Advanced vehicle control of heavy vehicles for automated highway systems

This dissertation is concerned with the lateral and longitudinal control of heavy vehicles for Automated Highway Systems.; Two kinds of models are derived for general multi-unit heavy vehicle systems: a complex simulation model and a simple control model. In the simulation model, each unit of a heavy vehicle system is treated as a rigid body with 6 degree-of-freedom unless constrained by hitching mechanisms. The roll and pitch motion coupling due to the holonomic constraints imposed by hitching mechanisms and the backward propagation of this coupling are modeled from the view point of geometry. The control model considers translational and yaw motions of each unit and the resulting equations of motion are given in closed analytical forms.; A physical model of the steering subsystem of heavy vehicles is derived by ignoring the dynamics of the hydraulic power assist unit. Based on the open-loop tests and the analysis of the physical model, a second order linear model of the steering subsystem is obtained. Then, a linear robust loop-shaping controller is designed in the frequency domain so that the local closed-loop dynamics of the steering subsystem has a good tracking performance.; The vehicle lateral control model is nonlinear and has two types of model uncertainties: dynamical nonlinear uncertainties and parametric uncertainties. Various nonlinear robust control techniques such as sliding mode control, adaptive robust control, and robust nonlinear control based on feedback linearization are sought. To further improve robust performance, the dynamics of the steering subsystem is considered in the lateral controller design. In doing so, to account for the saturation and rate limit in the steering subsystem, a nonlinear loop-shaping approach is proposed. An analogy between the road disturbance to a vehicle lateral control system and the Coulomb friction to a mechanical system is observed. Based on this observation, two feedforward compensators are proposed which can be used in combination with linear robust controllers to further improve tracking performance of the linear feedback control systems. (Abstract shortened by UMI.)...