Steering Moment Calculation Tool

This is a python script to compute the moment necessary to direct each front wheel, and the resulting moment at the steering wheel.

the script is available on GitLab.

Theoretical Background

The theory on which is based this tool is given in the Steering Moment Theory

Configuration

Before runing the calculation, you should edit the config.py file that containes all input values necessary to run the script.

The config.py can be downloaded, and is displayed hereafter:

# Result File Configuration
RESULT_FILENAME = "0_steering_calculation_Speed0_Ratio20_RightTurn_0latForce_2Wheels.txt"

# Vehicle and Tire Parameters
VEHICLE_MASS = 450  # kg
WEIGHT_DISTRIBUTION_FRONT = 0.7  # fraction of weight on front axle
GRAVITY = 9.81  # m/s²

# Tire Parameters
TIRE_CONTACT_PATCH_LENGTH = 0.10  # m https://iopscience.iop.org/article/10.1088/1757-899X/632/1/012022/pdf
TIRE_CONTACT_PATCH_WIDTH = 0.145  # m tire width R13 145/60
PNEUMATIC_TRAIL = 0.030  # m (typical range: 0.010-0.030) https://en.wikipedia.org/wiki/Pneumatic_trail

# Road and Friction Parameters
FRICTION_COEFFICIENT = 0.9  # dry asphalt (range: 0.7-1.0)

# Steering Geometry Parameters
CASTER_ANGLE = 5.0  # degrees (typical range: 2-8)
SCRUB_RADIUS = 0.015  # m (positive = outward offset, negative = inward)
KINGPIN_INCLINATION = 15.0  # degrees (typical range: 5-12)
MECANICAL_TRAIL = 0.015  # m (also called caster offset)

# Steering System Parameters
MECHANICAL_ADVANTAGE = 1.0  # additional mechanical advantage from power steering
BEARING_FRICTION_COEFFICIENT = 0.02  # internal friction losses
STEERING_GEARBOX_RATIO = 10.0 # ratio of the steering reduction gearbox, between the steering wheel and the steering column
STEERING_GEARBOX_EFFICIENCY = 0.9 # efficiency between input and output shaft
STEERING_RATIO = 2*STEERING_GEARBOX_RATIO  # steering wheel degrees per wheel degree

# Operating Conditions
DESIRED_AXIAL_FORCE = 0  # N (in case of braking)
DESIRED_LATERAL_FORCE = 0  # N (can be calculated from cornering requirements)
VEHICLE_SPEED = 0  # km/h (for dynamic calculations if needed)

# Additional Parameters
TIRE_PRESSURE = 2.2  # bar (affects pneumatic trail)
ROAD_CAMBER = 0.0  # degrees (road banking angle)

How to run the analysis

The analysis can then be run using following command line:

python steering_moment_calculator.py config.py