Vehicle Dynamics, Stability and Control 2014-01-0134
In the last years the number of electronic controllers of vehicle dynamics applied to chassis components has increased dramatically. They use lookup table of the primary order vehicle global parameters as yaw rate, lateral acceleration, steering angle, car velocity, that define the ideal behavior of the vehicle. They are usually based on PID controllers which compare the actual behavior of every measured real vehicle data to the desired behavior, from look up table. The controller attempts to keep the measured quantities the same as the tabled quantities by using ESP, TC (brakes and throttle), CDC (control shocks absorbers), EDIFF(active differential) and 4WS (rear wheels active toe). The performances of these controls are good but not perfect. The improvement can be achieved by replacement of the lookup tables with a fast vehicle model running in parallel to the real vehicle. This model will allow to anticipate the vehicle reactions to driver maneuvers or the effect of road conditions, and will simplify the regulations of the controller making hopefully them more smoother (feed forward control). Firstly a low dof model of suspensions kinematics with a reduced number of bodies can be used. Then a more complicate and fast model with an accurate representation of tires, steering, suspensions and powertrain components will be used and running inside of the central vehicle dynamics ecu. The subjects of measuring and calculating the real car secondary order parameters like forces and side slip on the contact patches to have more detail information to correct the car model when it diverts from the real car behavior are described in this article.