JP2017094970A - Vehicular attitude control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To gradually change the attitude of a vehicle more quickly than with conventional techniques, thereby improving the comfort of riding in the vehicle, in a situation where the inclination angle of a road surface greatly changes upward ahead of the vehicle.SOLUTION: A suspension control apparatus includes a preview sensor and a control device for estimating an inclination angle φ of a road surface on the basis of a result of detection by the preview sensor and controlling an active suspension. In the case of determining that a change amount of an upward inclination angle of a road surface within a given zone is equal to or higher than a reference value (S30, S40), the control device sets a guide line whose inclination angle changes more quickly and gradually than a change in the inclination angle of the road surface (S50) and controls vehicular heights at front and rear wheels through active suspension control so that the center of gravity G of the vehicle moves along the guide line, with a longitudinal direction of the vehicle in line with a direction of a tangential line relative to the guide line at the center of gravity G (S60).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an attitude control device for a vehicle such as an automobile.

  As a suspension for a vehicle, a suspension including an actuator for controlling a vertical stroke of the suspension or a force applied to the suspension is known. According to this type of suspension, by controlling the actuator, the vertical stroke of the suspension or the force applied to the suspension can be controlled, thereby changing the vehicle height at the wheel position and controlling the posture of the vehicle.

  For example, in Patent Document 1 below, when the inclination of the road surface in front of the vehicle is estimated and the road surface changes from a horizontal road to an uphill or downhill as the vehicle travels, the vehicle posture is An attitude control device that changes the vehicle height of a wheel position so as to change in a direction along an inclination is described. According to this type of attitude control device, the vehicle in the case where the road surface changes from a horizontal road to an uphill or downhill as the vehicle travels, as compared with the case where the vehicle height at the wheel position is not changed as described above. The front visibility can be improved.

JP 2009-234470 A

[Problems to be Solved by the Invention]
In the attitude control device described in Patent Document 1, when the road surface changes from a horizontal road to an uphill or downhill as the vehicle travels, the front wheel height increases or the rear wheel height increases. The attitude of the vehicle is controlled to rise forward by the reduction. Therefore, forward visibility when the vehicle transitions from the horizontal traveling state to the uphill traveling state is improved.

  However, since the range in which the vehicle height of the wheel position can be changed is limited, when the change in the inclination angle of the road surface when the road surface changes from a horizontal road to an uphill, the change amount is large, In some cases, the posture of the vehicle cannot be effectively changed in a direction along the slope of the road surface. In addition, when the vehicle shifts from the horizontal traveling state to the uphill traveling state, the posture of the vehicle is drastically changed, so that the riding comfort of the vehicle is lowered.

  The main problem of the present invention is to improve the riding comfort of the vehicle by changing the posture of the vehicle gently from an earlier stage than in the past in a situation where the inclination angle of the road surface in front of the vehicle changes greatly in the upward direction. That is.

[Means for Solving the Problems and Effects of the Invention]
According to the present invention, a vehicle height adjusting device for a front wheel, a vehicle height adjusting device for a rear wheel, a device for estimating an inclination angle of a road surface in the vehicle front-rear direction in front of the vehicle, and a vehicle height adjusting device for front wheels and rear wheels. And a control device for controlling the vehicle.

  When the control device determines that the amount of change in the upward inclination angle of the road surface within a predetermined distance is greater than or equal to the reference value, the inclination angle changes more quickly and gently than the change of the road surface inclination angle. A guide line is set, and the vehicle height adjustment device for the front wheels and the rear wheels is controlled so that the reference position of the vehicle moves along the guide line and the front-rear direction of the vehicle is directed in a direction tangent to the guide line at the reference position .

  According to the above configuration, when it is determined that the amount of change in the upward inclination angle of the road surface within the predetermined distance is greater than or equal to the reference value, the inclination angle is faster than the change in the inclination angle of the road surface and A gently changing guide line is set. Further, the vehicle height adjusting device for the front wheels and the rear wheels is controlled such that the reference position of the vehicle moves along the guide line and the front-rear direction of the vehicle is directed in a direction tangent to the guide line at the reference position.

  Therefore, in a situation where the inclination angle of the road surface in front of the vehicle greatly changes in the upward direction, the posture of the vehicle can be changed gently upward from earlier than in the past. Therefore, it is possible to avoid a sudden and large upward change in the posture of the vehicle, so that it is possible to improve the ride comfort of the vehicle in a situation where the road surface inclination angle changes greatly in the upward direction compared to the conventional case. it can.

  The guide line is composed of a region where the inclination angle of the road surface changes rapidly and a posture change region corresponding to the periphery thereof, a front and rear introduction region, and a convergence region. The range of the posture change region is the slope of the road surface. It is preferable that the angle is larger than the range of the region where the angle changes rapidly.

1 is a side view showing a first embodiment of a vehicle attitude control device according to the present invention. 1 is an enlarged plan view showing a first embodiment of a vehicle attitude control device according to the present invention. It is a flowchart which shows the stroke control routine in 1st embodiment. It is explanatory drawing which shows the situation where a vehicle moves uphill from a horizontal road about the case where the variation | change_quantity of the inclination angle of a road surface is more than a reference value. It is explanatory drawing which shows the condition where the magnitude | size of the variation | change_quantity of the inclination-angle of a road surface is more than a reference value in the condition where a vehicle moves from an uphill to a downhill. It is explanatory drawing which shows the preferable guide line containing the area | region of a clothoid curve. It is explanatory drawing which shows the condition where the magnitude | size of the variation | change_quantity of the inclination-angle of a road surface is more than a reference value in the condition where a vehicle moves to a downhill from a horizontal road. It is a flowchart which shows the principal part of the stroke control routine in a 1st modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First embodiment]
1 and 2 are a side view and a plan view, respectively, showing an outline of the vehicle suspension control apparatus 10 according to the first embodiment of the present invention. As shown in these drawings, the suspension control device 10 is applied to a vehicle 14 having left and right front wheels 12FL and 12FR that are steering wheels and left and right rear wheels 12RL and 12RR that are non-steering wheels. Yes. The vehicle 14 has front wheel suspensions 18FL and 18FR for suspending front wheels 12FL and 12FR from the vehicle body 16, and rear wheel suspensions 18RL and 18RR for suspending rear wheels 12RL and 12RR from the vehicle body 16, respectively.

  In addition, in the following description, the symbol which shows specific wheels, such as FL, is abbreviate | omitted when generically referring to the members provided on the plurality of wheels and the plurality of wheels. For example, the wheel 12 is used as a general term for the front wheels 12FL and 12FR.

  The vehicle 14 has front wheels 12FL and 12FR as drive wheels, rear wheels 12RL and 12RR as driven wheels, front wheel drive vehicles, front wheels 12FL and 12FR as driven wheels, and rear wheels 12RL and 12RR as rear wheels. Any of a drive vehicle and a four-wheel drive vehicle in which all four wheels are drive wheels may be used.

  The suspension control device 10 is an electronic control device that controls the actuators 20FL to 20RR, preview sensors 24FL and 24FR as prediction devices for predicting the height of the road surface 22 ahead of the vehicle 14, and the actuators 20FL to 20RR. 26. The actuators 20FL to 20RR change the vertical distance between the wheels 12FL to 12RR and the vehicle body 16 by controlling the vertical strokes of the suspensions 18FL to 18RR, respectively.

  Actuators 20FL-20RR cooperate with suspensions 18FL-18RR, respectively, to form active suspensions 28FL-28RR. The active suspensions 28FL and 28FR function as a front wheel height adjusting device that changes the vertical distance between the front wheels 12FL and 12FR and the vehicle body 16. Similarly, the active suspensions 28RL and 28RR function as a rear wheel height adjusting device that changes the vertical distance between the rear wheels 12RL and 12RR and the vehicle body 16.

  The active suspensions 28FL to 28RR may have any structure as long as the vertical distance between the wheel and the vehicle body can be changed by controlling the vertical stroke of the suspension. For example, the active suspension may supply and discharge oil to and from the hydropneumatic cylinder, as described in, for example, JP-A-4-100718. Alternatively, as described in, for example, Japanese Patent Application Laid-Open No. 2012-140020, the active suspension is configured to change the height of a mounting position of a suspension member such as a shock absorber with respect to a vehicle body side member or a wheel side member by an actuator. It may be.

  The preview sensors 24FL and 24FR are provided at the front end of the vehicle body 16 in front of the front wheels 12FL and 12FR, respectively. The preview sensors 24FL and 24FR irradiate the road surface 22 in front of the front wheels 12FL and 12FR with laser beams 25FL and 25FR, and detect the reflected light from the road surface 22, thereby detecting the height of the road surface 22 (the ground contact points of the front and rear wheels). ) (Height with reference to a straight line connecting). Laser light is irradiated so as to reciprocate in the left-right direction while reciprocating the irradiation point in the up-down direction. For the operation of the preview sensor and the detection of the height of the road surface, refer to, for example, International Publication No. 2012/32655, if necessary.

  As shown in FIG. 1, the irradiation point of the laser beam 25 on the road surface 22 when the amount of reciprocating scanning of the irradiation point in the vertical direction is 0 is set as a preview point Pp of the preview sensor 24. A distance in the vehicle front-rear direction between the ground contact point Pw of the front wheels 12FL and 12FR and the preview point Pp is defined as a preview distance Lp. The preview distance Lp is preferably larger than the wheel base Lw of the vehicle 14.

  The preview sensors 24FL and 24FR may be sensors other than the laser beam type sensor as long as the height of the road surface ahead of the vehicle can be detected. For example, a stereo camera or a monocular camera may be used, or a combination of a laser light type sensor and a stereo camera or a monocular camera may be used. Further, in FIG. 1 and FIG. 2, the preview sensors 24FL and 24FR are installed on the front bumper of the vehicle 14, but detect the height of the road surface in front of the front wheels like the upper edge of the inner surface of the windshield. It may be installed at any position where it can.

  The front wheels 12FL and 12FR are rotatably supported around the rotation axes 32FL and 32FR by corresponding wheel support members 30FL and 30FR, respectively, and are in contact with the road surface 22 by tires 34FL and 34FR. Similarly, the rear wheels 12RL and 12RR are rotatably supported around the rotation axes 32RL and 32RR by corresponding wheel support members 30RL and 30RR, respectively, and are in contact with the road surface 22 by tires 34RL and 34RR.

  The front wheel suspensions 18FL and 18FR include suspension arms 38FL and 38FR, respectively. The suspension arms 38FL and 38FR are swingably coupled to the vehicle body 16 by rubber bushing devices at the inner ends, and are pivotally coupled to the wheel support members 30FL and 30FR by joints such as ball joints at the outer ends. ing. In FIG. 2, only one suspension arm 38FL and 38FR, one rubber bushing device, and one joint are illustrated, but a plurality of these members may be provided.

  Similarly, the rear wheel suspensions 18RL and 18RR include suspension arms 38RL and 38RR, respectively. The suspension arms 38RL and 28RR are swingably coupled to the vehicle body 16 by rubber bushing devices at the inner ends, and are pivotally coupled to the wheel support members 30RL and 30RR by joints such as ball joints at the outer ends. ing. In FIG. 2, only one suspension arm 38RL and 38RR, one rubber bushing device, and one joint are shown, but a plurality of these members may be provided.

  The suspension arms 38FL and 28FR or the wheel support members 30FL and 30FR are connected to the lower ends of the shock absorbers 40FL and 40FR, respectively, and the upper ends of the shock absorbers 40FL and 40FR are connected to the vehicle body 16. Although not shown in detail in the drawing, suspension springs 42FL and 42FR are interposed between the vehicle body 16 and the shock absorbers 40FL and 40FR, respectively. The wheel support members 30FL and 30FR, the suspension arms 38FL and 38FR, the shock absorbers 40FL and 40FR, and the suspension springs 42FL and 42FR cooperate with each other to form the front wheel suspensions 18FL and 18FR. The front wheel suspensions 18FL and 18FR allow the front wheels 12FL and 12FR to be displaced vertically with respect to the vehicle body 16, respectively.

  Similarly, the lower ends of shock absorbers 40RL and 40RR are connected to the suspension arms 38RL and 38RR or the wheel support members 30RL and 30RR, respectively, and the upper ends of the shock absorbers 40RL and 40RR are connected to the vehicle body 16. Although not shown in detail in the figure, suspension springs 42RL and 42RR are interposed between the vehicle body 16 and the shock absorbers 40RL and 40RR, respectively. The wheel support members 30RL and 30RR, the suspension arms 38RL and 38RR, the shock absorbers 40RL and 40RR, and the suspension springs 42RL and 42RR cooperate with each other to form the rear wheel suspensions 18RL and 18RR. The rear wheel suspensions 18RL and 18RR allow the rear wheels 12RL and 12RR to be displaced vertically with respect to the vehicle body 16, respectively.

  The suspensions 18FL to 18RR may be any type of suspension as long as the wheels 12FL to 12RR are allowed to be displaced in the vertical direction with respect to the vehicle body 16, respectively. The suspensions 18FL to 18RR are preferably independent suspensions such as a McPherson strut type, a double wishbone type, a multi-link type, and a swing arm type. The suspension springs 42FL to 42RR may be arbitrary springs such as a compression coil spring and an air spring.

  Although not shown in detail in FIG. 1, the electronic control unit 26 includes a microcomputer and a drive circuit. The microcomputer has a general configuration in which a CPU, a ROM, a RAM, and an input / output port device are connected to each other via a bidirectional common bus.

  As shown in FIG. 1, in addition to signals indicating the height of the road surface 22 from the preview sensors 24FL and 24FR, a signal indicating the vehicle speed V is input from the vehicle speed sensor 44 to the electronic control unit 26. It has become. Further, a signal indicating the vertical acceleration Gbz of the vehicle body 16 is input from the acceleration sensor 46 to the electronic control device 26, and a signal indicating the vertical strokes SFL to SRR of the suspensions 18FL to 18RR is input from the stroke sensors 48FL to 48RR, respectively. It has become.

  In accordance with the flowchart shown in FIG. 2, when the road surface 22 has an up or down change, the electronic control unit 26 adjusts the front and rear wheels so that the vehicle 14 travels with a slant change according to the change. The vehicle height is controlled to control the inclination of the vehicle 14 in the front-rear direction, that is, the posture in the pitch direction.

  Specifically, the electronic control unit 26 estimates the inclination angle φ in the vehicle front-rear direction of the road surface 22 at the preview point Pp based on the detection results of the height of the road surface 22 by the preview sensors 24FL and 24FR. Whether or not there is an upward or downward change in the inclination angle φ is determined based on the change in the angle. Therefore, the electronic control device 26 functions as a device that cooperates with the preview sensors 24FL and 24FR to estimate the inclination angle φ of the road surface 22 in the vehicle front-rear direction in front of the vehicle 14.

  When the electronic control unit 26 determines that there is an upward change in the inclination angle φ and the change amount Δφ of the inclination angle φ within a predetermined distance L0 is greater than or equal to a reference value φc (a positive constant), A guide line is set for the vehicle 14 to smoothly incline upward and shift to the upward traveling. The predetermined distance L0 is preferably smaller than the wheel base Lw of the vehicle 14. Furthermore, as will be described in detail later, the electronic control unit 26 controls the strokes of the suspensions 18FL to 18RR by controlling the actuators 20FL to 20RR so that the vehicle 14 moves along the guide line.

  For example, FIG. 4 shows a situation in which the vehicle 14 moves from the horizontal road 22A to the uphill 22B when the change amount Δφ of the inclination angle φ of the road surface 22 is greater than or equal to the reference value φc. In FIG. 4, a guide line is indicated by 60, and the guide line 60 is a preferable movement locus of the center of gravity G of the vehicle 14. As will be described in detail later, the guide line 60 is obtained from the change in the inclination angle φ of the road surface 22 in the region 22X where the inclination angle φ between the horizontal road 22A and the uphill 22B changes suddenly and in the region around it. Is set so that the inclination angle changes quickly and gently.

  When the line extending through the center of gravity G and extending in the vehicle longitudinal direction is the reference line 62 of the vehicle 14, the strokes of the suspensions 18FL to 18RR are controlled so that the reference line 62 is tangent to the guide line 60 at the center of gravity G. The vehicle height of the front and rear wheels is controlled. The example shown in FIG. 4 is a situation in which the vehicle 14 moves from the horizontal path 22A to the uphill 22B, but the situation in which the vehicle 14 moves from the downhill to the uphill and the slope from the uphill with a small inclination angle. The same control is performed even when the vehicle moves to an uphill with a large angle.

  On the other hand, when the electronic control unit 26 determines that the inclination angle φ has a downward change and the amount of change Δφ in the inclination angle φ is greater than or equal to a reference value φd (a positive constant), the attitude of the vehicle 14 is determined. The strokes of the suspensions 18FL to 18RR are controlled by controlling the actuators 20FL to 20RR so as to be inclined forward.

  For example, FIG. 5 shows a situation in which the vehicle 14 moves from the uphill 22B to the downhill 22C when the magnitude of the change amount Δφ of the inclination angle φ of the road surface 22 is greater than or equal to the reference value φd. When the height of the road surface 22 ahead of the region 22Y where the inclination angle φ changes rapidly cannot be detected by the preview sensors 24FL and 24FR, the amount of change Δφ in the inclination angle φ is greater than or equal to the reference value φd. It may be determined that

  As shown in FIG. 5, in the area before the area 22Y where the inclination angle φ between the uphill 22B and the downhill 22C changes abruptly, the vehicle height of the front wheels is reduced and the vehicle of the rear wheels is reduced. By increasing the height, the posture of the vehicle 14 is controlled to lean forward. The forward inclination degree of the posture of the vehicle 14 is gradually increased as the vehicle 14 approaches the region 22Y.

  The example shown in FIG. 5 is a situation in which the vehicle 14 moves from the uphill 22B to the downhill 22C, but the situation in which the vehicle 14 moves from the horizontal road to the downhill and the downhill with a small inclination angle is inclined from the downhill. Similar control is performed even in a situation where the vehicle moves downhill with a large angle.

  Furthermore, when the electronic control unit 26 determines that there is no upward or downward change in the inclination angle φ, the skyhook is based on the vertical acceleration Gbz of the vehicle body 16 and the vertical strokes SFL to SRR of the suspensions 18FL to 18RR. Car body vibration control based on theory. The electronic control unit 26 also determines that the change amount Δφ of the tilt angle φ is less than the reference value φc and also determines that the magnitude of the change amount Δφ of the tilt angle φ is less than the reference value φd. Performs damping control of the vehicle body. Regarding the vibration control of the vehicle body based on the vertical acceleration Gbz and the vertical strokes SFL to SRR, refer to, for example, Japanese Patent Laid-Open No. 4-100718.

<Stroke control routine>
Next, a stroke control routine for the suspensions 18FL to 18RR in the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is repeatedly executed at predetermined time intervals when an ignition switch (not shown) is on. In the following description, the stroke control according to the flowchart shown in FIG. 2 is simply referred to as “control”.

  First, in step 10, a signal indicating the height of the road surface 22 detected by the preview sensors 24FL and 24FR is read. Based on the read average value of the road surface 22, the vehicle front-rear direction inclination angle φ of the road surface 22 at the preview point Pp is estimated, and the estimated value is sequentially stored in the RAM.

  In step 20, it is determined whether or not the guide line 60 has already been set. When an affirmative determination is made, the control proceeds to step 60, and when a negative determination is made, the control proceeds to step 30.

  In step 30, it is determined whether or not there is an upward change in the inclination angle φ in front of the vehicle 14 based on the change in the inclination angle φ. When a negative determination is made, control proceeds to step 70, and when an affirmative determination is made, control proceeds to step 40.

  In step 40, it is determined whether or not the change amount Δφ of the inclination angle φ within the predetermined distance L0 is equal to or larger than the reference value φc. When a negative determination is made, control proceeds to step 110, and when an affirmative determination is made, control proceeds to step 50. The change amount Δφ of the tilt angle φ may be φr−φf where φf and φr are the tilt angles of the front end and the front end within the predetermined distance L0, respectively.

  In step 50, a guide line 60 is set. The guide line 60 is composed of a region 22X where the inclination angle φ of the road surface 22 changes suddenly and a posture changing region corresponding to the region before and after the region 22X, an introduction region and a converging region ahead and behind the region 22X. This range is preferably larger than the range of the region 22X where the inclination angle φ of the road surface 22 changes rapidly.

  In the first embodiment, as shown in FIG. 6, the posture change area is an arc-shaped area 60B along an arc 61 having a radius R determined by the change amount Δφ of the inclination angle φ, and the introduction area The convergence regions are clothoid curve regions 60A and 60C located respectively before and after the arc-shaped region 60B. The clothoid curve region 60A is smoothly connected to the straight line portion 60D of the guide line 60 at the substantially straight front end, and smoothly connected to the arc region 60B at the rear end of the curve. On the contrary, the clothoid curve region 60C is smoothly connected to the arcuate line region 60B at the front end of the curve, and is smoothly connected to the straight line portion 60E of the guide line 60 at the substantially rear end of the straight line. In FIG. 6, a broken line 23 is a line obtained by translating the road surface 22 to the height of the center of gravity G when the vehicle 14 is traveling on the horizontal road 22A.

  When the vehicle height when the center of gravity G of the vehicle 14 is located at the straight line portion 60D is not the standard vehicle height, the straight line portion 60D or the clothoid curve region 60A exists so that there is a region for returning the vehicle height to the standard vehicle height. Preferably modified. Further, when the posture of the vehicle 14 is tilted forward or backward when the center of gravity G of the vehicle 14 is located at the straight portion 60D, the straight portion 60D has a region where the posture of the vehicle 14 is returned to the standard posture. Alternatively, the clothoid curve region 60A is preferably corrected.

  In step 60, the vehicle height control of the front and rear wheels is performed by controlling the strokes of the suspensions 18FL to 18RR so that the vehicle 14 travels with the reference line 62 of the vehicle 14 tangent to the guide line 60 at the center of gravity G. Is executed.

  In step 70, it is determined whether or not there is a downward change in the inclination angle φ ahead of the vehicle 14 based on the change in the inclination angle φ. When a negative determination is made, control proceeds to step 110, and when an affirmative determination is made, control proceeds to step 80.

  In step 80, it is determined whether or not the amount of change Δφ in the tilt angle φ is equal to or greater than a reference value φd. When a negative determination is made, control proceeds to step 110, and when an affirmative determination is made, control proceeds to step 100.

  In step 100, the vehicle height of the front wheel is reduced and the vehicle height of the rear wheel is increased and the increase / decrease amount is gradually increased in the region before the region 22Y, so that the posture of the vehicle 14 is controlled to lean forward. As the vehicle 14 approaches the region 22Y, the forward inclination is gradually increased.

  In step 110, damping control for damping the vibration of the vehicle body 16 is executed by controlling the actuators 20FL to 20RR. Note that step 110 may be omitted because vibration suppression control need not be performed.

<Operation of Suspension Control Device 10>
(1) When there is an upward change in the inclination angle φ and the amount of change Δφ in the inclination angle φ is large First, a negative determination is made in step 20, and an affirmative determination is made in steps 30 and 40. Line 60 is set. When the guide line 60 is set, an affirmative determination is made in step 20, so that in step 60 the vehicle 14 travels with the reference line 62 of the vehicle 14 tangent to the guide line 60 at the center of gravity G. The vehicle height is controlled. Therefore, compared with the case where the vehicle height control of the front and rear wheels is not performed, the vehicle 14 can smoothly travel uphill without changing the posture of the vehicle 14 abruptly.

(2) When there is a downward change in the inclination angle φ and the magnitude of the change amount Δφ in the inclination angle φ is large, a negative determination is made in steps 20 and 30, and an affirmative determination is made in steps 70 and 80. At 100, the attitude of the vehicle 14 is controlled to lean forward, and the forward lean degree gradually increases as the vehicle 14 approaches the region 22Y. Therefore, compared with the case where the forward lean posture is not controlled, the vehicle 14 can smoothly travel downhill on a travel road where the inclination angle φ changes downward. In addition, the laser beams 25FL and 25FR of the preview sensors 24FL and 24FR are irradiated to the road surface 22 in front of the vehicle at an early stage so that the height of the road surface 22 can be detected at an early stage.

(3) When there is no change in the inclination angle φ or the magnitude of the change amount Δφ is small If there is no change in the inclination angle φ, a negative determination is made in steps 20, 30 and 70. If the amount of change Δφ is small, a negative determination is made in step 40 or 80. In any case, in step 110, the vibration suppression control for suppressing the vibration of the vehicle body 16 is executed. Therefore, the vibration of the vehicle body 16 can be reduced and the riding comfort of the vehicle 14 can be improved as compared with the case where the vibration suppression control is not executed.

[First modification]
FIG. 7 shows a situation in which the vehicle 14 moves from the horizontal road 22A to the downhill 22C when the magnitude of the change amount Δφ of the inclination angle φ of the road surface 22 is equal to or larger than the reference value φd. As shown in FIG. 7, even in the first modified example, the vehicle height of the front wheels is reduced in the region before the region 22Y where the inclination angle φ between the horizontal road 22A and the downhill 22C changes rapidly. At the same time, the vehicle height of the rear wheel is increased, so that the posture of the vehicle 14 is controlled to lean forward. The forward inclination degree of the posture of the vehicle 14 is gradually increased as the vehicle 14 approaches the region 22Y.

The distances x, x ₀ , y, y ₀ are assumed to be the distances shown in FIG. Further, the angle formed by the laser beam 25 with respect to the longitudinal direction of the vehicle 14 when the amount of reciprocating scanning of the irradiation point in the vertical direction is 0 is defined as θ, and the angle formed by the longitudinal direction of the vehicle 14 with respect to the horizontal direction is defined as α. To do. When the elapsed time is t, the distances y ₀ , y, and x are represented by the following formulas (1) to (3), respectively. As shown in the following formula (4), the angle α is a value that varies with the angular velocity ω.
y ₀ = x ₀ * tan θ (1)
y = x * tan (θ + α) (2)
x = x ₀ −V * t (3)
α = ω * t (4)

The vertical distance between the reference line 62 of the vehicle 14 and the ground contact point of the front wheel 12F is defined as the front wheel stroke Sf, and the vertical distance between the reference line 62 of the vehicle 14 and the ground contact point of the rear wheel 12R is defined as the rear wheel stroke Sr. And From FIG. 7, if the strokes Sf and Sr of the front wheels and the rear wheels are controlled so as to be values represented by the following formulas (5) and (6), respectively, the preview sensor 24 can detect the road surface 22 on the downhill 22C as soon as possible. It can be seen that the situation can be such that the height can be detected.
Sf = −Lf * sin α + y (5)
Sr = Lr * sinα + y (6)

  Therefore, in the first modified example, the vehicle heights of the front and rear wheels are controlled so that the strokes Sf and Sr of the front wheels and the rear wheels have values represented by the above formulas (5) and (6), respectively. Although not shown in FIG. 7, Lf and Lr in the following formulas (5) and (6) are distances in the vehicle front-rear direction between the front and rear axles and the center of gravity G of the vehicle 14, respectively. It is.

  FIG. 8 is a flowchart showing a main part of a stroke control routine in the vehicle attitude control apparatus 10 according to the first modification of the present invention. In FIG. 8, the same step numbers as those shown in FIG. 2 are assigned to the same steps as those shown in FIG.

  In the first modification, steps other than steps 90 and 100 are executed in the same manner as in the first embodiment. If an affirmative determination is made in step 80, the strokes Sf and Sr of the front wheels and the rear wheels are calculated in step 90 according to the above equations (5) and (6). Then, in step 100, the vehicle heights of the front and rear wheels are controlled so that the strokes Sf and Sr of the front wheels and the rear wheels become values represented by the above formulas (5) and (6), respectively.

According to the first modification, in the situation where there is an upward change in the inclination angle φ and the change amount Δφ of the inclination angle φ is large, the same operational effects as in the case of the first embodiment can be obtained, In a situation where the vehicle 14 moves from the horizontal path 22A to the downhill 22C, the posture of the vehicle 14 can be reliably controlled to a preferable posture. In the first modification example, step 110 may be omitted.

Claims (1)

A vehicle height adjusting device for the front wheels, a vehicle height adjusting device for the rear wheels, a device for estimating the inclination angle of the road surface in the vehicle front-rear direction in front of the vehicle, a control device for controlling the vehicle height adjusting device for the front wheels and the rear wheels, When the control device determines that the amount of change in the inclination angle of the road surface in the upward direction within a predetermined distance is greater than or equal to a reference value, the inclination angle is the inclination angle of the road surface. A guide line that changes more quickly and gently than the change of the vehicle so that the reference position of the vehicle moves along the guide line and the front-rear direction of the vehicle is directed in the direction of the tangent to the guide line at the reference position A vehicle attitude control device for controlling a vehicle height adjusting device for the front and rear wheels.

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