Semi-active Suspension Control

Transcription

1 Semi-active Suspension Control

2 Emanuele Guglielmino Tudor Sireteanu Charles W. Stammers Gheorghe Ghita Marius Giuclea Semi-active Suspension Control Improved Vehicle Ride and Road Friendliness 123

3 Emanuele Guglielmino, PhD Italian Institute of Technology (IIT) Via Morego, Genoa Italy Tudor Sireteanu, PhD Gheorghe Ghita, PhD Institute of Solid Mechanics Romanian Academy C-tin Mille Street Bucharest Romania Charles W. Stammers, PhD Department of Mechanical Engineering University of Bath Bath BA2 7AY UK Marius Giuclea, PhD Department of Mathematics Academy of Economic Studies 6 Piata Romana Bucharest Romania ISBN e-isbn DOI / British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Control Number: Springer-Verlag London Limited MATLAB and Simulink are registered trademarks of The MathWorks, Inc., 3 Apple Hill Drive, Natick, MA , USA. Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Cover design: estudio Calamar S.L., Girona, Spain Printed on acid-free paper springer.com

4 Naturae phaenomena ex principiis mechanicis eodem argumentandi genere derivare liceret. Newton

5 Preface The fundamental goals of a car suspension are the isolation of the vehicle from the road and the improvement of road holding by means of a spring-type element and a damper. The inherent limitations of classical suspensions have motivated the investigation of controlled suspension systems, both semi-active and active. In a semi-active suspension the damper is generally replaced by a controlled dissipative element and no energy is introduced into the system. In contrast, an active suspension requires the use of a fully active actuator, and a significant energy input is generally required. Due to their higher reliability, lower cost and comparable performance semi-active suspensions have gained wide acceptance throughout the automotive engineering community. This book provides an overview of vehicle ride control employing smart semiactive damping systems. In this context the term smart refers to the ability to modify the control logic in response to measured vehicle ride and handling indicators. The latest developments in vehicle ride control stem from the integration of diverse engineering disciplines, including classical mechanics, hydraulics, biomechanics and control engineering as well as software engineering and analogue and digital electronics. This book is not intended to be a general-purpose text on vehicle dynamics and vehicle control systems (traction control, braking control, engine and emissions control etc.). The focus of this work is on controlled semi-active suspension systems for ride control and road friendliness using a multidisciplinary mechatronic approach. If effective control of a suspension is to be achieved, which makes the most of the potentialities of a semi-active damping device, it is paramount to understand the interactions between mechanical, hydraulic and electromagnetic sub-systems. The book analyses the different facets of the technical problems involved when designing a novel smart damping system and the technical challenges involved in its control. The emphasis of this work is not only on modelling and control algorithm design, but also on the practical aspects of its implementation. It describes the practical constraints encountered and trade-offs pursued in real-life

6 viii Preface engineering practice when designing and testing a novel smart damping system. Hence sound mathematical modelling is balanced by large sections on experimental implementation as well as case studies, where a variety of automotive applications are described, covering different applications of ride control, namely semi-active suspensions for a saloon car, seat suspensions for vehicles not equipped with a primary suspension and control of heavy-vehicle dynamic tyre loads to reduce road damage and improve handling. Within the book issues such as road holding, passenger comfort and human body response to vibration are thoroughly analysed. Appropriate control-oriented dampers models are described, along with their experimental validation. Vehicle ride and human body models are illustrated and robust algorithms are designed. The book is centered around two types of semi-active dampers: friction dampers and magnetorheological dampers. The former can be viewed as an out-ofthe-box non-conventional damper while the latter can be thought as a conventional controllable damper (it is used in several cars). Based on these two types of dampers in the course of the book it is shown how to design a semi-active damping system (using a friction damper) and how to implement an effective semi-active control system on a well-established damper (the magnetorheological damper). The book can be fruitful reading for mechanical engineering students (at both undergraduate and postgraduate level) interested in vehicle dynamics, electrical and control engineering students majoring in electromechanical and electrohydraulic control systems. It should be valuable reading for R&D and design engineers working in the automotive industry and automotive consultants. It can be of interest also to engineers, physicists and applied mathematicians working in the broad area of noise and vibration control, as many concepts can potentially be applied to other fields of vibration control. The book is structured as follows: Chapter 1 is a general introduction to active, semi-active and passive suspensions and introduces the fundamental concepts of vehicle ride and handling dynamics. Chapter 2 focusses on dampers modelling (including hysteresis modelling) and reviews the main vehicle ride and road surface models. Chapter 3 analyses the human body response to vibration via appropriate human body models based on recent studies in the field of biomechanics. Chapter 4 is dedicated to control algorithms. After a brief qualitative overview of the fundamentals of modern control theory, the main semi-active suspensions algorithms are introduced. The focus is on an algorithm known as balance logic, which is analysed from a mathematical viewpoint. Emphasis is also placed on robust algorithm design and on techniques to increase the reliability of the systems (e.g., anti-chattering algorithms). Chapter 5 details the design of a semi-active suspension system based on a friction damper. Chapter 6 illustrates the design of a magnetorheological-based semi-active suspension. Chapter 7 offers a comprehensive overview of the applications with a number of case studies including a friction damper-based suspension unit for a saloon car, a magnetorheological damper-based seat suspension for vehicles not equipped with

7 Preface ix primary suspensions which uniquely rely on this suspension mounted underneath the driver seat to provide ride comfort and semi-active suspension for heavy vehicles where the emphasis is not only on ride comfort but also on road damage reduction. Disclaimer All the experimental work and numerical simulations presented in this book are the result of academic research carried out at the University of Bath (UK) and at the Institute of Solid Mechanics of the Romanian Academy (Romania). All devices described in the book are purely experimental prototypes. Therefore in no circumstances shall any liability be accepted for any loss or damage howsoever caused to the fullest possible extent of the law that may result from the reader's acting upon or using the content contained in the publication.

8 Acknowledgements The authors wish to express their gratitude to Springer (London) for the invitation to write this book. Many thanks to our Editor Oliver Jackson for his guidance throughout this work. The book is the fruit of many years of research work. Most of the results presented were obtained at the Department of Mechanical Engineering, University of Bath (UK), which we would like to thank. We are deeply grateful to Professor Kevin Edge, Pro-Vice-Chancellor for Research of the University of Bath, for his contribution to the hydraulic control of friction dampers. We would like to thank the University for providing the technical facilities and would also like to express our gratitude to the technical staff of the Department of Mechanical Engineering without whom the manufacture of devices and test rigs and technical trouble-shooting would not have been possible. We wish to express our appreciation to the Royal Society of London for sponsoring a decade of collaboration with the Romanian Academy in Bucharest, where valuable contributions to this text were made. Thanks are also due to Dr Georgios Tsampardoukas for kindly providing valuable material on trucks. We finally wish to thank all the people whose input, support and sympathetic understanding was instrumental to the successful completion of such an undertaking.

9 Contents 1 Introduction Introduction Historical Notes on Suspensions Active and Semi-active Suspensions in the Scientific Literature Comfort in a Vehicle Comfort Assessment Introduction to Controlled Dampers Introduction to Friction Dampers Introduction to MR Dampers Dampers and Vehicle Modelling Introduction Phenomenology of Hysteresis Damper Hysteresis Modelling Bouc Wen Model Parameter A Parameter γ Parameter ν Parameter n Bouc Wen Parameter Identification Vehicle Ride Models Quarter Car Model Half Car Model Full Car Model Half Truck Model Tyre Modelling Road Modelling Human Body Analysis Introduction Human Body Response... 44

10 xiv Contents 3.3 Hysteretic Damping The Duffing Equation Suppression of Jumps Low-frequency Seated Human Model Multi-frequency Input Semi-active Control State Observer Luenberger State Observer Simple State Observer Ideal Control Results Seated Human with Head-and-Neck Complex Driver Seat (Including Cushions) Driver Body Head-and-Neck Complex (HNC) Analysis of the Head-and-Neck System Head Accelerations During Avoidance Manoeuvre Semi-active Control Algorithms Introduction PID Controllers Adaptive Control Robust Control Balance, Skyhook and Groundhook Balance Logic Skyhook Logic Groundhook Logic Displacement-based On Off Groundhook Logic Hybrid Skyhook Groundhook Logic Balance Logic Analysis Chattering Reduction Strategies SA Vibration Control of a 1DOF System with Sequential Dry Friction Sequential Damping Characteristics Free Vibration: Phase Plane Trajectories Free Vibration: Shock Absorbing Properties Harmonically-Excited Vibration Time Histories Amplitude Frequency Characteristics Random Vibration Simulation of White Noise Sample Functions Numerical Solution of the Equation of Motion Numerical Results Stability of SA Control with Sequential Dry Friction Quarter Car Response with Sequential Dry Friction Friction Dampers Introduction... 99

11 Contents xv 5.2 Friction Force Modelling Static Friction Models Dynamic Friction Models Seven-parameter Friction Model The Damper Electrohydraulic Drive Friction Damper Hydraulic Drive Modelling Power Consumption The Feedback Chain Pilot Implementation of Friction Damper Control Automotive Friction Damper Design Switched State Feedback Control Preliminary Simulation Results Friction Damper Electrohydraulic Drive Assessment Electrohydraulic Drive Parameters Validation Performance Enhancement of the Friction Damper System Damper Design Modification Hydraulic Drive Optimisation Friction Damper Controller Enhancement Magnetorheological Dampers Introduction Magnetorheological Fluids MR Fluid Devices Basic Operating Modes Flow Simulation Pressure-driven Flow Mode with Either Pole Fixed Direct Shear Mode with Relatively Movable Poles Squeeze-film Mode MR Damper Design Input Data and Choice of the Design Solution Selection of the Working MR Fluid MR Fluid Figures of Merit Choice of the MR Fluid Determination of the Optimal Gap Size and Hydraulic Design Controllable Force and Dynamic Range Parameters of the Hydraulic Circuit Magnetic Circuit Design MRD Modelling and Characteristics Identification Experimental Data Parametric Model Simulation Fuzzy-logic-based Model Modelling the Variable Field Strength GA-based Method for MR Damper Model Parameters Identification Case Studies Introduction

12 xvi Contents Some Aspects of Data Acquisition and Control Car Dynamics Experimental Analysis The Experimental Set-up Post-processing and Measurement Results Suspension Spring and Tyre Tests Passively-Damped Car Validation Case Study 1: SA Suspension Unit with FD Frequency-domain Analysis Time-domain Analysis Semi-active System Validation Case Study 2: MR-based SA Seat Suspension Numerical Results Conclusions Case Study 3: Road Damage Reduction with MRD Truck Suspension Introduction Half Truck and MR Damper Model Road Damage Assessment Road Damage Reduction Algorithm Time Response Truck Response on Different Road Profiles Truck Response to Bump and Pothole Robustness Analysis Trailer Mass Variation Tyre Stiffness Variation MRD Response Time Conclusions References Bibliography Authors Biographies Index