Model Predictive Path-Following Control for General n-Trailer Systems with an Arbitrary Guidance Point

This paper presents a method to stabilize a general vehicle-n-trailer configuration so that a specific point on the rearmost trailer follows a given reference path. The system can consist of any combination of on- and off-axle couplings. To achieve stabilization in forward and reverse driving, a model predictive control is used, which is based on a kinematic vehicle-trailer model. In order to follow the path with a specific point on the trailer, a coordinate transformation is applied to the cost function. This allows, amongst various applications, both the exact positioning of agricultural implements such as field sprayers and maneuvering double-turntable trailers with the rear edge of the trailer during alley docking. The optimization problem is solved with a real-time capable tailored gradient-based augmented Lagrangian approach. To validate the algorithm, simulations are performed against a dynamic two-track model with additive sensor noise. In one of the scenarios, an agricultural setup with one trailer in forward direction and a logistical setup with four trailers in reverse direction is demonstrated.