Active trailer steering control of an articulated system with a tractor and three full trailers for tractor-track following

We examine several control strategies to minimise off-tracking of a multi-axle steering system with a tractor and three full trailers, described by a linear yaw-plane model. Given any arbitrary tractor track desired real-time by the driver, control inputs are the steering angles of front axles of the trailers. A minimum Rearward Amplification Ratio (RWA), as a surrogate for minimum off-tracking, is used as the control criterion to arrive at an optimal LQR controller, which is remarkably robust to tyre-parameter variations. Actively steering trailers 1 and 2 is most cost-effective in achieving acceptable levels of RWA, with off-tracking practically eliminated.