Passive fault tolerant control of quadrotor UAV using regular and cascaded Sliding Mode Control

In this paper, two passive fault tolerant controllers based on Sliding Mode Control theory are designed for AscTec Pelican quadrotor. The first controller is a regular Sliding Mode Controller (SMC) that uses the robustness of SMC and its insensitivity to model uncertainties and disturbances to tolerate two different types of actuator faults. The latter controller is a cascaded SMC (CascSMC) with an inner loop fast SMC controlling the velocity system and tolerating its faults, and an outer loop SMC controlling the inner system (inner SMC and velocity system) with integrator. To tune the parameters of the controllers for their optimal values, a bio-inspired search algorithm called Ecological Search Algorithm (ESA) is used. SIMULINK results show that the proposed controllers are successful in controlling the quadrotor performing a helical path in the space in presence of two different actuator faults. Tests show that the cascaded SMC outperforms the regular SMC in handling tougher faults by compensating them quickly in its fast inner loop.