An identification scheme for robot actuator faults

We present a scheme for identifying the time profile of actuator faults that may affect a robot manipulator. Starting from our previous method for fault detection and isolation (FDI) based on generalized momenta, fault identification is additionally obtained through the H_∞-design of a state observer for uncertain systems. For each separate fault channel, the identifier consists of a linear filter driven by the corresponding residual signal. Under the weak assumption of bounded time derivative for the otherwise unknown fault input to be identified, the fault estimation error is shown to be ultimately uniformly bounded, with ultimate bound that can be set arbitrarily small. The information on the type and severity of the fault may then be used for reconfiguring the control strategy. Experimental results on a 2R planar manipulator are presented.