Consistent Path Planning for On-Axle-Hitching Multisteering Trailer Systems

In this paper, consistent path planning for a multisteering trailer system (MSTS) with on-axle hitching is addressed, such that all the bodies of the MSTS can follow a same motion path. A two-level path planner is designed. In the first level, a desired path profile (DPP) composed of a main path profile (MPP) that can be chosen as any of the widely used curves/splines, as well as multiple accessorial path profiles that are introduced to meet arbitrary initial states of the trailers, is planned. In the second level, to obtain different motion trajectories for the tractor and trailers from the same DPP, we consider consistent path planning for multiple bodies of the MSTS as a problem of formation tracking in a leader-follower configuration. It is further converted into an optimal control problem using the sum of the distance errors between adjacent bodies as the cost function and time-varying delays between adjacent bodies along the DPP as the system states. This problem is solved by the Gauss pseudospectral method to generate motion trajectories for multiple trailers, which approximately correspond to the same DPP. The simulation and experimental results are presented to show the effectiveness of the proposed method.