Publication

This thesis focuses on the design of steering control strategies in long combination of heavy vehicles. In particular, we consider the problem of controlling the steering angle of the axles of a unit called dolly, connecting a truck and a semi-trailer in a so called "Nordic combination" that has a total length of 25 meters and a weight of about 60 tons. The control problem can be stated as the problem of tracking a desired wheel angle with desired performance in a given ranges of vehicle speed and road friction. Designing a model-based control law is challenging due to the strong nonlinearities stemming from the interaction between the road and the tire contact patch. The thesis contribution are the designs of a (i) simple Proportional-Integral (PI) controller and (ii) a Linear Parameter Varying (LPV) controller, based on Linear Matrix Inequalities (LMI) techniques. Contribution (i) aims at showing the limitation of a simple linear controller, while the objective of contribution (ii) is to propose a design framework for low level steering control strategies operating in wide ranges of speed and road friction.