Suspension control system and suspension control method

Abstract

To provide a suspension control system which performs appropriate preview control according to road surface unevenness.SOLUTION: A suspension control system comprises a road-surface-distance detection part 12 which, by a distance sensor 11 attached to a vehicle body, detects a road surface distance from the distance sensor to a position on a road surface where a wheel W passes; a mean-road-surface-displacement calculation part 4 which calculates a mean road surface displacement of a plurality of road surface displacements that are obtained by subtracting vehicle height from road surface distances at a plurality of positions corresponding to a length of tire-ground contact length in a rolling direction of the wheel; and an actuator control part 5 which, on the basis of the mean road surface displacement, controls an active suspension so as to cause an attitude of the vehicle body stabilizes at a prescribed vehicle height.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a suspension control system and a suspension control method. [Background technology]

[0002] In recent years, efforts to provide access to sustainable transport systems that take into consideration vulnerable transport participants such as the elderly, people with disabilities, and children have been gaining momentum. To achieve this, we are focusing on research and development to further improve transport safety and convenience through development of vehicle behavior stability.

[0003] One of the active suspension control technologies that improves vehicle behavior stability is preview control, which detects road surface variations ahead using a preview sensor and controls the vertical movement of the vehicle traveling on the detected road surface according to the vertical acceleration of the vehicle body and the detected road surface variations. Various technologies have been devised to improve the control performance of this preview control.

[0004] For example, Patent Document 1 discloses that when a preview sensor is attached at an acute angle to the ground so that it can detect road surface displacement ahead of the vehicle, the preview distance (the distance to the position where road surface displacement is detected) fluctuates significantly due to the pitching motion of the vehicle. For this reason, it discloses that the sum of the preview distance and the travel distance is used as the preview position, road surface displacement (control information required to control the operation of the actuator) is stored for each preview position, and the road surface displacement is read out in the order of the preview positions when controlling the operation of the actuator. Furthermore, Patent Document 1 discloses that the road surface distance in which control information required to control the operation of the actuator is stored is preferably the tire contact length. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-183919 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the technology disclosed in Patent Document 1, which relates to vehicle behavior stability, the preview control margin time can be made longer than the actuator control delay time even when the vehicle is traveling at high speed, so the control performance of the preview control does not deteriorate. Furthermore, by setting the road surface interval in which control information required to control the operation of the actuator is stored equal to the tire contact length, it is possible to prevent an increase in the storage capacity of the control information.

[0007] However, if the width of a detected road surface displacement, such as a groove, is shorter than the tire contact length, the tire may overcome the road surface displacement and ignore it. However, the technology in Patent Document 1 may perform unnecessary actuator control based on the detected road surface displacement, which may result in reduced control performance.

[0008] The present invention aims to solve this problem by providing a suspension control system that performs appropriate preview control in response to road surface irregularities, thereby contributing to the development of sustainable transportation systems. [Means for solving the problem]

[0009] In order to solve the above problem, the suspension control system of the present invention comprises a road surface distance detection unit that uses a distance sensor attached to the vehicle body to detect the road surface distance from the distance sensor to the position on the road surface where the wheel passes; an average road surface displacement calculation unit that calculates an average road surface displacement of multiple road surface displacements by subtracting the vehicle height from the road surface distance for multiple positions corresponding to the tire contact length in the rolling direction of the wheel; and an actuator control unit that controls the active suspension based on the average road surface displacement so that the posture of the vehicle body is stabilized at a predetermined vehicle height. [Effects of the Invention]

[0010] According to the suspension control system of the present invention, preview control can be performed appropriately in response to road surface irregularities, improving ride comfort. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an overview of a suspension control system. [Figure 2] FIG. 4 is a side view showing the mounting structure of the distance sensor. [Figure 3] 10 is a diagram showing the relationship between the road surface displacement at each preview position of the road surface R and the tires of the wheels. FIG. [Figure 4A] FIG. 10 is a diagram showing the relationship between vehicle speed and tire contact length at a predetermined tire air pressure. [Figure 4B] FIG. 10 is a diagram showing the relationship between tire air pressure and tire contact length at a predetermined vehicle speed. [Figure 5] FIG. 10 is a diagram showing how three distance sensors detect road surface distances when the wheels are viewed from the front of the vehicle. [Figure 6] FIG. 10 is a diagram illustrating a processing procedure of a preview control unit. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a diagram illustrating an outline of a suspension control system according to an embodiment.

[0013] In the suspension control system of the embodiment, the actuator control unit 5 controls the active suspension D based on the skyhook theory etc. so that the posture of the body member 3 is stabilized at a predetermined vehicle height. At this time, the actuator control unit 5 acquires the road surface displacement ahead 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.

[0014] More specifically, wheels W (left and right front wheels) are provided below body members 3 that form the vehicle body, and active suspensions D and tires (not shown) of the wheels W absorb unevenness of the road surface R. The actuator control unit 5 controls the tires of the wheels W as a vibration model in which a spring W1 and a damper W2 are connected in parallel.

[0015] The active suspension D is configured in parallel with a suspension spring D1 and a variable damper D2 that controls the damping force using a hydraulic actuator or controls the damping force and thrust using electromagnetic force, and is interposed between the body member 3 and the wheel W. The actuator control section 5 controls the variable damper D2 as the control object.

[0016] The preview control unit 1 is installed on a vehicle body member 3 and includes a distance sensor 11 that measures the distance to multiple measurement points on the road surface R using ultrasound, laser light, or millimeter-wave radar, and a road surface distance detection unit 12 that detects the road surface distance in front of the wheel W based on the measurement value of the distance sensor 11. More specifically, the preview control unit 1 calculates the road surface displacement ahead of the wheel W by subtracting the vehicle height at the time of measurement (the mounting height of the distance sensor 11 from the ground contact point of the wheel W, or the road surface distance of the vehicle body member 3) from the detection value of the road surface distance detection unit 12. The vehicle height at the time of measurement in this case refers to the value calculated by the actuator control unit 5 as a control variable.

[0017] The preview control unit 1 adds the running position in the vehicle's traveling direction to the preview distance from the contact point of the wheel W to the measurement point of the road surface displacement, which is determined from the mounting position of the distance sensor 11 on the vehicle body, to determine the preview position (absolute position of the measurement point) on the road surface R, and stores the road surface displacement for each preview position in a storage unit (not shown). Note that the preview distance from the contact point of the wheel W to the measurement point of the road surface displacement is set to a value greater than the preview distance determined from the margin time and vehicle speed in preview control.

[0018] The average road surface displacement calculation unit 4, which will be described in detail later, is a processing unit that calculates the average road surface displacement at the preview position in accordance with the contact length of the wheels W. The calculated average road surface displacement is notified to the actuator control unit 5 and is used as forecast information for the road surface displacement in the preview control.

[0019] The preview control unit 1 and the actuator control unit 5 perform processing periodically. The preview control unit 1 detects road surface deformation prediction information, that is, road surface deformation (irregularity of the road surface) ahead of the wheel W that will pass after a predetermined time (leeway time), and the actuator control unit 5 performs skyhook control of the active suspension D based on the road surface deformation prediction information. This improves the ride comfort of the vehicle.

[0020] Specifically, it is preferable that the preview control unit 1 detects the road surface distance using the distance sensor 11 so as to obtain preview information on road surface displacement with a measurement cycle of 1000 Hz (1 msec / time) or more, or that the distance sensor 11 periodically detects the road surface distance so as to obtain preview information on road surface displacement at intervals of 15 to 30 mm.

[0021] In the suspension control system of the embodiment, a distance sensor 11 is installed on a vehicle body member 3, and a road surface distance detection unit 12, an average road surface displacement calculation unit 4, and an actuator control unit 5 are implemented in an ECU (Electronic Control Unit) of the vehicle. The installation of the distance sensor 11 will be described below.

[0022] The mounting structure of the distance sensor 11 below is illustrated in a simplified manner for the sake of convenience, and is not limited to this embodiment. Note that the forward direction of the vehicle is referred to as "front," the backward direction as "rear," the vertically upward side as "up," the vertically downward side as "down," and the vehicle width direction as "left" and "right." Furthermore, since the mounting structure of the vehicle sensor is symmetrical, the following description will mainly focus on one side (the left side) of the left and right sides, and will omit the description of the other side (the right side) as appropriate.

[0023] Fig. 2 is a side view showing the mounting structure of the distance sensor 11. 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 that forms the vehicle body.

[0024] The vehicle V is mainly configured to include a body member 3, an exterior member 2 that forms the outer portion (outer shell) of the vehicle V, and a distance sensor 11 that detects road surface conditions. As described above, the vehicle V is not particularly limited in its model or type as long as it is an automobile that includes the body member 3, the exterior member 2, and the distance sensor 11. In other words, the vehicle V may be a passenger car, a bus, a truck, a work vehicle, or the like.

[0025] The vehicle body member 3 supports the exterior member 2, and is configured to include a front side frame 31 (frame member), an upper member 32 (frame member), a bumper beam extension 33, a bumper beam 34 (frame member), and the like.

[0026] The exterior member 2 is configured to include 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 configured from a panel member made of, for example, synthetic resin. The front bumper 22 also has a front portion 22a in which an air intake and the like are provided, and a bottom portion 22b that extends rearward from the lower end of the front portion 22a. The front fender 23 is a panel member that covers the periphery of the wheel W (left front wheel).

[0027] The distance sensor 11 is a sensor that detects the state of the road surface R (road surface condition) ahead of the vehicle V 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. More specifically, the distance sensor 11 is attached to the outer side surface of the upper member 32 in the vehicle width direction. The distance sensor 11 is also located at the front end of the upper member 32 in the front-rear direction.

[0028] 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 indicated by the thick solid arrow. The distance sensor 11 is an infrared distance sensor that uses the triangulation principle, a method that converts the intensity of reflected infrared light emitted into distance, or a method that converts the flight time of laser light into distance, and can be appropriately selected from sensors of radar, camera, laser, etc. The distance sensor 11 is not limited to a single sensor, and may be configured by combining sensors of multiple types, such as camera and laser types.

[0029] 2, the distance sensor 11 is attached to a body member 3 so as to measure the distance to the road surface R vertically below. When the distance from the ground contact point of the wheel W by the mounting position of the distance sensor 11 is defined as the preview distance, the preview control unit 1 determines the road surface displacement of the road surface at the preview distance as the value obtained by subtracting the mounting height of the distance sensor 11 from the ground contact point of the wheel W (referred to as the vehicle height in this specification).

[0030] The distance sensor 11 may be attached to a vehicle body member 3 so as to measure the distance from a point vertically below the distance sensor 11 to the road surface R ahead of the vehicle. In this case, the road surface distance is the product of the distance detected by the distance sensor 11 and the sine of the ground angle, and the preview distance is the product of the distance detected by the distance sensor 11 and the cosine of the ground angle plus the distance from the contact point of the wheel W to the attachment position of the distance sensor 11. It is more preferable to correct the ground angle at which the distance sensor 11 is installed according to the pitching of the vehicle.

[0031] Next, the average road surface displacement calculation unit 4 (see FIG. 1) will be described with reference to FIG. FIG. 3 is a diagram showing the relationship between the road surface displacement at each preview position of the road surface R and the tire of the wheel W.

[0032] The average road surface deformation calculation unit 4 calculates the average value of road surface deformation based on road surface deformation at multiple preview positions corresponding to the length of the contact patch in the rolling direction of the wheel on the contact patch of the tire. This makes it possible to deal with changes in stress that the tire receives due to random road surface irregularities caused by the contact patch along the length of the wheel rolling direction.

[0033] In other words, when a depression (road surface deformation) narrower than the length of the tire contact patch in the wheel rolling direction occurs, the tire does not necessarily deform to follow the road surface deformation, but will ride over the narrow groove. Therefore, the average road surface deformation calculation unit 4 corrects the road surface deformation detected in preview corresponding to the contact patch, and sets it as the road surface deformation for preview control.

[0034] In detail, first, the average road surface displacement calculation unit 4 calculates the preview distance from the margin time for preview control and the vehicle speed, and adds the running position in the traveling direction of the vehicle to calculate the preview position on the road surface R to be preview controlled.

[0035] Next, the average road surface displacement calculation unit 4 determines a plurality of preview positions for recording road surface displacements corresponding to the tire contact length of the tire contact patch, with the preview position determined 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 of the determined preview positions.

[0036] 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 a plurality of road surface displacements, or may perform a weighted average by weighting the center of the tire contact length, or may perform a weighted average by weighting the wheel rolling direction.

[0037] In addition, since the average road surface displacement calculation unit 4 periodically calculates the road surface displacement for preview control while the vehicle is traveling, it can also be said that it calculates the average road surface displacement for preview control by calculating a moving average of the road surface displacement according to the tire contact length.

[0038] 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 patch length in the wheel rolling direction, but as will be described later, the road surface distance detection unit 12 may calculate a plurality of road surface distances in the wheel width direction, calculate the average, and calculate the road surface displacement at the preview position from the average road surface distance.The average road surface displacement calculation unit 4 may then calculate the average road surface displacement from the road surface displacements at the plurality of preview positions according to the tire contact patch length in the wheel rolling direction, and use this as the average road surface displacement for preview control.

[0039] In this way, the suspension control system can respond to changes in stress that the tire experiences due to random road surface irregularities caused by the contact patch along the length of the wheel in the rolling direction, while suppressing unnecessary actuator control that occurs when road surface irregularities that the tire does not contact are incorporated into the average road surface distance. This allows the suspension control system to appropriately control the actuator / suspension.

[0040] Next, a method for obtaining the tire contact length of the tire contact patch will be described with reference to FIGS. 4A and 4B.

[0041] The relationship between the tire's contact length as a wheel and vehicle speed and tire air pressure is that the contact length is determined by the degree of deformation near the contact area due to stress applied from the inside and outside to the tire's contact area, and the higher the vehicle speed (wheel speed), the greater the centrifugal force applied from the inside to the contact area, so the contact length becomes shorter, and the higher the air pressure, the shorter the contact length becomes because deformation due to the reaction force from the road surface is suppressed.If there is no tire deformation, the contact area will be represented by a dotted line.

[0042] 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), with the relationship between vehicle speed and tire contact length indicated by a dotted line.

[0043] The average road surface displacement calculation unit 4 (see Fig. 1) calculates the tire contact patch length from the tire pressure detected by the air pressure sensor provided on the vehicle and the vehicle speed detected by the vehicle ECU, based on the relational expression that is set for each tire pressure and shows the tire contact patch length versus vehicle speed as indicated by the dotted line in Fig. 4A. In this case, assuming that the tire pressure is set to a vehicle-specified air pressure (a standard air pressure specific to the vehicle), the tire contact patch length may be calculated from the vehicle speed based on the relational expression that shows the tire contact patch length versus vehicle speed corresponding to the vehicle-specified air pressure.

[0044] In addition, the average road surface displacement calculation unit 4 may define a relational equation, as shown by the solid line, that indicates multiple stages of tire contact patch length corresponding to each predetermined vehicle speed range for each tire air pressure, which approximates the relational equation that indicates tire contact patch length versus vehicle speed shown by the dotted line in Figure 4A, and calculate the tire contact patch length from the tire air pressure and vehicle speed.

[0045] More specifically, the average road surface displacement calculation unit 4 has a table that shows tire contact patch lengths for each vehicle speed zone for each tire pressure, and references this table to determine the tire contact patch length from the tire pressure and vehicle speed. If the vehicle is equipped with a tire pressure monitoring system (TPMS), which monitors tire pressure, the tire pressure can be obtained from the TPMS. TPMSs come in two types: direct types, which are equipped with an air pressure sensor and directly measure the air pressure in the tire air chamber, and indirect types, which are not equipped with an air pressure sensor and estimate tire pressure from the wheel speed. Tire pressure may be input not via the TPMS but by measuring it during a daily inspection before starting to drive the vehicle.

[0046] FIG. 4B is a graph showing the relationship between tire air pressure and tire contact length at a predetermined vehicle speed (for example, 60 km / h), and the relationship between tire air pressure and tire contact length is indicated by a dotted line.

[0047] The average road surface displacement calculation unit 4 (see Figure 1) calculates the tire contact patch length from the tire air pressure detected by the air pressure sensor installed in the vehicle and the vehicle speed detected by the vehicle's ECU, based on the relational equation indicating the tire contact patch length versus tire air pressure shown by the dotted line in Figure 4B, which is set for each vehicle speed.

[0048] In addition, the average road surface displacement calculation unit 4 may define a relational equation, as shown by a solid line, that indicates the tire contact patch length corresponding to each predetermined tire air pressure range for each vehicle speed, which is similar to the relational equation that indicates the tire contact patch length versus tire air pressure shown by the dotted line in Figure 4B, and calculate the tire contact patch length from the tire air pressure and vehicle speed.

[0049] As described above, the average road surface deviation calculation unit 4 calculates the tire contact patch length in the wheel rolling direction based on at least the vehicle speed or the tire air pressure, and calculates the average road surface deviation for preview control according to the tire contact patch length. In other words, in the suspension control system of this embodiment, the tire contact patch length in the average road surface deviation 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 the tire air pressure increase, the tire contact patch length decreases.

[0050] This improves the accuracy of calculating road surface displacement and increases the control accuracy of the actuator / suspension compared to when the tire contact length is kept constant.

[0051] 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 the vehicle speed and tire air pressure, and calculates the average road surface displacement for preview control according to the tire contact length. This simplifies the processing in the average road surface displacement calculation unit 4 and reduces the processing load on the average road surface displacement calculation unit 4. Note that although the graphs in Figures 4A and 4B are multi-stage graphs, they do not have to be multi-stage.

[0052] Next, a case where multiple distance sensors for detecting road surface displacement are provided in the width direction of the wheel will be described. Fig. 5 shows how three distance sensors 11 (11a, 11b, 11c) detect the road surface distance when the wheel W is viewed from the front of the vehicle.

[0053] The wheel W is in contact with the road surface R. As shown in Fig. 1, the distance sensors 11a, 11b, and 11c detect the distance to a measurement point (the tip of the arrow in the figure) on the measurement surface in front of the vehicle that corresponds to the center of the tire contact width of the wheel W or a predetermined width on the inside of the tire contact width.

[0054] By using the distance sensors 11a, 11b, and 11c to detect the distances to these measurement points, the preview control unit 1 can accurately calculate road surface displacement even when the tire contact width changes due to tire deformation caused by a change in the load applied to the wheel W due to steering angle operation such as cornering. In addition, the effects of stones, debris, and unevenness on the road surface can be reduced.

[0055] More specifically, the road surface distance detection unit 12 (see FIG. 1) of the preview control unit 1 calculates the average value of the distances detected by the distance sensors 11a, 11b, and 11c, and sets the average value of the distances to the three measurement points 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 set as the road surface distance. However, it is also possible to detect the distances to at least two measurement points. This improves the detection accuracy of road surface displacement even if the load applied to the wheels W changes due to steering angle operation such as cornering.

[0056] Alternatively, road surface distance detection unit 12 may define the distances detected by distance sensors 11a, 11b, and 11c as Xa, Xb, and Xc, define the weights of the distances of distance sensors 11a, 11b, and 11c as wa, wb, and wc, and calculate (wa×Xa+wb×Xb+wc×Xc) / (wa+wb+wc) as the road surface distance. In other words, road surface distance detection unit 12 may define the weighted average of the distances detected by distance sensors 11a, 11b, and 11c as the road surface distance.

[0057] When the road surface distance detection unit 12 determines the weighted average value as the road surface distance, the road surface distance detection unit 12 may calculate the weighted average value of the distance by increasing the weight wa on the side (distance sensor 11a) corresponding to the left side of the road contact width (left side in the vehicle traveling direction) and decreasing the weight wc on the opposite side (distance sensor 11c) when the vehicle is turning left. When the vehicle is turning right, the weighting is reversed.

[0058] In other words, road distance detection unit 12 may assign weights to the road distances ahead of the wheels detected by distance sensors 11a, 11b, and 11c, respectively, and calculate a weighted average as the road distance, with greater weighting being assigned to the inner side of the turn depending on the turning of the vehicle. This allows for appropriate control of the actuator / suspension in accordance with the condition of the road surface that the wheels actually pass over when turning.

[0059] The preview control unit 1 calculates the 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 traveling position in the vehicle's traveling direction to the preview distance from the contact point of the wheel W to the measurement point of the road surface displacement, which is determined from the vehicle body mounting positions of the distance sensors 11a, 11b, and 11c, to determine the preview position (absolute position of the measurement point) on the road surface R, and stores the road surface displacement for each preview position in a memory unit (not shown).

[0060] Then, the average road surface displacement calculation unit 4 calculates an 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 sets the average road surface displacement as the average road surface displacement for preview control.

[0061] This allows for more appropriate control of the actuator / suspension in response to random road surface irregularities in the vehicle width direction, as well as more appropriate control of the actuator / suspension when cornering.

[0062] Next, the processing procedure of the preview control unit 1 will be described with reference to FIG. The preview control unit 1 periodically performs the following processing.

[0063] In step 61, the road surface distance detection unit 12 detects the road surface distance ahead of the wheel W using the distance sensor 11.

[0064] In step 62, the preview control unit 1 adds the vehicle's traveling position in the direction of travel to the predicted distance from the contact 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 (position of the measurement point) on the road surface R.

[0065] In step 63, the preview control unit 1 subtracts the vehicle height at the time of measurement from the road surface distance detected by the road surface distance detection unit 12 to calculate the road surface displacement in front of the wheels W.

[0066] In step S64, the preview control unit 1 stores the road surface displacement calculated in step S63 as the road surface displacement at the preview position obtained in step S62.

[0067] In step S65, 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.

[0068] In step 66, the average road surface displacement calculation unit 4 calculates the preview distance from the margin time for preview control and the vehicle speed, and adds the running position in the vehicle's traveling direction to obtain the preview position on the road surface R to be preview controlled.

[0069] In step 67, the average road surface displacement calculation unit 4 obtains the tire contact patch length in the wheel rolling direction from at least the vehicle speed or the tire air pressure.

[0070] In step 68, the average road surface displacement calculation unit 4 sets the center of the tire contact length as the preview position and identifies a plurality of preview positions corresponding to the tire contact length.

[0071] In step S69, the average road surface displacement calculation unit 4 calculates the average road surface displacement by taking a simple average or a weighted average of the road surface displacements at the multiple preview positions identified in step S68.

[0072] In step S610, 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.

[0073] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, the tire contact length may be corrected according to the weight (number of passengers and / or cargo) by measuring the degree of suspension sinking. [Explanation of symbols]

[0074] 1 Preview control section 11 Distance Sensor 12 Road surface distance detection unit 2 Exterior materials 3 Body parts D. Active Suspension D1 Suspension spring D2 variable damper W wheels W1 spring W2 Damper 4. Average road surface displacement calculation section 5 Actuator control section

Claims

1. a road distance detection unit that detects a road distance from a distance sensor attached to a vehicle body to a position on the road surface on 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 by subtracting a vehicle height from the road surface distance for a plurality of the positions corresponding to the tire contact length in the rolling direction of the wheel; an actuator control unit that controls an active suspension based on the average road surface displacement so that the posture of the vehicle body is stabilized at a predetermined vehicle height; A suspension control system comprising:

2. The average road surface displacement calculation unit calculates the tire contact length in the rolling direction of the wheel based on at least the vehicle speed or the tire air pressure.

2. The suspension control system of claim 1.

3. 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 the vehicle speed and the tire air pressure.

2. The suspension control system of claim 1.

4. The road surface distance detection unit calculates the road surface distance from the distance sensor to the position of the road surface on which the wheel passes by averaging the road surface distances detected by a plurality of distance sensors provided in the width direction of the wheel.

4. The suspension control system according to claim 1, wherein the suspension control system is a suspension control system for controlling a vehicle.

5. The road surface distance detection unit weights the road surface distances detected by the plurality of distance sensors so that the weight is greater on the inner side of the turn according to the turning of the vehicle, and calculates a weighted average value as the road surface distance.

5. The suspension control system of claim 4.

6. detecting a road surface distance from a distance sensor attached to a vehicle body to a position on the road surface on which the wheels pass; calculating an average road surface displacement of a plurality of road surface displacements by subtracting a vehicle height from the road surface distance for a plurality of the positions corresponding to the tire contact length in the rolling direction of the wheel; controlling an active suspension based on the average road surface displacement so that the posture of the vehicle body is stabilized at a predetermined vehicle height; A suspension control method comprising:

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