Actuators and sensors fault detection for robot manipulators via second order sliding mode observers

A simple model based fault detection (FD) scheme suitable for robot manipulators is presented. The purpose is to detect and, possibly, identify a single fault acting on a specific input or on a specific output of the manipulator. Input signal estimators and output observers are considered in order to make the fault detection possible. By adopting a second order sliding mode (SOSM) approach to design the input laws of the observers, it is possible to establish satisfactory stability properties of the observation error, and reduce the chattering effect. The proposed approach is experimentally tested on a COMAU SMART3-S2 manipulator.