Summary Report – Fault Tolerant Robotic Architectures and Adaptive Control

D. Tesar, R. Hooper, S. Tosunolglu, R. Freeman
NASA Grant Number NAGG-411
April 1997

Abstract
This report described work in fault tolerance at the University of Texas at Austin that was funded and sponsored by NASA/JSC. The report described the technical goals the group strove to achieve and included a brief description of the individual projects focused on fault tolerance. The ultimate goal was to develop and test technology applicable to all future missions of NASA (lunar base, Mars exploration, planetary surveillance, space station, etc.).

Introduction
This report describes work developing fault tolerant redundant robotic architectures and adaptive control strategies for robotic manipulator systems which can dynamically accommodate drastic robot manipulator mechanism, sensor or control failures and maintain stable end-point trajectory control with minimum disturbance. Kinematic designs of redundant, modular, reconfigurable arms for fault tolerance were pursued at a fundamental level. The approach developed robotic testbeds to evaluate disturbance responses of fault tolerant concepts in robotic mechanisms and controllers. The development was implemented in various fault tolerant mechanism testbeds including duality in the joint servo motor modules, parallel and serial structural architectures, and dual arms. All have real-time adaptive controller technology, to react to mechanism or controller disturbances (failures) to perform real-time reconfiguration to continue the task operations. The developments fall into three main areas: hardware, software, and theoretical.

D. Tesar, J. Chladek, R. Hooper, D. Sreevijayan, C. Kapoor, J. Geisinger, M. Meaney. G. Browning, K. Rackers. “Advanced Development for Space Robotics with Emphasis on Fault- Tolerance.” 29th Aerospace Mechanism Symposium, May 17-19, 1995.