Mirko Čorić

Optimization of Active Suspension Control Trajectories Towards Vehicle Dynamics Performance Improvements

Doctoral thesis (in Croatian), Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia, 2017
Active suspension is commonly applied under the framework of vertical vehicle dynamics control aimed at improvements in the ride comfort. In this thesis, a pseudospectral collocation method of control trajectory optimization is used to investigate to what extent the fully active suspension application can be broadened to other vehicle dynamics control tasks. Enhancements of the vertical vehicle dynamics performance in the presence of emphasized road bumps and potholes are first investigated, taking into account realistic constraints of the suspension and its actuator. Next, enhancements of lateral vehicle dynamics performance in terms of path following error reduction are investigated for three types of double lane change maneuvers. The optimization approach is firstly applied to solely FAS actuator configurations, and then extended to combined FAS and active front and/or rear steering configurations. The lateral vehicle dynamics analysis is further extended to vehicle stabilization task for the sine-with-dwell maneuver. Finally, the analysis covers the braking distance reduction task based on a cooperative use of active suspension and anti-lock braking system actuators.The major contributions of the doctoral thesis are: 1) formulation and implemention of control variable optimization model for different active vehicle dynamics system configurations and different maneuvers, with nonlinear and discontinuous vehicle and tire dynamics effects included; 2) revealing active suspension control mechanisms for improving vehicle comfort, handling, and wheel damage resilience in the presence of discrete road disturbances, such as large bumps and potholes, and realistic suspension and actuator constraints; and 3) revealing active suspension control mechanisms for lateral vehicle stability improvement and braking distance reduction in the interaction with active steering systems, and ESP and ABS actuators.