Active suspension control systems: Theoretical issues and experimental results

This work bridges the gap between theoretical optimal control and applied vehicle dynamics. Various control schemes are suggested based on intuition, experience, and the vehicle dynamics literature. These control strategies are analyzed, and compared with relevant optimal strategies.; Roll moment distribution has long been appreciated by vehicle dynamists as important in determining vehicle handling characteristics. This phenomenon is shown to be inherently nonlinear. Various control schemes are suggested, including active damping and active roll moment distribution based on sliding mode control, feedback linearization, and intuition. The limits of variable damping are demonstrated. The intuitive active roll moment distribution control law is shown via simulation to perform well relative to the more complicated model based nonlinear controllers, as well as the active damper. The intuitive roll moment distribution algorithm is then implemented on an active suspension vehicle.; Two full vehicle active suspension controllers are then formulated to combine the intuitive active roll moment distribution algorithm with vehicle vibration isolation algorithms. One follows directly from Karnopp's skyhook damping notion, the other is a combination of Karnopp's skyhook damper and the Lotus modal control. Vibration isolation properties of the suggested algorithms are shown to compare well with linear-quadratic full state feedback optimal controllers. The results are control algorithms which simultaneously improve vehicle ride and handling, and are easily implemented.