Robustly fault tolerant Gough-Stewart platforms

Abstract

This paper derives new methods for analytically designing optimal generalized Gough-Stewart micromanipulators so they can meet wrench specifications in a fault tolerant manner. The manipulators are designed to tolerate “free swinging” prismatic actuator faults in which the failed actuator moves freely but cannot exert any force. For these “free swinging” failures, this paper introduces a new, stricter concept of fault tolerance termed “Robust Fault Tolerance” (RFT). This new concept of fault tolerance is stronger than earlier approaches, yet this paper finds a seven parameter class of machines that are RFT. To illustrate the power of this new approach, the algorithm is used to redesign a manipulator currently aboard the International Space Station to make it decoupled and RFT while reducing the actuator size by more than a factor of two.