Report

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

4. GROUP C 128

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

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