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Title:Active suspension co-design for lateral stability of rail vehicles
Author(s):Arora, Madhav
Advisor(s):Allison, James T.
Department / Program:Industrial&Enterprise Sys Eng
Discipline:Industrial Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Dynamic stability
Active suspensions
Rail car
Rail vehicle
Passenger rail car
Optimal control
Abstract:Railroad transportation is one of the most cost-effective and energy-efficient modes of land transportation. With an eye toward improving these efficiencies, many efforts have focused on developing high speed railways. Traditionally railways have utilized passive suspension systems, but maintaining dynamic stability at higher speeds demands enhancements to existing rail vehicle suspensions. One strategy to improve dynamic performance is to incorporate active or semi-active elements, such as force actuators or variable dampers, within the suspension system. Modern day road and rail vehicles often utilize such actively-controlled suspensions to improve stability, ride comfort and ride quality at high speeds. The dynamic performance of such mechatronically-controlled suspension systems is related closely to the congruence of the design of passive elements in conjunction with the chosen control system strategy. Historically, design of controlled dynamic systems has followed a sequential process (mechanical design followed by control design). In the field of mechatronics, engineers typically use design rules or heuristics that help account for design coupling, but cannot produce system optimal designs. Passive elements are optimally designed first, followed by the addition of controllers for system performance improvements. New integrated design strategies are required to realize the full potential of such advanced complex dynamic systems and to capitalize on design coupling. This thesis aims to explore and apply a recently developed synergistic approach to design of controlled dynamic systems, called co-design. Theoretical models of existing partitioned, optimization-based design methods are compared to this combined active and passive system design strategy. Parameters for a reduced and a full-scale rail vehicle model are then designed using the developed optimal design formulations. Different control techniques within the co-design framework are tested and compared. Typically feedback controllers are required for actual implementation of control strategies. Early-stage co-design strategies are normally based on open-loop control, therefore, are limited for functional implementation. However, co-design methods provide designers with better knowledge about the true performance limits of dynamic systems, help them make more informed design decisions, and provide a foundation for development of implementable feedback control systems. The results obtained in this thesis show significant improvements achieved by co-design strategies over passive system design and sequential design approaches. The results also demonstrate the potential of this framework in helping systematic selection of optimal plant design variables, controller architecture, and implementable control techniques. Future work includes designing practical feedback controllers built upon results from co-design strategies for rail vehicles using non-linear vehicle models to provide a complete active rail suspension solution.
Issue Date:2017-12-13
Rights Information:Copyright 2017 Madhav Arora
Date Available in IDEALS:2018-03-13
Date Deposited:2017-12

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