Articulated Vehicles

Being cost effective due to reduction in labour requirements and fuel consumption, and large load carrying capacity compared to single unit vehicles, Articulated Heavy Vehicles (AHVs) are among the most widely used means of road transport. On the other hand, AHVs impose higher highway safety concerns which are different from single unit vehicles; heavy weights, large dimensions, geometrical configuration, high centres of gravity, and inner forces acting on their articulation points are the main sources for these differences.

The presence of the articulation joint helps to reduce the effective wheelbase of the vehicle in order to improve low-speed turning ability, while large weights and high Centre of Gravity (CG) of AHVs reduce the high-speed stability in three different potentially unstable motions: jack-knifing, trailer swing, and rollover.

This research aims at developing high and low speed automatic trailer steering strategies to improve the vehicle performance and manoeuvrability. Passive semitrailer steering systems have been developed at the earlier stages of AHV research. Command steering, self-steering axle, and pivotal bogie systems are among the most common passive steering systems. Studies on the passive semitrailer steering systems have concluded that the passive steering systems improve low-speed manoeuvrability and tyre-road scrub; however they appear to diminish the high-speed lateral performance of the vehicle.

In this study a new approach to semitrailer active steering strategy is introduced. The control strategy is expected to provide a simpler yet sufficiently accurate approach to semitrailer steering, in comparison to the more sophisticated methods requiring intensive mathematical calculations and hardware requirements. The LQR control together with Quantum Particle Swarm Optimisation (QPSO) method is used to ensure the optimal solution avoiding manual tuning of design parameters.

Keywords: Articulated Vehicle, Tractor-Semitrailer, Active Steering, Optimal Control, Vehicle Safety