Road surface preview detection device

Abstract

The present invention provides a foresight road surface detection device that performs foresight control of an active suspension (D) based on a detected road surface displacement by the foresight road surface detection device (1) even in a case where a tire is deformed when a vehicle turns, etc. The foresight road surface detection device (1) of the present invention includes a distance sensor (11) provided to a vehicle body member (3) that detects a distance to a measurement point of a road surface in front of a vehicle, the measurement point corresponding to at least a central portion of a road surface contact portion of a wheel (W), and a distance calculation portion (12) that calculates a road surface distance from the vehicle body member (3) to the measurement point based on a detection value of the distance sensor (11), and detects a road surface displacement in front of the vehicle calculated from the road surface distance and a vehicle height of the vehicle body member (3) at a time when the distance is detected by the distance sensor (11) as a road surface state.

Description

TECHNICAL FIELD

[0001] The present application relates to a foresight road surface detecting device for an active suspension. BACKGROUND

[0002] As one of active suspensions for a vehicle such as an automobile, there is known an active suspension having a road surface detecting mechanism that senses a road surface displacement ahead by an optical sensor, a vehicle speed detecting mechanism that senses a vehicle speed, an up-and-down acceleration detecting mechanism that is installed to a vehicle body at a portion corresponding to a front wheel and senses an up-and-down acceleration of the vehicle body, and a storage mechanism that stores information of the road surface displacement and information of the up-and-down acceleration in time series, and in the case where it is determined that a detection abnormality of the road surface displacement has occurred, an up-and-down acceleration of a portion of the vehicle body corresponding to a rear wheel when the vehicle has traveled a wheel base distance is estimated from the up-and-down acceleration stored in the storage mechanism based on the wheel base and the vehicle speed, and a foresight control is performed on an actuator of the rear wheel based on the estimated up-and-down acceleration (see Patent Document 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-96922 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the technology of Patent Document 1, since the case where the tire is deformed when the vehicle turns, etc. is not taken into consideration, there is a possibility that the ride comfort is deteriorated.

[0008] The present application aims at solving the above problem, and to perform a foresight control on an active suspension based on a road surface displacement detected by a foresight road surface detecting device even in the case where the tire is deformed when the vehicle turns, etc.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] In order to solve the foregoing problems, the foresight road surface detecting device of the present application includes a distance sensor that is provided to a vehicle body member and detects a distance to a measurement point of a road surface ahead of a vehicle, the measurement point corresponding to at least a central portion of a road surface contact portion of a wheel, and a distance calculating portion that calculates a road surface distance from the vehicle body member to the measurement point based on a detection value of the distance sensor, and the foresight road surface detecting device detects a road surface displacement ahead of the vehicle calculated from the road surface distance and a vehicle height of the vehicle body member at the time when the distance is detected by the distance sensor as a road surface state.

[0011] EFFECTS OF THE INVENTION

[0012] The preview road surface detection device according to the present application can detect road surface displacement with high precision even in the case where the tire is deformed when the vehicle turns, and thus can perform preview control of the active suspension, and ride comfort is improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram that explains an outline of a suspension system of a vehicle.

[0014] Figure 2 is a side view that shows a mounting configuration of a distance sensor.

[0015] Figure 3 The configuration of the distance sensor is explained.

[0016] Figure 4 Other configurations of the distance sensor are explained.

[0017] BRIEF DESCRIPTION OF DRAWINGS

[0018] 1 preview road surface detection device

[0019] 11 distance sensor

[0020] 12 distance calculation section

[0021] 2 exterior member

[0022] 3 vehicle body member

[0023] D active suspension

[0024] D1 suspension spring

[0025] D2 variable shock absorber

[0026] W wheel

[0027] W1 spring

[0028] W2 shock absorber

[0029] 4 preview control section

[0030] 5 suspension control section DETAILED DESCRIPTION

[0031] Hereinafter, an embodiment of the present application will be explained in detail.

[0032] Figure 1 is a diagram that explains an outline of a suspension system of a vehicle of the preview road surface detection device 1 that applies the embodiment.

[0033] In the suspension system, the suspension control section 5 controls the active suspension D based on the skyhook theory or the like so that the attitude of the vehicle body member 3 is stabilized. At this time, the preview control section 4 acquires the road surface displacement in front of the vehicle detected by the preview road surface detection device 1 as the preview information, and compensates for the response delay of the active suspension D, thereby seeking to improve the ride comfort.

[0034] In detail, the vehicle body member 3 that forms the vehicle body has a wheel W (front wheel on the left and right) on the lower side thereof, and the active suspension D and the tire (not shown) of the wheel W absorb the unevenness of the road surface R. The suspension control section 5 controls the tire of the wheel W using a vibration model in which a spring Wl and a shock absorber W2 are connected in parallel.

[0035] The active suspension D is composed of a suspension spring Dl and a variable shock absorber D2 that controls the damping force using a hydraulic actuator or controls the damping force and the thrust using an electromagnetic force, and is sandwiched between the vehicle body member 3 and the wheel W.

[0036] The suspension control section 5 controls the variable shock absorber D2 as a control target.

[0037] The preview road surface detection device 1 includes a distance sensor 11 that is provided to the vehicle body member 3 and measures the distance to a plurality of measurement points of the road surface R using an ultrasonic wave, a laser, or a millimeter wave radar, and a distance calculation section 12 that calculates the road surface displacement in front of the wheel W based on the measurement value of the distance sensor 11.

[0038] In more detail, the preview road surface detection device 1 calculates the road surface displacement in front of the wheel W by subtracting the vehicle height (road surface distance of the vehicle body member 3) at the time of measurement from the detection value of the distance calculation section 12. The vehicle height at the time of measurement at this time is a value calculated by the suspension control section 5 as a control variable.

[0039] The preview control section 4 calculates the required time until the measurement point of the road surface displacement is passed based on the vehicle speed at the time of measurement of the road surface displacement and the distance from the grounding point of the tire to the measurement point of the road surface displacement in the advancing direction of the vehicle calculated based on the installation position of the distance sensor 11.

[0040] The preview road surface detection device 1 and the preview control section 4 detect the preview information of the road surface displacement, that is, the state (unevenness) of the road surface in front of the wheel W that will be passed after a prescribed time, by periodically performing processing.

[0041] Since the suspension control section 5 controls the active suspension D based on the preview information of the road surface displacement, it is possible to improve the ride comfort.

[0042] Next, the installation structure of the preview road surface detection device 1 will be described.

[0043] In the pre-view road surface detection device 1 of the embodiment, the distance sensor 11 is provided to the vehicle body member 3, and the distance calculation portion 12 is installed to the ECU (Electronic Control Unit) of the vehicle. The installation of the distance sensor 11 is described below.

[0044] For convenience of explanation, the installation configuration of the distance sensor 11 is simplified and is not limited to the embodiment. Note that the advancing direction of the vehicle is described as "front", the retreating direction is described as "rear", the vertically upper side is described as "up", the vertically lower side is described as "down", the vehicle width direction is described as "left" and "right". Also, since the installation configuration of the vehicle sensor is symmetrical in the left and right directions, the description of one side (left side) is mainly described below, and the description of the other side (right side) is appropriately omitted.

[0045] Figure 2 is a side view showing the installation configuration of the distance sensor 11. Note that the outline of the vehicle V is shown by a double-dotted line in Figure 2 .

[0046] As shown in Figure 2 , the distance sensor 11 is fixed to the vehicle body member 3 that forms the vehicle body, and is configured.

[0047] The vehicle V is configured to mainly include the vehicle body member 3, the exterior member 2 that forms the outer side portion (outline) of the vehicle V, and the distance sensor 11 that detects the road surface state. The vehicle V is a car that has the vehicle body member 3, the exterior member 2, and the distance sensor 11 as such, and the form and type thereof are not particularly limited. That is, the vehicle V is a passenger car, a bus, a truck, a work vehicle, or the like.

[0048] 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.

[0049] The exterior member 2 is configured to include a hood 21, a front bumper 22 (bumper), and a front fender 23. The hood 21 is a panel member that covers the upper surface of the front of the front window glass. The front bumper 22 is located at the front side of the vehicle V, and is configured by a panel member made of, for example, synthetic resin. Also, the front bumper 22 has a front surface portion 22a provided with an air inlet and the like, and a bottom surface portion 22b that extends toward the rear from the lower end of the front surface portion 22a. The front fender 23 is a panel member that covers the periphery of the wheel W (left front wheel).

[0050] The distance sensor 11 is a sensor that detects the state (road surface state) of the road surface R in front of the vehicle V 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.

[0051] In detail, the distance sensor 11 is installed on the side surface of the upper member 32 on the vehicle width direction outer side. In addition, the distance sensor 11 is located at the front end portion of the upper member 32 in the front-rear direction.

[0052] The distance sensor 11 in the present embodiment is configured to detect the road surface distance from the road surface R in front of the wheel W as indicated by the bold arrow. In addition, the distance sensor 11 can be appropriately selected from among sensors of a radar type, a camera type, a laser type, and the like. In addition, as the distance sensor 11, not only a single sensor but also a plurality of sensors of the camera type, the laser type, and the like can be combined.

[0053] Next, the configuration of the distance sensor 11 of the preview road surface detection device 1 will be described based on Figure 3

[0054] The distance sensor 11 of the present embodiment is configured by three infrared type distance sensors 11a, 11b, and 11c of a triangulation principle, a method of converting the reflected light intensity of emitted infrared light into a distance, a method of distance conversion of the time of flight of laser light, and the like.

[0055] Figure 3 A case where the distance is detected by the distance sensor 11 (11a, 11b, 11c) when the wheel W is viewed from the front of the vehicle is shown.

[0056] The wheel W is in contact with the road surface R at the road surface contact surface of the tire. Also, as shown in Figure 1 the distance sensor 11a, 11b, 11c detects the distance between the measurement point (arrowhead end of the figure) of the measurement surface in front of the vehicle and the corresponding portion of the road surface contact width of the wheel W or the prescribed width on the inner side of the road surface contact width. By detecting the distance from the measurement point by the distance sensor 11a, 11b, 11c, the preview road surface detection device 1 can calculate the road surface displacement even in a case where the tire deforms and the road surface contact width changes due to a load applied to the wheel W by a steering angle operation such as a turn. That is, the preview road surface detection device 1 does not set the position corresponding to the end portion of the road surface contact width of the tire in a collapsed or floated state as the measurement point. In more detail, it is preferable that the position of the measurement point be set to the front of the vehicle corresponding to the central portion of the road surface contact width of the wheel W or the prescribed width on the inner side of the road surface contact width in a state where an occupant is not on board and the vehicle is placed on a flat road surface.

[0057] The distance calculation portion 12 (refer to Figure 1 ) of the preview road surface detection device 1 calculates the average value of the distances detected by the distance sensors 11a, 11b, 11c as the road surface distance. In Figure 3 ​The three distance sensors 11a, 11b, 11c are shown in FIG. 3, and the case where the average of the distances to the three measurement points is set as the road surface distance is described. The distance to at least two measurement points is detected. Thus, the detection accuracy of the road surface displacement can be improved.

[0058] In the above description, the case where the distance sensors 11a, 11b, 11c find the road surface distance of the measurement point in front of the vehicle corresponding to the central portion of the road surface ground contact width or the prescribed width on the inner side of the road surface ground contact width even if the load applied to the wheel W changes is described. Next, the case where the distance calculation section 12 finds the road surface distance of the measurement point in front of the vehicle in accordance with the change in the load applied to the wheel W (change in the road surface ground contact width) is described. Figure 4

[0059] Figure 4 The case where the distance sensors 11 (11a, 11b, 11c, 11d, 11e) detect the road surface distance when the wheel W is viewed from the front of the vehicle is shown. In Figure 4 , the distance sensors 11 are increased by the distance sensors 11d, 11e so as to be able to detect the distance between the measurement point in front of the vehicle corresponding to the ground contact portion in contact with the road surface when the load applied to the wheel W changes.

[0060] In the preview road detection device 1, when the distances measured by the distance sensors 11a, 11b, 11c, 11d, 11e are set as Xa, Xb, Xc, Xd, Xe, and the weights of the distances of the distance sensors 11a, 11b, 11c, 11d, 11e are set as wa, wb, wc, wd, we, the distance calculation section 12 calculates (wa x Xa + wb x Xb + wc x Xc + wd x Xd + we x Xe) / (wa + wb + wc + wd + we) as the road surface distance. That is, the distance calculation section 12 calculates the weighted average of the distances detected by the distance sensors 11 as the road surface distance.

[0061] Also, in the case where the vehicle is straight ahead, the distance calculation section 12 increases the weights wa, wb, wc of the distance sensors 11a, 11b, 11c corresponding to the central portion of the road surface ground contact width and decreases the weights wd, we of the distance sensors 11d, 11e, and calculates the weighted average of the distances. For example, the weights wa, wb, wc are set to 1, and the weights wd, we are set to 0, and the weighted average of the distances is calculated as the road surface distance.

[0062] ​Further, in the case where the vehicle is turning right, the distance calculating section 12 increases the weights wb, wc, we of the distance sensors 11b, 11c, 11e corresponding to the left side of the road surface contact width (the left side with respect to the vehicle traveling direction), decreases the weights wd, wa of the distance sensors 11d, 11a, and calculates a weighted average of the distances. For example, the weighted average of the distances is calculated as the road surface distance by setting the weights wb, wc, we to 1 and the weights wd, wa to 0.

[0063] Further, in the case where the vehicle is turning right, the distance calculating section 12 increases the weights wb, wc, we of the distance sensors 11b, 11c, 11e corresponding to the left side of the road surface contact width (the left side with respect to the vehicle traveling direction), decreases the weights wd, wa of the distance sensors 11d, 11a, and calculates a weighted average of the distances. For example, the weighted average of the distances is calculated as the road surface distance by setting the weights wb, wc, we to 1 and the weights wd, wa to 0.

[0064] That is, the preview road surface detecting device 1 gives a weight to each of the distances in front of the plurality of wheels detected by the distance sensors 11 and calculates a weighted average as the road surface distance, and makes the arrangement such that the outer peripheral side in the turn is given a large weight in correspondence with the turn of the vehicle.

[0065] Note that, in either the left turn or the right turn, when comparing the outer wheel in the turn and the inner wheel in the turn of the vehicle, the centrifugal force acting on the outer wheel in the turn is large (the load applied is large) in the turn. Therefore, the collapse of the tire of the outer wheel in the turn is larger than that of the inner wheel in the turn of the vehicle in the turn.

[0066] Further, in either the left turn or the right turn, when comparing the outer peripheral side in the turn and the inner peripheral side in the turn of the tire, the centrifugal force acting on the outer peripheral side in the turn is large (the load applied is large) in the turn. Therefore, even in the same tire, the collapse of the portion on the outer peripheral side in the turn is large.

[0067] According to the above description, since the road surface distance of the measurement point in front of the vehicle is changed in accordance with the change in the road surface contact width of the wheel W, it is possible to improve the detection accuracy of the road surface displacement.

[0068] Note that the present application is not limited to the above-described embodiments, and various design changes can be made within the scope of the gist thereof.

Claims

1. A pre-viewing road surface detection device characterized by comprising: including: a distance sensor provided to a vehicle body member, which detects a distance to a measurement point on a road surface in front of the vehicle, the measurement point including a central portion of a road surface contact width of a wheel and corresponding to a contact portion; and a distance calculation portion which calculates a road surface distance from the vehicle body member to the measurement point based on a detection value of the distance sensor, the distance calculation portion respectively weights distances in front of a plurality of wheels detected by the distance sensor, and calculates a weighted average value as a road surface distance, in a case where the vehicle is straight ahead, the weight of the distance of the central portion is increased, in a case where the vehicle is right turning, the weight of the distance on the left side is increased, in a case where the vehicle is left turning, the weight of the distance on the right side is increased, a road surface displacement in front of the vehicle calculated from the road surface distance and a vehicle height of the vehicle body member at the time when the distance is detected by the distance sensor is detected as a road surface state.

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