Fault tolerant control based on continuous twisting algorithms of a 3-DoF helicopter prototype

Fault tolerant controllers, based on the Continuous Twisting Algorithm (CTA), are designed for robust stabilization of a three-degree-of-freedom (3-DoF) helicopter prototype. Voltage variations (faults) in the actuators are detected and isolated by means of residual-based equations and exploiting the third-order sliding mode differentiator (SMD). Proposed fault detection and isolation (FDI) scheme is tested with intermittent and persistent faults induced by software. A unknown-input sliding mode observer (SMO) is developed to compare and highlight the performance of the proposed FDI-SMD respect to the classic FDI-SMO. Finally, simulations and real-time experiments confirm that CTA-based controllers counteract additive faults. Filtering the signals from residual equations is suggested in order to mitigate the effects of noises and neglected (parasitic) dynamics on the detectors.