Dissertations / Theses on the topic 'Automotive Suspension And Steering Systems'

This thesis considers the neural network learning control of a variable-geometry automotive active suspension system which combines most of the benefits of active suspension systems with low energy consumption. Firstly, neural networks are applied to the control of various simplified automotive active suspensions, in order to understand how a neural network controller can be integrated with a physical dynamic system model. In each case considered, the controlled system has a defined objective and the minimisation of a cost function. The neural network is set up in a learning structure, such that it systematically improves the system performance via repeated trials and modifications of parameters. The learning efficiency is demonstrated by the given system performance in agreement with prior results for both linear and non-linear systems. The above simulation results are generated by MATLAB and the Neural Network Toolbox. Secondly, a half-car model, having one axle and an actuator on each side, is developed via the computer language, AUTOSIM. Each actuator varies the ratio of the spring/damper unit length change to wheel displacement in order to control each wheel rate. The neural network controller is joined with the half-car model and learns to reduce the defined cost function containing a weighted sum of the squares of the body height change, body roll and actuator displacements. The performances of the neurocontrolled system are compared with those of passive and proportional-plusdifferential controlled systems under various conditions. These involve various levels of lateral force inputs and vehicle body weight changes. Finally, energy consumption of the variable-geometry system, with either the neurocontrol or proportional-plus-differential control, is analysed using an actuator model via the computer simulation package, SIMULINK. The simulation results are compared with those of other actively-controlled suspension systems taken from the literature.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2007.
Includes bibliographical references (p. 195-201).
The design of existing suspension systems typically involves a compromise solution for the conflicting requirements of comfort and handling. For instance, cars need a soft suspension for better comfort, whereas a stiff suspension leads to better handling. Cars need high ground clearance on rough terrain, whereas a low center of gravity (CG) height is desired for swift cornering and dynamic stability at high speeds. It is advantageous to have low damping for low force transmission to vehicle frame, whereas high damping is desired for fast decay of oscillations. To eliminate these trade-offs, a novel design for a customizable automotive suspension system with independent control of stiffness, damping and ride-height is proposed in this thesis. This system is capable of providing the desired performance depending on user preference, vehicle speed, road conditions and maneuvering inputs. The design, fabrication and control of the customizable suspension prototype are discussed. The application of variable stiffness and variable ride-height suspension system to achieve improved vehicle dynamics is studied. Application to control of vehicle dynamics parameters required bandwidth and power input beyond the capability of the first prototype.
(cont.) To eliminate the bandwidth restrictions of the prototype, a variable-stiffness pneumatic suspension system capable of instantaneous stiffness change with essentially no power input and no ride-height change, is developed. This is done by supporting the vehicle on air springs and connecting each air spring volume to multiple auxiliary volumes through On-Off valves. By adequately choosing N unequal auxiliary volumes, this system can achieve 2N stiffness settings. This suspension has been incorporated in a car suspension. The design, fabrication, and testing of the suspension system are reported in this thesis. A detailed frequency-domain model for the air-spring with auxiliary volumes is developed. Based on this modeling and testing, the performance limits and practical applicability of this system are discussed. The proposed variable stiffness isolator is capable of instantaneous stiffness change with no power input and no dimension change; moreover the isolator is inexpensive, robust and light. As a result, it is readily applicable to several other vibration isolation applications with conflicting stiffness requirements (such as a precision motion stages) or time-varying stiffness requirements (such as prosthetic limbs) and these applications are discussed.
by Hrishikesh V. Deo.
Ph.D.

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 101-103).
The automotive industry is constantly challenged with meeting and exceeding customer expectations while reducing time to market of new products in order to remain competitive. Providing new features and functionality into vehicles for customer satisfaction is becoming more challenging and driving design complexity to a higher level. Although traditional methods of Product Development Failure Mode identification such as FMEA (Failure Mode and Effect Analysis) or FTA (Fault Three Analysis) have been used to analyze failures in automotive systems, there are limitations when it comes to design errors, flawed requirements, human factors implications, and component interaction accidents in which all components operated as required but the system behavior was not as expected. In order to determine if there is room for improvement in current automotive product development process, this thesis applies Dr. Nancy Leveson's Systems-Theoretic Process Analysis (STPA) technique to compare and contrast with a Failure Modes and Effects Analysis (FMEA) approach as used in the automotive industry through a case study. A formal method of comparing results is proposed. This study found limitations with FMEA in terms of identifying unsafe interactions between systems, anticipating human error and other behaviors dependent on human interaction, identifying engineering design flaws, and producing requirements. STPA was able to find causes that had a direct relationship with those found in FMEA while also finding a portion of causes related to a higher level of abstraction of those in FMEA. STPA also found a subset of causes that FMEA was not able to find, which relate mainly to engineering design flaws and system interaction.
by Rodrigo Sotomayor Martínez.
S.M. in Engineering and Management

The fundamental properties of various automotive suspension systems are theoretically investigated on the basis of simple vehicle models subjected to realistic inputs chosen to represent road surfaces of different qualities. The vehicle response is evaluated through a performance index representing ride comfort, dynamic tyre load and suspension working space parameters, and interpreted in the light of these individual parameters together with the implications of the suspension design for attitude control and steering behaviour. Linear analysis procedures are followed in studying the passive, active and slow-active suspension systems while suitable simulations are used for the non-linear semi-active suspension systems. Linear optimal control theory is used to determine the optimal parameters of the active and slow-active suspension systems. Semi-active suspension behaviours are evaluated on the basis of applying the optimal active parameters to each system, but the semi-active damper can only dissipate energy and switches off when external power would be needed for the system to follow the optimal active control law. Results are generated and discussed for each of these types of system and their performance capabilities are compared with each other. Conclusions concerning the practical viability of each of the systems are drawn.

Cette thèse traite de la synthèse et de la mise en œuvre en temps réel (RT) de schémas de contrôle prédictif non linéaire paramétré (pNMPC) pour les systèmes de suspension semi-active des automobiles. Le schéma pNMPC est basé sur une technique d'optimisation par simulation en boîte noire. Le point essentiel de la méthode est de paramétrer finement le profil d'entrée et de simuler le système pour chaque entrée paramétrée et d'obtenir la valeur approximative de l'objectif et de la violation des contraintes pour le problème pNMPC. Avec les résultats obtenus de la simulation, l'entrée admissible (si elle existe) ayant la valeur objective minimale ou, à défaut, la valeur de violation de contrainte la plus faible est sélectionnée et injectée dans le système et ceci est répété indéfiniment à chaque période de décision. La méthode a été validée expérimentalement sur dSPACE MicroAutoBoX II (MABXII) et les résultats montrent de bonnes performances de l'approche proposée. La méthode pNMPC a également été étendue à une méthode pNMPC parallélisée et la méthode proposée a été mise en œuvre pour le contrôle du système de suspension semi-active d'un demi-véhicule. Cette méthode a été mise en œuvre grâce à des unités de traitement graphique (GPU) qui servent de plate-forme modèle pour la mise en œuvre d'algorithmes parallèles par le biais de ses processeurs multi-cœurs. De plus, une version stochastique de la méthode pNMPC parallélisée est proposée sous le nom de schéma pNMPC à Scénario-Stochastique (SS-pNMPC). Cette méthode a été mise en œuvre et testée sur plusieurs cartes NVIDIA embarquées pour valider la faisabilité de la méthode proposée pour le contrôle du système de suspension semi-active d'un demi-véhicule. En général, les schémas pNMPC parallélisés offrent de bonnes performances et se prêtent bien à un large espace de paramétrage en entrée. Enfin, la thèse propose un outil logiciel appelé "pNMPC - A code generation software tool for implementation of derivative free pNMPC scheme for embedded control systems". L'outil logiciel de génération de code (S/W) a été programmé en C/C++ et propose également une interface avec MATLAB/Simulink. Le logiciel de génération de code a été testé pour divers exemples, tant en simulation que sur du matériel embarqué en temps réel (MABXII), et les résultats semblent prometteurs et viables pour la mise en œuvre de la RT pour des applications réelles. L'outil de génération de code S/W comprend également une fonction de génération de code GPU pour une mise en œuvre parallèle. Pour conclure, la thèse a été menée dans le cadre du projet EMPHYSIS et les objectifs du projet s'alignent sur cette thèse et les méthodes pNMPC proposées sont compatibles avec la norme eFMI
This thesis discusses the synthesis and real-time (RT) implementation of parameterized Nonlinear Model Predictive Control (pNMPC) schemes for automotive semi-active suspension systems. The pNMPC scheme uses a black-box simulation-based optimization method. The crux of the method is to finitely parameterize the input profile and simulate the system for each parameterized input and obtain the approximate objective and constraint violation value for the pNMPC problem. With the obtained results from the simulation, the input with minimum objective value or the least constraint violation value is selected and injected into the system and this is repeated in a receding horizon fashion. The method was experimentally validated on dSPACE MicroAutoBoX II (MABXII) and the results display good performance of the proposed approach. The pNMPC method was also augmented to parallelized pNMPC and the proposed method was implemented for control of semi-active suspension system for a half car vehicle. This method was implemented by virtue of Graphic Processing Units (GPUs) which serves as a paragon platform for implementation of parallel algorithms through its multi-core processors. Also, a stochastic version of the parallelized pNMPC method is proposed which is termed as Scenario-Stochastic pNMPC (SS-pNMPC) scheme and the method was implemented and tested on several NVIDIA embedded boards to verify and validate the RT feasibility of the proposed method for control of semi-active suspension system for a half car vehicle. In general, the parallelized pNMPC schemes provide good performance and also, fares well for large input parameterization space. Finally, the thesis proposes a software tool termed “pNMPC – A code generation software tool for implementation of derivative free pNMPC scheme for embedded control systems”. The code generation software (S/W) tool was programmed in C/C++ and also, provides interface to MATLAB/Simulink. The S/W tested for variety of examples both in simulation as well as on RT embedded hardware (MABXII) and the results looks promising and viable for RT implementation for real world applications. The code generation S/W tool also includes GPU code generation feature for parallel implementation. To conclude, the thesis was conducted under the purview of the EMPHYSIS project and the goals of the project align with this thesis and the proposed pNMPC methods are amenable with eFMI standard

L'objectif principale de cette thèse est de développer contrôleurs innovants MIMO pour la dynamique véhicule tout en préservant la stabilité du véhicule dans les situations de conduite critiques. Des stratégies de commandes innovatrices ont été introduites pour résoudre cette problématiques. En effet, ces travaux se base sur travaux l'utilisation de la commande LPV/Hinf pour contrôler simultanément les actionneurs de freinage, braquage et de suspensions pour réaliser les objectives du contrôle.Aussi de stratégies d'estimation du profil de route très intéressant et qui peuvent apporter une solution industrielle très intéressante pour développer des contrôleurs qui assurent adaptative aux différentes conditions de route.Aussi des stratégies de commande tolérante aux défauts actionneurs ont été établi en exploitant les caractéristiques de la commande LPV pour compenser la perte de certains actionneurs (en sachant que la voiture est un système sur actionné). Des implémentations ont été effectuées sur des bancs de test et sur un véhicule réel pour prouver l'efficacité des stratégies
The main issue of this thesis is to work out new Global Chassis MIMO controllers that enhance the overall dynamics of the vehicle while preserving the vehicle stability in critical driving situations. Many innovative strategies have been explored and finalized to deal with these problematics. Various solutions have been given to deal with the vehicle stability and performance objectives. Indeed, many works based on the LPV/Hinf approach have been developed to control simultaneously the braking, steering and suspension actuators. On the other hand, innovative road profile estimation strategies have been introduced and validated via experimental procedures, providing new cheap and easily implementable techniques to estimate the road profile characteristics. Then, the vehicle control is adapted, depending on the road roughness (since it influences greatly the behaviour and the stability of the car). Several fault tolerant control strategies have been also considered to handle the actuators failures while keeping the vehicle stability, safety and enhancing the dynamical behaviour of the car in dangerous and critical driving situations.The general content of this thesisis as follows :-PART I : Theoretical backgrounds and vehicle modeling.-PART II : Road adaptive control vehicle dynamics.-PART III : Global chassis control using several actuators.Also, during this thesis and using the previous works of the advisors and the thesis results, a Matlab ToolBox "Automotive" has been developed to provide a bench test for the different automotive control studies. Implementations on test beds and real vehicle are also achieved to prove the efficiency of the proposed strategies

Millimeter-wave systems introduce a set of particular severe requirements from the antenna point of view in order to achieve specific performances. In this sense, high directive antennas are required to overcome the huge extra path loss. Moreover, each particular application introduces additional requirements. For example, in very high throughput (VHT) wireless personal area networks (WPANs) communication systems at 60 GHz band beam-steering antennas are needed to deal with high user random mobility and human-body shadowing characteristic of indoor environments. Similarly, beam-steering capabilities are also needed in automotive radar applications at 79 GHz, since the determination of the exact position of an object is essential for most of the functions realized by the radar sensor. In the same way, beam-scanning, which is still commonly mechanically performed nowadays, is also needed in passive imaging systems at 94 GHz. Finally, from the integration perspective, the antennas must be small, low-profile, light weight and low-cost, in order to be successfully integrated in a commercial millimeter-wave wireless system. For these reasons, many types of antenna structures have been considered to achieve high directivity and beam-steering capabilities for the aforementioned millimeter-wave communication, radar and imaging applications at 60, 79 and 94 GHz. The most part of the currently adopted solutions are based on the expensive, complex and bulky phased-array antena concept. Actually, phased-array antenna systems can scan the beam at a fast rate. However, they require a complex integration of many expensive, lossy and bulky circuits, such as solid-state phase shifters and beam-forming networks. This doctoral thesis has contributed to the study, development, and assessment of the performance of innovative antena solutions in order to improve the existing architectures at millimeter-wave frequencies, conveniently solving the problems related specifically to short-range high data rate communication systems at 60 GHz WPAN band (including future 5G millimeter-wave systems), automotive radar sensors at 79 GHz band, and communications, radar, and imaging systems at 94 GHz. The specific goals pursued in this work, focused on defining an alternative antenna architecture able to achieve a full reconfigurable 2-D beam-scanning of high gain radiation beams at millimeter-wave frequencies, has been fulfilled. In this sense, this thesis has been mainly devoted to study in depth and practically develop the fundamental part of an innovative switched-beam antenna array concept: novel inhomogeneous gradient-index dielectric flat lenses, which, despite their planar antenna profile configurations, allow full 2-D beam-scanning of high gain radiation beams. A transversal study, going from theoretical investigations, passing by numerical analysis, new fabrication strategies, performance evaluation, and to full experimental assessment of the new antenna architectures in real application environment has been successfully carried out.
Los sistemas a frecuencias de ondas milimétricas introducen una serie de requisitos muy estrictos desde el punto de vista de la antena con el objetivo de conseguir unos rendimientos específicos. En este sentido, se requieren antenas con una muy alta directividad con tal de conseguir superar las enormes pérdidas adicionales por propagación. Además, cada aplicación en concreto introduce unos requisitos adicionales. Por ejemplo, en redes de área personal de alta velocidad para sistemas de comunicación a la banda de 60 GHz, antenas con la capacidad de reconfiguración del haz de radiación son necesarias para poder tratar la problemática de la alta movilidad de los usuarios en entornos cerrados. De la misma forma, capacidades de reconfiguración de la orientación del haz de radiación son necesarias en aplicaciones relacionadas con radar de automoción a 79 GHz, dado que la determinación de la posición exacta de un objeto es esencial para muchas de las funciones del sensor de radar. De forma muy similar, la capacidad de apuntamiento del haz, que muchas veces todavía se realiza mediante sistemas mecánicos, es también imprescindible en sistemas de escaneo para aplicaciones biomédicas y de seguridad a 94 GHz. Finalmente, desde la perspectiva de la integración, las antenas deben ser eléctricamente pequeñas, ligeras, y económicas para poder ser incorporadas a un sistema inalámbrico comercial a frecuencias de onda milimétricas. Por todos estos motivos, diferentes tipos de estructuras de antenas han sido propuestos para conseguir alta directividad, junto con capacidades de reconfiguración y apuntamiento del haz de radiación para las aplicaciones anteriormente mencionadas y descritas en la banda de 60, 79, y 94 GHz. La solución tradicionalmente adoptada en este tipo de casos està estrictamente basada en el siempre caro, complejo y aparatoso concepto del phased-array. De hecho, los phased-arrays permiten el rápido escaneo de haces de radiación de alta directividad. Sin embargo, el hecho que requieran una compleja integración de muchos y caros componentes a alta frecuencia, tales como desfasadores de estado sólido o redes de conformación, los cuales introducen ciertos niveles de pérdidas, siendo además aparatosos, hacen que esta solución resulte inviable. La presente tesis doctoral contribuye al estudio, desarrollo, y ensayo experimental del rendimiento de soluciones de antenas innovadoras para la mejora de las existentes arquitecturas de antena en la banda frecuencial de las ondas milimétricas, convenientemente solucionando los problemas asociados específicamente a los sistemas de comunicación de corto alcance y alta velocidad a 60 GHz (incluyendo los futuros sistemas 5G a milimétricas), a los sistemas de radar de automoción a 79 GHz, y a los sistemas de comunicación, radar, y escaneo para aplicaciones a 94 GHz. Los objetivos específicos perseguidos en este trabajo académico, focalizados en definir una arquitectura alternativa de antena, capaz de conseguir una completa reconfiguración y escaneo de los haces de radiación en dos dimensiones del espacio a frecuencias de onda milimétricas, se han conseguido plenamente. En este sentido, esta tesis doctoral ha sido dedicada esencialmente al estudio en profundidad y desarrollo práctico de la parte fundamental del innovador concepto del switchedbeam array: nuevas lentes dieléctricas inhomogéneas de gradiente de índice con estructura plana, las cuales, a pesar de su configuración física totalmente llana, permiten una reconfiguración total, en dos dimensiones del espacio, de haces de radiación de alta directividad. Un estudio eminentemente transversal, que abarca desde la investigación teórica, pasando por el análisis numérico, nuevas metodologías y técnicas de fabricación, evaluación de rendimientos, hasta una completa caracterización y ensayo del rendimiento en entornos reales de aplicación de las nuevas arquitecturas de antena, se ha llevado a cabo con total éxito.
Els sistemes a freqüències d'ones mil·limètriques introdueixen una sèrie de requisits molt estrictes des del punt de vista de l'antena per tal d’aconseguir uns rendiments específics. En aquest sentit, es requereixen antenes amb una alta directivitat per aconseguir superar les enormes pèrdues addicionals per propagació. A més a més, cada aplicació en concret introdueix uns requeriments addicionals . Per exemple, en xarxes d'àrea personal d'alta velocitat per a sistemes de comunicació a la banda de 60 GHz, antenes amb la capacitat de reconfiguració del feix de radiació són necessàries per tal de poder tractar la problemàtica de l'alta mobilitat dels usuaris en entorns tancats . De la mateixa manera, capacitats de reconfiguració de l'orientació del feix de radiació són necessàries en aplicacions associades a radar d'automoció a 79 GHz, donat que la determinació de la posició exacta d'un objecte és essencial per moltes de les funcions portades a terme pels ens or del radar. De forma molt similar, la capacitat d'apuntament del feix, que moltes vegades encara es realitza per mitjà de sistemes mecànics, és també imprescindible en sistemes d'escaneig per aplicacions mèdiques i de seguretat a 94 GHz. Finalment, des de la perspectiva de la integració, les antenes han de ser petites en termes elèctrics, lleugeres, i econòmiques per tal de poder ser incorporades en un sistema sense fils comercial a freqüència d'ones mil·limètriques. Per aquestes raons , diversos tipus d'estructures d'antenes han sigut proposats per aconseguir alta directivitat, conjuntament amb la capacitat d'apuntament del feix de radiació per les aplicacions anteriorment descrites a les bandes de 60, 79, i 94 GHz. La solució tradicionalment adoptada en aquests casos és estrictament basada en el sempre car, complexe, i aparatós concepte del phased-array. De fet, els phased-arrays tenen la capacitat de reconfigurar a gran velocitat feixos de radiació d'alta directivitat. Tot i això, el fet que requereixin la complexa integració de molts components cars a alta freqüència, amb certs nivells de pèrdues i aparatosos, com són els desfasadors d'estat sòlid, i les xarxes de conformació, fan d'aquesta solució inviable. La present tesis doctoral contribueix a l'estudi, des envolupament, i assaig experimental del rendiment de solucions d'antenes innovadores per tal de millorar les existents arquitectures d'antena a la banda freqüencial de les ones mil·limètriques, convenientment solucionant els problemes associats específicament als sistemes de comunicació de rang proper d'alta velocitat a 60 GHz (incloent els futurs sistemes 5G a mil·limètriques ), als sistemes de radar d'automoció a la banda dels 79 GHz, i als sistemes de comunicació, radar, i escaneig per aplicacions a 94 GHz. Els objectius específics perseguits en aquest treball acadèmic, focalitzats en definir una arquitectura d'antena alternativa, capaç d'aconseguir una completa reconfiguració i escaneig dels feixos de radiació en dues dimensions de l'espaia freqüències d'ona mil·limètriques , s'han plenament aconseguit. En aquest sentit, aquesta tesis doctoral s'ha dedicat essencialment a l'estudi en profunditat i desenvolupament pràctic de la part fonamental de l'innovador concepte del switched-beam array: noves lents dielèctriques inhomogenees de gradient d'índex amb estructura planar, les quals, tot i preservar una configuració física totalment plana, permeten una reconfiguració total en dues dimensions de l'espai de feixos de radiació d'alta directivitat. Un estudi transversal, que comprèn des de la investigació teòrica, passant per l'anàlisi numèric, noves metodologies i tècniques de fabricació, avaluació de rendiments, fins a una completa caracterització i assaig del rendiment en entorns reals d'aplicació de les noves arquitectures d'antena s'ha dut a terme amb total èxit.

Suspension systems and wheels play a critical role in vehicle dynamics performance of a car in areas such as ride comfort and handling. Lumped parameter models (LPMs) are commonly used for assessing the performance of vehicle suspension systems. However, there is a lack of clarity with regard to the relative capabilities of different LPM configurations. A comprehensive comparative study of three most commonly used LPMs of increasing complexity has been carried out in the current work. The study reported here has yielded insights into the capabilities of the considered LPMs in predicting response time histories which may be used for assessing ride comfort. A shortcoming of available suspension system models appears to be in representation of harsh situations such as jounce movement which cause full compression of springs leading to ‘jerks’ manifested as high values of rate of change of acceleration of sprung mass riding on a wheel. In the current research work, a modified nonlinear quarter-car model is proposed to account for the contact force that results in jerk-type response. The numerical solution algorithm is validated through the simulation of an impact test on a car McPherson strut in a Drop Weight Impact Testing Tower developed in CAR Laboratory, CPDM. This is followed by a detailed comparison of HCM and QCM to examine their suitability for such analysis. For decades, wheel bearings in vehicles have been designed using simplified analytical approaches based on Hertz contact theory and test data. In the present work, a hybrid approach has been developed for assessing the load bearing capacity of a wheel ball bearing set. According to this approach, the amplitude of dynamic wheel load can be obtained from a lumped parameter analysis of a suspension system, which can then be used for detailed static finite element analysis of a wheel bearing system. The finite element modelling approach has been validated by successfully predicting the load bearing capacity of an SKF ball bearing set for an acceptable fatigue life. For the first time, using a powerful commercial explicit finite element analysis tool, a detailed dynamic analysis has been carried of a deep groove ball bearing with a rotating inner race. The analysis has led to a consistent representation of complex motions consisting of rotations and revolutions of rolling elements, and generated insights into the stresses developed in the various components such as balls and races. In conclusion, a simple yet effective fuzzy logic-based yaw control algorithm has been presented in the current research. According to this algorithm, two inputs i.e. a yaw rate error and a driver steering angle are used for generating an output in the form of an additive steering angle which potentially can aid a driver in avoiding straying from an intended path.

Yes
This paper reports on an experimental investigation into braking-related steering drift in motor vehicles, and follows on from a previous paper by the authors in which it was concluded that braking can cause changes in wheel alignment that in turn affect the toe-steer characteristics of each wheel and therefore the straight-line stability of the vehicle during braking. Changes in suspension geometry during braking, their magnitude and the relationships between the braking forces and the suspension geometry and compliance are further investigated in an experimental study of wheel movement arising from compliance in the front suspension and the steering system of a passenger car during braking. Using a kinematic and compliance (K&C) test rig, movement of the front wheels and the suspension subframe, together with corresponding changes in suspension and steering geometry under simulated braking conditions, have been measured and compared with dynamic measurements of the centre points of the front wheels. The results have enabled the causes and effects of steering drift during braking to be better understood in the design of front suspension systems for vehicle stability during braking.

碩士
大葉大學
機械與自動化工程學系
107
The purpose of this paper is to use the functions of Computer Aided Engineering Analysis (CAE). Dynamic and static simulation analysis of the suspension system in front of the vehicle The model ' performs dynamic and static simulation analysis of this suspension system model under the action state. Drawing and using SolidWorks software ANSYS finite element analysis software analysis Static stress is statically analyzed using the Workbench module on ANSYS. The limit element analysis software can be roughly cut into three parts: pre-processor Solver and postprocessor. Construct a suspension system in the ANSYS/ Motion template (Preprocessor) module software The model is completed and the car body model of the front wheel comfort system is applied to the carcass movement analysis. Analytical type (ANSYS) is based on the Postprocessor type and then constructed The vehicle front wheel suspension system model is used for dynamic simulation analysis. Keywords: SolidWorks, ANSYS, Motion Preprocessor Postprocessor Analysis of Ming Zunxun

碩士
國立雲林科技大學
機械工程系碩士班
93
Suspension design is the key technology of both ride comfort and handling safety. It’s very important to design the ideal spring and damper for ride quality. The active suspension system is another practical approach to improve not only ride comfort but also handling safety. This paper aims at dynamic simulation and analysis of the automotive active suspension system under the condition of driving a car on the regular road. Integrating MATLAB with CAE simulation software ADAMS controls actuator force by PID controller with tracking car body displacement to restrain car vibration, it can achieve the expected requirement of riding comfort. At first, the research applies a quarter-car to simulate and analyze, then verifies with theoretical model for the basis of research on the automotive active suspension systems.

碩士
崑山科技大學
機械工程研究所
95
The objective of the research is about the performance of an ABC (Active Body Control) system, that is, a quarter-car active suspension system used in the Mercedes-Benz vehicle. Investigate the suspension system dynamic behavior for vehicle driving on different road profile disturbance. First, we modeled the ABC active suspension system, including suspension strut, hydraulic system, and 3/3 suspension strut control valve, and proceeded the experiment to verify this model. Furthermore, the parameters of ABC system were obtained by using the Response Surface Methodology of Experimental Design Method and Multi-objective Optimization. Next, use different optimal controllers to control the active suspension system. For the riding comfort, the purpose is to minimize the displacement and vertical acceleration of the body. The optimal controllers include Optimal-PID, LQR (Linear Quadratic Regulator), and LQG (Linear Quadratic Gaussian). The MATLAB/Simulink software package was used to build the simulation program according to the ABC mathematic model. Finally, the results of the simulation and experimentation of the dynamic response behavior for vehicle driving on different road profile disturbance by using different optimal controllers were obtained and compared. This ensures that the simulation results are the same as the actual vehicle dynamic behavior.

Lam Hiu Fung.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.
Includes bibliographical references (leaves 106-111).
Abstracts in English and Chinese.
abstract --- p.i
摘要 --- p.iii
acknowledgements --- p.v
table of contents --- p.vi
list of figures --- p.viii
list of tables --- p.xi
Chapter 1 --- introduction --- p.1
Chapter 1.1 --- Controllable Suspension System --- p.1
Chapter 1.1.1 --- Automotive Suspension System --- p.2
Chapter 1.1.2 --- Controllable Devices --- p.4
Chapter 1.1.3 --- MR Fluid and Damper --- p.5
Chapter 1.2 --- Vibration Control --- p.5
Chapter 1.2.1 --- Active Control --- p.5
Chapter 1.2.2 --- Semi-active Control --- p.6
Chapter 1.2.3 --- Robust Control --- p.7
Chapter 1.3 --- Research Objective --- p.7
Chapter 1.4 --- Thesis Outline --- p.8
Chapter 2 --- PARAMETRIC STUDY OF SUSPENSION SYSTEMS --- p.9
Chapter 2.1 --- System Models and Transmissibility --- p.9
Chapter 2.1.1 --- Passive Suspension System --- p.10
Chapter 2.1.2 --- Skyhook Suspension System --- p.15
Chapter 2.1.3 --- Groundhook Suspension System --- p.24
Chapter 2.1.4 --- Hybrid Suspension System --- p.32
Chapter 2.1.5 --- Comparison among four suspension systems --- p.41
Chapter 2.2 --- Characteristics analysis --- p.45
Chapter 2.2.1 --- Passive Suspension System --- p.45
Chapter 2.2.2 --- Skyhook Suspension System --- p.47
Chapter 2.2.3 --- Groundhook Suspension System --- p.50
Chapter 2.2.4 --- Hybrid Suspension System --- p.52
Chapter 2.3 --- Stability --- p.54
Chapter 2.3.1 --- Stability in the Sense of Lyapunov for Suspension Systems --- p.54
Chapter 2.3.2 --- Stability for four Suspension Systems --- p.57
Chapter 2.4 --- Optimization --- p.63
Chapter 2.4.1 --- Single-Degree-of-Freedom Passive System --- p.63
Chapter 2.4.2 --- Two-Degree-of-Freedom Passive System --- p.65
Chapter 2.4.3 --- Hybrid Suspension System --- p.67
Chapter 3 --- SUSPENSION SYSTEM WITH VIBRATION CONTROLLER --- p.71
Chapter 3.1 --- Two-Degree-of-Freedom Quarter Car Model --- p.71
Chapter 3.2 --- MR Damper --- p.73
Chapter 3.3 --- Vibration Controller --- p.75
Chapter 3.3.1 --- System Controller: Sliding Mode Control --- p.76
Chapter 3.3.2 --- Damper Controller: Continuous-state Control --- p.83
Chapter 4 --- SIMULATION RESULTS --- p.85
Chapter 4.1 --- Transmissibility analysis --- p.86
Chapter 4.2 --- Simulation --- p.89
Chapter 4.2.1 --- Test by Bump Excitation --- p.89
Chapter 4.2.2 --- Test by Random Excitation (White noise) --- p.91
Chapter 4.2.3 --- Test by Road Elevation Profile --- p.95
Chapter 5 --- CONCLUSIONS AND FUTURE WORK --- p.99
Chapter 5.1 --- Summary --- p.99
Chapter 5.2 --- Future Work and Further Development --- p.100
Chapter 5.2.1 --- Parametric study of the MR suspension system --- p.100
Chapter 5.2.2 --- Systematic method for selecting control gains --- p.101
Chapter 5.2.3 --- New control algorithm --- p.101
Chapter 5.2.4 --- Extension to half and full car models --- p.102
Chapter 5.2.5 --- System implementation --- p.102
appendix
Chapter A.1 --- Additional information of the transmissibility of unsprung mass.… --- p.103
Chapter A.2 --- Additional figures of the random excitation test: --- p.104
BIBLIOGRAPHY --- p.106

The possible benefits of employing inerters in automotive suspensions are explored for passenger comfort and handling. Different suspension strut designs in terms of the relative arrangement of springs, dampers and inerters have been considered and their performance compared with that of a conventional system. An alternate method of electrically realizing complex mechanical circuits by using a linear motor (or a rotary motor with an appropriate mechanism) and a shunt circuit is then proposed and evaluated for performance. However, the performance improvement is shown from simulations to be significant only for very stiff suspensions, unlike those in passenger vehicles. Hence, the concept is not taken up for prototyping. Variable damping can be implemented in suspension systems in various ways, for example, using magneto-rheological (MR) fluids, proportional valves, or variable shunt resistance with a linear electromagnetic motor. Hence for a generic variable damping system, a control algorithm is developed which can provide more comfort and better handling simultaneously compared to a passive system. After establishing through simulations that the proposed adaptive control algorithm can demonstrate a performance better than some controllers in prior-art, it is implemented on an actual vehicle (Cadillac STS) which is equipped with MR dampers and several sensors. In order to maintain the controller economical so that it is practically viable, an estimator is developed for variables which require expensive sensors to measure. The characteristic of the MR damper installed in the vehicle is obtained through tests as a 3-dimensional map relating suspension speed, input current and damping force and then used as a look-up table in the controller. Experiments to compare the performance of different controllers are carried out on smooth and rough roads and over speed bumps.

博士
國立成功大學
機械工程學系碩博士班
101
In order to enhance ride comfort, this study utilized the concepts of semi-active and active suspension systems to design various dampers to reduce the vibration in accordance with the chassis dynamics. For semi-active suspension system, this study developed a continuous adjustable damper and experimentally evaluated its damped responses. The proposed adjustable damper was subsequently incorporated into a quarter car system. For the aspects of controller design, the fuzzy-skyhook controller and the hybrid fuzzy sliding mode controller were employed and compared with results of the quarter car semi-active suspension system. With the full car analysis, a road simulation and a dynamic model for full vehicle suspension system were built to evaluate vibration suppression of the proposed adjustable dampers under rough road excitation. When a vehicle runs on a random road, the improvement on coupled vibration are essential. Regarding the coupled characteristics of a full car for the semi-active suspension system, a decoupling controller was designed to avoid the phenomena. For active suspension system, this study designed an active hydraulic damper that combined a hydraulic actuator and a shock absorber. The active hydraulic damper was subsequently incorporated into a quarter car system under random road excitation. With regard to controller design, the self-tuning fuzzy sliding mode controller was employed and compared with passive and semi-active suspension systems for their responses. The active hydraulic dampers were set on the dynamic model for full vehicle suspension system to examine its performance. The decoupling controller was designed to improve the stability of the vehicle. Three types of ride comfort analyses: namely PSD, Meister chart, and vibration-weighted accelerations were conducted on the quarter car and full car based on ISO2631-1. The experimental results indicated that the developed controllers can significantly improve the performance in both vibration suppression and ride comfort.

No
A vehicle that deviates laterally from its intended path of travel when the brakes are applied is considered to demonstrate ‘instability’ in the form of an unexpected and undesirable response to the driver input. Even where the magnitude of lateral displacement of the vehicle is small (i.e. ‘drift’ rather than ‘pull’) such a condition would be considered unacceptable by manufacturers and customers. Steering ‘drift’ during braking can be caused by several factors, some of which relate to vehicle design and others to external influences such as road conditions. The study presented here examines the causes and effects of steering drift during straight-line braking. A comparative analysis is made between two types of vehicle model: one built with rigid suspension components and the other with flexible components. In both the cases, the vehicle behaviour is simulated during braking in a straight line, and responses including lateral acceleration, yaw rate, and lateral displacement of the vehicle are predicted and analysed under fixed steering control. Suspension/steering geometry characteristics, namely toe steer and caster angle, have been studied to understand how the effect of variations in these parameters differs in models with rigid or flexible components drift during straight-line braking. Results from both vehicle models show that differences between rigid and flexible components can affect the predicted steering drift propensity. The differences between the two models have emphasized the importance of using flexible (compliant) components in vehicle handling simulations to achieve better correlation between prediction and experiment.

This paper presents a multidegrees-of-freedom non-linear multibody dynamic model of a vehicle, comprising front and rear suspensions, steering system, road wheels, tyres and vehicle inertia. The model incorporates all sources of compliance, stiffness and damping, all with non-linear characteristics. The vehicle model is created in ADAMS (automatic dynamic analysis of mechanical systems) formulation. The model is used for the purpose of vehicle handling analysis. Simulation runs, in-line with vehicle manoeuvres specified under ISO and British Standards, have been undertaken and reported in the paper.