Vehicle Dynamics Modeling and Control of the TowPlow, A Stee

Vehicle Dynamics Modeling and Control of the TowPlow,

A Steerable Articulated Snow Plowing Vehicle System

By

Jae Young Kang

B.S. (Sungkyunkwan University, Korea) 2009

M.S. (Sungkyunkwan University, Korea) 2011

DISSERTATION

Submitted in partial satisfaction of the requirements for the degree of

DOCTOR OF PHILOSOPHY

in

Mechanical and Aerospace Engineering

in the

OFFICE OF GRADUATE STUDIES

of the

UNIVERSITY OF CALIFORNIA

DAVIS

Approved:

____________________________

Steven A. Velinsky, Chair

____________________________

Donald L. Margolis

___________________________

Sanjay S. Joshi

Committee in Charge

2014

UMI Number: 3646318

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UMI 3646318

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Abstract

The TowPlow is a novel type of snowplow that consists of a conventional snowplow vehicle and a steerable, plow-mounted trailer. The trailer is equipped with hydraulic-powered steerable axles so that it can be steered up to 30 degrees with respect to the tractor. The combination of the front plow of the towing snowplow and the trailer-equipped plow is able to clear a path up to approximately 24-ft wide, which is the width of two typical traffic lanes. While the TowPlow may increase the efficiency and performance of the snow removal operation, the stability of the system under the harsh winter conditions may be compromised by implementation of the steerable trailer, and safety of the system must be ensured. The kinematic characteristics of the TowPlow are derived using instantaneous centers of velocity. Based on the derived equations, the relation between the radius of curvature and the trailer wheel steering angle that allows the tractor-trailer to maintain its initial articulation angle is defined to be used in a kinematics-based control of the TowPlow. Then, a linear dynamic model is developed in order to investigate the dynamic behavior of this system and its stability limits. Dynamic simulations of various maneuvers are performed, and kinematics-based control is implemented to investigate performance of the trailer’s corrective steering. The goal is to ensure that the trailer does not intrude into adjacent lanes during plowing operations while also ensuring that both lanes are sufficiently cleared. Even though the control input is obtained from kinematic analysis, which does not take forces and inertia into account, the simulation results clearly show that the corrective steering helps the TowPlow meet its performance goals.

Also, a nonlinear dynamic model of the TowPlow for longitudinal, lateral, and yaw motions is developed with the state variables of longitudinal velocity, lateral velocity and yaw rate of the towing unit, yaw rate of the trailer unit, and the articulation angle between the two units. The model includes a modified Dugoff’s tire friction model, tire rotation dynamics and the load transfer effect. The model is validated through full-scale experiments of the TowPlow under both steady-state and transient conditions. For completion of the nonlinear dynamic model, a snow resistance model is developed to estimate the snow resistant forces on each plow of the TowPlow. Dynamic simulations of the nonlinear TowPlow model including the snow resistance are performed without any controller. The effect of the snow resistance on the dynamics and stability of the TowPlow is discussed for various maneuvers such as cornering, slalom, up and down hill, and split friction coefficient braking.

Finally, an active steering control of the trailer axle is introduced to prevent the TowPlow from intruding into the adjacent lane and also from missing certain portions of the lane during its snow removal operation. The linear quadratic regulator (LQR) based closed-loop controller is developed utilizing the linear TowPlow model. Performance of the LQR controller is compared to that of a simple PI controller. Dynamic simulations of the TowPlow with the trailer active steering control are performed for the same maneuvers simulated with the uncontrolled system. The comparison of the simulation results between the controlled system and the uncontrolled system clearly demonstrates that the implementation of active steering control for the trailer axle will improve safety and efficiency of the TowPlow. Such control keeps the TowPlow from either intruding into the adjacent lane or missing large portions of the lane by maintaining its total articulation angle in its snow removal operation.

Acknowledgements

First, I would like to thank my advisor, Professor Steven A. Velinsky for his immeasurable support and supervision. I deeply appreciate his technical insight and management of the AHMCT. I learned many things from him. It was great opportunity for me to work with him at AHMCT.

I would like to also thank my dissertation committee, Professor Donald L. Margolis and Professor Sanjay S. Joshi, for their time, consideration, and encouragement.

I would also like to thank Duane Bennett, George Bur …… 此处隐藏：5574字，全部文档内容请下载后查看。喜欢就下载吧 ……