1、Analysis Techniques for Racecar Data Acquisition Jrge SegersANALYSIS TECHNIQUES FOR RACECAR DATA ACQUISITIONOther SAE titles of interest: Hands-On Race Car Engineer By John H. Glimmerveen (Product Code: R-323) Formula 1 Technology By Peter Wright and Tony Matthews (Product Code: R-230) Race Car Vehi
2、cle Dynamics By William F. Milliken and Douglas L. Milliken (Product Code: R-146) Fundamentals of Vehicle Dynamics By Thomas D. Gillespie (Product Code: R-114) For more information or to order a book, contact SAE at 400 Commonwealth Drive Warrendale, PA 15096-0001 phone (724) 776-4970; fax (724) 776
3、-0790 e-mail CustomerServicesae.org; website http:/store.sae.org. iiANALYSIS TECHNIQUES FOR RACECAR DATA ACQUISITION JRGE SEGERS Warrendale, Pennsylvania, USA Copyright 2008 SAE International eISBN: 978-0-7680-4379-2All rights reserved. No part of this publication may be reproduced, stored in a retr
4、ieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth Drive Warrendale, PA 15096-0001-USA Email: permission
5、ssae.org Tel: 724-772-4028 Fax: 724-772-4891 Library of Congress Cataloging-in-Publication Data Segers, Jorge. Analysis techniques for racecar data acquisition / Jorge Segers. p. cm. ISBN 978-0-7680-1655-0 1. Automobiles, Racing-Dynamics-Data processing. 2. Automobiles, Racing-Performance-Measuremen
6、t. 3. Automobiles, Racing-Testing. I. Title. TL243.S43 2008 629.2280287dc22 2007047077 SAE International 400 Commonwealth Drive Warrendale, PA 15096-0001 USA Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-1615 Email: CustomerServicesae.org Copyright 2008 SAE I
7、nternational ISBN 978-0-7680-1655-0 SAE Order No. R-367 Printed in USA ivTABLE OF CONTENTS Preface ix Acknowledgments xi Chapter 1 Introduction What Is This Book All About? 1 What Is Data Acquisition? 2 Hardware 6 Chapter 2 Data Analysis Software Requirements General Requirements for Data Acquisitio
8、n Software 9 Different Wavs of Displayina Data 9 Keeping Notes with Data Files 10 Mathematical Channels 11 Data Overlays 11 Filtering 13 Exporting Data to Other Software Packages 14 Getting Organized. 14 Chapter 3 The Basics Check the Cars Vital Signs 19 Lap Markers and Segment Times 21 Comparing La
9、ps 22 Inertial Track Mapping 26 GPS and Track Mapping 27 The Beginners Data Logging Kit 28 Chapter 4 Straight-Line Acceleration Torque and Horsepower .33 Traction and Longitudinal Slip 35 ABS/TCS and Slip Ratios 38 Time Versus Distance 39 The Importance of Corner Exiting Speed 40 Drag Racing Specifi
10、cs 40 Chapter 5 Braking Maximizing Braking Speed 45 Braking Effort 45 Braking Points 46 Lockup 47 Brake Balance 48 Pedal Travel 49 Chapter 6 Gearing Upshifting 51 Downshifting 54 The Gear Chart 54 Total Gear Ratio Channel 55 Determining Correct Gear Ratios 56 Chapter 7 Cornering The Cornering Sequen
11、ce 59 Traction Circle 60 Effects of Speed 62 Throttle Histogram 63 Steering 64 Attitude Velocity 68 Front and Rear Lateral Acceleration .68 TABLE OF CONTENTS vChapter 8 Quantifying Roll Stiffness Distribution Front and Rear Roll Gradient 71 Using Roll Gradients as a Setup Tool 74 Front and Rear Roll
12、 Angle Ratio 76 Using the Roll Ratio as a Setup Tool 78 Suspension Troubleshooting 78 Pitch Gradient 79 Chapter 9 Wheel Loads and Weight Transfer Lateral Weight Transfer 81 Longitudinal Weight Transfer 83 Banking and Grade Effects 83 Total Wheel Loads 85 Determining Wheel Loads with Modal Analysis 8
13、6 Measuring Wheel Loads with Suspension Load Cells 93 Tire Spring Rates 94 Chassis Torsion 95 Chapter 10 Frequencies and Shock Absorbers Damping Analysis 97 Shock Speed Histogram 99 Introducing Frequency Analysis 104 Frequency Analysis Versus Time-Space Analysis. 107 Theoretical Analysis 108 Suspens
14、ion Optimization Using Frequency Analysis 111 Modal Analysis 112 Modal Frequency Issues 115 Nonlinear Considerations 117 Frequency Analysis from Sensor Data 118 Chapter 11 Aerodynamics Aerodynamic Measurements 121 Air Density 122 Dynamic Pressure 123 The Coastdown Test 124 Measurina the Aerodvnamic
15、Downforce 126 Airbox Efficiency 128 Chapter 12 Analyzing the Driver Improving Driver Performance 131 Driving Style Evaluation 132 Throttle Application 132 Braking 134 Shifting Gears 136 Cornering 136 Drivina Line . 137 Driving Line Analysis Using GPS 139 Driving Line Analysis Using Video Feed 139 Dr
16、iver Consistency over Multiple Laps 140 Chapter 13 Simulation Tools Introduction 141 Suspension Kinematics Simulation 142 Lap Time Simulation 143 A Simulated Example 145 viChapter 14 Using the Data Acquisition System for Developing a Race Strategy Fuel Consumption 149 Tire Wear and Driver Consistenc
17、y. . 151 Chapter 15 Introduction to Measurement Analog-Digital Conversion: Accuracy Implications 153 Sensor Selection and Application 154 Measurement Uncertainty 156 Temperature Sensors 158 Pressure Sensors . 160 Displacement Sensors 161 Acceleration Sensors 161 Speed Sensors 163 Strain Gages 163 Pi
18、tot Tube. 165 Oxygen Sensors 165 GPS 165 Laser Distance Sensors 166 List of Symbols 169 References . 173 Bibliography. 175 Index 177 About the Author. 185 TAB LE OF CONTENTS viiviiiPREFACE A proven way for athletes to be successful in any sporting discipline is for them to record their performance,
19、analyze what has happened, and draw con- clusions from the factors that influence that performance. Marathon runners log their running speed and distance with their heart rate to optimize their training schedules. Football players record their games on video to evaluate techniques, performance, and
20、tactics. Chess players write down every move in a game to replay and analyze it afterward. They measure something, learn from it, and try to use it to their advantage next time. In motor racing, sophisticated recording devices are used in conjunction with numerous sensors to record what the car and
21、its driver are doing. Engineers often are employed full-time to maintain the system, analyze the recorded data, and draw the correct conclusions from it. Motor racing is known for high-end technology, and this technology changes every day. Ten years ago, racecar data acquisition was somewhat limited
22、 to well-funded teams in high-profile championships. Nowadays, the cost of elec- tronics has decreased dramatically. Powerful computers are available for very little expense. Data acquisition systems are now sold for the price of a single rac- ing tire. This means data acquisition has become accessi
23、ble to everyone. Whatever the price of the data acquisition system, it is a waste of money if the recorded data is not interpreted correctly. This book contains enough infor- mation to prevent the investment in a data acquisition system from being a waste of money. Whether measuring the performance
24、of a Formula One racecar or that of a road-legal street car on the local drag strip, the dynamics of the vehicles and their drivers remain the same. Identical analysis techniques apply. This book contains a collection of techniques for analyzing data recorded by any vehicles data acquisition system.
25、 It details how to measure the performance of the vehi- cle and driver, what can be learned from it, and how this information can be used to your advantage the next time the vehicle hits the track. PREFACE ixxACKNOWLEDGMENTS When I began working in motor racing in 1998, I soon learned that this busi
26、ness is a team effort. The sum of the qualities of each member determines the teams success. Eight years later, when I wrote this book, I learned this also is a team effort, very similar to running a successful racing team. That is why I would like to begin by appropriately crediting “my“ team. Firs
27、t, I would like to thank everyone at SAE International for guiding this project in the right direction. Special thanks go out to Martha Swiss, intellectual property manager, and Terri Kelly, administrative assistant, as well as Terry Wilson for artwork. A big contributor to this book was Josep Fontd
28、ecaba I. Buj, engineering director at Creuat S.L., not only for writing the greater part of Chapter 10, but especially for the many discussions we had about suspension setup and data analysis. His input added immeasurable value to this book. David Brown and Andrew Durant at Race Technology gave me d
29、etailed insight about GPS-based data acquisition techniques. I would like to thank them for providing me with the hardware that was used to create much of the data traces used throughout this book. Their company is proof that data acquisition can be affordable for all motor racing disciplines. I am
30、proud to have Pi Research support the creation of this book. The information and analysis files supplied by this company were invaluable. Thanks go out to Thomas Buckler and Michael de Cock. The following people deserve credit for taking the time to evaluate the manuscript and for providing me with
31、invaluable feedback: Peter Wright (con- sultant to the FIA), Dr. Wolfgang Ullrich (head of Audi Sport), John Glimmerveen (author of the book Hands-on Racecar Engineer), Doug and Bill Milliken (authors of the book Racecar Vehicle Dynamics), and William C. Mitchell (head of Mitchell Software). This bo
32、ok addresses what I know about racecar data acquisition, and what I know is influenced greatly by the people I had a chance to work with. Therefore, my great respect goes out to all the engineers, mechanics, and team owners that were there to teach me. I hope I can repay these debts when they read t
33、his book. Every graph in this book was created by a racecar driver. Many of these graphs resulted in successful track performance, pole positions, race victories, and championships. I thank all of these drivers for providing me with data to analyze. Finally, I would like to thank Henrik Roos of the
34、Simbin Development Team for triggering my interest in writing. He gave me the idea to write a book on this little-documented subject in the first place. Jrge Segers ACKNOWLEDGMENTS xixiiCHAPTER 1 INTRODUCTION O ne of the most important weapons a racecar team can employ is information. The more infor
35、mation it can gather (and process), the better its judgment will be in making key decisions. Data acquisition provides engineers with the information they and the team require to evaluate vehicle performance. What Is This Book All About? Nowadays, almost every racecar is equipped with a data logging
36、 device that can measure almost every performance parameter of the vehicle and its driver. These measurements can be used to exam- ine the effects of setup changes or changing track conditions, driving style, and causes of perfor- mance variations or component failures. This book covers the use of e
37、lectronic data logging systems in racecars. It is not a how-to man- ual for installing a data logger, selecting different components, or choosing the most appropriate con- figuration, although these topics are discussed briefly. This book is primarily about analyzing the endless data streams produce
38、d by the system. It is also about using this information to evaluate and optimize a given racecars setup. The data logging system provides informa- tion about how a car-driver combination is per- forming at a particular location on a racetrack. This book takes the analysis a step further and tries t
39、o determine why the car/driver is performing in this particular way at this particular place on the track. Upon completing the book, the reader will have the insight to effectively use competition car data acquisition. Useful literature addressing racecar data acquisition and data analysis already h
40、as been pub- lished. However, in this work a mathematical approach to data analysis is emphasized, with the primary intention being to show the reader how even a limited amount of data can provide useful information about racecar dynamics. Figure 1.1 Racecar data logging systems record user-defined
41、parameters while the car is in motion. These data can be downloaded afterwards to a computer and analyzed. (Courtesy of GLPK-Carsport) In the early days of motor racing, many of the engineers decisions were based on intuition and experience. The stopwatch, tire pressure gauge, pyrometer, and drivers
42、 comments served as the data logging system. Nowadays, the electronic data acquisition system provides almost everything the engineer needs to know about the cars behavior. As the degree of competition increases, costs of racing and testing increase. Because of this, there is a greater demand for un
43、derstanding the racecar dynamics to increase testing efficiency, educate drivers, and provide them with the tools to educate themselves. It is also important to provide the parameters to simulate the dynamic behavior of the car. This more than justifies the use of data acquisi- tion, and in the past
44、 this was indeed only possible at the higher echelons of motor racing. However, times have changed, and data acquisition is now a com- mon technique from Formula One and Indy cars to clubsport championships and karting. The configuration of the book is as follows: Chapter 1: This chapter is an intro
45、duction to data acquisition. What is data acquisitions pur- pose? What should one measure? What are the hardware requirements? What are the latest devel- opments in data acquisition? Chapter 2: What should one require from the analysis software? What different ways can data be displayed? How can one
46、 manipulate the data channels? Chapter 3: During race weekends or test sessions, time limitations require the engineer to be able to quickly find what he needs in the logged data. Developing the ability to read the graphs is required. INTRODUCTION 1Chapter 4: In this chapter, straight-line accelerat
47、ion is analyzed as well as the ability of the racecar to overcome the external resistances acting upon it. Chapter 5: Acceleration usually is fol- lowed by braking. This chapter covers the perfor- mance analysis of the cars braking system. Chapter 6: Most racecars carry a gearbox to adapt the vehicl
48、e torque to a wide range of veloc- ities. This chapter discusses shifting techniques and the choice of the proper gear ratios for a given racetrack. Chapter 7: How can the cars cornering balance be evaluated? How does one diagnose oversteering and understeering? Chapter 8: In this chapter, methods t
49、o quantify the roll stiffness and its distribution on the front and rear axles are covered. Chapter 9: This chapter addresses how the loads at the tires contact patches are calculated and investigates the effects of lateral and longitudi- nal load transfer. Figure 1.2 This graph shows the signals recorded from four potentiometers mounted on the suspension as well as the damper acceleration of the left front wheel. The area indicated shows what happened to the wheels when the photograph in Figure 1.1 was taken. Chapter 10: The shock absorbers determine the transien
