JP2000318416A - Vehicular characteristic detection device and control device of vehicle mounting this device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately grasp a vehicular running characteristic, in a vehicular charactristic detection device for detecting the vehicular running charactristic. SOLUTION: Wheel speed sensors 12a-12d for outputting a signal responding to a wheel speed and pressure sensors 14a-14d for outputting the signal responding to the air pressure of a tire are provided on a wheel. The frequency of the output signal of the wheel speed sensors 12a-12d is analyzed and the resonance frequency of upper/lower direction and front/rear direction under the car body spring is grasped. The spring constant K under the car body spring is calculated from such resonance frequency. Based on the relation between the air pressure P on the tire and spring constant K, the kind of the tire is specified and the deterioration of the tire and suspension and the softening of the tire are generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle characteristic detecting device for detecting running characteristics of a vehicle, and a control device for a vehicle equipped with the vehicle characteristic detecting device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 7-69232
As disclosed in Japanese Patent Application Laid-Open No. H10-260, there is known an apparatus that detects tire pressure and changes the control characteristics of a vehicle when the pressure drops below a reference value. In a situation where the tire pressure is decreasing, for example, when vehicle control such as rear wheel steering control or turning behavior control is performed under the same conditions as when the tire pressure is maintained in a normal state, the vehicle There is a possibility that the turning performance of the vehicle decreases and the traveling stability decreases. For this reason, in order to properly control the vehicle, it is necessary to consider the tire pressure. In the above-mentioned conventional device, when the tire pressure drops below the reference value,
The control characteristics of the vehicle are changed so that a decrease in turning performance and running stability is prevented. Therefore, according to the above-described conventional device, even when the tire air pressure is reduced, it is possible to prevent a decrease in running performance during traction, braking, and turning.

[0003]

Incidentally, the normal value of the tire pressure differs depending on the type of the tire. For this reason, in order to maintain the running performance at a high level in the above-described conventional device, it is necessary to change a reference value for determining a decrease in tire air pressure according to the type of tire. However, in the above-mentioned conventional device, the type of tire is not considered.

[0004] The running characteristics of a vehicle change in accordance with the tire pressure and also change in accordance with the state of the tire and suspension. That is, when the tires and the suspension harden due to a decrease or deterioration of the air temperature, or when the tires are softened due to an increase in the air temperature or the like, the driving performance during driving, braking, and turning decreases. Therefore, in order to maintain the running performance at a high level, it is necessary to reflect not only the air pressure of the tire but also the state of the tire and the suspension in the vehicle control. However, in the above-mentioned conventional device, only the tire air pressure is detected, and the state of the tire and the state of the suspension are not considered.

The present invention has been made in view of the above points, and has as its first object to provide a vehicle characteristic detecting device capable of accurately grasping the running characteristics of a vehicle.
A second object of the present invention is to provide a vehicle control device capable of appropriately controlling a vehicle equipped with such a vehicle characteristic detection device according to the traveling characteristics without deteriorating the traveling performance.
The purpose of.

[0006]

A first object of the present invention is to provide an air pressure detecting means for detecting an air pressure of a tire and a resonance parameter for detecting a parameter relating to a resonance characteristic of an unsprung portion of a vehicle body. Detecting means, the air pressure detected by the air pressure detecting means, and a vehicle characteristic detecting means for detecting a running characteristic of the vehicle based on the parameters detected by the resonance parameter detecting means, This is achieved by a vehicle characteristic detecting device.

In the present invention, the tire pressure is detected and a parameter relating to the resonance characteristics of the unsprung portion of the vehicle body is detected. The parameters related to the resonance characteristics change according to the tire pressure and also change according to the running characteristics of the vehicle such as the type of the tire and the state of the tire and the suspension. Therefore, according to the present invention, the running characteristics of the vehicle can be accurately detected based on the relationship between the tire air pressure and the parameters related to the resonance characteristics of the unsprung portion of the vehicle body.

In this case, as described in claim 2, in the vehicle characteristic detecting means according to claim 1, the resonance parameter detecting means may detect a resonance frequency of an unsprung portion of the vehicle body. According to a third aspect of the present invention, in the vehicle characteristic detecting unit according to the first aspect, the resonance parameter detecting unit may detect a spring constant of an unsprung portion of the vehicle body.

According to a second aspect of the present invention, there is provided a control device for a vehicle equipped with the vehicle characteristic detecting device according to any one of the first to third aspects. 4. The vehicle characteristic detecting device according to claim 1, further comprising a control characteristic changing unit configured to change a control characteristic of the vehicle in accordance with a traveling characteristic of the vehicle detected by the detecting unit. This is achieved by the control device of the vehicle.

In the present invention, a vehicle is equipped with a vehicle characteristic detecting device for detecting a traveling characteristic. In the vehicle control device, the control characteristics are changed according to the traveling characteristics detected by the vehicle characteristic detection device. That is, vehicle control suitable for the running characteristics of the vehicle is executed. Therefore,
ADVANTAGE OF THE INVENTION According to this invention, a vehicle control can be performed appropriately, without reducing the driving performance of a vehicle.

[0011]

FIG. 1 is a block diagram of a vehicle characteristic detecting device according to an embodiment of the present invention. The vehicle characteristic detection device of the present embodiment includes a vehicle characteristic determination electronic control unit (hereinafter, referred to as a characteristic determination ECU) 10. Characteristic determination ECU1
0 is connected to wheel speed sensors 12a to 12d disposed on the wheels FL, FR, RL, RR. The wheel speed sensors 12a to 12d generate pulse signals at a cycle corresponding to the wheel speed of each wheel. The characteristic determination ECU 10 detects the wheel speeds Vwfl, Vwfr, Vwrl, Vwrr of each wheel based on the output signals of the wheel speed sensors 12a to 12d.

Each wheel has a built-in pressure sensor 14a to 14d for outputting a signal corresponding to the internal pressure of the tire constituting the wheel. The pressure sensors 14a to 14d are provided with transmission units 16a to 16d. In the vicinity of each wheel, receiving sections 18a to 18 of pressure sensors 14a to 14d are provided.
d is provided. Output signals of the pressure sensors 14a to 14d are transmitted from the transmitting units 16a to 16d to the receiving units 18a to 18d.
d. Receiver 1 of pressure sensors 14a to 14d
A characteristic determination ECU 10 is connected to 8a to 18d. The characteristic determination ECU 10 detects the internal pressure of each tire, that is, the air pressure P of each tire, based on the output signal of the pressure sensor 14. Hereinafter, the pressure sensors 14a to 14d are collectively referred to as a pressure sensor 14.

The characteristic determination ECU 10 includes an outside air temperature sensor 2
0 and the steering angle sensor 22 are connected. The outside air temperature sensor 20 outputs a signal according to the temperature around the vehicle. The steering angle sensor 22 outputs a signal corresponding to the operation angle of the steering wheel operated by the driver. The characteristic determination ECU 10 detects the outside air temperature T based on the output signal of the outside air temperature sensor 20 and detects the steer angle θ based on the output signal of the steer angle sensor 22. An alarm lamp 24 is connected to the characteristic determination ECU 10.
The warning lamp 24 is driven by a drive signal supplied from the characteristic determination ECU 10 when the running performance of the vehicle is reduced as described later. This notifies the vehicle occupant that the running performance of the vehicle is degraded.

By the way, while the vehicle is running, the vehicle receives forces in the vertical direction and the front-rear direction due to minute irregularities formed on the road surface. An elastic member such as a suspension or a tire is interposed between the vehicle body and the road surface. For this reason,
When the vehicle receives the above-described force, minute vibrations in the vertical and longitudinal directions are generated under the spring of the vehicle body. In this case, the minute vibration is transmitted to the wheel, and the minute vibration component appears in the resonance frequency in the output signal of the wheel speed sensor 12.

FIG. 2 shows the result of frequency analysis when the fast Fourier transform is performed on the wheel speed Vw in the vehicle of this embodiment. In FIG. 2, the horizontal axis represents the frequency (H
z), and the vertical axis indicates the power spectrum density G (f). As shown in FIG. 2, two peak values appear in the power spectrum density G (f) of the wheel speed Vw. The vicinity of 12 to 14 Hz is the resonance frequency in the vertical direction below the body spring, and the vicinity of 37 to 39 Hz is the resonance frequency in the front and rear direction below the body spring.

When the air pressure of the tire decreases, the spring constant of the rubber portion of the tire decreases. Further, when the tire is softened, the spring constant under the vehicle body spring decreases. Further, when the tire or suspension deteriorates, the tire or suspension hardens, and the spring constant under the vehicle body spring increases. When the spring constant changes in this manner, the resonance frequencies in the vertical and longitudinal directions below the body spring change. Specifically, the resonance frequency shifts to a lower frequency side when the spring constant decreases, and shifts to a higher frequency side when the spring constant increases.

Therefore, when the unsprung resonance frequency increases even though the tire air pressure is maintained at a constant value, it can be determined that the tire or suspension has hardened. Hardening of tires and suspensions is caused not only by a decrease in ambient temperature but also by their deterioration. For this reason, when the ambient temperature does not change under the above-mentioned circumstances, it can be determined that the tire or suspension has deteriorated. If tires and suspensions have deteriorated, it is not appropriate to apply an excessive load to such wheels.

Further, when the unsprung resonance frequency becomes low even though the tire air pressure is maintained at a constant value, it can be determined that the tire or suspension has softened. It can be determined that such softening has occurred due to a rise in ambient temperature. Even if such softening occurs excessively, it is not appropriate to apply an excessive load to such wheels.

On the other hand, when the tire pressure decreases as the resonance frequency of the unsprung body decreases, the running characteristics of the vehicle do not decrease as long as the tire pressure falls within a normal range corresponding to the type of tire. Can be determined. On the other hand, when the tire pressure falls below the normal value, it can be determined that the running performance of the vehicle is reduced. If the tire pressure is low, it is not appropriate to apply an excessive load to the wheels. Note that the normal air pressure of the tire differs depending on the type of the tire.

FIG. 3 is a map showing the relationship between the tire air pressure P that changes according to the type of tire and the spring constant K under the vehicle body. In FIG. 3, the regions surrounded by solid lines indicate the ranges in which the illustrated tires can be determined. Since the studless tire is made of a material having high flexibility, the spring constant K under the vehicle body spring can be kept small irrespective of the tire air pressure. Also, since the sporty tire is configured to have a low flatness, the spring constant K under the vehicle body is large, and decreases linearly with a decrease in tire air pressure. Further, since the run flat tire is configured so that the running of the vehicle can be maintained even when the air pressure of the tire becomes low, the spring constant K
Is largely maintained regardless of tire pressure. As described above, if the relationship between the tire pressure P and the spring constant K under the vehicle body is grasped, the type of the tire can be specified.

If the air pressure P of the tire falls below a normal range set according to the type of the specified tire, it can be determined that the running performance of the vehicle is degraded. If the spring constant K under the vehicle body changes excessively even though the tire air pressure P does not deviate from the normal range, it can be determined that the state of the tire or the suspension has changed. . Therefore, by detecting the tire air pressure P and the spring constant K under the vehicle body, the state of the tire and suspension, that is, the running characteristics of the vehicle can be accurately recognized.

FIG. 4 shows a flowchart of an example of a control routine executed by the characteristic determination ECU 10 in the vehicle characteristic detecting device of the present embodiment to realize the above functions. The routine shown in FIG. 4 is a periodic interrupt routine that is started every predetermined time. When the routine shown in FIG. 4 is started, first, the process of step 100 is executed. The routine shown in FIG. 4 is executed for each wheel.

In step 100, the wheel speed sensor 12,
Based on the pressure sensor 14, the outside temperature sensor 20, and the steering angle sensor 22, the wheel speed Vw, the tire pressure P, the outside temperature T, and the steering angle θ are detected. In step 102, a vertical Fourier transform is performed on the detected wheel speed Vw to calculate the vertical and longitudinal resonance frequencies under the vehicle body spring, and the vehicle body spring is calculated based on the calculated resonance frequency. Lower spring constant K
Is calculated.

In step 104, the tire air pressure is increased to a predetermined pressure ΔP0 from the previous routine to the current routine.
It is determined whether or not the above has changed. Note that the predetermined change rate ΔP
0 is the minimum change in air pressure at which the tire mounted on the vehicle can be determined to have been changed from an old tire to a new tire, and is set to a larger value than when the tire pressure changes due to a burst or the like. I have. When the change rate ΔP of the tire air pressure changes to a predetermined change rate ΔP0 or more, it can be determined that the tire has been replaced. Therefore, ΔP ≧ ΔP0
Is satisfied, the process of step 106 is executed next.

In step 106, the type of the tire currently mounted on the vehicle is specified by referring to the map shown in FIG. In step 108, the normal range (lower limit value PTi1, upper limit value PTi2) of the air pressure in the tire specified in step 106, and the variation ΔKT1 of the unsprung body spring constant allowed in a vehicle equipped with such a tire. Is read. This step 108
Is executed, the normal range of the tire pressure (lower limit value Pdwsh, upper limit value Pupsh) and the change amount ΔKsh of the spring constant are set in accordance with the type of the tire. It should be noted that as the outside air temperature increases, the tire softens and the spring constant under the vehicle body spring decreases. Also, during turning of the vehicle, a large load acts on the tire on the turning outer wheel side, so that the spring constant under the vehicle body spring increases. Therefore, in setting the above parameters, the outside air temperature and the steering angle are taken into account.

In step 110, the above step 100
It is determined whether or not the tire pressure P detected in the step is within the normal range set in the above step 108. As a result, when Pdwsh ≦ P ≦ Pupsh holds, it can be determined that the tire air pressure is a normal value. Therefore, when such a determination is made, the process of step 112 is performed next. On the other hand, when Pdwsh ≦ P ≦ Pupsh is not established, it can be determined that the tire air pressure is not a normal value and the traveling performance of the vehicle is reduced. Therefore, when such a determination is made, the process of step 114 is executed next.

In step 112, it is determined whether or not the change amount ΔK of the spring constant under the vehicle body which has changed from the previous routine to the current routine is equal to or smaller than the threshold value ΔKsh set in step 108. . as a result,
If | ΔK | ≦ ΔKsh holds, it can be determined that the spring constant under the vehicle body spring has changed within an appropriate range according to the type of tire. Therefore, if such a determination is made, the current routine ends. On the other hand, | ΔK | ≦ Δ
If Ksh does not hold, it can be determined that the spring constant under the vehicle body spring has been unduly changed due to deterioration of the tire or suspension even though the tire air pressure is within the normal value range. . Therefore, when such a determination is made, the process of step 114 is executed next.

In step 114, it is determined that the running performance of the vehicle is degraded, and such a signal is output to the outside. When the process of step 114 is performed, the alarm lamp 24 is driven, and the vehicle occupant is notified that the running characteristics have deteriorated. According to the above processing, the type of the tire can be specified based on the air pressure of the tire and the spring constant under the vehicle body, and the state of the tire and the suspension under the vehicle body can be recognized. For this reason, according to the present embodiment, it is possible to determine whether or not the running performance of the vehicle at the present time is deteriorating by comparing the unsprung state of the vehicle body with that of the normal case.

FIG. 5 is a system configuration diagram of a rear wheel steering device 30 of a vehicle equipped with the vehicle characteristic detecting device of the present embodiment. The rear wheel steering device 30 includes a rear wheel steering electronic control unit (hereinafter, referred to as a rear wheel steering ECU) 32. The rear wheel steering device 30 generates a force to steer the rear wheels under the control of the rear wheel steering ECU 32. The rear wheel steering device 30 includes a rack bar 36 that connects the left rear wheel RL and the right rear wheel RR to each other via a knuckle arm 34. An electric motor 38 is engaged with the rack bar 36. The electric motor 38 is connected to the rear wheel steering ECU 32, and supplies a steering force corresponding to the command signal to the rack bar 36 by receiving a command signal from the rear wheel steering ECU 32. The rear wheel steering device 30 steers the rear wheels RL and RR using the electric motor 38 as a power source.

The rear wheel steering ECU 32 is connected to a rear wheel steering angle sensor 40 and the above-described steering angle sensor 22. The rear wheel steering angle sensor 40 is provided on the rack bar 36 and outputs a signal corresponding to the steering angle of the rear wheels RL, RR. The steering angle sensor 22 is fixed to a steering shaft 44 that rotates together with the steering wheel 42. The rear wheel steering ECU 32 detects the steering angle δr of the rear wheels RL and RR based on the output signal of the rear wheel steering angle sensor 40, and determines the steering angle θ of the steering wheel 42 based on the output signal of the steering angle sensor 22. To detect.

The wheel speed sensor 12, which outputs a pulse signal corresponding to the wheel speed, is provided to the rear wheel steering ECU 32.
Also, a yaw rate sensor 46 that outputs a signal corresponding to the rotational angular velocity generated around the center of gravity of the vehicle is connected.
The rear wheel steering ECU 32, based on these output signals,
The wheel speed Vw and the yaw rate γ of each wheel are detected. The rear wheel steering ECU 32 further includes the above-described characteristic determination ECU.
10 are connected. As will be described later, the rear wheel steering ECU 32 determines whether or not the running performance of the vehicle has decreased based on a signal supplied from the characteristic determination ECU 10, and changes the control characteristics when turning the rear wheels.

Hereinafter, the contents of the control executed in the rear wheel steering device 30 of the present embodiment will be described. Front wheel FL,
When the FR is steered, that is, when the vehicle is turning, and when the vehicle receives a strong crosswind,
A yaw rate γ occurs around the center of gravity of the vehicle. In this case, if an appropriate yaw rate γ according to the wheel speed Vw and the steering angle θ is realized, it can be determined that the vehicle is traveling while maintaining a stable behavior. On the other hand, the wheel speed V
If an appropriate yaw rate γ according to w and the steering angle θ has not been realized, it can be determined that the vehicle behavior is unstable, that is, the running stability is reduced. Therefore, in order to realize high running stability, it is appropriate to change the yaw rate γ generated around the center of gravity of the vehicle to a yaw rate corresponding to the wheel speed Vw and the steering angle θ.

When the vehicle is turning, the direction in which the vehicle body is facing is different from the direction in which the center of gravity travels. Less than,
The angle during this time is referred to as the vehicle body slip angle β. When the vehicle body slip angle β is large, it can be determined that the vehicle has a large skid. In such a case, it can be determined that the vehicle has not been properly steered in response to the steering operation, and it can be determined that the steering responsiveness has been reduced. Further, when the vehicle is turned in the reverse direction in a situation where the vehicle body slip angle β is large, the turning back of the vehicle body becomes excessive, and it becomes impossible to realize excellent running stability. Therefore, in order to achieve high running stability and high steering response,
It is appropriate to reduce the vehicle body slip angle β.

In this embodiment, the rear wheel steering ECU 32
Are the steering angle θ of the steering wheel 42 and the wheel speed V
A target vehicle body slip β and yaw rate γ are calculated in accordance with a preset map w. Hereinafter, the vehicle body slip angle and the yaw rate are referred to as a target vehicle body slip angle βdes and a target yaw rate γdes, respectively.
Further, the rear wheel steering ECU 32 calculates the steering angle θ, the wheel speed Vw.
By substituting the rear wheel steering angle δr and the yaw rate γ into a predetermined vehicle motion model, the vehicle body slip angle estimated to have occurred in the vehicle is calculated. Hereinafter, this vehicle body slip angle is referred to as an estimated vehicle body slip angle βe.

In this embodiment, the rear wheel steering ECU 32
Is the target vehicle slip angle βdes and the estimated vehicle slip angle β
e and the deviation between the target yaw rate γdes and the actual yaw rate γ |
A drive signal having an appropriate duty ratio is supplied to the electric motor 38 so that γdes−γ | is reduced. According to such a method, the vehicle body slip angle β and the yaw rate γ
Of the rear wheels RL, RR can be steered so that the vehicle speed coincides with the target value. As a result, it is possible to realize excellent running stability and excellent steering response.

FIG. 6 is a system configuration diagram of a turning behavior control device (hereinafter, referred to as a VSC device) 50 of a vehicle equipped with the vehicle characteristic detecting device of the present embodiment. The VSC device 50
Turning behavior electronic control unit (hereinafter referred to as turning ECU)
52 are provided. The VSC device 50 includes a turning ECU 52
, An appropriate braking force is generated on each wheel to stabilize the turning behavior of the vehicle.

In this embodiment, the vehicle has a hydraulic pressure control device 54 for generating a braking force on the wheels. The hydraulic pressure control device 54 includes a brake pedal 56. The brake pedal 56 is connected to a vacuum booster 58. The vacuum booster 58 is connected to the brake pedal 56.
When the brake pedal is depressed, an assist force having a predetermined boosting ratio with respect to the brake pedal force is generated. Vacuum booster 5
8, a master cylinder 60 is fixed. Inside the master cylinder 60, a hydraulic chamber 62 is formed. In the hydraulic chamber 62, a master cylinder pressure is generated according to the resultant force of the brake depression force and the assist force.

A switching valve 66 communicates with the hydraulic chamber 62 of the master cylinder 60 via a hydraulic passage 64. The switching valve 66 is also connected to the pump 7 via a hydraulic passage 68.
0 and the accumulator 72. Pump 7
0 indicates that the brake fluid is sucked from the auxiliary reservoir 74 and the brake fluid is supplied to the hydraulic passage 6 at a predetermined discharge pressure.
8 is discharged. The accumulator 72 is provided with the pump 7
Store the discharge pressure of brake fluid discharged from 0,
In a predetermined case, the brake fluid is discharged toward the switching valve 66.

A wheel cylinder (not shown) provided on each wheel communicates with the switching valve 66 via a hydraulic passage 76. The switching valve 66 is normally in the hydraulic passage 64
The hydraulic valve is a two-position solenoid valve that makes the hydraulic pressure passage 76 and the hydraulic pressure passage 76 conductive, and a drive signal is supplied from the turning ECU 52 to make the hydraulic pressure passage 68 and the hydraulic pressure passage 76 conductive. Each wheel cylinder is provided with a control valve 80a-80d. The control valves 80a to 80d are two-position solenoid valves that maintain an open state in a normal state and are closed when a drive signal is supplied from the turning ECU 52.

The turning ECU 52 is connected to the wheel speed sensor 12, the steering angle sensor 22, and the yaw rate sensor 46 described above. The turning ECU 52 detects the wheel speed Vw, the steering angle θ, and the yaw rate γ based on these output signals. Further, a lateral acceleration sensor 82 is connected to the turning ECU 52. Lateral acceleration sensor 8
2 outputs a signal corresponding to the acceleration in the vehicle width direction acting on the vicinity of the center of gravity of the vehicle. The turning ECU 52 detects the lateral acceleration Gy based on the output signal of the lateral acceleration sensor 82.
Further, the turning ECU 52 includes the above-described characteristic determination ECU 1
0 is connected. The turning ECU 52 determines whether or not the running performance of the vehicle has decreased based on a signal supplied from the characteristic determination ECU 10 as described later, and changes the control characteristics for stabilizing the turning behavior of the vehicle.

When a proper yaw rate γ corresponding to the wheel speed Vw and the steering angle θ is realized during turning of the vehicle, it can be estimated that the vehicle is turning while maintaining stable turning behavior. . On the other hand, when an excessive yaw rate γ is generated with respect to the wheel speed Vw and the steering angle θ, it can be estimated that the vehicle has an oversteer tendency, that is, the vehicle has a spin tendency. When the yaw rate γ is insufficient with respect to the wheel speed Vw and the steering angle θ, it can be estimated that the vehicle has an understeer tendency, that is, the vehicle has a driftout tendency.

In this embodiment, as a criterion for determining whether or not the turning behavior of the vehicle is stable, the spin degree SV
And the degree of drift DV. The spin degree SV is
This is the degree of oversteer tendency during turning of the vehicle. In addition, the drift degree DV is a degree of an understeer tendency during turning of the vehicle. Hereinafter, the spin degree SV and the drift degree DV will be described.

When the vehicle has a tendency to spin, both the vehicle body slip angle β and the rate of change dβ / dt have large values. Therefore, in this embodiment, the spin degree SV
Is defined as follows using the constants k1 and k2. SV = k1.beta. + K2.d.beta. / Dt (1) Further, the change rate d.beta./dt of the vehicle body slip angle .beta.
The vehicle body slip angle β can be expressed by the following equation using the lateral acceleration Gy acting on the vehicle, the wheel speed Vw, and the yaw rate γ, respectively.

Dβ / dt = (Gy / Vw) −γ (2) β = ∫ ｛(Gy / Vw) −γ｝ dt (3) In the present embodiment, the above parameters Gy and Vw , Γ
Are respectively detected based on output signals of various sensors. Therefore, according to the present embodiment, the vehicle body slip angle β and the rate of change dβ / dt can be calculated, and the spin degree SV for determining the spin tendency of the vehicle can be accurately obtained.

On the other hand, when the vehicle tends to drift out, the yaw rate γ actually generated around the center of gravity C has a smaller value than the target yaw rate γdes assumed based on the steering angle θ and the wheel speed Vw. I have. Therefore, in the present embodiment, the drift degree DV is determined by the deviation Δγ between the actual yaw rate γ and the target yaw rate γdes, and the constant k3
Is defined using the following equation.

DV = k 3 · Δγ (4) In the present embodiment, the actual yaw rate γ is detected based on the output signal of the yaw rate sensor, and the target yaw rate γ des is the output of the steering angle sensor 22. It is calculated based on the relationship between the signal and the output signal of the wheel speed sensor 12. Therefore, according to the present embodiment, the deviation between the actual yaw rate γ and the target yaw rate γdes can be calculated,
The drift DV for determining the understeer tendency of the vehicle can be accurately obtained.

In the present embodiment, the turning ECU 52 calculates the spin degree SV and the drift degree DV by using the above-described method, and judges that the vehicle has a spin tendency when the spin degree SV is equal to or larger than a predetermined value SV0. And the drift degree D
When V is equal to or greater than the predetermined value DV0, it is determined that the vehicle has a tendency to drift out. Then, an appropriate braking force is generated on each wheel so that the spin tendency or the drift tendency is suppressed.

Hereinafter, referring to FIG. 7, the VSC of this embodiment will be described.
The contents of the control executed in the device 50 will be described. FIG. 7 is a diagram schematically illustrating a control principle executed when the turning behavior becomes unstable under the situation where the vehicle turns left in the VSC device 50 of the present embodiment. In the drawing, the point "C" represents the center of gravity of the vehicle. As shown in the figure, when the vehicle makes a left turn, a yaw rate γ is generated around the center of gravity C of the vehicle in a counterclockwise direction. On the other hand, when the vehicle turns right, a yaw rate γ is generated clockwise around the center of gravity of the vehicle.

When a braking force Fbrk is generated on the front wheel FR on the turning outer wheel side as shown by a solid arrow in FIG. 7 during the left turning of the vehicle, the braking force Fbrk is turned leftward with respect to the vehicle center of gravity C. Acts as a torque in the direction that prevents rotation. Therefore, if a braking force is generated on the front wheel FR or FL on the turning outer wheel side during turning of the vehicle, the yaw rate γ occurring in the vehicle can be suppressed. On the other hand, when the braking force Fbrk is generated on the rear wheels RL, RR as shown by the broken arrows in FIG. 7, the center of gravity C of the vehicle moves toward the front wheels FL, FR, and the centripetal force inward in the turning direction is reduced. Increase. Further, the braking force Fbrk generated on the rear wheel RL on the inside of the turn acts on the center of gravity C as a torque in a direction to assist the turn of the vehicle. Therefore, if a braking force is generated on the rear wheels RL and RR while the vehicle is turning, the yaw rate γ can be assisted.

In this embodiment, the turning ECU 52 estimates the behavior of the vehicle while the vehicle is running. When the vehicle is in a drift-out tendency according to the estimation result, a drive signal is supplied to the switching valve 66 and the control valves 80a and 80b. In this case, the pump 70 and the accumulator 7
2, high-pressure brake fluid is supplied to the wheel cylinders of the rear wheels RL and RR. On the other hand, if the vehicle is spinning to the left turning side, the switching valve 66 and the control valve 80
a, 80c, and 80d. in this case,
High-pressure brake fluid is supplied from the pump 70 and the accumulator 72 to the wheel cylinder of the front wheel FR.
When high-pressure brake fluid is guided to the wheel cylinder, a braking force is generated on the wheels. Therefore, according to the present embodiment, it is possible to stabilize the turning behavior of the vehicle when the vehicle tends to drift out or spin.

By the way, for example, when the tire pressure of only one of the four wheels is lowered or the tires are deteriorated, the rear wheel steering control or the VSC control does not reduce the running performance. Under the same conditions as described above, there is a possibility that an excessive load may act on such wheels even though the running performance of the vehicle is degraded.
If an excessive load acts on the wheels, the tires may burst or the tires easily exceed the grip limit, and the turning performance and running stability of the vehicle may be reduced. Therefore, it is not appropriate to execute the rear wheel steering control or the VSC control under the same conditions as when the running performance is not reduced under the situation where the running performance of the vehicle is deteriorated.

FIG. 8 shows a flowchart of an example of a control routine executed by the rear wheel steering ECU 32 in the rear wheel steering device 30 of the present embodiment in consideration of the case where the running performance of the vehicle is reduced. The routine shown in FIG. 8 is a periodic interrupt routine that is started every predetermined time. When the routine shown in FIG. 8 is started, first, the process of step 120 is executed.

In step 120, the wheel speed sensor 12a
~ 12d, steering angle sensor 22, rear wheel steering angle sensor 40,
And, based on the yaw rate sensor 46, the wheel speed Vwf
1, Vwfr, Vwrl, Vwrr, steer angle θ, rear wheel steering angle δr, and yaw rate γ are detected. In step 122, the target vehicle body slip angle βdes is determined by referring to a predetermined map representing the relationship between the steering angle θ and the wheel speed Vw.
And the target yaw rate γdes are calculated.

In step 124, the estimated vehicle body slip angle estimated to have occurred in the vehicle is obtained by substituting the wheel speed Vw, the steering angle θ, the rear wheel steering angle δr, and the yaw rate γ into a predetermined vehicle motion model. βe is calculated. In step 126, the deviation Δβ = | βdes−βe | between the target vehicle body slip angle βdes and the estimated vehicle body slip angle βe, and the deviation Δγ = | γdes−γ | between the target yaw rate γdes and the actual yaw rate γ are calculated.

In step 128, the deviations Δβ and Δγ
Are both calculated to be "0". After the process of step 128 is performed,
The electric motor 38 is driven such that the steering angle δr of the rear wheels FL and FR matches the target rear wheel steering angle δrdes. Step 13
If it is 0, it is determined whether or not the driving characteristic reduction signal output from the characteristic determination ECU 10 has been received. When the running characteristic deterioration signal is supplied, it can be determined that the running performance of the vehicle is deteriorated. In such a case, in order to stabilize the behavior of the vehicle, the rear wheels RL, R
It is effective to steer R at a lower speed than usual. Therefore, when it is determined that the driving characteristic deterioration signal has been received, the process of step 132 is executed next. On the other hand, when the running characteristic deterioration signal is not supplied, it is appropriate to execute the rear wheel steering control as usual. Therefore, if it is determined that the running characteristic deterioration signal has not been received, the process of step 134 is executed next.

In step 132, a process is executed to set the motor current I supplied to the electric motor 38 to a value obtained by subtracting the predetermined value α from the predetermined value I0. Step 13
In step 4, a process is performed to set the motor current I supplied to the electric motor 38 to a predetermined value I0. In step 136, a drive signal is supplied to the electric motor 38 at a duty ratio corresponding to the motor current I calculated in step 132 or 134. When this step 136 is executed, the steering angle δr of the rear wheels RL, RR changes according to the drive signal.

According to the above processing, the motor current supplied to the electric motor 38 can be changed depending on whether the running performance of the vehicle is degraded. Electric motor 38
When the motor current supplied to the motor decreases, the electric motor 3
8 operates at a lower speed than normal, and the rear wheels R
L and RR reach the desired steering angle δr over a relatively long time. Therefore, according to the present embodiment, it is possible to prevent the rear wheels RL and RR from being rapidly steered even when the running performance of the vehicle is deteriorated. Therefore, according to the present embodiment, it is possible to reliably prevent the turning performance and the running stability from being lowered due to the lowered running characteristics of the vehicle.

FIG. 9 shows a turning EC in the VSC device 50 of the present embodiment in consideration of the case where the running performance of the vehicle is degraded.
4 shows a flowchart of an example of a control routine executed by U52. The routine shown in FIG. 9 is a regular interruption routine started at predetermined time intervals. When the routine shown in FIG. 9 is started, first, the process of step 150 is executed.

In step 150, the wheel speed sensor 12a
~ 12d, steer angle sensor 22, yaw rate sensor 4
6, based on the output signal of the lateral acceleration sensor 82, the wheel speed Vw, the steer angle θ, the yaw rate γ, and
Lateral acceleration Gy is detected. In step 152, the change rate dβ / d of the vehicle body slip angle β is calculated according to the above equation (2).
t = (Gy / Vw)-[gamma] is calculated, and the vehicle body slip angle [beta] is calculated according to the above equation (3), that is, by integrating the rate of change.

In step 154, the above-described step 152
And the rate of change dβ /
By substituting dt into the above equation (1), the spin degree S
V is calculated. In step 156, the above step 1
The target yaw rate γdes is calculated based on the wheel speed Vw and the steering angle θ detected at 50.

In step 158, the above-mentioned step 150 is executed.
Between the yaw rate γ detected in step 156 and the target yaw rate γdes calculated in step 156 above | γdes−γ |
Is calculated, and the deviation DV is calculated by substituting the deviation into the above equation (4). Step 160
Then, it is determined whether or not the running characteristic reduction signal output from the characteristic determination ECU 10 has been received. When the running characteristic deterioration signal is supplied, it can be determined that the running performance of the vehicle is deteriorated. In such a case, in order to stabilize the turning behavior, it is appropriate to start the VSC control earlier than usual. Therefore, when it is determined that the driving characteristic deterioration signal has been received, the process of step 162 is executed next. On the other hand, when the running characteristic deterioration signal is not supplied, it is appropriate to start the VSC control as usual. Therefore, if it is determined that the running characteristic deterioration signal has not been received, the process of step 164 is executed next.

In step 162, the spin degree SVsh, which is a condition for starting the VSC control, is changed from a predetermined value SV0 to a predetermined value A.
Are subtracted from the predetermined value DV0, and the drift degree DVsh, which is a start condition of the VSC control, is set to a value obtained by subtracting the predetermined value B from the predetermined value DV0. The predetermined value SV0 and the predetermined value DV0 are threshold values of the VSC control executed when the traveling performance of the vehicle is not degraded. Further, the predetermined values A and B are such that A> 0,
This is a preset value that satisfies B> 0. After the processing of step 162 is executed, VSC control is thereafter executed according to a threshold value smaller than predetermined values SV0 and DV0.

In step 164, the spin degree SVsh is set to a predetermined value SV0, and the drift degree DVsh is set to a predetermined value D0.
The processing for setting V0 is performed. After the process of step 164 is executed, VSC control is thereafter executed according to the predetermined values SV0 and DV0. In step 166, the spin degree SV calculated in step 154 is compared with the threshold value SVsh set in step 162 or 164.
It is determined whether or not the above is satisfied,
The drift degree DV calculated in step 58 is calculated in step 16
It is determined whether or not it is equal to or greater than the threshold value DVsh set in 2 or 164. As a result, SV ≧ SVsh and D
If both V ≧ DVsh are not satisfied, it can be determined that the VSC control start condition has not been satisfied. In this case, there is no need to generate a braking force on the wheels. Therefore, SV ≧ SV
If it is determined that both sh and DV ≧ DVsh do not hold, the current routine is terminated.

On the other hand, if SV ≧ SVsh or DV ≧ DVsh is satisfied, it can be determined that the VSC control start condition has been satisfied. Therefore, SV ≧ SVsh or DV ≧ DV
If it is determined that sh is satisfied, then step 168 is performed.
Is performed. In step 168, processing for generating a braking force on any of the wheels is performed. Specifically, when the vehicle tends to spin, the switching valve 66, the control valve 80a or 80b, and the control valve 80 are controlled so that a braking force is generated on the front wheel FL or FR on the turning outer wheel side.
A drive signal is supplied to c and 80d. When the vehicle has a tendency to drift, the switching valve 66 and the control valves 80a, 80a,
A drive signal is supplied to 80b. After the process of step 168 is executed, a torque is generated around the center of gravity of the vehicle so that the tendency of the vehicle to spin or drift is suppressed. When the process of step 168 ends, the current routine ends.

According to the above processing, the threshold value of the VSC control can be changed according to whether or not the running performance of the vehicle is reduced. When the threshold value of the VSC control decreases, the VSC control is easily performed. For this reason, according to the present embodiment, even when the running performance of the vehicle is reduced, the vehicle can be prevented from becoming prone to spin or drift. Therefore, according to the present embodiment, the turning behavior can be reliably stabilized.

In the above embodiment, the characteristic judgment E
The CU 10 detects the wheel speed of each wheel based on the output signals of the pressure sensors 14 a to 14 d. By detecting the unsprung resonance frequency, the "resonance parameter detecting means" recited in the claims detects the state of the tire or suspension based on the tire air pressure P and the unsprung resonance frequency of the vehicle body. The "vehicle characteristic detecting means" described in the claims is realized respectively.

In the above embodiment, the rear wheel steering device 30 and the VSC device 50 correspond to the "control device" described in the claims, and the rear wheel steering E
The CU 32 executes the processing of the above step instead of the above step, and the turning ECU 52 executes the processing of the above step 162 instead of the above step 164. Has been realized.

In the above embodiment, the control characteristics of the rear wheel steering device 30 and the VSC device 50 are changed according to the running characteristics of the vehicle. However, the present invention is not limited to this. It is also possible to apply to a suspension device and a fuel injection amount control device. In this case, the suspension device or the fuel injection amount control device corresponds to a “control device” described in the claims.

In the above embodiment, the rear wheel steering device 30 and the VSC device 50 are connected to the characteristic determination ECU 10.
, The control threshold value is lowered by one step when a driving characteristic reduction signal is received from the ECU. However, the present invention is not limited to this.
The control threshold value may be changed in multiple stages by changing the signal output from the controller, or may be changed linearly.

Further, in the above embodiment, the signal output from the characteristic determination ECU 10 is supplied to both the rear wheel steering device 30 and the VSC device 50.
The present invention is not limited to this, and it is also possible to supply only one of them. Next, a second embodiment of the present invention will be described with reference to FIG.

In the first embodiment, the state of the tires and suspensions, that is, the running characteristics of the vehicle, is first determined by the characteristic determination ECU 10 to execute a fast Fourier transform on the wheel speed signal output from the wheel speed sensor 12. Accordingly, the resonance frequency under the vehicle body is calculated, and the resonance frequency is estimated based on the spring constant under the vehicle body estimated from the calculated resonance frequency.

On the other hand, in the present embodiment, the running characteristics of the vehicle are as follows.
2. A disturbance applied to a normal tire is estimated on the basis of the wheel speed signal output by the control unit 2 and is estimated based on a spring constant K of a torsion spring and a damping coefficient D of a damper estimated from the disturbance. Is done. FIG. 10 is a diagram illustrating a tire model used in the present embodiment.

In this embodiment, the output signal of the wheel speed sensor 12 is supplied to a disturbance observer in the ECU 10. The disturbance observer is configured based on a tire model shown in FIG. As shown in FIG.
The rim side 202 corresponding to the rigid wheel and the belt side 204 corresponding to the elastic tire mounted on the outer periphery of the wheel are connected by a torsion spring 206 and a damper 208 connected in parallel with each other. It can be modeled as being done. In this case, the state equation shown in the following equation (1) is established, and the rotational motion of the wheel 200 is represented as a linear system. In the above tire model, a wheel speed sensor 12 will output a signal corresponding to the angular velocity omega _R of the rim 202.

[0074]

(Equation 1)

Where ω _R : angular velocity of the rim side 202 ω _R ': angular acceleration of the rim side 202 ω _B : angular velocity of the belt side 204 ω _B ': angular acceleration of the belt side 204 θ _RB : rim side K: spring constant of torsion spring 206 D: damping coefficient of damper 208 J _R : moment of inertia of rim side 202 J _B : moment of inertia of belt side 204 T _d : road surface In the state equation of the above equation (1), there is no parameter corresponding to the driving / braking torque T ₁ .
(1) focuses on particular vibration of the state equation of the rotational movement of the wheel 200 of the type, and to represent the variation component on vibration for each parameter, a fixed value the driving and braking torque T ₁ in relation to the other parameters Because they considered it. That is,
In the state equation of Equation (1), the angular velocities ω _R and ω _B , the torsion angle θ _RB , the spring constant K, and the damping coefficient D are variable components excluding the fixed components.

The output signal of the wheel speed sensor 12 is filtered to extract only a fluctuation component within a set frequency band, and is supplied to a disturbance observer. The disturbance observer, the variation component of the angular velocity omega _R is input. Now, if the spring constant K of the torsion spring 206 and the damping coefficient D of the damper 208 change to K = K + ΔK and D = D + ΔD, respectively, due to a change in the state of the wheel 200, the state equation of the above equation (1) becomes The following equation (2) is obtained.

[0077]

(Equation 2)

That is, the spring constant K and the damping coefficient D
However, changing to K = K + ΔK and D = D + ΔD respectively is equivalent to adding a disturbance represented by the last term on the right side of Expression (2) to a normal tire. Such disturbances include:
The change amount ΔK of the spring constant K and the change amount ΔD of the damping coefficient D are included. The spring constant K and the damping coefficient D change according to the state of the wheel 200 such as tire pressure and deterioration. Therefore, by estimating the above disturbance, the wheel 2
00 state change can be estimated.

In this embodiment, the above disturbance is estimated by a disturbance observer. When treating the torque _Td from the road surface as a disturbance, the disturbance to be estimated is represented by the following equation (3).

[0080]

(Equation 3)

However, theoretically, only one element of the disturbance [w] can be estimated. Therefore, the second element w ₂ of the disturbance [w] is estimated. Disturbance w ₂ is,
It is expressed by the following equation (4). _{w 2 = (ΔD / J B} ) (ω R -ω B) + (ΔK / J B) θ RB -T d / J B + n ··· (4) where, n is the disturbance of the second element only estimate It is an error term caused by not doing so.

Thus, the state equation of the wheel 200 is
The following equation (5) is obtained.

[0083]

(Equation 4)

The disturbance observer estimates disturbance as one of the state variables of the system. Therefore, (4)
To include the disturbance w ₂ of the formula to the state of the system to approximate the dynamics of the disturbance w ₂ to be estimated by the following equation (6). w ₂ ′ = 0 (6) This means that a continuously changing disturbance is approximated stepwise (zero-order approximation), and the disturbance estimation speed of the disturbance observer is changed by the disturbance to be estimated. The above approximation is well tolerated by making it sufficiently large compared to From the above equation (6), when the disturbance w ₂ is included in the state of the system,
An extension system of the following equation (7) is configured.

[0085]

(Equation 5)

In the above equation (7), only the angular velocity ω _R of the rim side portion 202 can be detected, and [ω _B θ _RB
w ₂ ] ^T (= state [z]) cannot be detected.
Therefore, if a disturbance observer is configured based on this system, the disturbance w ₂ and the state variable ω _B , which cannot be detected originally,
θ _RB can be estimated. To simplify the description, the vectors and matrices in equation (7) are decomposed and expressed as follows.

[0087]

(Equation 6)

In this case, the state [z] = [ω _B θ _RB w
₂ ] The configuration of the minimum dimension observer for estimating ^T is represented by the following equation (8). [Z _p '] = [A ₂₁ ] [x _a ] + [A ₂₂ ] [z _p ] + [B ₂ ] [u] + [G] ｛[x _a ']-([A ₁₁ ] [x _a ] + [A ₁₂ ] [z _p ] + [B ₁ ] [u])｝ = ([A ₂₁ ]-[G] [A ₁₁ ]) [x _a ] + ([A ₂₂ ]-[G] [ A _12]) [z _p] + [G] [x _a '] + ([B _2] - [G] [B _1]) [u] (8) where [z _p]: [z estimate of] [z _p ']: rate of change in the estimated value [z _p] [G]: gain determines the estimated speed of the disturbance observer the error between the estimated value and the true value [z] [z _p] [e ] Is set to [e] = [z]-[z _p ], and the change rate of the error [e] is set to [e ′], the following equation (9) is established.

[E ′] = ([A ₂₂ ] − [G] [A ₁₂ ]) [e] (9) This represents the estimated characteristic of the disturbance observer, and is represented by a matrix ([A ₂₂ ] The eigenvalue of [G] [A ₁₂ ]) becomes the pole of the disturbance observer. Therefore, the estimated speed of the disturbance observer increases as the eigenvalue moves away from the origin on the left half surface of the s-plane. The observer gain [G] may be set to a desired estimated speed.

[0090] According to the disturbance observer is configured as described above, on the basis of the angular velocity omega _R computed from the wheel speed Vw of the wheel 200, the damping coefficient D of the spring constant K and a damper 208 of the torsion spring 206 respectively ΔK and Δ
In the case where only a change D, disturbance w ₂ is estimated, further, the angular velocity omega _B and torsion angle theta _RB is estimated. Then, using the least squares method, the change amount ΔK of the spring constant K and the change amount ΔD of the damping coefficient D are estimated, and the state change of the wheel 200 is estimated.

Therefore, according to the present embodiment, the state of the tires and suspension, that is, the running characteristics of the vehicle, is accurately detected based on the spring constant, the damping coefficient D, and the tire air pressure P in the tire model described above. This makes it possible to determine whether or not the running performance of the vehicle is degraded. When the traveling performance of the vehicle is degraded, the rear wheels RL,
The RR is prevented from being rapidly steered, and the own vehicle is prevented from becoming prone to spin or drift. For this reason, according to the present embodiment, it is possible to reliably avoid a decrease in turning performance and traveling stability due to a decrease in traveling characteristics of the vehicle.

In the above embodiment, the characteristic judgment E
The CU 10 estimates the spring constant K of the torsion spring 206 and the damping coefficient D of the damper 208 based on the output signal of the wheel speed sensor 12, whereby the “resonance parameter detecting means” described in the claims makes the Air pressure P,
The "vehicle characteristic detecting means" described in the claims is realized by detecting the state of the tire or the suspension based on the spring constant K of the torsion spring 206 and the damping coefficient D of the damper 208.

[0093]

As described above, according to the first to third aspects of the present invention, the running characteristics of the vehicle can be accurately grasped. According to the invention described in claim 4, the vehicle can be appropriately controlled without lowering the traveling performance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vehicle characteristic detecting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a result of frequency analysis when a fast Fourier transform is performed on a wheel speed Vw in the embodiment.

FIG. 3 is a map showing a relationship between an air pressure P of a tire and a spring constant K under a vehicle body spring, which change according to the type of the tire.

FIG. 4 is a flowchart of an example of a control routine executed in the vehicle characteristic detecting device of the embodiment.

FIG. 5 is a system configuration diagram of a rear wheel steering device on which the vehicle characteristic detecting device of the present embodiment is mounted.

FIG. 6 is a system configuration diagram of a vehicle turning behavior control device equipped with the vehicle characteristic detection device of the present embodiment.

FIG. 7 is a diagram schematically illustrating a control principle executed when the turning behavior becomes unstable under the situation where the vehicle turns left in the VSC device of the present embodiment.

FIG. 8 is a flowchart of an example of a control routine executed in the rear wheel steering device of the embodiment.

FIG. 9 is a flowchart of an example of a control routine executed in the VSC device according to the embodiment.

FIG. 10 is a diagram showing a tire model used in a second embodiment of the present invention.

[Explanation of symbols]

10 Vehicle characteristic judgment electronic control unit (Characteristic judgment EC
U) 12a to 12d Wheel speed sensors 14a to 14d Pressure sensors 30 Rear wheel steering device 32 Rear wheel steering electronic control unit (rear wheel steering ECU) 38 Electric motor 50 Turning behavior control device (VSC device) 52 Turning behavior electronic control unit (Turning ECU) 66 Switching valve 80a-80d Control valve FL, FR, RL, RR Wheel

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) B62D 7/14 B62D 7/14 A // B62D 101: 00 107: 00 111: 00 113: 00 137: 00 (71) Applicant 000004260 DENSO Corporation 1-1-1, Showa-cho, Kariya-shi, Aichi (72) Inventor Hideki Ohashi 1-Toyota-cho, Toyota-shi, Aichi-ken Toyota Motor Corporation (72) Inventor Masahiro Yoneya Toyota-cho, Toyota-shi, Aichi No. 1 Toyota Motor Co., Ltd. (72) Inventor Koji Umeno 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi, Japan 1 Toyota Toyota Central Research Laboratory Co., Ltd. (72) Inventor Toshiaki Nakagawa, Nagakute-cho, Aichi-gun, Aichi No. 41, Chochu Yokomichi 1 Toyota Central Research Laboratory Co., Ltd. (72) Inventor Yukio Mori 2-1-1 Asahi-cho, Kariya-shi, Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Kenji Asano Asahi, Kariya-shi, Aichi Prefecture 2-chome, Aisin Seiki Co., Ltd. (72) Inventor Yuichi Inoue Ai 3-1-1, Showa-cho, Kariya, Japan F-term in DENSO Corporation (reference) 3D001 AA02 AA12 DA17 EA02 EA08 EA16 EA36 EA42 EA46 EB13 EC11 ED06 3D032 CC39 DA03 DA24 DA29 DA33 DA52 DA73 DA93 DB02 DB13 DC03 DC35 DD02 DE02 FF01 FF03 3D034 CC02 CC09 CD04 CD06 CD07 CD13 CD20 CE03 CE13 3D045 BB40 GG00 GG25 GG26 GG28 3D046 BB21 GG10 HH08 HH15 HH16 HH21 HH25 HH36 HH55

Claims (4)

[Claims] 1. An air pressure detecting means for detecting an air pressure of a tire, a resonance parameter detecting means for detecting a parameter relating to a resonance characteristic of an unsprung portion of a vehicle body, an air pressure detected by the air pressure detecting means, and the resonance A vehicle characteristic detecting device comprising: vehicle characteristic detecting means for detecting running characteristics of a vehicle based on the parameter detected by the parameter detecting means. 2. The vehicle characteristic detecting device according to claim 1, wherein the resonance parameter detecting unit detects a resonance frequency of a unsprung portion of the vehicle body. 3. The vehicle characteristic detecting device according to claim 1, wherein the resonance parameter detecting unit detects a spring constant of a unsprung portion of the vehicle body. 4. A control device for a vehicle equipped with the vehicle characteristic detecting device according to claim 1, wherein the vehicle characteristic is determined according to the driving characteristic of the vehicle detected by the driving characteristic detecting means. 4. A control device for a vehicle equipped with the vehicle characteristic detecting device according to claim 1, further comprising control characteristic changing means for changing the control characteristic of the vehicle.