Roll motion control with a fully active suspension system: High-Level Motion Control and Low-Level Actuator Implementation

Abstract

During cornering, vehicle roll motion directly affects lateral load transfer, tire force distribution, and handling consistency. This thesis therefore investigates roll-gradient shaping for a fully active suspension system in simulated cornering maneuvers and driver-in-the-loop tests, with emphasis on how body-level roll objectives can be realized through actuator-level force generation. The proposed method combines a high-level body-motion controller with a low-level hydraulic actuator controller. At the high level, lateral acceleration is estimated from vehicle speed and steering input and used to generate a feedforward roll moment, while proportional-integral (PI) feedback is applied to roll, pitch, and heave states. The resulting generalized force and moment targets are transformed into corner suspension-force commands through a pseudoinverse force-allocation method. At the low level, the required damper forces are converted into continuously controlled damper (CCD) current commands and motor-pump unit (MPU) flow-rate commands using supplier-based lookup tables and mode-switching logic. The controller is implemented in MATLAB/Simulink and evaluated in both IPG CarMaker and the VI-CRT driver-in-the-loop real-time simulator. In CarMaker, the proposed controller tracks prescribed roll-gradient targets and produces suspensionforce distributions that remain consistent with the intended vehicle behavior. The low-level controller also shows satisfactory force-tracking performance, with the main deviations appearing near rapid force reversals. In the VI-CRT simulator, the controller preserves the expected roll characteristics over a wide lateral acceleration range under real-time driving conditions, despite driver input variability and transient steering effects. Overall, the results show that roll-motion control for a fully active suspension system should be evaluated as a connected body-level and actuator-level problem. Highlevel motion objectives and low-level actuator behavior must therefore be considered together when evaluating active suspension concepts.