Suspension control device and suspension device

1. A suspension control device for controlling a damping force of a suspension, comprising:

a road surface determining section configured to determine a road surface condition; and

a control variable calculating section configured to calculate, in accordance with a result of the determination by the road surface determining section, a steering-based desired control variable which is to be referred to in controlling the damping force of the suspension,

the control variable calculating section comprising:

a first desired control variable calculating section configured to calculate a first desired control variable which is to be referred to in calculating the steering-based desired control variable;

a second desired control variable calculating section configured to calculate a second desired control variable which is to be referred to in calculating the steering-based desired control variable;

a multiplying section configured to multiply a value of the first desired control variable by a coefficient in accordance with the result of the determination by the road surface determining section; and

a selecting section configured to select the steering-based desired control variable from a plurality of candidates including the first desired control variable multiplied by the coefficient and the second desired control variable,

the first desired control variable calculating section being configured to calculate the first desired control variable with reference to a steering torque signal indicative of a steering torque which is applied to a steering member used by a driver for steering,

the second desired control variable calculating section being configured to calculate the second desired control variable with reference to a steering angle signal of the steering member.

2. The suspension control device according to claim 1 , wherein the road surface determining section includes:

a high-pass filter configured to act on a reference signal for carrying out the determination of the road surface condition;

a low-pass filter provided in a stage subsequent to the high-pass filter; and

a coefficient determining section configured to determine the coefficient in accordance with an output from the low-pass filter.

3. The suspension control device according to claim 2 , wherein the coefficient determining section sets the coefficient such that the coefficient outputted in a case where an output from the low-pass filter is not less than a predetermined threshold is smaller than the coefficient outputted in a case where the output from the low-pass filter is less than the predetermined threshold.

4. The suspension control device according to claim 3 , wherein the road surface determining section determines the road surface condition with reference to a wheel speed signal indicative of a wheel speed.

5. The suspension control device according to claim 2 , wherein the road surface determining section determines the road surface condition with reference to a wheel speed signal indicative of a wheel speed.

6. The suspension control device according to claim 1 , wherein the road surface determining section determines the road surface condition with reference to a wheel speed signal indicative of a wheel speed.

7. A suspension device comprising:

a suspension; and

a control section configured to control a damping force of the suspension,

the control section comprising:

a road surface determining section configured to determine a road surface condition; and

a control variable calculating section configured to calculate, in accordance with a result of the determination by the road surface determining section, a steering-based desired control variable which is to be referred to in controlling the damping force of the suspension,

the control variable calculating section comprising:

a first desired control variable calculating section configured to calculate a first desired control variable which is to be referred to in calculating the steering-based desired control variable;

a second desired control variable calculating section configured to calculate a second desired control variable which is to be referred to in calculating the steering-based desired control variable;

a multiplying section configured to multiply a value of the first desired control variable by a coefficient in accordance with the result of the determination by the road surface determining section; and

a selecting section configured to select the steering-based desired control variable from a plurality of candidates including the first desired control variable multiplied by the coefficient and the second desired control variable,

the first desired control variable calculating section being configured to:

calculate the first desired control variable with reference to a steering torque signal indicative of a steering torque which is applied to a steering member used by a driver for steering; and

output, as the first desired control variable, a control variable having a higher value selected from between a control variable calculated with reference to a torque indicated by the steering torque signal and a control variable calculated with reference to a torque speed indicating a change over time in the torque,

the second desired control variable calculating section being configured to:

calculate the second desired control variable with reference to a steering angle signal of the steering member; and

output, as the second desired control variable, a control variable having a higher value selected from between a control variable calculated with reference to a steering angle indicated by the steering angle signal and a control variable calculated with reference to a steering angle speed indicating a change over time in the steering angle.