Damping control

The damping control can increase the ride quality and steering stability simultaneously. The damping control controls by classifying it into the sky hook control and adaptive control. The sky hook control performs the independent control by classifying the vehicle movement into the bounce, roll and pitch to improve the ride quality. The adaptive control ensures the driving stability at the specific driving conditions such as sudden lane change, sudden acceleration and sudden braking. The target current

determined by each situation is achieved through the solenoid valve PWM [0~100%] control. 

The vertical velocity of vehicle body and damper is calculated using the vertical acceleration sensor signal of the vehicle body and wheels. The sky hook control determines the optimum damping force for 4 wheels using the speed of vehicle body and damper and controls the solenoid current of each wheel in real time.

1. Deciding the road surface

   For optimal control according to the each road condition, it controls by classifying the road conditions into 7 types [Normal, rough road 1, rough road 2, wave, continuous wave, mound, port hole]. The road condition is judged by the vertical acceleration sensor of the vehicle body. When more than 2 road conditions are judged simultaneously, it controls the road condition determined by priority that is set in advance. The road judgement can be corrected through the parameter calibration.

2. Bounce controlling

   The vertical velocity of vehicle body can be obtained by integrating the vehicle's vertical acceleration signal and the bounce velocity is calculated by adding up the vertical velocity of each wheel (4EA). The required damping force is determined by multiplying the bounce velocity for each vehicle speed by proportional gain and the maximum damping force can be limited. The bounce proportional gain and the maximum damping force can be corrected by the calibration parameter and can control the independent value of front/rear wheels.

3. Pitch control

   The vertical velocity of vehicle body can be obtained by integrating the vehicle's vertical acceleration signal and the pitch velocity is calculated by the difference between the vehicle body speed of front and rear wheels. The required damping force is determined by multiplying the pitch velocity for each vehicle speed by proportional gain and the maximum damping force can be limited. The pitch proportional gain and the maximum damping force can be corrected by the calibration parameter and can control the independent value of front/rear wheels.

4. Roll control

   The vertical velocity of vehicle body can be obtained by integrating the vehicle's vertical acceleration signal and the roll velocity is calculated by the difference between the vehicle body speed of left and right wheels. The required damping force is determined by multiplying the roll velocity for each vehicle speed by proportional gain and the maximum damping force can be limited. The roll proportional gain and the maximum damping force can be corrected by the calibration parameter and can control the independent value of front/rear wheels.

5. Damping speed estimation

   The damper velocity can be estimated using the difference between the vertical velocity of wheels and vehicle body and the vertical velocity of wheels and vehicle body can be obtained by integrating the acceleration sensor signal. The rear wheel acceleration can be estimated through the vehicle's speed information and the front wheel acceleration sensor.

6. Directivity check

   The finally required damping force of sky hook is determined through the "Passivity Condition". The "Passivity Check" determines the necessity of damping force control of damper. If the required damping force and the damper velocity are in the same direction, finally required damping force is set through the solenoid current control and if the direction is opposite, it is set as soft damping force.