JP2024035938A - Suspension control system and suspension control method - Google Patents

Abstract

The present invention provides a suspension control system that performs appropriate preview control depending on road surface irregularities. The suspension control system of the present invention includes a road surface distance detection unit 12 that detects a road surface distance from the distance sensor to a position on the road surface through which a wheel W passes by a distance sensor 11 attached to a vehicle body; An average road surface displacement calculation unit 4 calculates an average road surface displacement of a plurality of road surface displacements obtained by subtracting the vehicle height from the road surface distance at a plurality of positions corresponding to the tire contact length in the direction, and a vehicle body posture is calculated based on the average road surface displacement. The vehicle also includes an actuator control section 5 that controls the active suspension so that the vehicle height is stabilized at a predetermined height. [Selection diagram] Figure 1

Description

The present invention relates to a suspension control system and a suspension control method.

In recent years, there has been an increase in efforts to provide access to sustainable transportation systems that take into account vulnerable transportation participants such as the elderly, people with disabilities, and children. To achieve this, we are focusing on research and development to further improve traffic safety and convenience through development of vehicle behavior stability.

One of the active suspension control technologies that improves the stability of vehicle behavior is to detect the displacement of the road surface in front of the vehicle using a preview sensor, and then adjust the vertical movement of the vehicle body as it travels on the detected road surface according to the vertical acceleration of the vehicle body and the detected road surface displacement. There are preview controls to control. Various techniques have been devised to improve the control performance of this preview control.

For example, Patent Document 1 states that when the preview sensor is attached at an acute angle to the ground so as to be able to detect road surface displacement in front of the vehicle, the preview distance (distance to the road surface displacement detection position) is ) varies greatly depending on Therefore, the sum of the preview distance and the travel distance is used as the preview position, and the road surface displacement (control information necessary to control actuator operation) is stored for each preview position, and when controlling the actuator operation, the preview position is It is disclosed that the road surface displacement is read out in the order of .
Further, Patent Document 1 discloses that it is desirable that the road surface interval in which control information necessary for controlling the operation of the actuator is stored is equal to the tire ground contact length.

Japanese Patent Application Publication No. 2011-183919

By the way, according to the technology of Patent Document 1 related to vehicle behavior stability, even when the vehicle speed is high, the margin time for preview control can be made longer than the control delay time of the actuator, so the control performance of preview control does not deteriorate. . Further, by making the road surface interval in which the control information necessary for controlling the operation of the actuator is stored equal to the tire contact length, it is possible to suppress an increase in the storage capacity of the control information.

However, if the width of the detected road surface displacement, such as a groove, is shorter than the tire contact length, the tire may overcome the road surface displacement and be ignored. However, in the technology of Patent Document 1, the detected road surface displacement Based on this, unnecessary actuator control may be performed and control performance may deteriorate.

An object of the present invention is to solve this problem and provide a suspension control system that performs appropriate preview control depending on road surface irregularities. This in turn contributes to the development of sustainable transportation systems.

In order to solve the above problem, the suspension control system of the present invention includes a road surface distance detection section that detects a road surface distance from the distance sensor to a position on the road surface through which a wheel passes, using a distance sensor attached to a vehicle body; an average road surface displacement calculation unit that calculates an average road surface displacement of a plurality of road surface displacements obtained by subtracting a vehicle height from the road surface distance with respect to the plurality of the positions corresponding to the tire contact length in the rolling direction; and an actuator control unit that controls an active suspension so that the attitude of the vehicle body is stabilized at a predetermined vehicle height.

According to the suspension control system of the present invention, preview control can be performed appropriately depending on the unevenness of the road surface, and ride comfort is improved.

1 is a diagram illustrating an overview of a suspension control system. FIG. 3 is a side view showing the mounting structure of the distance sensor. It is a figure which shows the relationship between the road surface displacement for each preview position of the road surface R, and the tire of a wheel. FIG. 3 is a diagram showing the relationship between vehicle speed and tire ground contact length at a predetermined tire air pressure. FIG. 3 is a diagram showing the relationship between tire air pressure and tire ground contact length at a predetermined vehicle speed. FIG. 3 is a diagram illustrating how three distance sensors detect road surface distance when the wheels are viewed from the front of the vehicle. FIG. 3 is a diagram illustrating a processing procedure of a preview control unit.

Embodiments of the present invention will be described in detail below.
FIG. 1 is a diagram illustrating an overview of a suspension control system according to an embodiment.

In the suspension control system of the embodiment, the actuator control unit 5 controls the active suspension D so that the attitude of the vehicle body member 3 is stabilized at a predetermined vehicle height based on the skyhook theory or the like. At this time, the actuator control unit 5 obtains the road surface displacement in front of the vehicle detected by the preview control unit 1 as preview information, and compensates for the response delay of the active suspension D, thereby improving ride comfort.

Specifically, wheels W (left and right front wheels) are provided below the vehicle body member 3 forming the vehicle body, and the active suspension D and the tires (not shown) of the wheels W absorb unevenness of the road surface R. The actuator control unit 5 controls the tire of the wheel W as a vibration model in which a spring W1 and a damper W2 are connected in parallel.

The active suspension D is configured in parallel with a suspension spring D1 and a variable damper D2 that controls damping force using a hydraulic actuator or controls damping force and thrust using electromagnetic force. It is interposed between.
The actuator control unit 5 controls the variable damper D2 as a control target.

The preview control unit 1 includes a distance sensor 11 that is installed on the vehicle body member 3 and measures the distance to a plurality of measurement points on the road surface R using ultrasonic waves, laser light, or millimeter wave radar, and a , a road surface distance detection unit 12 that detects a road surface distance in front of the wheels W.
More specifically, the preview control unit 1 determines the vehicle height at the time of measurement (the installation height of the distance sensor 11 from the grounding point of the wheel W or the road surface distance of the vehicle body member 3) from the detected value of the road surface distance detection unit 12. By subtracting it, the road surface displacement in front of the wheel W is calculated. At this time, the vehicle height at the time of measurement refers to a value calculated as a control variable by the actuator control unit 5.

The preview control unit 1 adds the traveling position of the vehicle in the traveling direction to the predicted distance from the grounding point of the wheel W to the measurement point of the road surface displacement, which is determined from the vehicle body mounting position of the distance sensor 11, to determine the predicted position on the road surface R. (absolute position of the measurement point) is determined, and the road surface displacement for each predicted position is stored in a storage unit (not shown). Note that the predicted distance from the grounding point of the wheel W to the road surface displacement measurement point is set to a value larger than the preview distance found from the margin time and vehicle speed in preview control.

The average road surface displacement calculation section 4 is a processing section that calculates the average road surface displacement at the preview position according to the contact length of the wheel W, although the details will be described later. The calculated average road surface displacement is notified to the actuator control unit 5, and is used as preview information of the road surface displacement in preview control.

The preview control section 1 and the actuator control section 5 perform processing periodically. The preview control unit 1 detects prediction information of road surface displacement, that is, the road surface displacement (unevenness of the road surface) in front of the wheel W passing after a predetermined time (margin time), and the actuator control unit 5 detects prediction information of the road surface displacement. The active suspension D is skyhook controlled based on the information. This improves the ride comfort of the vehicle.

Specifically, the preview control unit 1 detects the road surface distance using the distance sensor 11 to obtain predictive information of road surface displacement with a measurement cycle of 1000 Hz (1 msec/times) or more, or detects road surface displacement at intervals of 15 to 30 mm. It is preferable that the distance sensor 11 detects the road surface distance periodically so as to obtain predictive information.

In the suspension control system of the embodiment, a distance sensor 11 is installed on the vehicle body member 3, and a road surface distance detection section 12, an average road surface displacement calculation section 4, and an actuator control section 5 are implemented in an ECU (Electronic Control Unit) of the vehicle. . Below, attachment of the distance sensor 11 will be explained.

The mounting structure of the distance sensor 11 described below is illustrated in a simplified manner for convenience of explanation, and is not limited to this embodiment. In addition, the traveling direction of the vehicle will be described as "front", the backward direction as "rear", the vertically upper side as "up", the vertically lower side as "down", and the vehicle width direction as "left" and "right". Furthermore, since the mounting structure of the vehicle sensor is bilaterally symmetrical, one of the left and right sides (the left side) will be mainly explained below, and the explanation of the other side (the right side) will be omitted as appropriate.

FIG. 2 is a side view showing the mounting structure of the distance sensor 11. In addition, in FIG. 2, the outer shape of the vehicle V is shown by a two-dot chain line.
As shown in FIG. 2, the distance sensor 11 is configured to be fixed to a vehicle body member 3 forming a vehicle body.

The vehicle V mainly includes a vehicle body member 3, an exterior member 2 forming an outer part (outer shell) of the vehicle V, and a distance sensor 11 that detects road surface conditions. As described above, the type and type of the vehicle V is not particularly limited as long as it includes the vehicle body member 3, the exterior member 2, and the distance sensor 11. That is, the vehicle V is a passenger car, a bus, a truck, a work vehicle, or the like.

The vehicle body member 3 supports the exterior member 2 and includes a front side frame 31 (frame member), an upper member 32 (frame member), a bumper beam extension 33, a bumper beam 34 (frame member), etc. .

The exterior member 2 includes an engine hood 21, a front bumper 22 (bumper), and a front fender 23. The engine hood 21 is a panel member that covers the upper surface in front of the windshield. The front bumper 22 is located on the front side of the vehicle V, and is made of a panel member made of, for example, synthetic resin. Further, the front bumper 22 has a front part 22a provided with an air intake and the like, and a bottom part 22b extending rearward from the lower end of the front part 22a. The front fender 23 is a panel member that covers the periphery of the wheel W (left front wheel).

The distance sensor 11 is a sensor that detects the state of the road surface R in front of the vehicle V (road surface state) and controls the active suspension D of the vehicle V, and is fixed to an upper member 32 located in front of the wheels W. .
Specifically, the distance sensor 11 is attached to the outer side surface of the upper member 32 in the vehicle width direction. Further, the distance sensor 11 is located at the front end of the upper member 32 in the front-rear direction.

The distance sensor 11 in this embodiment is configured to detect the road surface distance between the wheel W and the road surface R immediately in front of it, as shown by the thick solid line arrow. The distance sensor 11 is an infrared distance sensor based on the triangulation principle, a method that converts the reflected light intensity of emitted infrared light into a distance, or a method that converts the flight time of a laser beam into a distance, and is a radar type, The sensor can be appropriately selected from camera type, laser type, and other types of sensors. Further, the distance sensor 11 is not limited to a single sensor, and may be configured by combining sensors of a plurality of types, such as a camera type and a laser type.

In FIG. 2, the distance sensor 11 is attached to the vehicle body member 3 so as to measure the distance to the road surface R vertically below. When the distance from the grounding point of the wheel W to the mounting position of the distance sensor 11 is defined as the predicted distance, the preview control unit 1 determines the mounting position of the distance sensor 11 from the grounding point of the wheel W based on the road surface distance detected by the distance sensor 11. The value obtained by subtracting the height (referred to as vehicle height in this specification) is defined as the road surface displacement of the road surface that is a foreseeable distance away.

The distance sensor 11 may be attached to the vehicle body member 3 so as to measure the distance from vertically below the distance sensor 11 to the road surface R in front of the vehicle. In this case, the product of the distance detected by the distance sensor 11 and the sine of the ground angle is the road surface distance, and the product of the distance detected by the distance sensor 11 and the cosine of the ground angle is calculated from the grounding point of the wheel W to the distance sensor. The preview distance is the sum of the distances separated by 11 mounting positions. It is even better if the angle from the ground at which the distance sensor 11 is installed is corrected in accordance with the pitching of the vehicle.

Next, the average road surface displacement calculating section 4 (see FIG. 1) will be explained with reference to FIG.
FIG. 3 is a diagram showing the relationship between the road surface displacement for each predicted position of the road surface R and the tires of the wheels W.

The average road surface displacement calculation unit 4 calculates an average value of road surface displacement based on road surface displacements at a plurality of predicted positions corresponding to the length of the contact surface of the tire in the rolling direction of the wheel on the contact surface of the tire. This makes it possible to cope with changes in stress that the tire receives due to random road surface irregularities caused by the contact surface along the length of the wheel in the rolling direction.

In other words, regarding a concavity (road surface displacement) whose width is narrower than the length of the tire contact surface in the rolling direction of the wheel, the tire does not necessarily deform to follow the road surface displacement, but if it is a narrow groove, it will overcome it. Therefore, the average road surface displacement calculation unit 4 corrects the preview-detected road surface displacement corresponding to the ground contact surface, and uses the corrected road surface displacement as the preview-controlled road surface displacement.

Specifically, first, the average road surface displacement calculation unit 4 calculates the preview distance from the preview control margin time and the vehicle speed, adds the traveling position of the vehicle in the traveling direction, and calculates the preview position on the road surface R on which the preview control is performed. .

Next, the average road surface displacement calculation unit 4 determines a plurality of preview positions for recording road surface displacement corresponding to the tire contact length of the tire contact surface, using the preview position obtained above as the center of the tire contact length. Then, the average road surface displacement calculation unit 4 obtains the road surface displacement for each predicted position.

The average road surface displacement calculation unit 4 calculates the average value of the acquired road surface displacements, and sets it as the average road surface displacement at the preview position. At this time, the average road surface displacement calculation unit 4 may simply average the plurality of road surface displacements, weight the center of the tire contact length and weight the average, or weight the wheel rolling direction and weight the average. It may be averaged.

Note that the average road surface displacement calculation unit 4 periodically calculates the road surface displacement of the preview control while the vehicle is running, so it calculates the moving average of the road surface displacement according to the tire contact length and calculates the average road surface displacement of the preview control. It can also be said that we are looking for.

Although FIG. 3 shows a case where the average road surface displacement calculation unit 4 calculates the average road surface displacement for preview control according to the tire contact length in the rolling direction of the wheel, as will be described later, the road surface distance detection unit 12 A plurality of road surface distances are determined in the width direction, the average is calculated, and the road surface displacement at the predicted position is calculated from the average road surface distance. Then, the average road surface displacement calculation unit 4 may calculate the average road surface displacement from the road surface displacements at a plurality of preview positions according to the tire contact length in the rolling direction of the wheel, and use the calculated average road surface displacement as the average road surface displacement for preview control. good.

In this manner, the suspension control system responds to changes in stress that the tire receives due to random road surface irregularities due to the contact surface along the length of the wheel's rolling direction, or handles road surface irregularities that the tire is not in contact with over the road surface distance. Unnecessary actuator control that occurs by incorporating the value into the average value can be suppressed. This allows the suspension control system to properly control the actuator/suspension.

Next, a method for obtaining the tire contact length of the tire contact surface will be described with reference to FIGS. 4A and 4B.

The relationship between the contact length of a tire as a wheel, vehicle speed, and tire air pressure is determined by the degree of deformation near the contact point due to stress applied from the inside to the outside of the tire's contact point, and the vehicle speed (wheel speed) The higher the air pressure, the greater the centrifugal force applied from the inside to the vicinity of the ground contact area, resulting in a shorter contact length, and the higher the air pressure, the less deformation in response to the reaction force from the road surface, resulting in a shorter contact length. Note that if the deformation of the tire is zero, the contact area will be a dot/line.

FIG. 4A is a graph showing the relationship between vehicle speed and tire contact length at a predetermined tire air pressure (for example, 220 kPa), and the relationship between vehicle speed and tire contact length is shown by a dotted line.

The average road surface displacement calculation unit 4 (see FIG. 1) detects the tire contact length with an air pressure sensor installed in the vehicle based on a relational expression indicating the tire contact length with respect to the vehicle speed shown by the dotted line in FIG. 4A, which is set for each tire air pressure. The tire contact length is calculated from the tire air pressure and the vehicle speed detected by the vehicle's ECU. At this time, assuming that the tire air pressure is set to the vehicle specified air pressure (vehicle-specific standard air pressure), calculate the tire ground contact length from the vehicle speed based on the relational expression that indicates the tire ground contact length with respect to the vehicle speed corresponding to the vehicle specified air pressure. It may be calculated.

In addition, the average road surface displacement calculation unit 4 calculates the tire contact length in multiple stages corresponding to each predetermined vehicle speed section for each tire air pressure by approximating the relational expression indicating the tire contact length with respect to the vehicle speed shown by the dotted line in FIG. 4A. The relational expression shown in is defined as a solid line, and the tire ground contact length may be calculated from the tire air pressure and vehicle speed.

Specifically, the average road surface displacement calculation unit 4 provides a table showing the tire contact length for each vehicle speed section for each tire pressure, and refers to this table to calculate the tire contact length from the tire pressure and vehicle speed. In addition, in the case of a vehicle equipped with a system for monitoring tire pressure called TPMS (Tire Pressure Monitoring System), the tire pressure can be acquired from the TPMS. There are two types of TPMS: a direct type that is equipped with an air pressure sensor and directly measures the air pressure in the tire air chamber, and an indirect type that is not equipped with an air pressure sensor and estimates the tire air pressure from the wheel speed. The tire air pressure may be measured at the time of daily inspection before the start of driving of the vehicle and may be input instead of the TPMS.

FIG. 4B is a graph showing the relationship between tire air pressure and tire ground contact length at a predetermined vehicle speed (for example, 60 km/h), and the relationship between tire air pressure and tire ground contact length is shown by a dotted line.

The average road surface displacement calculation unit 4 (see FIG. 1) uses an air pressure sensor installed in the vehicle to detect the tire contact length with respect to the tire air pressure, which is set for each vehicle speed and is shown by the dotted line in FIG. 4B. The tire contact length is calculated from the tire air pressure and the vehicle speed detected by the vehicle's ECU.

In addition, the average road surface displacement calculation unit 4 indicates the tire contact length corresponding to each predetermined tire pressure section for each vehicle speed, which approximates the relational expression indicating the tire contact length with respect to the tire pressure shown by the dotted line in FIG. 4B. A relational expression may be defined as shown by a solid line, and the tire contact length may be calculated from the tire air pressure and vehicle speed.

As described above, the average road surface displacement calculation unit 4 calculates the tire contact length in the rolling direction of the wheel based on at least the vehicle speed or tire air pressure, and calculates the average road surface displacement for preview control according to the tire contact length. There is. That is, in the suspension control system of the embodiment, the tire contact length in the average road surface displacement calculation unit 4 is changed based on at least one of the vehicle speed and the tire air pressure. Specifically, as the vehicle speed and tire air pressure increase, the tire contact length becomes shorter.

As a result, it is possible to improve the calculation accuracy of the road surface displacement and the control accuracy of the actuator/suspension compared to the case where the tire contact length is constant.

In addition, the average road surface displacement calculation unit 4 calculates the tire contact length in the rolling direction of the wheel in multiple stages based on at least one of vehicle speed and tire air pressure, and performs preview control on the average road surface according to the tire contact length. I'm looking for displacement.
Thereby, the processing in the average road surface displacement calculation section 4 can be simplified, and the processing load on the average road surface displacement calculation section 4 can be reduced. Note that although FIGS. 4A and 4B show multi-stage graphs, the graphs do not have to be multi-stage.

Next, a case will be described in which a plurality of distance sensors for determining road surface displacements are provided in the width direction of the wheel. FIG. 5 shows how the three distance sensors 11 (11a, 11b, 11c) detect the road surface distance when the wheels W are viewed from the front of the vehicle.

The wheels W are in contact with the road surface of the tires on the road surface R. As shown in FIG. 1, the distance sensors 11a, 11b, and 11c are arranged at measurement points ( Detect the distance (tip of the arrow in the figure).

The distance sensors 11a, 11b, and 11c detect the distance of these measurement points, so that preview control can be performed even when the load applied to the wheel W changes due to steering angle operation such as cornering, deforms the tire, and changes the tire contact width. Part 1 can accurately calculate road surface displacement. It can also reduce the effects of stones and dirt falling on the road, as well as road irregularities.

Specifically, the road surface distance detection section 12 (see FIG. 1) of the preview control section 1 calculates the average value of the distances detected by the distance sensors 11a, 11b, and 11c, and uses the average value as the road surface distance. In FIG. 5, three distance sensors 11a, 11b, and 11c are shown, and the average value of the distances to the three measurement points is used as the road surface distance. do. Thereby, even if the load applied to the wheels W changes due to steering angle manipulation such as cornering, the detection accuracy of road surface displacement can be improved.

Furthermore, the road surface distance detection unit 12 sets the distances detected by the distance sensors 11a, 11b, and 11c to Xa, Xb, and Xc, and sets the distance weights of the distance sensors 11a, 11b, and 11c to wa, wb, and wc, The road surface distance may be determined by calculating Xa+wb×Xb+wc×Xc)/(wa+wb+wc). That is, the road surface distance detection unit 12 may use the weighted average value of the distances detected by the distance sensors 11a, 11b, and 11c as the road surface distance.

When the road surface distance detection section 12 uses the weighted average value as the road surface distance, the road surface distance detection section 12 detects the left side of the road surface width (the left side in the direction of vehicle movement) when the vehicle is turning left. ) may be calculated by increasing the weight wa on the side (distance sensor 11a) and decreasing the weight wc on the opposite side (distance sensor 11c). If the vehicle is turning right, the weighting is reversed.

In other words, the road surface distance detection unit 12 weights each of the road surface distances in front of the plurality of wheels detected by the distance sensors 11a, 11b, and 11c, calculates a weighted average value as the road surface distance, and calculates the weighted average value as the road surface distance. , a larger weight may be placed on the inner circumferential side of the turn. As a result, the actuator/suspension can be appropriately controlled in accordance with the condition of the road surface that the wheels actually pass during turning.

The preview control unit 1 calculates a road surface displacement by subtracting the vehicle height at the time of measurement from the average or weighted average road surface distance calculated by the road surface distance detection unit 12. Then, the preview control unit 1 adds the running position of the vehicle in the traveling direction to the predicted distance from the grounding point of the wheel W to the measurement point of the road surface displacement, which is determined from the mounting positions of the distance sensors 11a, 11b, and 11c on the vehicle body. , the predicted position (absolute position of the measurement point) on the road surface R is obtained, and the road surface displacement for each predicted position is stored in a storage unit (not shown).

Then, the average road surface displacement calculation unit 4 calculates the average road surface displacement from the road surface displacements at a plurality of preview positions according to the tire contact length in the rolling direction of the wheel, and uses the calculated average road surface displacement as the average road surface displacement for preview control.

This allows for more appropriate control of the actuator/suspension in response to random road irregularities in the vehicle width direction, as well as more appropriate control of the actuator/suspension during turns.

Next, the processing procedure of the preview control section 1 will be explained with reference to FIG.
The preview control unit 1 periodically performs the following processing.

In step 61, the road surface distance detection unit 12 detects the road surface distance in front of the wheel W using the distance sensor 11.

In step 62, the preview control unit 1 adds the traveling position of the vehicle in the traveling direction to the predicted distance from the grounding point of the wheel W to the measurement point of the road surface displacement, which is determined from the vehicle body mounting position of the distance sensor 11, and Find the predicted position (position of the measurement point) in R.

In step 63, the preview control unit 1 subtracts the vehicle height at the time of measurement from the road distance detected by the road distance detection unit 12 to calculate the road surface displacement in front of the wheels W.

At step 64, the preview control unit 1 stores the road surface displacement calculated at step S63 as the road surface displacement at the preview position determined at step S62.

In step 65, the preview control unit 1 determines whether or not the current time is the timing for preview control, and if it is the timing for preview control (Yes in S65), the process proceeds to step S66. If it is not the timing for preview control (No in S65), the process ends.

In step 66, the average road surface displacement calculating unit 4 obtains a preview distance from the margin time for preview control and the vehicle speed, and adds the traveling position of the vehicle in the traveling direction to obtain a preview position on the road surface R to be subjected to preview control. .

In step 67, the average road surface displacement calculation unit 4 obtains the tire contact length in the wheel rolling direction from at least the vehicle speed or tire air pressure.

In step 68, the average road surface displacement calculating unit 4 sets the center of the tire contact length as a preview position, and specifies a plurality of preview positions corresponding to the tire contact length.

In step 69, the average road surface displacement calculation unit 4 calculates an average road surface displacement by simply averaging or weighted averaging the road surface displacements at the plurality of predicted positions identified in step S68.

In step 610, the average road surface displacement calculation unit 4 notifies the actuator control unit 5 of the average road surface displacement calculated in step S69 as the road surface displacement for preview control.

The present invention is not limited to the above-described embodiments, and various design changes are possible without departing from the gist thereof. For example, the tire ground contact length may be corrected according to the weight (passengers and loaded luggage) by measuring the degree of depression of the suspension.

1 Preview control section 11 Distance sensor 12 Road surface distance detection section 2 Exterior member 3 Vehicle body member D Active suspension D1 Suspension spring D2 Variable damper W Wheel W1 Spring W2 Damper 4 Average road surface displacement calculation section 5 Actuator control section

Claims (6)

a road surface distance detection unit that uses a distance sensor attached to the vehicle body to detect a road surface distance from the distance sensor to a position on the road surface over which the wheels pass;
an average road surface displacement calculation unit that calculates an average road surface displacement of a plurality of road surface displacements obtained by subtracting a vehicle height from the road surface distance with respect to the plurality of positions corresponding to the tire contact length in the rolling direction of the wheel;
an actuator control unit that controls an active suspension so that the attitude of the vehicle body is stabilized at a predetermined vehicle height based on the average road surface displacement;
A suspension control system comprising: The suspension control system according to claim 1, wherein the average road surface displacement calculation unit calculates the tire contact length in the rolling direction of the wheel based on at least vehicle speed or tire air pressure. 2. The suspension control system according to claim 1, wherein the average road surface displacement calculation unit calculates the tire contact length in the rolling direction of the wheel in multiple stages based on at least one of vehicle speed and tire air pressure. The road surface distance detection section is characterized in that the road surface distance from the distance sensor to a position on the road surface through which the wheel passes is determined by averaging road surface distances detected by a plurality of distance sensors provided in the width direction of the wheel. The suspension control system according to any one of claims 1 to 3. The road surface distance detection section calculates a weighted average value as the road surface distance by weighting the road surface distances detected by the plurality of distance sensors so that the inner circumference of the turn has a larger weight according to the turn of the vehicle. The suspension control system according to claim 4. detecting a road surface distance from the distance sensor to a position on the road surface through which the wheels pass, using a distance sensor attached to the vehicle body;
calculating an average road surface displacement of a plurality of road surface displacements obtained by subtracting a vehicle height from the road surface distance with respect to the plurality of positions corresponding to the tire contact length in the rolling direction of the wheel;
controlling an active suspension so that the attitude of the vehicle body is stabilized at a predetermined vehicle height based on the average road surface displacement;
A suspension control method comprising:

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