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Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese University | Noura H.,United Arab Emirates University | Bateman F.,French Air Force Academy
2014 IEEE Conference on Control Applications, CCA 2014 | Year: 2014

In this paper, an emergency controller is developed for AscTec Pelican quadrotor suffering a severe failure in one of its motors or rotors. With one of its motors badly damaged, it is impossible to perform the control of a quadrotor using old control strategies or conventional fault tolerant control techniques. The emergency controller designed in this paper detects online any failure or fault in the quadrotor UAV motors, and whenever a severe fault (one which the Passive Fault Tolerant Sliding Mode Controller of the quadrotor cannot hold) occurs the controller applies some weight modifications so the three remaining motors are used to control the UAV as a trirotor. The controller uses a nonlinear sliding mode observer as Fault Diagnosis and Identification (FDI) unit to detect and estimate the magnitude of the fault online. SIMULINK results show that the proposed controller is fast in fault detection and successful in controlling the damaged quadrotor until it finishes its path. © 2014 IEEE. Source


Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese International University | Bateman F.,French Air Force Academy | Noura H.,United Arab Emirates University
2015 IEEE Conference on Control and Applications, CCA 2015 - Proceedings | Year: 2015

In this paper, Second Order Sliding Mode technique is used to develop a Passive Fault Tolerant Controller (PFTC) for octorotor UAVs. Super twisting algorithm is applied to form the discontinuous part of the controller. Optimal controller gains are found using Ecological Systems Algorithm, a bio-inspired optimization algorithm made to search within the stability region of the controller. An Active Fault Tolerant Controller (AFTC) version of the controller is designed using Pseudo-Inverse and Dynamic control re-allocation methods. SIMULINK based simulation results show the effectiveness of the proposed controllers which exceed the performance of First Order Sliding Mode active fault tolerant controller. © 2015 IEEE. Source


Merheb A.-R.,Aix - Marseille University | Noura H.,United Arab Emirates University | Bateman F.,French Air Force Academy
Conference on Control and Fault-Tolerant Systems, SysTol | Year: 2013

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. © 2013 IEEE. Source


Merheb A.-R.,Aix - Marseille University | Merheb A.-R.,Lebanese International University | Noura H.,United Arab Emirates University | Bateman F.,French Air Force Academy
International Journal of Applied Mathematics and Computer Science | Year: 2015

In this paper, sliding mode control is used to develop two passive fault tolerant controllers for an AscTec Pelican UAV quadrotor. In the first approach, a regular sliding mode controller (SMC) augmented with an integrator uses the robustness property of variable structure control to tolerate partial actuator faults. The second approach is a cascaded sliding mode controller with an inner and outer SMC loops. In this configuration, faults are tolerated in the fast inner loop controlling the velocity system. Tuning the controllers to find the optimal values of the sliding mode controller gains is made using the ecological systems algorithm (ESA), a biologically inspired stochastic search algorithm based on the natural equilibrium of animal species. The controllers are tested using SIMULINK in the presence of two different types of actuator faults, partial loss of motor power affecting all the motors at once, and partial loss of motor speed. Results of the quadrotor following a continuous path demonstrated the effectiveness of the controllers, which are able to tolerate a significant number of actuator faults despite the lack of hardware redundancy in the quadrotor system. Tuning the controller using a faulty system improves further its ability to afford more severe faults. Simulation results show that passive schemes reserve their important role in fault tolerant control and are complementary to active techniques. © 2015 by Hassan Noura. Source


Bateman F.,Aix - Marseille University | Bateman F.,French Air Force Academy | Noura H.,United Arab Emirates University | Ouladsine M.,Aix - Marseille University
IEEE Transactions on Aerospace and Electronic Systems | Year: 2011

A fault detection and diagnosis (FDD) and a fault-tolerant control (FTC) system for an unmanned aerial vehicle (UAV) subject to control surface failures are presented. This FDD/FTC technique is designed considering the following constraints: the control surface positions are not measured and some actuator faults are not isolable. Moreover, the aircraft has an unstable spiral mode and offers few actuator redundancies. Thus, to compensate for actuator faults, the healthy controls may move close to their saturation values and the aircraft may become uncontrollable; this is critical due to its open-loop unstability. A nonlinear aircraft model designed for FTC researches has been proposed. It describes the aerodynamic effects produced by each control surface. The diagnosis system is designed with a bank of unknown input decoupled functional observers (UIDFO) which is able to estimate unknown inputs. It is coupled with an active diagnosis method in order to isolate the faulty control. Once the fault is diagnosed, an FTC based on state feedback controllers aims at sizing the stability domain with respect to the flight envelope and actuator saturations while setting the dynamics of the closed-loop system. The complete system was demonstrated in simulation with a nonlinear model of the aircraft. © 2006 IEEE. Source

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