A cooperative control strategy for yaw rate and sideslip angle control combining torque vectoring with rear wheel steering

Abstract

Automobiles are becoming more and more complex as multiple control systems are integrated into the vehicle platform. This paper investigates the coordination of active rear steering (RWS) and torque vectoring (TV) -which is enabled by independent electric motors at the rear axle -in controlling vehicle lateral dynamics. Specifically, the proposed controller aims at enhancing vehicle handling performance and stability while cornering. The coordination of the two control systems is achieved by weighting their contribution based on their impact on vehicle dynamics according to the working condition. The impact of each control system is assessed by means of phase portraits. These plots are in fact a very powerful tool for analyzing vehicle nonlinear dynamics as they readily display vehicle stability properties and map equilibrium point locations and movement to changing parameters and control inputs. Based on phase portrait analysis, a performance index is thus proposed, which weights more the control action (TV or RWS) capable of leading the vehicle at the nearest equilibrium point with the fastest rate. The controller performance is assessed through numerical simulations carried out using a nonlinear 14 dofs vehicle model. Results are compared with ones of the two controllers alone (RWS and TV) in different cornering maneuvers and considering different adherence conditions.

Towards Active Safety Driving: Controller Design of an Active Rear Steering System for Intelligent Vehicles

“…The SMPC controller is designed based on the discrete 4WS vehicle dynamic model, i.e., Equation (10). Firstly, the tracking control error is defined as e k = y k − y r k (11) where y r k is the reference value for tracking.…”

“…As for the AFS technique, the machine and human driver must address the shared control of the front steering system [8,9]. However, in the ARS technique, a human driver and the machine can independently control the front and rear steering systems [10]. As a result, the technique issue of control authority allocation and conflict resolution does not exist.…”

Optimal Cooperative Brake Distribution Strategy for IWM Vehicle Accounting for Electric and Friction Braking Torques

“…Driver model is needed to run close loop maneuver. It is path follower coupled with a cruise control to follow reference speed [10]. e path follower is a proportional controller based on distance error and heading error (see Figure 3):…”

“…To further analyze the controls performance in straight driving, two urban driving cycles, the NEDC [32] and WLTP [10], are simulated. e tests have been performed using the vehicle model described above and using a PI controller on vehicle speed to make the vehicle follow the velocity profile.…”

“…Another interesting feature offered by DEMs is the possibility of easily applying Torque Vectoring (TV) to improve the stability and performance of the car ( [8][9][10][11]). Furthermore, antilock braking systems (ABS) can benefit from EMs higher promptness, even when compared to hydraulic actuated mechanical brakes, thus reducing the car stopping distance ( [2,3]).…”