Integrated Vehicle Chassis Control Based on Direct Yaw Moment and Active Front Steering

Abstract

This paper presents an advanced integrated control system which combines two fuzzy logic controllers for the Direct Yaw Moment (DYC) and Active Front Steering (AFS) in order to improve vehicle handling and cornering stability. Based on a well-developed and validated fourteen degrees of freedom full vehicle model with non-linear tire characteristics, a reference bicycle car model is introduced to compare and therefore control both the yaw rate and side slip angle of the vehicle body.Three input variables are considered by the two controllers namely; the yaw rate, the sideslip angle, and the steering wheel angle. The control action of the direct yaw moment is carried out by generating a differential braking across the front wheels, while the control action of the active steering is carried out by modifying the steering wheel angle. The controller design is carried out by fuzzy logic which suits the non-linearity of the derived model. In addition, all necessary membership functions are given to define the linguistic variables of the input and output variables. Consequently, the correlation between input and output variables are defined by the rule base tables.The numerical modelling is carried out through the MATLAB / Simulink environment which suits the control and optimization process. Different simulation results are carried out by considering standard test maneuvers with different driving speeds such as J-turn, fishhook, and lane change. The simulation results are compered during four cases namely, the conventional system without control, the DYC controller only, the AFS controller only and the integrated DYC and AFS controllers. The results show a substantial improvement of the vehicle stability in terms of vehicle lateral acceleration, side slip angle, yaw rate and roll angle for the developed integrated DYC and AFS controllers compared to that of the individual controller or the conventional system without control.

Design and Assessment of a Speed-Based Integrated Active Vehicle Controller for Lateral Stability

“…Model outputs are the desired lateral stability criteria: yaw rate, sideslip angle, lateral acceleration, etc. In steady state, the desired values of the vehicle sideslip angle and yaw rate, are expressed as follows [7], [15], [24], [26] • Desired sideslip angle…”

“…To limit lateral forces resulting from large lateral accelerations, the upper limits of the yaw rate and side slip angle are suggested as [15], [24], [26], [27S]:…”