Suspension control system and suspension control method

Abstract

This suspension control system is provided with: a road surface distance detection unit (12) that, by means of a distance sensor (11) attached to a vehicle body, detects a road surface distance from the distance sensor to the position of a road surface through which a wheel (W) passes; an average road surface displacement calculation unit (4) that calculates an average road surface displacement of a plurality of road surface displacements obtained by subtracting the vehicle height from road surface distances relating to a plurality of positions corresponding to tire ground contact lengths in the wheel rolling direction; and an actuator control unit (5) that controls the active suspension so as to stabilize the orientation of the vehicle body at a predetermined vehicle height on the basis of the average road surface displacement, thereby performing appropriate preview control in accordance with the unevenness of the road surface.

Description

Technical Field

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

[0002] In recent years, traffic participants, especially vulnerable groups such as the elderly, the disabled, and children, have been actively promoted to enter sustainable transportation systems. With this goal in mind, the inventors of this application have devoted themselves to research and development related to vehicle behavior stability to further improve traffic safety and convenience.

[0003] One of the active suspension control technologies for improving the vehicle's behavior stability is preview control, which uses a preview sensor to detect the displacement of the road surface ahead and controls the up and down movement of the vehicle body traveling on the detected road surface based on the up and down acceleration of the vehicle body and the detected road surface displacement. Various technologies are considered to improve the control performance of the preview control.

[0004] For example, Patent Document 1 discloses the following: When the angle of the preview sensor to the ground is set to an acute angle so as to detect the displacement of the road surface in front of the vehicle, the preview distance (the distance to the detection position of the road surface displacement) varies greatly according to the pitch motion (bumping) of the vehicle. Therefore, the sum of the preview distance and the travel distance is used as the preview position, the road surface displacement (control information required for controlling the operation of the actuator) is stored for each preview position, and the road surface displacement is read in the order of the preview positions when controlling the operation of the actuator.

[0005] In addition, Patent Document 1 discloses that it is preferable that the road surface interval for storing control information required for controlling the operation of the actuator is set to the tire contact length.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-183919 Summary of the invention

[0009] However, according to the technology of Patent Document 1 related to vehicle behavior stability, even when the vehicle speed is high, the margin time for performing preview control can be made longer than the control delay time of the actuator, so that the control performance of the preview control does not deteriorate. In addition, the road surface interval for storing control information required for controlling the operation of the actuator is made equal to the tire contact length, thereby suppressing the increase in the storage capacity of the control information.

[0010] However, when the width of the road surface displacement detected by a groove is shorter than the tire contact length, the road surface displacement can sometimes be ignored by the tire running over it. However, in the technology of Patent Document 1, unnecessary actuator control is performed based on the detected road surface displacement, resulting in reduced control performance.

[0011] The purpose of the present invention is to solve this problem and provide a suspension control system that performs appropriate preview control according to the unevenness of the road surface, and further contribute to the development of a sustainable transportation system.

[0012] In order to solve the above-mentioned problems, the suspension control system of the present invention comprises: a road surface distance detection unit, which detects the road surface distance from the distance sensor to the position of the road surface through which the wheel passes through by means of a distance sensor installed on the vehicle body; an average road surface displacement calculation unit, which calculates the average road surface displacement of multiple road surface displacements obtained by subtracting the vehicle height from the road surface distance related to the multiple positions, wherein the multiple positions correspond to the tire contact length in the rolling direction of the wheel; and an actuator control unit, which controls the active suspension based on the average road surface displacement in such a way that the posture of the vehicle body is stabilized at a specified vehicle height.

[0013] Effects of the Invention

[0014] According to the suspension control system of the present invention, it is possible to appropriately perform preview control according to the unevenness of the road surface, thereby improving ride comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram for explaining the outline of a suspension control system.

[0016] Figure 2 It is a side view showing the mounting structure of the distance sensor.

[0017] Figure 3 1 is a diagram showing the relationship between the road surface displacement and the tire of the wheel at each preview position of the road surface R.

[0018] Figure 4A This is a graph showing the relationship between vehicle speed and tire contact length at a predetermined tire pressure.

[0019] Figure 4B This is a graph showing the relationship between tire air pressure and tire contact length at a predetermined vehicle speed.

[0020] Figure 5 The diagram shows how the three distance sensors detect the road surface distance when the wheels are viewed from the front of the vehicle.

[0021] Figure 6 It is a diagram for explaining the processing procedure of the preview control unit. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described in detail.

[0023] Figure 1 It is a diagram for explaining the outline of the suspension control system according to the embodiment.

[0024] In the suspension control system of the embodiment, based on the Skyhook theory, etc., the actuator control unit 5 controls the active suspension D so that the posture of the vehicle body component 3 is stabilized at a predetermined vehicle height. 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 seeking to improve the ride comfort.

[0025] Specifically, wheels W (left and right front wheels) are provided on the lower side of a body member 3 forming the vehicle body, and an active suspension D and tires (not shown) of the wheels W absorb the unevenness of a 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 shock absorber W2 are connected in parallel.

[0026] The active suspension D is constituted by a suspension spring D1 and a variable damper D2 in parallel, and is interposed between the vehicle body member 3 and the wheel W. The variable damper D2 controls the damping force using a hydraulic actuator or controls the damping force and thrust by electromagnetic force.

[0027] The actuator control unit 5 performs control on the variable damper D2 as a control target.

[0028] The preview control unit 1 includes: a distance sensor 11 which is provided on the vehicle body member 3 and measures the distance to a plurality of measuring points on the road surface R by ultrasonic wave, laser or millimeter wave radar; and a road surface distance detection unit 12 which detects the road surface distance in front of the wheel W based on the measurement value of the distance sensor 11.

[0029] More specifically, the preview control unit 1 calculates the road surface displacement in front of the wheel W by subtracting the vehicle height at the time of measurement (the installation 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 at this time refers to the value calculated as a control variable by the actuator control unit 5.

[0030] The preview control unit 1 adds the travel position of the vehicle in the traveling direction to the preview distance from the ground contact point of the wheel W to the measurement point of the road surface displacement obtained from the vehicle body mounting position of the distance sensor 11, thereby obtaining a preview position (absolute position of the measurement point) in the road surface R, and stores the road surface displacement at each preview position in a storage unit (not shown). In addition, the preview distance from the ground contact point of the wheel W to the measurement point of the road surface displacement is set to a value larger than the preview distance obtained from the spare time in the preview control and the vehicle speed.

[0031] Although described in detail later, the average road surface displacement calculation unit 4 is a processing unit that calculates the average road surface displacement at the preview position based on the ground contact length of the wheel W. The calculated average road surface displacement is notified to the actuator control unit 5 as preview information of the road surface displacement in the preview control.

[0032] The preview control unit 1 and the actuator control unit 5 perform processing periodically. The preview control unit 1 detects preview information of road surface displacement, that is, the road surface displacement (road surface unevenness) ahead that the wheel W passes through after a predetermined time (spare time), and the actuator control unit 5 performs skyhook control on the active suspension D based on the preview information of road surface displacement. Thus, the ride comfort of the vehicle is improved.

[0033] Specifically, the preview control unit 1 preferably detects the road surface distance based on the distance sensor 11 in a manner to obtain preview information of road surface displacement with a measurement period of more than 1000 Hz (1 msec / time), or periodically detects the road surface distance based on the distance sensor 11 in a manner to obtain preview information of road surface displacement at intervals of 15 to 30 mm.

[0034] In the suspension control system of the embodiment, the distance sensor 11 is provided on the vehicle body member 3, and the road surface distance detection unit 12, the average road surface displacement calculation unit 4, and the actuator control unit 5 are installed in the vehicle ECU (Electronic Control Unit).

[0035] For the sake of convenience, the following installation structure of the distance sensor 11 is briefly illustrated, which is not limited to the present embodiment. In addition, the vehicle's traveling direction is "front", the backward direction is "rear", the vertical upper side is "up", the vertical lower side is "down", and the vehicle width direction is "left" and "right" for description. In addition, the installation structure of the vehicle sensor is bilaterally symmetrical, so the following mainly describes one side (left side), and the description of the other side (right side) is appropriately omitted.

[0036] Figure 2 1 is a side view showing the installation structure of the distance sensor 11. Figure 2 , the outer shape of the vehicle V is indicated by a two-dot chain line.

[0037] like Figure 2 As shown, the distance sensor 11 is designed to be fixed to the body part 3 which forms the body.

[0038] The vehicle V is mainly composed of a body member 3, an exterior member 2 forming an outer portion (outer contour) of the vehicle V, and a distance sensor 11 for detecting a road surface condition. As such, the vehicle V is not particularly limited in form or type as long as it is a motor vehicle having the 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.

[0039] 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 cross member extension 33, a bumper cross member 34 (frame member), and the like.

[0040] The exterior component 2 is composed of a hood 21, a front bumper 22 (bumper), and a front fender 23. The hood 21 is a panel component that covers the upper surface in front of the front glass. The front bumper 22 is located on the front surface side of the vehicle V, and is composed of a panel component made of, for example, synthetic resin. In addition, the front bumper 22 has a front surface portion 22a provided with an air intake, etc., and a bottom portion 22b extending from the lower end of the front surface portion 22a toward the rear. The front fender 23 is a panel component that covers the periphery of the wheel W (left front wheel).

[0041] 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 the upper member 32 located in front of the wheel W.

[0042] Specifically, the distance sensor 11 is attached to the side surface on the outer side in the vehicle width direction of the upper member 32. In addition, the distance sensor 11 is located at the front end portion of the upper member 32 in the front-rear direction.

[0043] As shown by the thick solid arrow, the distance sensor 11 in this embodiment is configured to detect the road surface distance between the road surface R immediately in front of the wheel W. In addition, the distance sensor 11 is an infrared distance sensor based on the triangulation principle, a method of converting the reflected light intensity of the emitted infrared light into a distance, or a method of converting the distance by the flight time of the laser, and can be appropriately selected from radar type, camera type, laser type and other sensors. In addition, the distance sensor 11 is not limited to a single sensor, and can be composed of a combination of sensors of multiple types such as camera type and laser type.

[0044] Figure 2In the embodiment, the distance sensor 11 is mounted on the vehicle body member 3 in such a manner as to measure the distance to the road surface R vertically below. When the distance corresponding to the distance from the grounding point of the wheel W and the mounting position of the distance sensor 11 is set as the preview distance, the preview control unit 1 subtracts the mounting height (referred to as the vehicle height in this specification) of the distance sensor 11 from the grounding point of the wheel W from the road surface distance detected by the distance sensor 11 as the road surface displacement at the road surface separated by the preview distance.

[0045] The distance sensor 11 may be mounted on the vehicle body member 3 in such a manner as to measure the distance from the vertically lower side of 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 set as the road surface distance, and the value obtained by adding the product of the distance detected by the distance sensor 11 and the cosine of the ground angle to the distance from the ground contact point of the wheel W and the mounting position of the distance sensor 11 is set as the preview distance. The ground angle at which the distance sensor 11 is installed may be corrected according to the bumping of the vehicle.

[0046] Next, through Figure 3 , the average road surface displacement calculation unit 4 (refer to Figure 1 ).

[0047] Figure 3 1 is a diagram showing the relationship between the road surface displacement and the tire of the wheel W at each preview position of the road surface R.

[0048] The average road surface displacement calculation unit 4 calculates an average of road surface displacements based on road surface displacements at a plurality of preview positions corresponding to the length of the contact surface in the wheel rolling direction in the contact surface of the tire. This makes it possible to cope with stress changes to which the tire is subjected due to irregular road surface irregularities caused by the contact surface within the length in the wheel rolling direction.

[0049] That is, for a depression (road surface displacement) whose width is narrower than the length of the tire contact patch in the wheel rolling direction, the tire does not necessarily deform to follow the road surface displacement, and the tire will pass through a narrow groove. Therefore, the average road surface displacement calculation unit 4 corrects the preview detected road surface displacement corresponding to the contact patch and uses it as the preview controlled road surface displacement.

[0050] Specifically, first, the average road surface displacement calculation unit 4 obtains a preview distance from the margin time of the preview control and the vehicle speed, and adds the travel position of the vehicle in the traveling direction to obtain a preview position on the road surface R of the preview control.

[0051] Next, the average road surface displacement calculation unit 4 determines a plurality of preview positions corresponding to the tire contact length of the tire contact patch and recording the road surface displacement, using the above-determined preview position as the center of the tire contact length. The average road surface displacement calculation unit 4 obtains the road surface displacement at each of the obtained preview positions.

[0052] 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, or may weight the center of the tire contact length to perform weighted average, or may weight the center of the tire contact length to perform weighted average.

[0053] The average road surface displacement calculation unit 4 periodically obtains the road surface displacement of the preview control during the running of the vehicle, and therefore it can be said that the average road surface displacement of the preview control is obtained by taking a moving average of the road surface displacement according to the tire contact length.

[0054] Figure 3 , the average road surface displacement calculation unit 4 calculates the average road surface displacement of the preview control based on the tire contact length in the wheel rolling direction, but as described later, the road surface distance detection unit 12 calculates a plurality of road surface distances in the wheel width direction and calculates the average thereof, and calculates the road surface displacement at the preview position from the average road surface distance. Furthermore, 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 corresponding to the tire contact length in the wheel rolling direction, and set it as the average road surface displacement of the preview control.

[0055] As described above, the suspension control system can cope with the stress changes to which the tire is subjected due to irregular road surface irregularities generated based on the contact surface within the length in the wheel rolling direction, and can suppress unnecessary actuator control caused by, for example, introducing road surface irregularities that the tire does not contact into the average value of the road surface distance. Thus, the suspension control system can perform appropriate control of the actuator / suspension.

[0056] Next, through Figure 4A and Figure 4B , explaining a method for obtaining the tire contact length of the tire contact patch.

[0057] The relationship between the contact length of the tire as a wheel and the vehicle speed or tire pressure is that the contact length is determined based on the deformation degree near the contact part caused by the stress from the inside and from the outside applied to the contact part of the tire. The higher the vehicle speed (wheel speed), the greater the centrifugal force applied from the inside to the contact part, thereby shortening the contact length. The higher the air pressure, the more the deformation relative to the reaction force from the road surface is suppressed, thereby shortening the contact length. In addition, if the deformation of the tire is zero, the contact part becomes a point or a line.

[0058] Figure 4A It is a graph showing the relationship between the vehicle speed and the tire contact length at a predetermined tire pressure (eg, 220 kPa), and the relationship between the vehicle speed and the tire contact length is shown by a dotted line.

[0059] The average road surface displacement calculation unit 4 (refer to Figure 1 ) is based on the indication set for each tire pressure and the Figure 4A The tire contact length is calculated from the tire pressure detected by the air pressure sensor provided in the vehicle and the vehicle speed detected by the vehicle ECU, using the relationship between the vehicle speed and the tire contact length shown by the dotted line. At this time, it is also possible to calculate the tire contact length from the vehicle speed based on the relationship between the tire contact length and the vehicle speed corresponding to the vehicle specified air pressure, assuming that the tire pressure is set to the vehicle specified air pressure (standard air pressure unique to the vehicle).

[0060] In addition, the average road surface displacement calculation unit 4 may determine a relational expression as shown by a solid line to calculate the tire contact length from the tire pressure and the vehicle speed. The relational expression as shown by the solid line is approximately the same as that expressed by Figure 4A The relationship between the vehicle speed and the tire contact length is shown by the dotted line, and the tire contact length corresponding to each predetermined vehicle speed interval at each tire pressure is shown in multiple stages.

[0061] In detail, the average road surface displacement calculation unit 4 sets a table indicating the tire contact length for each vehicle speed interval for each tire pressure, and refers to the table to obtain the tire contact length from the tire pressure and the vehicle speed. In addition, in the case of a vehicle equipped with a system for monitoring tire pressure, such as TPMS (Tire Pressure Monitoring System), the tire pressure can be obtained from the TPMS. The TPMS can be a direct method that has an air pressure sensor and directly measures the air pressure of the tire air chamber, and an indirect method that does not have an air pressure sensor and estimates the tire pressure from the wheel speed. The tire pressure may not be input by the TPMS, but the pressure measured during the daily inspection before the start of driving the vehicle may be input.

[0062] Figure 4B It is a graph showing the relationship between tire air pressure and tire contact length at a predetermined vehicle speed (eg, 60 km / h), and the relationship between tire air pressure and tire contact length is shown by a dotted line.

[0063] The average road surface displacement calculation unit 4 (refer to Figure 1 ) is based on the representation set relative to each vehicle speed and the Figure 4BThe tire contact length is calculated from the tire pressure detected by the tire pressure sensor provided in the vehicle and the vehicle speed detected by the ECU of the vehicle in the relationship between the tire pressure and the tire contact length shown by the dotted line.

[0064] In addition, the average road surface displacement calculation unit 4 may determine a relational expression as shown by a solid line to calculate the tire contact length from the tire pressure and the vehicle speed, wherein the relational expression is approximately expressed by Figure 4B The dotted line in FIG. 8 is a relational expression of tire pressure relative to tire contact length, and represents the tire contact length corresponding to each predetermined tire pressure interval at each vehicle speed.

[0065] As described above, the average road surface displacement calculation unit 4 obtains the tire contact length in the wheel rolling direction based on at least the vehicle speed or the tire pressure, and obtains the average road surface displacement of the preview control based on the tire contact length. 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 pressure. Specifically, if the vehicle speed and the tire pressure increase, the tire contact length becomes shorter.

[0066] This can 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 fixed.

[0067] The average road surface displacement calculation unit 4 obtains the tire contact length in the wheel rolling direction in multiple stages based on at least one of the vehicle speed and the tire pressure, and obtains the average road surface displacement of the preview control based on the tire contact length.

[0068] This makes it possible to simplify the processing in the average road surface displacement calculation unit 4 and reduce the processing load of the average road surface displacement calculation unit 4. Figure 4A and Figure 4B In FIG. 1 , a multi-stage diagram is shown, but it may not be a multi-stage diagram.

[0069] Next, a case where a distance sensor for obtaining a plurality of road surface displacements in the width direction of the wheel is provided will be described. Figure 5 The figure shows how the three distance sensors 11 (11a, 11b, 11c) detect the road surface distance when the wheel W is viewed from the front of the vehicle.

[0070] The wheel W makes contact with the road surface contact surface of the tire on the road surface R. Figure 1 As shown, the distance sensors 11a, 11b, 11c detect the distance to the center of the tire contact patch of the wheel W or to a measuring point (arrow tip in the figure) on the measuring plane in front of the vehicle corresponding to a predetermined width inside the tire contact patch.

[0071] The distance sensors 11a, 11b, and 11c detect the distances of the measurement points, and thus the preview control unit 1 can accurately calculate the road surface displacement even when the tire deforms and the tire contact width changes due to the load applied to the wheel W caused by the steering angle operation such as turning. In addition, the influence of stones and garbage dropped on the road surface and unevenness of the road surface can be reduced.

[0072] In detail, the road distance detection unit 12 (see Figure 1 ) Calculate the average value of the distances detected by the distance sensors 11a, 11b, and 11c and use it as the road surface distance. Figure 5 , three distance sensors 11a, 11b, and 11c are shown, and the average value of the distances to the three measuring points is used as the road surface distance, but the distances to at least two measuring points may be detected. Thus, even if the load applied to the wheel W changes due to steering angle operation such as turning, the detection accuracy of the road surface displacement can be improved.

[0073] In addition, the road distance detection unit 12 may be configured such that the distances detected by the distance sensors 11a, 11b, 11c are set to Xa, Xb, and Xc, and the weights of the distances of the distance sensors 11a, 11b, and 11c are set to wa, wb, and wc, and (wa×Xa+wb×Xb+wc×Xc) / (wa+wb+wc) is calculated and set as the road distance. That is, the road distance detection unit 12 may be configured such that the weighted average of the distances detected by the distance sensors 11a, 11b, and 11c is set as the road distance.

[0074] Furthermore, when the road distance detection unit 12 sets the weighted average value as the road distance, the road distance detection unit 12 may calculate the weighted average value of the distance by increasing the weight wa of the side (distance sensor 11a) corresponding to the left side (toward the left side of the vehicle's traveling direction) of the road contact width and decreasing the weight wc of the opposite side (distance sensor 11c) when the vehicle is turning left. When the vehicle is turning right, the weighting method is reversed.

[0075] That is, the road distance detection unit 12 may be configured to weight the road distances ahead of the plurality of wheels detected by the distance sensors 11a, 11b, and 11c and calculate the weighted average value as the road distance, and to give a large weight to the inner peripheral side of the turn according to the turn of the vehicle. Thus, it is possible to perform appropriate control of the actuator / suspension in accordance with the state of the road surface that the wheels actually pass through when turning.

[0076] 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. The preview control unit 1 also calculates the preview position (absolute position of the measurement point) on the road surface R by adding the travel position of the vehicle in the traveling direction to the preview distance from the ground contact point of the wheel W to the measurement point of the road surface displacement obtained from the vehicle body mounting positions of the distance sensors 11a, 11b, and 11c, and stores the road surface displacement at each preview position in a storage unit (not shown).

[0077] 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 corresponding to the tire contact lengths in the wheel rolling direction, and sets the average road surface displacement as the average road surface displacement for preview control.

[0078] As a result, the actuator / suspension can be controlled more appropriately in response to irregular road surface irregularities in the vehicle width direction, and the actuator / suspension can be controlled more appropriately during cornering.

[0079] Next, through Figure 6 , describing the processing sequence of the preview control unit 1.

[0080] The preview control unit 1 periodically performs the following processing.

[0081] 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 .

[0082] In step 62, the preview control unit 1 adds the travel position of the vehicle in the traveling direction to the preview distance from the ground contact point of the wheel W to the measurement point of the road surface displacement obtained from the vehicle body mounting position of the distance sensor 11, and obtains the preview position on the road surface R (the position of the measurement point).

[0083] In step 63 , the preview control unit 1 calculates the road surface displacement in front of the wheel W by subtracting the vehicle height at the time of measurement from the road surface distance detected by the road surface distance detection unit 12 .

[0084] 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 .

[0085] In step 65, the preview control unit 1 determines whether the current time point is the preview control timing, and if it is the preview control timing (Yes in S65), the process proceeds to step S66. If it is not the preview control timing (No in S65), the process ends.

[0086] In step 66 , the average road surface displacement calculation unit 4 obtains the preview distance from the margin time of the preview control and the vehicle speed, and adds the travel position of the vehicle in the traveling direction to obtain the preview position on the road surface R where the preview control is performed.

[0087] 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 the tire pressure.

[0088] In step 68 , the average road surface displacement calculation unit 4 sets the center of the tire contact length as the preview position, and determines a plurality of preview positions corresponding to the tire contact length.

[0089] In step S69 , the average road surface displacement calculation unit 4 calculates the average road surface displacement by simply averaging or weighted averaging the road surface displacements at the plurality of preview positions determined in step S68 .

[0090] In step 610 , average road surface displacement calculation unit 4 notifies actuator control unit 5 of the average road surface displacement calculated in step S69 as the road surface displacement for preview control.

[0091] The present invention is not limited to the above-mentioned embodiment, and various design changes can be made within the scope of the gist thereof. For example, the tire contact length can be corrected according to the weight (passengers and cargo) by measuring the sinking degree of the suspension.

[0092] Description of Reference Numerals

[0093] 1Preview control unit

[0094] 11. Distance sensor

[0095] 12Road distance detection unit

[0096] 2Exterior parts

[0097] 3 Body parts

[0098] D Active suspension

[0099] D1 suspension spring

[0100] D2 variable damper

[0101] W wheel

[0102] W1 Spring

[0103] W2 shock absorber

[0104] 4Average road surface displacement calculation unit

[0105] 5Actuator control unit.

Claims

1. A suspension control system, characterized in that: have: a road surface distance detection unit that detects a road surface distance from the distance sensor to a position of the road surface on which the wheel passes by using a distance sensor mounted on the 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 associated with a plurality of the positions corresponding to a tire contact length in a rolling direction of the wheel; The actuator control unit controls the active suspension so that the posture of the vehicle body is stabilized at a predetermined vehicle height based on the average road surface displacement.

2. The suspension control system according to claim 1, characterized in that: The average road surface displacement calculation unit obtains a tire contact length in a rolling direction of the wheel based on at least the vehicle speed or the tire pressure.

3. The suspension control system according to claim 1, characterized in that: The average road surface displacement calculation unit obtains 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 pressure.

4. The suspension control system according to any one of claims 1 to 3, characterized in that: The road surface distance detection unit averages road surface distances detected by a plurality of distance sensors provided along the width direction of the wheel to obtain a road surface distance from the distance sensor to a position on the road surface through which the wheel passes.

5. The suspension control system according to claim 4, characterized in that: The road surface distance detection unit weights the road surface distances detected by the plurality of distance sensors so that the inner peripheral side of the turn has a greater weight according to the turn of the vehicle, and calculates a weighted average value as the road surface distance.

6. A suspension control method, characterized in that: The steps include: The step of detecting, by a distance sensor mounted on the vehicle body, a road surface distance from the distance sensor to a position of the road surface on which the wheel passes; a step of calculating an average road surface displacement of a plurality of road surface displacements obtained by subtracting a vehicle height from the road surface distance associated with a plurality of said positions, wherein the plurality of said positions correspond to a tire contact length in a rolling direction of said wheel; and The step of controlling 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.

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