| Description |
Trailer operations are very common in both daily life and industry. Trailer operations, especially trailer backing operations, can be conducted using autonomous systems, which are more efficient and accurate than human drivers and thus can save time and money. This dissertation presents three studies for building a high performance autonomous trailer control system, which are the automated parameter identification, the simple trailer control method considering sideslip, and the trailer jackknifing analysis. In the first study, a dual control method is designed to identify trailer-related parameters while controlling the vehicle to follow a given path. The identification enhancer designed as a part of the dual controller can ensure accurate estimation result even on the most identification-hostile path. This method is designed so that trailer-related parameters can be accurately identified while the vehicle-trailer system is conducting other operations, autonomous or manual. Then, when the system needs to conduct a trailer operation, the trailer-related parameters have been accurately identified and there is no need to allocate extra time and space for identification. Experimental results are provided to verify the dual controller design. In the second study, a curvature-based trailer control method is developed. This method is easy to implement and applicable for both trailer forward and backward operations. Additionally, the curvature-based method provides higher tracking accuracy, especially on paths with varying curvature. This method is also designed with sideslip taken into consideration, which ensures high path tracking performance in the presence of significant side slope and/or centripetal acceleration. Simulation and experimental results are provided to demonstrate the performance of this control method. In the third study, a thorough analysis of trailer jackknifing behavior is provided. In trailer control, jackknifing usually refers to the situation where the hitch angle is uncontrollable, which typically means that the magnitude of hitch angle keeps increasing regardless of what steering angle is applied. This situation is very common during trailer backing. If it is not handled properly, the vehicle and trailer may collide and result in physical damage. Detailed derivations are provided to understand jackknifing behavior and calculate jackknife limits. The derivation results are verified in simulations and experiments. This study can help the trailer controller to identify jackknife states and recover from or avoid jackknifing. By combining the three studies, autonomous trailer operation can be done with high performance both in tracking accuracy and efficiency. Physical damage from unhindered jackknifing can also be avoided. |
