Truss (VGT) manipulator, developed and constructed at the University of Toronto Institute for Aerospace Studies. The objective of this dissertation is to examine this new technology to determine its kinematics and control characteristics. In order to examine the kinematics properties of Trussarm, a kinematics model is developed. An algorithm to represent the macroscopic geometry of Trussarm as an equivalent discrete model (a serial open chain of simple 3-DOF gimbal modules) is presented. Redundancy resolution based on the equivalent discrete model is developed, and, the kinematics and differential kinematics of a Trussarm module are derived. Through experiments and simulations, the control characteristics of Trussarm including workspace, dexterity, speed, and tracking accuracy, are determined. Furthermore, a new control algorithm is developed to improve the control performance of Thussarm. The experimental results suggest that Trussarm possesses many advantages over conventional manipulators although its accuracy suffers from its physical size and complexity. However, the accuracy may be improved with closed-loop position control. |
