Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
MULTIVARIABLE CONTROL ANALYSIS OF AN ACTIVE SUSPENSION SYSTEM
Submission Author:
Felipe Marques Farias Filho , AL , Brazil
Co-Authors:
Felipe Marques Farias Filho, Lucas da Silva Rigobello, Maíra Martins da Silva, Marcelo Becker
Presenter: Felipe Marques Farias Filho
doi://10.26678/ABCM.COBEM2021.COB2021-0524
Abstract
Comfort is one of the most valued features for passenger cars. It can be improved by developing active suspension systems targeting to control the wheels' vertical movements and the vehicle, correcting and compensating for imperfections in the track with greater efficiency than the standard suspension system. One alternative to control these dynamic systems is to use optimal control, like Linear Quadratic Regulators (LQR), which are full-state feedback controllers whose tuning depends on weight coefficients matrices. Usually, these coefficients are determined by experience and trial. For large systems, this might be an arduous task. In addition, a disadvantage of this type of controllers is their lack of robustness. This work aims to design an LQR controller for an active suspension system modelled with four degrees of freedom. In this proposal, the weight coefficients are derived by solving an optimization problem that considers different sources of uncertainty in the model: vehicle mass, tire stiffness and damping coefficients of the front and rear suspension. The optimization problem created for obtaining the weight coefficients was solved using the Pattern Search algorithm. The objective function considers the vehicle's vertical acceleration, required actuation energy, and a contact index between the vehicle and the track. Three alternatives for the controller are analyzed considering different weights for the energy-related term. These are compared with the standard system when excited by a bump. The same terms of the objective function have been used for this comparison. The designed systems reduced the accommodation times and amplitudes of the vehicle's vertical acceleration. The characteristics of the track contact index have been little affected. Therefore, the designed active suspension system is able to provide more comfort and still maintain the vehicle's controllability, hence preserving its safety features.
Keywords
Active suspension, LQR, control, Optimization, Pattern Search
