Optimisation of steering geometry - ADAMS
initial Parameters (Before optimisation):
i. Caster angle vs Steering Wheel Angle:
Caster angle at 0 steering wheel angle is found out to be 5.369 deg.
ii. Caster Moment arm vs Steering wheel angle:
Caster Moment arm at 0 steering angle is 8.5806mm.
iii. KPI vs Steering Wheel Angle
The KPI is found out to be 10.0855 at 0 deg steering wheel angle
iv. Steer Axis Offset (Resultant) vs Steering Wheel Angle:
the steer axis offset is found out to be 85.774mm.
v. Steer axis longitudinal offset vs Steering Wheel Angle:
The logitudnal steer axis offset is -18.7407mm
vi. Scrub Radius vs Steering Wheel Angle:
At 0 deg steering wheel angle the scrub radius is 33.8081mm
Modified Hardpoints:
Parameters after Modification:
i. Caster angle vs Steering Wheel Angle:
Caster angle at 0 steering wheel angle is found out to be 4.0232 deg.
ii. Caster Moment arm vs Steering wheel angle:
Caster Moment arm at 0 steering angle is 20.22mm.
iii. KPI vs Steering Wheel Angle
The KPI is found out to be 12.9855 deg at 0 deg steering wheel angle
iv. Steer Axis Offset (Resultant) vs Steering Wheel Angle:
the steer axis offset is found out to be 84.8984mm.
v. Steer axis longitudinal offset vs Steering Wheel Angle:
The logitudnal steer axis offset is -0.0347mm
vi. Scrub Radius vs Steering Wheel Angle:
At 0 deg steering wheel angle the scrub radius is 20.2251mm
Comparision and Explanation of effect of the changes:
i. Caster:
Initial Value: 5.369 deg
Modified value: 4.0232 deg
having high caster increases steering effort but makes increases stability in straight line, noe the caster is reduced so this would reduce steerting effort but might hinder straight line stability.
ii. Caster Moment Arm:
Iniital Value: 8.5806mm.
Modified Value: 20.22mm.
The increase in the caster moment arm given more self alinging torque, might interfere with the skid warning.
iii. KPI:
Initial Value: 10.0885 deg
Final value: 12.9855 deg
the increase in KPI will aid the selfcentering but might make the make the steer feel heavy.
iv. Steering Axis Offset (resultant):
Initial Value: 85.774mm
Final Value: 84.8984mm
A high offset will introduce torque steer in front wheel drive cars and stability issues are introduced due to logitudnal offset.
v.Sttering Axis Offset (Logitudnal):
Initial Value: -18.7407mm
Final Value: -0.0347mm
This make the vehicle more stable.
vi. Scrub Radius:
Inital Value: 33.8081mm
Final Value: 20.2251mm
lowering the scrub radius will reduce unneccerary torque intro dued on the tire during braking and if the grip level of the tires is not equal then it might turn the car.
Controlling of the parameters:
All the parameters which are measured on the side view (ZX plane) of the car like Caster angle, Caster moment arm are linked.
All the parameters which are viewed from the front view (ZY plane) of the car like KPI, Steering axis offsets and scrub radius are linked.
there might be minute variation of the parameter in side view when the front view parameters are changed and vice versa like steer axis offset