Enhancing Safety of Actively-Steered Articulated Vehicles
Subtitle: PhD Dissertation
Published: March 2009
Place of publication: Cambridge, UK
Description: Summary

This dissertation describes research on active trailer steering to improve roll stability and safety of articulated heavy vehicles at high speeds, and increase the manoeuvrability and reduce the road and tyre wear at low speeds.

A prototype active semitrailer steering system was available on an instrumental test vehicle and a path following controller was developed in a previous project. The primary aim of this project is to improve roll stability of articulated vehicles at high speeds.

Chapter 1 presents a literature review concerned with the background to trailer steering, rollover prevention, vehicle parameter and state estimation, and integrated steering and braking.

Chapter 2 presents simulation results of various brake actuation events on articulated vehicles with path following control. It is shown that the vehicle is stable under braking with path following control provided the Anti-lock Braking System is functioning. Active trailer steering can compensate the changing direction of trailer body caused by the braking forces and thus maintain the vehicle's yaw stability.

Chapter 3 and 4 present a strategy for estimating vehicle parameters and states. This strategy is examined in simulation and then validated in vehicle tests. The results show that the algorithms work effectively to estimate the vehicle parameters and states.

Chapter 5 develops an optimal active trailer steering controller at high speeds and a PID controller at low speeds. The high-speed controller ensures good path tracking in steady-state manoeuvres and reduces the lateral acceleration of the trailer CoG in transient manoeuvres. The low-speed controller ensures good path tracking for all manoeuvres. Simulations show that the active trailer steering controller can reduce lateral acceleration significantly, while maintaining acceptable path error.

Chapter 6 presents experimental tests on active steering controller in a full sized test vehicle. The tests verify the simulation results and show that the active steering is beneficial at all speeds. The active steering vehicle improves the roll stability by reducing the lateral acceleration of trailer CoG up to 27% while maintaining path tracking performance as good as a passive vehicle at high speeds. It is more manoeuvrable at low speeds, reducing the tyre wear and causing less road damage.
Table of contents: pagenum: 1-21
label: 1
class: chapter
title: Introduction; pagenum: 22-38
title: Investigation of Braking with Path Following Controller
class: part
label: 2; pagenum: 39-90
title: Vehicle Parameter and State Estimation
class: part
label: 3; pagenum: 91-114
title: Test of Vehicle Parameter and State Estimation
class: part
label: 4; pagenum: 115-203
label: 5
class: part
title: Active Trailer Steering Controller; pagenum: 204-235
title: Controller Implementation and Vehicle Test
class: part
label: 6; pagenum: 236-241
title: Conclusions and Recommendations
class: part
label: 7