  This paper focuses on sensor fault detection and compensation for robotic
manipulators. The proposed method features a new adaptive observer and a new
terminal sliding mode control law established on a second-order integral
sliding surface. The method enables sensor fault detection without the need to
know the bounds on fault value and/or its derivative. It also enables fast and
fixed-time fault-tolerant control whose performance can be prescribed
beforehand by defining funnel bounds on the tracking error. The ultimate
boundedness of the estimation errors for the proposed observer and the
fixed-time stability of the control system are shown using Lyapunov stability
analysis. The effectiveness of the proposed method is verified using numerical
simulations on two different robotic manipulators, and the results are compared
with existing methods. Our results demonstrate performance gains obtained by
the proposed method compared to the existing results.
