Hanbyeol La1, Gwangrok Lee1, Cheoljun Yang1, Taejin Ahn1 , Seongeun Park1, Hyun Oh1, Kwangseok Oh1

1School of ICT, Robotics & Mechanical Engineering, Hankyong National University

An Investigation on Steering Load of Self-Manufacture EV carto Human Driver by Universal Joint Angle

The Korean Society of Automotive Engineers 2021

⚫ Motivation

- In our previous vehicle, there were problems that driver feels discomfort in the steering

and handling performance was relatively low due to limited universal joint angle.

- Therefore, new design approach is needed for improving driver convenience and

handling performance.

Objective

⚫ In this study, Universal joint angle was redesigned for driver

convenience and handling performance by considering allowable angle

of Universal Joint.

- The steering load that driver feels was reduced by redesigning a rack pinion

pedestal and universal joint angle.

Methodology

Introduction Performance Evaluation

Conclusion

⚫ In this study, a rack pinion pedestal and universal joint angle were redesigned by

considering the allowable angle of the universal joint to reduce the driver steering

load and improving handling performance.

⚫ To validate the redesigned self-manufacture EV car, the steady state condition

experiment was conducted by applying the designed rack pinion pedestal and

universal joint angle. It was shown that the steering load on driver and turning

radius were decreased.

Reference

[1[1 J. Kim, W. Yoo, and J. Sim, “Angular velocity of steering column according to spider cross angle in

the universal joint,” , pp.713-718, 2000.

[2] S. F. Asokanthan, and M. Hwang, “Torsional instabilities in a system incorporating a Hooke’s joint,”

Transaction of the ASME, Vol. 118, No. 3, pp.368-374, 1996.

⚫ Rack-pinion pedestal designed in consideration of steering angle.

- In this study, allowable angle of the universal joint has been used for a rack pinion

pedestal

- By designing a pedestal with a 45-degree plane, the operating angle of the former

80 degrees changed to 35 degrees.

- Based on the input-output angle relationship, the experimental test was

conducted by 45 degrees of steering wheel angle, where the angle difference is

the most severe.

- As a result of the experiment, it was shown that the steering turning radius was

increased and the steering sensitivity decreased accordingly.

- At the same steering angle, the steering load on the driver was decreased

because the output shaft was rotated at a smaller angle.

- The following tables show how hard the driver feels when the steering is

suddenly turned to 15 degrees while the car is driving at a constant speed of

about 5 kilometers per hour.

- Each average value of the previous vehicle and the current vehicle was 88 points

and 34 points, and the difference between the average values was 54 points.

( Out of 100 points )

[Experiment on steering load to human by universal joint angle(45 deg steering + steady state turning) ]

⚫ Setting operation of the universal joint

- All universal joints using cross repeat acceleration and deceleration twice per

rotation, as shown in the figure below.

- The larger the angle at which the two axes intersect, the greater the acceleration

and deceleration, and the more severe the vibration.

[ Before Redesigning]

(a) Initial condition for steering experiment (steering wheel angle = 45 deg )

(a) Evaluation values for steering hardness experiment

(b) Analysis results of steering hardness

⚫ Performance evaluation using actual self-manufacture EV car

[ After Redesigning ]

(b) Experiment result (Steady state turning)

[ Experiment on steering load by universal joint angle ]

Division

Value [-]

Former Current

Average 88 34

Maximum 90 40

Minimum 80 30

[ Before Redesigning] [ After Redesigning ]