Suspension control device

1. A suspension control device for a vehicle having a variable-damping-force damper of which the damping force is adjustable based on input signals, the suspension control device comprising:

a wheel speed sensor configured to detect wheel speed of the vehicle;

a basic input amount calculating controller configured to calculate a basic input amount of the vehicle, based on wheel speed fluctuation amount in the wheel speed detected by the wheel speed sensor;

a first target current setting controller configured to set a first target current for the variable-damping-force damper, based on the basic input amount;

an acceleration sensor configured to detect a body acceleration of the vehicle;

a second target current setting controller configured to set a second target current for the variable-damping-force damper, based on the body acceleration detected by the acceleration sensor;

a vehicle behavior controller which controls behavior of the vehicle; and

a damper controller configured to control damping force of the variable-damping-force of damper, based on at least one of the first target current and the second target current;

wherein the damper controller controls the damping force of the variable-damping-force damper based on the first target current when the vehicle behavior controller is not operating, and controls the damping force of the variable-damping-force damper based on the second target current when the vehicle behavior controller is operating.

2. The suspension control device according to claim 1 ,

wherein the acceleration sensor includes

a longitudinal acceleration sensor configured to detect a longitudinal acceleration in the longitudinal direction of the vehicle, and

a lateral acceleration sensor configured to detect a lateral acceleration in the lateral direction of the vehicle;

and wherein the second target current setting controller includes:

a second pitch controller configured to set a second pitch control target current based on the detected longitudinal acceleration of the vehicle,

a second roll controller configured to set a second roll control target current based on the detected lateral acceleration of the vehicle, and

a third target current selecting controller configured to select greater one of the second pitch control target current and the second roll control target current as the second target current.

3. The suspension control device according to claim 2 ,

wherein the second pitch controller sets the second pitch control target current such that the greater the longitudinal acceleration of the vehicle is, the greater the second pitch control target current is.

4. The suspension control device according to claim 2 ,

wherein the second roll controller sets the second roll control target current such that the greater the lateral acceleration of the vehicle is, the greater the second roll control target current is.

5. The suspension control device according to claim 1 ,

wherein the first target current setting controller includes

a quantity-of-state calculating controller configured to calculate a quantity of state of the vehicle by inputting the basic input amount to a vehicle model representing behavior of the vehicle, and

a skyhook controller configured to set a skyhook control target current based on the quantity of state of the vehicle;

and wherein the first target current setting controller sets the first target current based on the skyhook control target current.

6. The suspension control device according to claim 5 , wherein the quantity of state of the vehicle includes a sprung speed and a stroke speed of a suspension of the vehicle.

7. The suspension control device according to claim 1 ,

wherein the first target current setting controller includes

a first pitch controller configured to set a first pitch control target current based on the basic input amount;

and wherein the first target current setting controller sets the first target current based on the first pitch control target current.

8. The suspension control device according to claim 1 ,

wherein the first target current setting controller includes

a first roll controller configured to set a first roll control target current based on the basic input amount;

and wherein the first target current setting controller sets the first target current based on the first roll control target current.

9. The suspension control device according to claim 1 , wherein the basic input amount is an unsprung load of a suspension of the vehicle.

10. The suspension control device according to claim 1 , wherein the vehicle behavior controller includes at least one of an antilock brake system, a traction control system, and a vehicle stability assist control system, and

wherein the damper controller determines if the vehicle behavior controller is operating or not.

11. A suspension control method for a vehicle having a variable-damping-force damper of which the damping force is adjustable based on input signals, the method comprising:

(i) calculating, by using a computer, a basic input amount of the vehicle, based on wheel speed fluctuation amount in wheel speed detected by a wheel speed sensor;

(ii) setting, by using the computer, a first target current for the variable-damping-force damper, based on the basic input amount;

(iii) setting, by using the computer, a second target current for the variable-damping-force damper, based on a body acceleration detected by an acceleration sensor;

(iv) determining, by using the computer, whether a vehicle behavior controller is operating; and

(v) controlling, by using the computer, the damping force of the variable-damping-force damper based on the first target current when the vehicle behavior controller is not operating, and when the vehicle behavior controller is operating, controlling the damping force of the variable-damping-force damper based on the second target current.