Function Allocation Based Vehicle Suspension/Steering System Extension Control and Stability Analysis

Abstract

Considering coupled dynamics between vehicle suspension and steering systems, the dynamic model for full-vehicle integrated system is built. The deviation and deviation derivative are chosen as the characteristic quantities, and the extension set is established. The three measure modes of the classical domain, extension domain and non-domain are divided according to the correlation function. The control functions are allocated in different extension sets, and the corresponding control algorithms are separately designed to form the function allocation based extension controller(FAEC), in order to improve integrated system control performance as far as possible. The closed-loop control systems are constituted by the optimal controller and FAEC, and the simulation and test is carried out. The results demonstrate that the FAEC can further improve the control performance of the integrated system, which has the ability of obtaining better control effects than the optimal control. The integrated control system stability is analyzed when utilizing the suspension and steering system parameters as the variables by different control methods. The analysis results show that adopting the FAEC, the control system is with better stability. When increasing suspension damping, vehicle velocity and the front-wheel steering angle to certain values, vehicle time-domain responses' instability degree increases. And when changing the FAEC error weighted coefficients, it brings different degrees of influences to the integrated control system performance. If increasing the extension controller function control coefficient constantly, it leads the vehicle control system to instability.