Sensor fault detection for fault tolerant operation of parallel manipulators

A sensor fault detection method intended to allow fault tolerant operation of parallel manipulators is introduced. A class of three-branch parallel manipulators each branch consisting of three main-arm joints supporting a mobile platform through passive spherical end-joints is considered. The method is based on comparison of forward displacement solutions for different combinations of redundant joint sensing. In simulation the fault detection scheme works without error. In application of fault detection for a three-branch hand controller the scheme is found not to be as successful. Data analysis is performed to examine the sources of algorithmic failure. It is concluded that high accuracy in the passive spherical branch end joints and low noise sensors are required to facilitate fault detection