Theory of Ground Vehicles

A leading and authoritative text for advancing ground vehicle mobility

Theory of Ground Vehicles, Fifth Edition presents updated and expanded coverage of the critical factors affecting the performance, handling, and ride essential to the development and design of road and off-road vehicles.

Replacing internal combustion engines with zero-emission powerplants in ground vehicles to eliminate greenhouse gas emissions for curbing climate change has received worldwide attention by both the vehicle industry and governmental agencies. To enhance safety, traffic flow, and operating efficiency of road transport, automated driving systems have been under active development. With growing interest in the exploration of the Moon, Mars, and beyond, research in terramechanics for guiding the development of extraterrestrial rovers has been intensified. In this new edition, these and other topics of interest in the field of ground vehicle technology are explored, and technical data are updated. New features of this edition include:

• Expanded coverage of the fundamentals of electric drives, hybrid electric drives, and fuel cell technology
• Introduction to the classification and operating principles of the automated driving system and cooperative driving automation
• Applications of terramechanics to guiding the development of extraterrestrial rovers
• Elaboration on the approach to achieving the optimal operating efficiency of all-wheel drive off-road vehicles
• Introduction to updated ISO Standards for evaluating vehicle ride

An updated and comprehensive text and reference for both the educational and professional communities, Theory of Ground Vehicles, Fifth Edition will prove invaluable to aspiring and practicing engineers seeking to solve real-world road and off-road vehicle mobility problems.

J. Y. Wong is Professor Emeritus, Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Canada. He received his PhD and DSc from the University of Newcastle upon Tyne, England. He is also the author of Terramechanics and Off-Road Vehicle Engineering. An internationally recognized leading expert in ground vehicle mobility, he is on the editorial/advisory boards of a number of international journals. He has received numerous awards from learned societies for his research accomplishments.

PREFACE TO THE FIFTH EDITION

PREFACE TO THE FOURTH EDITION

PREFACE TO THE THIRD EDITION

PREFACE TO THE SECOND EDITION

PREFACE TO THE FIRST EDITION

CONVERSION FACTORS

LIST OF SYMBOLS

ACRONYMS

INTRODUCTION

1 MECHANICS OF PNEUMATIC TIRES

1.1 Tire Forces and Moments

1.2 Rolling Resistance of Tires

1.3 Tractive (Braking) Effort and Longitudinal Slip (Skid)

1.3.1 Tractive Effort and Longitudinal Slip

1.3.2 Braking Effort and Longitudinal Skid

1.4 Cornering Properties of Tires

1.4.1 Slip Angle and Cornering Force

1.4.2 Slip Angle and Aligning Torque

1.4.3 Camber and Camber Thrust

1.4.4 Characterization of Cornering Behavior of Tires

1.4.5 The Magic Formula

1.5 Performance of Tires on Wet Surfaces

1.6 Ride Properties of Tires

1.7 Tire/Road Noise

References

Problems

2 MECHANICS OF VEHICLE–TERRAIN INTERACTION–TERRAMECHANICS

2.1 Applications of the Theory of Elasticity to Predicting Stress Distributions in the Terrain under Vehicular Loads

2.2 Applications of the Theory of Plastic Equilibrium to the Mechanics of Vehicle–Terrain Interaction

2.3 Empirically Based Models for Predicting Off-Road Vehicle Mobility

2.3.1 NATO Reference Mobility Model (NRMM)

2.3.2 Empirical Models for Predicting Single Wheel Performance

2.3.3 Empirical Models Based on the Mean Maximum Pressure

2.3.4 Limitations and Prospects for Empirically Based Models

2.4 Measurement and Characterization of Terrain Response

2.4.1 Characterization of Pressure–Sinkage Relationships

2.4.2 Characterization of the Response to Repetitive Normal Loading

2.4.3 Characterization of Shear Stress–Shear Displacement Relationships

2.4.4 Characterization of the Response to Repetitive Shear Loading

2.4.5    Bekker-Wong Terrain Parameters

2.5 A Simplified Physics-Based Model for the Performance of Tracked Vehicles

2.5.1 Motion Resistance of a Track

2.5.2 Tractive Effort and Slip of a Track

2.6 An Advanced Physics-Based Model for the Performance of Vehicles with Flexible Tracks

2.6.1 Approach to the Prediction of Normal Pressure Distribution under a Track

2.6.2 Approach to the Prediction of Shear Stress Distribution under a Track

2.6.3 Prediction of Motion Resistance and Drawbar Pull as Functions of Track Slip

2.6.4 Experimental Substantiation

2.6.5 Applications to Parametric Analysis and Design Optimization

2.7 An Advanced Physics-Based Model for the Performance of Vehicles with Long-Pitch Link Tracks

2.7.1 Basic Approach

2.7.2 Experimental Substantiation

2.7.3 Applications to Parametric Analysis and Design Optimization

2.8 Physics-Based Models for the Cross-Country Performance of Wheels (Tires)

2.8.1 Motion Resistance of a Rigid Wheel

2.8.2 Motion Resistance of a Pneumatic Tire

2.8.3 Tractive Effort and Slip of a Wheel (Tire)

2.9 A Physics-Based Model for the Performance of Off-Road Wheeled Vehicles

2.9.1 Basic Approach

2.9.2 Experimental Substantiation

2.9.3 Applications to Parametric Analysis

2.10 Slip Sinkage

2.10.1 Physical Nature of Slip Sinkage

2.10.2 Simplified Methods for Predicting Slip Sinkage

2.11 Applications of Terramechanics to the Study of Mobility of Extraterrestrial Rovers and Their Running Gears

2.11.1 Predicting the Performance of Rigid Rover Wheels on Extraterrestrial  

Surfaces Based on Test Results Obtained on Earth

2.11.2 Performances of Lunar Roving Vehicle Flexible Wheels Predicted

Using the Model NWVPM and Correlations with Test Data

2.12   Finite Element and Discrete Element Methods for the Study of Vehicle–Terrain Interaction

2.12.1 The Finite Element Method

2.12.2 The Discrete (Distinct) Element Method

References

Problems

3 PERFORMANCE CHARACTERISTICS OF ROAD VEHICLES

3.1 Equation of Motion and Maximum Tractive Effort

3.2 Aerodynamic Forces and Moments

3.3 Internal Combustion Engines

3.3.1 Performance Characteristics of Internal Combustion Engines

3.3.2 Emissions of Internal Combustion Engines

3.4   Electric Drives

3.4.1    Elements of an Electric Drive

3.4.2 Characteristics of Battery Electric Vehicles

3.5   Hybrid Electric Drives

3.5.1 Types of Hybrid Electric Drive

3.5.2 Characteristics of Energy Consumption and Emissions of Hybrid Electric Vehicles

3.6 Fuel Cells

3.6.1 Polymer Electrolyte Membrane Fuel Cells

3.6.2 Characteristics of Fuel Cell Vehicles

3.7 Transmissions for Vehicles with Internal Combustion Engines

3.7.1 Manual Gear Transmissions

3.7.2 Automatic Transmissions

3.7.3 Continuous Variable Transmissions

3.7.4 Hydrostatic Transmissions

3.8 Prediction of Vehicle Performance

3.8.1 Acceleration Time and Distance

3.8.2 Gradeability

3.9 Operating Fuel Economy of Vehicles with Internal Combustion Engines

3.10   Internal Combustion Engine and Transmission Matching

3.11 Braking Performance

3.11.1 Braking Characteristics of a Two-Axle Vehicle

3.11.2 Braking Efficiency and Stopping Distance

3.11.3 Braking Characteristics of a Tractor–Semitrailer

3.11.4 Antilock Brake Systems

3.11.5 Traction Control Systems

References

Problems

4 PERFORMANCE CHARACTERISTICS OF OFF-ROAD VEHICLES

4.1 Drawbar Performance

4.1.1 Drawbar Pull and Drawbar Power

4.1.2 Drawbar (Tractive) Efficiency

4.1.3 All–Wheel Drive

4.1.4 Coefficient of Traction

4.1.5 Weight-to-Power Ratio for Off-Road Vehicles

4.2 Fuel Economy of Cross-Country Operations

4.3 Transport Productivity and Transport Efficiency

4.4 Mobility Map and Mobility Profile

4.5 Selection of Vehicle Configurations for Off-Road Operations

References

Problems

5 HANDLING CHARACTERISTICS OF ROAD VEHICLES

5.1 Steering Geometry

5.2 Steady-State Handling Characteristics of a Two-Axle Vehicle / 367

5.2.1 Neutral Steer

5.2.2 Understeer

5.2.3 Oversteer

5.3 Steady-State Response to Steering Input

5.3.1 Yaw Velocity Response

5.3.2 Lateral Acceleration Response

5.3.3 Curvature Response

5.4 Testing of Handling Characteristics

5.4.1 Constant Radius Test

5.4.2 Constant Speed Test

5.4.3 Constant Steer Angle Test

5.5 Transient Response Characteristics

5.6 Directional Stability

5.6.1 Criteria for Directional Stability

5.6.2 Vehicle Stability Control

5.7   Driving Automation

5.7.1 Classification of Levels of Driving Automation

5.7.2 Automated Driving Systems and Cooperative Driving Automation

5.8 Steady-State Handling Characteristics of a Tractor–Semitrailer

5.9 Simulation Models for the Directional Behavior of Articulated Road Vehicles

References

Problems

6 STEERING OF TRACKED VEHICLES

6.1 Simplified Analysis of the Kinetics of Skid-Steering

6.2 Kinematics of Skid-Steering

6.3 Skid-Steering at High Speeds

6.4 A General Theory for Skid-Steering on Firm Ground

6.4.1 Shear Displacement on the Track–Ground Interface

6.4.2 Kinetics in a Steady-State Turning Maneuver

6.4.3 Experimental Substantiation

6.4.4 Coefficient of Lateral Resistance

6.5 Power Consumption of Skid-Steering

6.6 Skid Steering Systems for Tracked Vehicles

6.6.1 Clutch/Brake Steering System

6.6.2 Controlled Differential Steering System

6.6.3 Planetary Gear Steering System

6.7 Articulated Steering

References

Problems

7 VEHICLE RIDE CHARACTERISTICS

7.1 Human Response to Vibration

7.1.1 International Standard ISO 2631/1-1985

7.1.2 International Standard ISO 2631–1:1997/Amd.1:2010

7.1.3 Absorbed Power

7.2 Vehicle Ride Models

7.2.1 Two-Degrees-of-Freedom Vehicle Model for Vertical Vibrations of Sprung and Unsprung Mass

7.2.2 Numerical Methods for Determining the Response of a Quarter-Car Model to Irregular Surface Profile Excitation

7.2.3 Two-Degrees-of-Freedom Vehicle Model for Pitch and Bounce

7.3 Introduction to Random Vibration

7.3.1 Surface Elevation Profile as a Random Function

7.3.2 Frequency Response Function

7.3.3 Evaluation of Vehicle Vibration in Relation to Ride Comfort Criteria

7.4 Active and Semiactive Suspensions

7.4.1    Active Suspensions

7.4.2    Semi-Active Suspensions

References

Problems

8 INTRODUCTION TO AIR-CUSHION VEHICLES

8.1 Air-Cushion Systems and Their Performances

8.1.1 Plenum Chambers

8.1.2 Peripheral Jets

8.2 Resistances of Air-Cushion Vehicles

8.3 Suspension Characteristics of Air-Cushion Systems

8.3.1 Heave (or Bounce) Stiffness

8.3.2 Roll Stiffness

8.4 Directional Control of Air-Cushion Vehicles

References

Problems

INDEX

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