Adaptive Backstepping Based Sensor and Actuator Fault Tolerant Control of a Manipulator

The purpose of this research is to propose and design fault tolerant control (FTC) scheme for a robotic manipulator, to increase its reliability and performance in the presence of actuator and sensor faults. To achieve the said objectives, a hybrid control law relying on observer and hardware redundancy-based technique has been formulated in this paper. Non-linear observers are designed to estimate the unknown states. The comparison of actual states and observed states lead to fault identification, this is followed by fault tolerance accomplished with redundant sensors. For actuator fault tolerance, fault estimation and controller reconfiguration techniques are applied in addition to nominal control law. Fault estimation is based on adaptive back-stepping technique and it is further used to construct actuator fault tolerant control. The proposed method is applied to a six degree of freedom (DOF) robotic manipulator model and the effectiveness of this technique is verified by LabVIEW simulations. Simulation results witnessed the improved tracking performance in the presence of actuator and sensor failures.