Publication

High Capacity Transport projects aim at introducing longer and heavier vehicle combinations to European roads. This thesis focuses on an A-double combination (trucksemitrailer- dolly-semitrailer). To enhance safety and maneuverability of such combination, active steering is employed on the dolly's axles. In this thesis dierent strategies are developed and compared for low-level steering control. To this end, rst a control oriented steering model is proposed, using the Pacejka tire model. Then the steering actuator is estimated, based on measurement data from its supplier, using predictor based subspace identication algorithm. The control problem is to track the reference steering angle, desired by the high-level controller. The controller must provide good performance while rejecting disturbances and noises regardless of velocity and load. Before synthesizing the controller, frequency analysis of the disturbances is performed. First a simple PID controller is developed, based on xed structure H1 design and compared with a PI controller formulated by linearizing the simulator, provided by Volvo Trucks. Then a 2 DoF H1 controller is designed in a general form. Finally, to cope with the variation of load and velocity a Linear Parameter Varying (LPV) controller is proposed. Because the actuator has magnitude and rate limits, the control loop has to be augmented with anti-windup compensator. The controllers are then compared in both frequency- and time domain. The results are also validated on Volvo's high fidelity simulator for critical maneuvers, such as low speed U-turn or high speed lane-change.