Commande hybride d'un système à suspension active

Abstract

This thesis proposes the modeling of an electrohydraulic active suspension system, the development of control laws and their implementation in real time for validation purposes. The control strategies employed and developed by using linear, nonlinear and adaptive control approaches with simple or hybrid structures. In this thesis, we have developed a hybrid nonlinear control structure for controlling the position and the force applied to an active suspension bench representing the active suspension of a vehicle. The hybrid structure merges two nonlinear controllers using two low pass filters. This structure consists of a nonlinear control law which contains variable functions and gains. The controllers are developed using the sliding mode because of its robustness despite the chattering produced in the control law. In a sliding mode control, the most important thing to deal with is the reduction of chatter. The exponential reaching law is one of the existing techniques to reduce chattering in a nonlinear control law. The technique has been tested in simulation as well as in real time for validation purposes in this thesis. To improve the performance of the proposed controller in the previous paragraph, we added another sliding surface based fuzzy logic controller for the validation tests. In the fuzzy logic controller, the inputs are the sliding surfaces of the position and the force which are instantaneously calculated in the system. The fuzzy logic controller updates the gains of the filters efficiently to improve the performance of the proposed controller used in the hybrid structure. The stability of the hybrid structure is enhanced by the stability of each controller used in this structure. The popularity of PID controller motivated us to integrate it in the hybrid structure. Since the PID controller is easy to integrate in the industrial applications and embedded systems, a PID based hybrid controller is built and tested to track a desired force by keeping the position within its limits. The hybrid structure composed of PID controllers and sliding mode controllers has proved its validity through simulation and real-time tests. The results show that a hybrid controller can reduce the disturbance exerted on an active suspension system and follow a desired force trajectory generated from the system parameters. This double aspect cannot be achieved by a simple controller and even a nonlinear controller. Simple controllers are made to achieve a single objective (force or position) and sometimes to keep variables within their limits. On the other hand, the hybrid structure has become increasingly popular as it is used in multitask applications such as robotics. In other words, the hybrid structure with many controllers has proved its efficiency in several areas. In the same direction, a dual loop PID controller (PIDDL) was developed and presented in adaptive form through adaptive functions to control the position of active suspension bench. The PIDDL could be integrated into the hybrid structure to have a new structure based on an extension of a PID controller. Fuzzy logic controllers are used into an adaptive structure with feedbacks between the same controllers to update the essential gains of PID and PIDDL controllers. The PIDDL controller with variable gains has been tested and validated through a series of comparisons with the PID and other controllers. The results proved the validity of the proposed controller by surpassing the other controllers in terms of performance.

Date	19 Jun 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Jean-Pierre Kenné (Supervisor) & Claude Kaddissi (Co-supervisor)