Preview road surface detection device and preview road surface detection method

Abstract

To provide a preview road surface detection device capable of inhibiting detection waves transmitted from a plurality of transmitters from being received while being confused.SOLUTION: A preview road surface detection device comprises: a distance sensor which comprises a plurality of transmitters and at least one receiver mounted on a vehicle body member so as to be arranged in a direction intersecting a vehicle travel direction, and which detects a value related to a distance between the vehicle body member and a measurement point on a road surface ahead of a vehicle and corresponding to at least part of a road surface contact part of a wheel; and a distance calculation section which calculates a road surface distance, as the distance from the vehicle body member to the measurement point, on the basis of the detection value detected by the distance sensor. Each transmitter transmits a detection wave with a difference in time from the adjacent transmitter.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a preview road surface detection device and a preview road surface detection 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] Furthermore, in order to improve the behavioral stability of a vehicle, a conventional active suspension for vehicles such as automobiles includes road surface detection means that detects road surface displacement ahead using an optical sensor, vehicle speed detection means that detects vehicle speed, vertical acceleration detection means that is attached to the vehicle body at a location corresponding to the front wheels and detects the vertical acceleration of the vehicle body, and storage means that stores information on road surface displacement and vertical acceleration in chronological order; when it is determined that the detection of road surface displacement is abnormal, the vertical acceleration of a location corresponding to the rear wheels of the vehicle body when the vehicle has traveled a distance of the wheelbase based on the wheelbase and vehicle speed is estimated from the vertical acceleration stored in the storage means, and the rear wheel actuator is subjected to preview control in accordance with the estimated vertical acceleration (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-96922 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional technologies have a problem in that laser waves emitted from multiple road surface sensors may be confused, and there is a need for more accurate recognition of road surface conditions. Therefore, in order to solve the above problem, the present application aims to provide a preview road surface detection device that can prevent detection waves emitted from multiple transmitters from being received in a confused manner, thereby contributing to energy efficiency. [Means for solving the problem]

[0006] (1) In order to solve the above problem, the preview road surface detection device of the present invention comprises a plurality of transmitters and at least one receiver attached to a body member in a row facing in a direction intersecting the vehicle's direction of travel, a distance sensor that detects a value related to the distance between the body member and a measurement point on the road surface in front of the vehicle that corresponds to at least a portion of the wheel's road contact area, and a distance calculation unit that calculates the road surface distance, which is the distance from the body member to the measurement point, based on the detection value detected by the distance sensor, and the transmitters emit detection waves with a time difference from adjacent transmitters.

[0007] According to such a preview road surface detection device, it is possible to provide a preview road surface detection device that can prevent detection waves transmitted from a plurality of transmitters from being received in a confused manner.

[0008] (2) In the preview road surface detection device of the present invention, the detection wave is emitted from the transmitter toward the road surface, and the detection wave is a laser wave or a millimeter wave.

[0009] Such a preview road surface detection device makes it easy to accurately calculate the road surface distance.

[0010] (3) In the preview road surface detection device of the present invention, at least one of the multiple transmitters, when the transmitter is designated as a first transmitter, further has a second transmitter located in at least one of the forward and backward directions of the vehicle's travel direction relative to the first transmitter, and the first transmitter and the second transmitter emit the detection waves with a time difference.

[0011] This type of preview road surface detection device can prevent confusion of the emitted detection waves when estimating the amount of movement of the vehicle body in the pitch direction based on the detection values ​​detected by the first transmitter and the second transmitter. Confusion between detection waves from different positions in the front and rear of the vehicle body can have a significant impact on malfunction. This can prevent the occurrence of such a potentially significant malfunction.

[0012] (4) In the preview road surface detection device of the present invention, one or more of the receivers are arranged at the end in the vehicle width direction, and the transmitter is installed so that its transmission direction is tilted toward the one or more of the receivers.

[0013] Such a preview road surface detection device can improve reception sensitivity when receiving with fewer receivers, while suppressing confusion of detection waves emitted from transmitters with little time difference in transmission, especially detection waves emitted simultaneously.

[0014] (5) In the preview road surface detection device of the present invention, the plurality of transmitters are divided into a plurality of groups, and the plurality of transmitters simultaneously emit the detection waves for each group.

[0015] With this type of preview road surface detection device, the total transmission frequency per unit time of the multiple transmitters as a whole can be improved compared to when there is only one transmitter that can transmit simultaneously.

[0016] (6) In the preview road surface detection device of the present invention, a plurality of receivers are installed, and the transmission directions of the plurality of transmitters that simultaneously transmit the detection waves are tilted toward different receivers among the plurality of receivers.

[0017] Such a preview road surface detection device can improve reception sensitivity when receiving with fewer receivers, while suppressing confusion of detection waves emitted from transmitters with little time difference in transmission, especially detection waves emitted simultaneously.

[0018] (7) In order to solve the above problem, the preview road surface detection method of the present invention includes a distance detection step in which a value related to the distance between a body member and a measurement point on the road surface in front of the vehicle corresponding to at least the center of the wheel's road contact area is detected using a plurality of transmitters and at least one receiver attached to the body member in a line perpendicular to the vehicle's direction of travel, and a distance calculation step in which the road surface distance, which is the distance from the body member to the measurement point, is calculated based on the detection value detected in the distance detection step, and in the distance detection step, the transmitters emit detection waves with a time difference from adjacent transmitters.

[0019] According to this preview road surface detection method, it is possible to provide a preview road surface detection method that can prevent detection waves transmitted from a plurality of transmitters from being received in a confused manner.

[0020] The above items (1) to (7) can be combined arbitrarily as needed. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a preview road surface detection device that can prevent detection waves transmitted from a plurality of transmitters from being received in a confused manner. [Brief explanation of the drawings]

[0022] [Figure 1]FIG. 1 is a diagram illustrating an overview of a suspension system of a vehicle. [Figure 2] FIG. 2 is a side view of a vehicle showing the mounting structure of a distance sensor. [Figure 3] FIG. 1(a) shows the arrangement of distance sensors, and FIG. 1(b) shows the transmission order from transmitters. [Figure 4] FIG. 10 is another diagram showing the arrangement of distance sensors (a) and the transmission order from transmitters (b). [Figure 5] FIG. 2 is a view of the vicinity of the left front wheel of the vehicle viewed from above toward below the vehicle. [Figure 6] FIG. 1 is a diagram illustrating an example of the arrangement of a transmitter and a receiver. [Figure 7] FIG. 10 is a diagram illustrating another example of the arrangement of a transmitter and a receiver. [Figure 8] FIG. 10 is a diagram illustrating another example of the arrangement of a transmitter and a receiver. [Figure 9] FIG. 10 is another diagram showing the transmission sequence from the transmitters. [Figure 10] FIG. 10 is another diagram showing the transmission sequence from the transmitters. DETAILED DESCRIPTION OF THE INVENTION

[0023] (Suspension system) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an outline of a suspension system 3 of a vehicle to which a preview road surface detection device 1 of the present embodiment is applied.

[0024] The suspension system 3 includes a preview road surface detection device 1, a preview control unit 4, a suspension control unit 5, a vehicle body member 30, an active suspension D, and wheels W. The preview road surface detection device 1 also includes a distance calculation unit 12 and a distance sensor 11. The distance sensor 11 also includes a transmitter 11a and the like and a receiver 14. The transmitter 11a and the like and the receiver 14 are not shown in FIG. 1, but will be shown in FIG. 3 and thereafter.

[0025] In the suspension system 3, the suspension control unit 5 controls the active suspension D so as to stabilize the posture of the vehicle body member 30. This control is performed based on, for example, the skyhook theory.

[0026] (Road surface displacement) In controlling the active suspension D, first, the preview road surface detection device 1 acquires the road surface displacement L2 ahead of the vehicle. Here, the road surface displacement L2 is the distance between the road surface R that the wheel W is currently in contact with and the measurement point P in the direction perpendicular to the road surface R. The road surface R refers to the ground surface that the wheel W is in contact with. The measurement point P refers to the point on the ground surface to which the distance sensor 11 measures the distance. The measurement point P is also the point on the road surface R through which the wheel W is scheduled to pass. The road surface displacement L2 is also called preview information.

[0027] (Preview control section) Next, the preview control unit 4 acquires the road surface displacement L2 from the preview road surface detection device 1. Then, based on the value of the road surface displacement L2, it compensates for the response delay of the active suspension D. In this way, the suspension system 3 aims to improve the ride comfort of the vehicle.

[0028] (Vehicle configuration) The suspension system 3 will be described in more detail with reference to Fig. 2. Fig. 2 is a side view of a vehicle V showing the mounting mechanism of the distance sensor 11. The vehicle V includes a vehicle body B and wheels W. The members that make up the vehicle body B include a vehicle body member 30. The wheels W are provided on the underside of the vehicle body member 30. Fig. 2 shows the front wheels of the wheels W. The front wheels include a left wheel and a right wheel. Fig. 2 shows the left wheel of the left and right wheels.

[0029] (Vibration model) The active suspension D and the tire portion of the wheel W absorb the unevenness of the road surface R. The suspension control unit 5 shown in FIG. 2 controls the tire portion of the wheel W as a vibration model. This vibration model is a vibration model in which a spring W1 and a damper W2 are arranged in parallel.

[0030] (active suspension) The active suspension D can control the damping force using a suspension spring D1 and a hydraulic actuator. Alternatively, the active suspension D can be configured with a suspension spring D1 and a variable damper D2 arranged in parallel. The variable damper D2 is a damper whose damping force and thrust are controlled by electromagnetic force. The active suspension D is provided between the vehicle body member 30 and the wheel W.

[0031] (Suspension control unit) The suspension control unit 5 controls the variable damper D2 as a control target.

[0032] (actuator) The active suspension D may be provided with an actuator. The operation of the actuator allows for smoother preview control of the suspension. When an actuator is provided, it is preferable that an actuator control unit for controlling the actuator is also provided. The actuator control unit can be provided as a part of the suspension control unit 5, for example.

[0033] (Preview road surface detection device) The preview road surface detection device 1 is installed on a vehicle body member 30. The preview road surface detection device 1 includes a distance sensor 11 and a distance calculation unit 12.

[0034] (distance sensor) Distance sensor 11 measures the distance between vehicle body member 30 and measurement point P on road surface R. The distance between vehicle body member 30 and measurement point P on road surface R is defined as road surface distance L1. This measurement is performed using ultrasonic waves, laser light, millimeter wave radar, or the like.

[0035] (Distance calculation section) The distance calculation unit 12 calculates the road surface displacement L2 ahead of the wheel W based on the measurement value of the distance sensor 11. Specifically, the preview road surface detection device 1 calculates the road surface displacement L2 ahead of the wheel W by subtracting the vehicle height L3 at the time of measurement from the road surface distance L1 calculated by the distance calculation unit 12. The vehicle height L3 is the distance between the vehicle body member 30 and the road surface R at the road contact portion 41.

[0036] That is, road surface distance L1-vehicle height L3=road surface displacement L2. When calculating road surface displacement L2, vehicle height L3 can also be found by referring to the value calculated by suspension control unit 5 as a control variable.

[0037] (Time required to reach) The preview control unit 4 calculates the time required for the wheel W to travel to the measurement point P of the road surface displacement L2 from the vehicle speed when the road surface displacement L2 was measured and the distance in the traveling direction of the vehicle V from the tire contact point to the measurement point P of the road surface displacement L2. This required time is defined as the required arrival time. Note that the distance in the traveling direction of the vehicle V from the tire contact point to the measurement point P of the road surface displacement L2 can also be calculated by referring to information related to the installation position of the distance sensor 11.

[0038] (Predictive Information) The preview road surface detection device 1 and the preview control unit 4 can periodically perform the above-mentioned process for determining the road surface displacement L2. This makes it possible to obtain preview information for the road surface displacement L2. As mentioned above, the preview information is information about the road surface condition ahead of the wheel W, which will pass after a predetermined time. The road surface condition includes the road surface displacement L2 and the unevenness of the road surface R.

[0039] The suspension control unit 5 controls the active suspension D based on the preview information of the road surface displacement L2. Therefore, the suspension control unit 5 can improve the ride comfort of the vehicle V.

[0040] (Installation of preview road surface detection device) As described above, the preview road surface detection device 1 of this embodiment includes the distance sensor 11 and the distance calculation unit 12. Of these, the distance sensor 11 is installed on a vehicle body member 30. On the other hand, the distance calculation unit 12 is implemented in an ECU (Electronic Control Unit) of the vehicle V.

[0041] (Installation of distance sensor) The installation of the distance sensor 11 will be specifically described with reference to Fig. 2. Note that the installation structure of the distance sensor 11 described below and other structures of the vehicle V shown in Fig. 2 are simplified for the sake of convenience. Furthermore, the installation of the distance sensor 11 is not limited to that described below.

[0042] (Direction definition) In the following description, the traveling direction of the vehicle V is referred to as the "forward" direction, the backward direction as the "rear" direction, the vertically upward direction as the "up" direction, the vertically downward direction as the "down" direction, and the vehicle width direction as the "left" direction and the "right" direction. In addition, the mounting structure of a vehicle sensor such as the distance sensor 11 is generally symmetrical. Therefore, in the following description, one side (the left side) of the left and right sides will be mainly described, and the description of the other side (the right side) will be omitted as appropriate.

[0043] Fig. 2 is a side view of the vehicle V showing the mounting structure of the distance sensor 11. In Fig. 2, the outer shape of the vehicle V is indicated by a two-dot chain line. (Body) The vehicle V includes a vehicle body B as a main component. The vehicle body B includes, in addition to a vehicle body member 30, an exterior member 20, a distance sensor 11, and the like. The distance sensor 11 is fixed to the vehicle body member 30.

[0044] The exterior member 20 is a member that forms an outer portion of the vehicle V. The exterior member 20 forms the outer shell of the vehicle V. On the other hand, the distance sensor 11 is a device that detects road surface conditions.

[0045] (vehicle) The vehicle V is not particularly limited in its form and type as long as it is an automobile equipped with the body member 30, the exterior member 20, and the distance sensor 11. The vehicle V may be, for example, a passenger car, a bus, a truck, a work vehicle, or the like.

[0046] Each component will be described in more detail below. (Body components) The vehicle body member 30 has a function of supporting the exterior member 20. The vehicle body member 30 is also configured to include a front side frame 31, an upper member 32, a bumper beam extension 33, and a bumper beam 34. The front side frame 31, the upper member 32, and the bumper beam 34 may also be referred to as frame members.

[0047] (exterior materials) The exterior member 20 includes an engine hood 21, a front bumper 22, and a front fender 23. The front bumper 22 may also be simply referred to as a bumper.

[0048] 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. The front bumper 22 has a front portion 22a where 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 wheels W.

[0049] (Installation of distance sensor) The distance sensor 11 is a sensor that detects the state of the road surface R in front of the vehicle V. The distance sensor 11 is fixed to the upper member 32. As described above, the upper member 32 is a member that constitutes the vehicle body member 30. The upper member 32 is disposed in front of the wheels W.

[0050] More specifically, the distance sensor 11 is attached to the outer side surface in the vehicle width direction of the upper member 32. The distance sensor 11 is also located at the front end of the upper member 32 in the front-rear direction.

[0051] (Distance sensor configuration) The distance sensor 11 of this embodiment is configured to detect a road surface distance L1 on the road surface R immediately in front of the wheel W, as shown by an arrow A1 in FIG. 2. The road surface distance L1 is the distance between the vehicle body member 30 and a measurement point P on the road surface R. The distance sensor 11 can be appropriately selected from various types of sensors, such as radar, camera, and laser. The distance sensor 11 does not have to be configured with a single type of sensor. The distance sensor 11 can also be configured with a combination of sensors of multiple types, such as a camera type and a laser type.

[0052] (Transmitter and receiver) Next, distance detection by the distance sensor 11 will be described with reference to Fig. 3. Fig. 3(a) shows the state of the distance sensor 11 when the wheel W is viewed from the front of the vehicle V. The distance sensor 11 of this embodiment is equipped with five transmitters 11a to 11e. Each transmitter emits a detection wave toward the road surface R. The emitted detection wave is reflected by the road surface R and received by a receiver. The receiver will be described later with reference to Fig. 6 etc.

[0053] The detection wave may be, for example, a laser wave or a millimeter wave. Furthermore, the method for detecting distance using the transmitter and receiver is not particularly limited. Various detection methods can be used, such as a method based on the triangulation principle, a method that converts the intensity of reflected light of emitted light into distance, or a method that converts the time of flight of laser light into distance.

[0054] The detection of distance will be described in detail. As shown in FIG. 3(a), a wheel W is in contact with a tire-road contact surface S1 of a road surface R. Then, five transmitters 11a to 11e emit detection waves toward a measurement surface S2 of the road surface. The transmitters shown in FIG. 3(a) are designated, in order from the outer side in the vehicle width direction to the inner side in the vehicle width direction, as a first transmitter 11a, a second transmitter 11b, a third transmitter 11c, a fourth transmitter 11d, and a fifth transmitter 11e. The detection waves emitted by the respective transmitters are designated as a first detection wave Ra, a second detection wave Rb, a third detection wave Rc, a fourth detection wave Rd, and a fifth detection wave Re.

[0055] FIG. 3(a) shows the width of the portion where the tire W contacts the road surface R as a road contact width L4. In the configuration shown in FIG. 3(a), of the five transmitters, the fourth detection wave Rd emitted from the fourth transmitter 11d and the fifth detection wave Re emitted from the fifth transmitter 11e are emitted toward a measurement plane S2 that is more inward in the vehicle width direction than the road contact width L4. By arranging the transmitters in this manner, the road surface distance can be determined over a wider range. This allows a wider range of road surface conditions to be grasped. As a result, the road surface condition can be recognized more accurately. Furthermore, even when the traveling direction of the vehicle V shifts laterally, i.e., when the vehicle V turns left or right, the suspension can be more appropriately controlled.

[0056] The transmitter placement shown in FIG. 3(a) is an example, and the transmitter positions can be changed as appropriate. Furthermore, the receivers that receive the detection waves emitted by the transmitters and reflected by the road surface R can be placed at any appropriate position. For example, the receivers may be integrated with each transmitter and placed at each transmitter. Alternatively, the receivers may be separate from the transmitters and placed at positions different from the transmitters. Furthermore, the number of transmitters and the number of receivers do not have to be the same. The receiver may receive detection waves emitted from multiple transmitters. This will be explained in more detail later.

[0057] (Timing of transmission) In the preview road surface detection device 1 of this embodiment, the transmitters transmit detection waves with a time difference between adjacent transmitters. This will be described based on FIG. 3(b). FIG. 3(b) is a diagram showing the transmission order of detection waves from each transmitter. As shown in FIG. 3(b), after the first transmitter 11a transmits, the second transmitter 11b, which is adjacent to the first transmitter 11a, does not transmit. The third transmitter 11c, which is not adjacent to the first transmitter 11a, transmits after the first transmitter 11a. The same applies to the next transmitter. After the third transmitter 11c, the fourth transmitter 11d, which is adjacent to the third transmitter 11c, does not transmit. After the third transmitter 11c, the fifth transmitter 11e, which is not adjacent to the third transmitter 11c, transmits. Thereafter, transmission is repeated in the order shown in FIG. 3(b). As described above, the transmitters do not transmit consecutively with adjacent transmitters, and are adjusted so that there is a time difference between the transmitters that transmit and the transmitters that transmit.

[0058] The above-mentioned transmission timing can be adjusted in the same way even if the number of transmitters changes. This will be explained based on Figures 4(a) and 4(b). Figure 4(a) is a diagram corresponding to Figure 3(a), and Figure 4(b) is a diagram corresponding to Figure 3(b). The number of transmitters differs between the configuration shown in Figure 4 and the configuration shown in Figure 3. In the configuration shown in Figure 3, the number of transmitters is five. In contrast, the number of transmitters in the configuration shown in Figure 4 is six. In the configuration shown in Figure 4, a sixth transmitter 11f is further arranged inside the fifth transmitter 11e in the vehicle width direction. The detection wave transmitted by this sixth transmitter 11f is the sixth detection wave Rf.

[0059] As shown in the transmission order in Figure 4(b), even when the number of transmitters is six, the timing of transmission is adjusted so that a transmitter does not transmit consecutively with an adjacent transmitter. This causes each transmitter to transmit with a time difference from its adjacent transmitter.

[0060] (Transmitter transmission frequency) The frequency of transmission of the transmitter is not particularly limited. The frequency of transmission can be, for example, 1000 Hz or higher. That is, a frequency of 1 msec / transmission. Alternatively, the frequency of transmission can be set to a measurement cycle of 15 mm / transmission or more and 30 mm / transmission or less. Note that the distance here refers to the distance traveled by the transmitter.

[0061] (Transmitter placement in front and behind) In Figures 3 and 4, multiple transmitters are mounted in a line facing a direction intersecting the traveling direction of the vehicle V. In other words, multiple transmitters are arranged in a line in the vehicle width direction. The transmitters can also be arranged in a line in the traveling direction of the vehicle V. This will be explained based on Figure 5. Figure 5 is a view of the vicinity of the left front wheel of the vehicle V viewed from above and below the vehicle V.

[0062] 5, a first front transmitter 11F1 is disposed in front of the second transmitter 11b in the traveling direction, and a first rear transmitter 11B1 is disposed behind the second transmitter 11b in the traveling direction.

[0063] 5, the second transmitter 11b and the first front transmitter 11F1 transmit detection waves with a time difference. Also, the second transmitter 11b and the first rear transmitter 11B1 transmit detection waves with a time difference. This makes it possible to prevent the detection waves from being received in a confused manner.

[0064] It should be noted that with regard to the transmitters in the front and rear directions, it is not necessary to provide both a front transmitter and a rear transmitter, and only one of the front transmitter and the rear transmitter may be provided.

[0065] Arranging the transmitters in the longitudinal direction in the traveling direction of the vehicle V allows for more accurate preview control when the vehicle V is turning, for example. However, if confusion occurs when receiving detection waves, it can easily lead to serious malfunctions. In this regard, the preview road surface detection device of this embodiment can prevent confusion of detection waves between the transmitters arranged in the longitudinal direction. This is because the transmitters emit detection waves with a time difference.

[0066] (How to place the receiver) There are various ways to arrange the receiver. For example, as explained above, the receiver can be arranged integrally with the transmitter. In contrast, Figures 6 to 8 show configurations in which the receiver is arranged in a position separate from the transmitter. Also, Figures 6 to 8 each show a different arrangement of the receiver and transmitter.

[0067] In one example of how the receivers may be arranged, one or more receivers may be arranged at the ends in the vehicle width direction, and the transmitter may be mounted so that its transmission direction is inclined toward the one or more receivers.

[0068] 6, the transmitter and receiver 14 are arranged in a sensor housing 16. In the sensor housing 16, five transmitters, the first transmitter 11a to the fifth transmitter 11e, are arranged side by side in the vehicle width direction. The receiver 14 is arranged at one end of the sensor housing 16 in the vehicle width direction.

[0069] Furthermore, the direction of transmission of the detection wave from each transmitter is not perpendicular to the road surface R. The transmission direction is inclined toward the receiver 14. This allows the detection wave reflected by the road surface R to reach the receiver 14 efficiently. Therefore, even when reception is performed with fewer receivers 14, a decrease in reception sensitivity can be suppressed.

[0070] Next, an example of arrangement shown in Fig. 7 will be described. The example of arrangement shown in Fig. 7 differs from the example of arrangement shown in Fig. 6 in that two receivers 14 are provided in the sensor housing 16. Specifically, a first receiver 14a is arranged at one end of the sensor housing 16 in the vehicle width direction, and a second receiver 14b is arranged at the other end of the sensor housing 16 in the vehicle width direction.

[0071] The first detection wave Ra transmitted by the first transmitter 11a, the second detection wave Rb transmitted by the second transmitter 11b, and the third detection wave Rc transmitted by the third transmitter 11c are received by the first receiver 14a, while the fourth detection wave Rd transmitted by the fourth transmitter 11d and the fifth detection wave Re transmitted by the fifth transmitter 11e are received by the second receiver 14b.

[0072] To ensure efficient reception, the transmission directions of detection waves from first transmitter 11a, second transmitter 11b, and third transmitter 11c are inclined toward first receiver 14a. In contrast, the transmission directions of detection waves from fourth transmitter 11d and fifth transmitter 11e are inclined toward second receiver 14b. With this arrangement, when reception is performed using a small number of receivers, detection waves can be received efficiently while reducing the load per receiver.

[0073] (Simultaneous transmission) The arrangement example shown in FIG. 7 can be used when multiple transmitters simultaneously transmit detection waves and the transmission directions of the transmitters are tilted toward different receivers. For example, consider a case where the third transmitter 11c and the fourth transmitter 11d simultaneously transmit detection waves. The transmission direction of the third transmitter 11c is tilted toward the first receiver 14a. On the other hand, the transmission direction of the fourth transmitter 11d is tilted toward the second receiver 14b. In this way, the transmission directions of the simultaneously transmitted detection waves can be tilted toward different receivers. This makes it possible to prevent the detection waves transmitted by adjacent transmitters from being confused with each other.

[0074] (Vertical transmission) Even when the number of receivers is small, the direction of transmission of the detection wave from each transmitter is not limited to being inclined toward the receiver 14. As shown in FIG. 8, even when there is only one receiver, the direction of transmission of the detection wave from each transmitter can be perpendicular to the road surface R. In such a configuration, it is easy to make the sensor housing 16 smaller, because the distance between the transmitter and receiver 14 in the vehicle width direction can be shortened.

[0075] (Grouping) The grouping of transmitters will now be described. The transmitters can be divided into multiple groups. The transmitters for each group simultaneously emit detection waves. In other words, multiple transmitters belonging to the same group simultaneously emit detection waves. The following explanation will be based on Figs. 9 and 10. Figs. 9 and 10 are both diagrams showing the transmission order from the transmitters. The number of transmitters differs between the transmission order shown in Fig. 9 and the transmission order shown in Fig. 10. The configuration shown in Fig. 9 has five transmitters. On the other hand, the configuration shown in Fig. 10 has six transmitters. In terms of the arrangement of the transmitters, the transmission order in Fig. 9 corresponds to the arrangement in Fig. 3(a). On the other hand, the transmission order in Fig. 10 corresponds to the arrangement in Fig. 4(a).

[0076] (Grouping) In the transmission order shown in FIG. 9, the first transmitter 11a, the third transmitter 11c, and the fifth transmitter 11e belong to the first group. The remaining second transmitter 11b and the fourth transmitter 11d belong to the second group. The three transmitters belonging to the first group transmit simultaneously. Next, the two transmitters belonging to the second group transmit simultaneously. This is repeated in order thereafter. This makes it possible to increase the transmission frequency while preventing adjacent transmitters from transmitting simultaneously.

[0077] As described above, the transmission order shown in Fig. 10 has one more transmitter than the transmission order shown in Fig. 9. Therefore, in addition to the second transmitter 11b and the fourth transmitter 11d, a sixth transmitter 11f has been added to the second group. As a result, the number of transmitters belonging to both the first group and the second group is now three.

[0078] Even if the number of transmitters increases, the transmission order can be the same as that explained in Figure 9. That is, first, three transmitters belonging to the first group transmit simultaneously. Then, three transmitters belonging to the second group transmit simultaneously. This is repeated in order thereafter. In this way, even if the number of transmitters increases, the transmission frequency can be increased while preventing adjacent transmitters from transmitting simultaneously.

[0079] (Preview road surface detection method) The preview road surface detection device 1 of this embodiment can also be used to execute the following preview road surface detection method. That is, the preview road surface detection method includes a distance detection step of detecting a value related to the distance between the vehicle body member 30 and a measurement point P on the road surface ahead of the vehicle that corresponds to at least the center portion 43 of the road contact portion 41 of the wheel W, using a plurality of transmitters and at least one receiver 14 attached to the vehicle body member 30 in a line facing a direction intersecting the traveling direction of the vehicle V, and a distance calculation step of calculating the road surface distance L1, which is the distance from the vehicle body member 30 to the measurement point P, based on the detection value detected in the distance detection step, in which the transmitters emit detection waves with a time difference between adjacent transmitters in the distance detection step.

[0080] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes, modifications, and combinations are possible. [Explanation of symbols]

[0081] 1 Preview road surface detection device 3. Suspension system 4 Preview control section 5 Suspension control section 11 Distance Sensor 11a to f transmitter 12 Distance calculation unit 14 Receiver 16 Sensor housing 20 Exterior materials 41 Road surface area 43 Central part 30 Body parts B body D. Active Suspension D1 Suspension spring D2 variable damper L1 road surface distance L2 Road surface displacement L3 vehicle height L4 Road surface width P measurement point R Road surface V vehicle W wheels W1 spring W2 Damper Ra to Re detection wave

Claims

1. A preview road surface detection device, a distance sensor that includes a plurality of transmitters and at least one receiver attached to a vehicle body member in a line in a direction intersecting the vehicle's traveling direction, and that detects a value related to the distance between the vehicle body member and a measurement point on the road surface ahead of the vehicle that corresponds to at least a portion of the road contact portion of the wheel; a distance calculation unit that calculates a road distance, which is a distance from the vehicle body member to the measurement point, based on a detection value detected by the distance sensor, The transmitters transmit detection waves with a time difference from adjacent transmitters, and a transmission order is set, and the transmitter that transmits after any one transmitter transmits a detection wave is a transmitter that is provided at a position where there is at least one other transmitter between the transmitter and the first transmitter. Preview road surface detection device.

2. The detection wave is transmitted from the transmitter toward a road surface, The preview road surface detection device according to claim 1 , wherein the detection wave is a laser wave or a millimeter wave.

3. At least one of the plurality of transmitters further includes a second transmitter at least one of a forward direction and a rearward direction in a traveling direction of the vehicle relative to the first transmitter, when the first transmitter is defined as the first transmitter; 3. The preview road surface detection device according to claim 1, wherein the first transmitter and the second transmitter emit the detection waves with a time difference.

4. The one or more receivers are arranged at ends in a vehicle width direction, The preview road surface detection device according to claim 3 , wherein the transmitter is attached so that the direction of transmission is inclined toward the one or more receivers.

5. A preview road surface detection method, comprising: a distance detection step of detecting a value relating to the distance between the vehicle body member and a measurement point on the road surface in front of the vehicle, the measurement point corresponding to at least the center of the road contact portion of the wheel, using a plurality of transmitters and at least one receiver attached to the vehicle body member in a line in a direction intersecting the traveling direction of the vehicle; a distance calculation step of calculating a road surface distance, which is a distance from the vehicle body member to the measurement point, based on the detection value detected in the distance detection step, In the distance detection step, the transmitters transmit detection waves with a time difference from adjacent transmitters, and a transmission order is set, and the transmitter that transmits after any one transmitter transmits a detection wave is a transmitter that is provided at a position where there is at least one other transmitter between the transmitter and the first transmitter. Preview road surface detection method.

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