Abstract
For the last 25 years, active chassis systems have become wide spread among automotive production, with the development of Anti Blocking System and Electronic Stability Program for braking systems, Active Damping, Hydractive suspensions, Active Body Control, Active Roll Control for suspension systems, and Active Front/ Rear for steering systems. X by Wire technologies is the next step in R&D, introducing new tuning parameters. The possibility to break mechanical links between each wheel offers new degrees of freedom for control. One of today´s questions is how to use the full potential of active systems´ combination, with a global performance higher than the sum of each system´s performance (1+1>2?). When many systems have yaw control properties, how does the vehicle´s controller (the ESP) select which the one to use when necessary?
Our paper presents a development technique, based on optimal solution algorithms, for research engineers tuning multi-parameters controllers. For given driving conditions, it helps to find the optimal combination of commands for many actuators. A Matlab / Simulink based vehicle dynamic model allows the use of external controllers for active chassis systems. The first step is to tune a few stand-alone controllers (ESP and/or AFS) for certain driving conditions, such as split-µ braking or brake cornering. With the help of optimisation codes available in Matlab or developed for this purpose, we find the optimal control commands (constant or time-variant) for the same driving conditions (split-µ braking or brake cornering) with the same active systems (braking and/or steering), and we prove we get better results. The main idea is to get the best results possible without any control law, and to define the control laws. This helps the evaluation of new chassis systems at an early stage, and the choice of actuators when no control law is yet available.
Keywords - Chassis, active, intersystem, control, optimisation