Doctoral Dissertations (FEAS)

Permanent URI for this collectionhttps://hdl.handle.net/10155/401

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Browsing Doctoral Dissertations (FEAS) by Subject "Active trailer steering"

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    Autonomous driving control strategies for multi-trailer articulated heavy vehicles with active safety system
    (2023-05-01) Rahimi, Amir; He, Yuping
    This study aims to develop automated driving strategies and integrated active control system for multi-trailer articulated heavy vehicles (MTAHVs) to enhance road transport efficiency, directional performance, and safety. To this end, a MTAHV with the configuration of A-train double was selected to be the subject vehicle, and the required vehicle models were generated. The corresponding nonlinear TruckSim model was employed as the virtual for co-simulations. The original contributions of the thesis in autonomous driving control of MTAHVs include: 1) a lateral preview driver model for MTAHVs was developed using the optimal preview control method; 2) a longitudinal motion-planning and control strategy using fuzzy sets was also devised; 3) an integrated control system was designed for coordinating autonomous driving and active trailer and dolly steering (ATDS) using a model predictive control (MPC) technique; and 4) a model-based predictive motion planning method was developed using the Frenet-Serret frame. The proposed lateral preview driver model may operate in two modes according to varied forward speed: i) in high-speed operations, the lateral stability is prioritized, and the high-speed and stability-oriented mode is activated; ii) while in low-speed curved path negotiations, the path-following off-tracking performance is emphasized, and the low-speed path-following mode is activated. It also takes benefits of the vehicle units’ body-fixed reference frames for lateral deviation calculations to mimic the driver’s local perception of vehicle position and reference path. If the so-called driver neuromuscular delay is set to zero, the driver model may perform as an autonomous human-like controller for vehicle lateral motion control. The devised longitudinal motion planner considers the road curvature over a preview horizon to regulate vehicle forward speed. It is featured with the predictive and compensatory throttle/brake actuations to assure all the vehicle units’ lateral stability. The MPC-based control method integrates the ATDS into the automated tractor steering and speed control, while the ATDS is activated to operate in either high-speed or low-speed mode, thereby improving the directional performance. The developed trajectory planner benefits from a model-based predictive approach to customize the generated trajectory to enhance the lateral stability in high-speed evasive maneuvers. The innovative findings of this dissertation will contribute to the advancement and development of autonomous driving control for MTAHVs.
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    Design synthesis of articulated heavy vehicles with active trailer steering systems
    (2010-04-01) Islam, Md. Manjurul; He, Yuping
    A new design synthesis method for articulated heavy vehicles (AHVs) with an active trailer steering (ATS) system is examined and evaluated. Due to their heavy weights, large sizes, and complex configurations, AHVs have poor maneuverability at low speeds, and low lateral stability at high speeds. Various passive trailer steering and ATS systems have been developed for improving the low-speed maneuverability. However, they often have detrimental effects on the high-speed stability. To date, no systematic design synthesis method has been developed to coordinate the opposing design goals of AHVs. In this thesis, a new automated design synthesis approach, called a Single Design Loop (SDL) method, is proposed and investigated. The SDL method has the following distinguished features: 1) the optimal active design variables of ATS systems and the optimal passive vehicle design variables are searched in a single design loop; 2) in the design process, to evaluate the vehicle performance measures, a driver model is developed and it „drives‟ the vehicle model based on the well-defined testing specifications; and 3) the ATS controller derived from this method has two operational modes: one for improving the lateral stability at high speeds and the other for enhancing path-following at low speeds. To demonstrate the effectiveness of the new SDL method, it is applied to the design of an ATS system for an AHV with a tractor/full-trailer. In comparison to a conventional design approach, the SDL method can search through solutions in a much larger design space, and consequently it provides a more comprehensive set of optimal designs..