Report
INDEX
1. INTRODUCTION - 6
2. GROUP A - 8
A.1- INTRODUCTION AND GROUP STRUCTURE - 9
A.1.1- Project Objectives and Calculated Variables - 9
A.1.1.1- Subjective and Objective Assessment - 9
A.1.1.1.1- Vehicle Handling - 11
A.1.1.1.2- Frequency Response Test - 12
A.1.1.2- Group Function - 13
A.1.1.2.1- Models - 14
A.1.1.2.1.1- Simple Model - 14
A.1.1.2.1.2- Full Model - 15
A.1.1.2.1.3-Steering Wheel Torque - 15
A.1.1.2.1.4- CARSIMED - 15
A.1.1.2.2- Modifications - 16
A.1.1.3- Links with Other Groups -16
A.2- Description of the models - 18
A.2.1- Quick description - 18
A.2.1.1-The simple model - 18
A.2.1.1.1- The roll axis assumption - 18
A.2.1.1.2- The construction of the model - 19
A.2.1.1.3- The forces applications assumptions - 21
A.2.1.2- The full model - 24
A.2.1.2.1- The construction of the model - 24
A.2.2- The reasons to keep two models - 26
A.2.3- Explanations about the linear and non-linear analysis -27
A.3- Description of the improvements - 29
A.3.1- Identification of the sources of errors - 29
A.3.1.1- List of the potential sources of errors - 29
A.3.2- Improvements chosen - 30
A.3.2.1- Body stiffness - 30
A.3.2.2- Mechanical trail, pneumatic trail and caster angle - 31
A.3.2.3- Variation of the speed during the test - 33
A.3.2.4- Tyre relaxation - 34
A.3.2.4- Scrub derivative - 37
A.4-STEERING INPUT - 42
A.4.1- The linear model - 42
A.4.2- The non-linear model - 42
A.4.3- Defining the shape of the Steering input signal - 43
A.4.4- Using Experimental Steering input signal -48
A.5- Comparison between the Full Model and the Simple Model - 50
A.5.1- Lateral Acceleration – Gain - 53
A.5.2- Lateral acceleration – Phase - 54
A.5.3- Roll rate – Gain - 54
A.5.4- Yaw rate Gain & Phase - 54
A.5.5- Conclusion - 55
A.6- Sensitivity Trials for the Full Model - 56
A.6.1- Nominal Values - 57
A.6.2- Changed values - 57
A.6.3- Conclusion - 80
A.7- Overall conclusion for Group A - 81
A.7.1- Future work - 81
A.7.1.1- Some parameters have not been considered in the model - 82
A.7.1.2- Detailed study of frequency response curves - 82
3. GROUP B - 83
B.1-MEASUREMENT OF THE WHEEL INERTIA ABOUT ITS SPIN AXIS - 84
B.1.1-Description of the experimen - 84
B.1.2-Data, Formula and Results - 84
B.2-REPARTITION OF THE WEIGHT ON THE WHEEL AXIS - 86
B.2.1-Settings - 86
B.2.2-Electronic scales - 86
B.2.3-Measurements - 87
B.2.4-Exploitation of the results: determination of the center of mass. - 88
B.3-Rolling Radius - 90
B.3.1-Introduction - 90
B.3.2-Method - 90
B.3.3-Results - 92
B.3.3.4-Discussion -92
B.4-CAMBER AND CASTOR ANGLES, PNEUMATIC TRAIL AND
KING PIN INCLINATION - 94
B.4.1-Camber angle - 94
B.4.2-Castor angle - 95
B.4.3-Pneumatic trail - 97
B.4.4-King pin inclination - 97
B.4.5-Discussion - 97
B.5-MECHANICAL TRAIL - 98
B.6-SUSPENSION DERIVATIVES - 100
B.6.1-Set up - 100
B.6.2-Results - 101
B.6.3-Conclusion - 103
B.7-SUSPENSION DERIVATIVES (II) - 104
B.8-Steering gear ratio - 107
B.8.1-Introduction - 107
B.8.2-Method - 107
B.9-CORNERING STIFFNESS - 110
B.10-FRONT ROLL STIFFNESS -113
B.10.1-Introduction - 113
B.10.2-Method - 113
B.10.3-Discussion - 114
B.11-SUSPENSION DAMPING FACTOR - 116
B.11.1-Requirement to perform the test - 116
B.11.2-Front axle damping - 116
B.11.3-Rear axle Damping - 125
C.1-INTRODUCTION - 129
C.2-YAW AND ROLL RATE GYROSCOPES - 131
C.2.1-Background about gyroscopes - 131
C.2.2- Procedure for calibrating the gyros - 132
C.2.2.1- Construction of the pendulum - 133
C.2.2.2- Fitting the gyros on the pendulum - 133
C.2.2.3- Mathematical approach for calibrating the gyroscopes - 137
C.3-LATERAL AND LONGITUDINAL ACCELERATIONS - 143
C.3.1-Expectation and choice of the accelerometer - 143
C.3.1.1- Our main accelerometer performances are - 143
C.3.2- Calibration of the linear accelerometer - 144
C.3.2.1-Power supply and acquisition chain - 149
C.3.3- Mounting of the accelerometer -149
C.4-STEERING ANGLE MEASUREMENT - 150
C.4.1-Requirements -150
C.4.2-Potentiometer choice and specifications - 152
C.4.3-Potentiometer mounting - 153
C.4.4-Potentiometer calibration - 154
C.5-POWER SUPPLY - 156
C.5.1-First approach - 156
C.5.1.1- High voltage supply -156
C.5.1.2- Low voltage supply - 156
C.5.2-second approach - 160
C.6- THE DATA ACQUISITION SYSTEM - 162
C.6.1- Introduction - 162
C.6.2- Steps of data acquisition -163
C.6.2.1- DBK18 – Signal Conditioning - 164
C.6.2.2 DaqBook -166
C.6.2.3 DaqView – Software - 167
C.6.3- Aliasing - 170
5. GROUP D - 171
D.1- Summary - 172
D.2-Introduction - 173
D.2.1-What is signal processing and why do we need it for this application? - 173
D.2.2-Role of signal processing group within the assignment - 175
D.3- Background to frequency analysis - 178
D.4- Matlab programs - 181
D.5- Results from the airfield test - 186
D.6- Carsim educational - 194
D.6.1-CarSimEd - 194
D.6.1.1- Construction of the vehicle model in Carsimed - 195
D.6.1.2- Simulation of the tests using Carsimed - 198
D.7-Achievements of the Group - 206
D.8-Dynamics 2001 Graphic User Interface - 207
D.8.1-Introduction - 207
D.8.1-GUI Description - 208
6. PROJECT MANAGEMENT - 215
6.1 Creation of the Management Team - 215
6.2 Groups and Tasks -216
6.3 Evolution of the Project - 218
6.4 Communication - 226
6.5 conclusions - 226
7. Airfield test - 227
7.1 Considerations - 228
7.1.1 Conditions of the test - 230
7.2 The pre-test - 230
7.3 The Test - 231
8. Final comparisons - 234
8.1 Summary of the features of all cases - 241
8.2 Comparisons between models and airfield test - 242
8.3 Comparison between laden and unladen cases - 243
9. Conclusions - 244
Appendix - 245
A 1.- Group A. hierarcical structure of the simple model
A 2.- group a. hierarcical structure of the full model
A 3.- group a. AUTOSIM code
A 4.- group b. addendum
A 5.- group c. instruments specifications
A 6.- group d. Matlab files
A7.- management team. minutes meetings