THE DEVELOPMENT OF ASSIST TORQUE MAP EXPONENTIAL CURVE CONTROL ALGORITHM FOR ELECTRIC POWER STEERING SYSTEM (EPS)

What is assist torque?
Motor-driven power steering (MDPS) uses an electric motor rather than hydraulic system to assist the driver of a vehicle.
How?
The sensor detects the force and torque of the steering wheel, and the computer module applies assistive torque the motor, which connects to either the steering gear or steering column.
EPS characteristic curve is to determine the regulation of change of EPS assist torque according to the speed of the vehicle and the steering torque of the driver.
What is torque map?
Torque map is the main element of an EPS controller.
It determines how much steering torque is assisted by the motor.
The shape of the torque map determines how the steering feels for the driver.
The slope of the torque map is the steepest when the velocity is zero.
Then decreases with an increase in speed.
Because the torque that is needed to steer is the largest when the vehicle is parked, and the steering needs to feel heavier for the driver when a vehicle is going fast to achieve stability ([1]Crandall, 1978).