JP3317112B2 - Spin limit detection device and spin prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin limit detecting device and a spin preventing device, and more particularly, to a spin limit detecting device for comprehensively estimating a ground contact state of an entire vehicle from resonance characteristics of a yawing vibration model, and the spin limit detecting device. The present invention relates to a spin prevention device that uses a limit detection device to prevent spin.

[0002]

2. Description of the Related Art A friction coefficient between a wheel and a road surface is measured,
As a technique for performing control based on this coefficient of friction, an electronically controlled power steering apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 4-230472 is known.

A method of measuring a friction coefficient disclosed in Japanese Patent Application Laid-Open No. Hei 4-230472 is disclosed in Japanese Patent Application Laid-Open No. HEI 4-230472. Steer,
The reaction force against the cornering force and self-aligning torque generated on the rear wheels by this periodic steering is detected by a reaction force sensor such as a load cell, and the cornering power and self-aligning power are detected based on the detected reaction force value. Is calculated. Then, the road surface friction coefficient is measured based on a calculation result based on the relationship between the power and the road surface friction coefficient.

[0004]

However, in the case of the above-mentioned conventional measuring method, the coefficient of friction of the road surface of the rear wheel can be detected, but the degree of danger of drift-out or spin has reached. However, there is a problem that it is not possible to determine a margin with respect to the traveling limit of the vehicle.

In order to determine the margin, it is necessary to provide a means for detecting the road surface friction coefficient on the front wheels, and further provide a means for estimating the state of the entire vehicle from the road surface friction coefficients of the front and rear wheels. is there. Therefore, the system becomes complicated and disadvantageous in terms of compactness, economy, and reliability.

[0006] Further, this method cannot be applied to a four-wheel steering vehicle, and the reaction force against the cornering force and the self-aligning torque is directly detected by a reaction force sensor such as a load cell. This is disadvantageous in terms of detection accuracy and detection sensitivity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle running in an environment where there is a lot of disturbance from a road surface, a risk of tire grip, drift-out, and spin. Simple, high response,
Another object of the present invention is to provide detection to a driver with a high degree of accuracy and further application to driving stabilization control.

[0008]

In order to achieve the above object, a spin limit detecting device according to the present invention comprises an inertial body comprising a vehicle body and a torsion element around a yaw rotation axis comprising a tire and a suspension system. Exciting yaw moment generating means for minutely vibrating the inertial body by adding a yaw moment that vibrates minutely at the natural angular frequency of the yawing motion vibration system to the inertial body in the yawing motion vibration system, and the state quantity of the yawing motion vibration system Excitation response detection means for detecting the response component generated by the minute excitation of the excitation yaw moment generation means, and resonance characteristic calculation for calculating the resonance characteristics of the yawing motion vibration system and detecting the spin limit state of the vehicle body from the resonance characteristics Means.

Further, the spin prevention device of the present invention includes the above-described spin limit detection device, target yaw rate calculation means for calculating a target yaw rate from a steering angle, a difference between a target yaw rate and an actual yaw rate, and the spin limit detection device. Anti-spin-moment generating means for determining a spin based on the calculated resonance characteristic of the yawing motion vibration system and generating an anti-spin moment.

First, a model of a yawing motion vibration system of a vehicle is derived, and the principle of the present invention will be described based on the model.

Assuming that the sideslip angles of the left and right wheels of a four-wheeled vehicle are equal and ignoring the roll of the vehicle body, the movement of the vehicle will be
The equation of motion that can be handled by a two-wheeled wheel model and describes the motion of the vehicle is as follows.

MvV {(dβ / dt) + γ} = 2Cf + 2Cr (1) Iz (dγ / dt) = 2LfCf-2LrCr (2) where Mv is the inertial mass of the vehicle, V is the vehicle speed, Cf is the front wheel cornering force, Cr is the rear wheel cornering force, Iz is the yawing moment, Lf is the distance between the vehicle center of gravity and the front wheel axle, Lr is the distance between the vehicle center of gravity and the rear wheel axle, β is the vehicle The side slip angle at the center of gravity, γ is the yaw angular velocity (yaw rate), and t is time.

On the other hand, the cornering power of the front wheels is Kf,
Kr for rear wheel cornering power, β for front wheel sideslip angle
f, the side slip angle of the rear wheel is βr, and the actual steering angle is δ, the cornering forces Cf, Cr of the front and rear wheels are expressed as follows.

Cf = −Kfβf = −Kf ｛β + (Lfγ / V) −δ｝ (3) Cr = −Krβr = −Kr ｛β− (Lrγ / V)｝ (4) , The cornering forces Cf and Cr of the front and rear wheels are
All show saturation characteristics as shown in FIG. 1 for the sideslip angles βf and βr of the front and rear wheels.

Equations (3) and (4) are replaced by equations (1) and (2)
, The following equations (5) and (6), which are basic equations of motion describing the vehicle motion in the horizontal plane, are obtained.

MvV (dβ / dt) +2 (Kf + Kr) β + ｛MvV + 2 (LfKf−LrKr) / V｝ γ = 2Kfδ (5) 2 (LfKf−LrKr) β + Iz (dγ / dt) +2 (Lf ² ) Kf + Lr ² Kr) γ / V = 2LfKfδ (6) Here, in order to consider the yawing motion, basically, the equation of motion of Expression (6) may be considered. The input of the yawing motion is, as shown in FIG.
2 are yaw moment components Yf and Yr. When the yaw moment components generated in the respective tires are collectively expressed, they can be expressed by a road surface model represented by one friction element 14 as shown in FIG.

In the model of FIG. 3, taking into account each deformation of the tire and the suspension existing between the vehicle body inertia mass Mv and the road surface, if the tire and the suspension are approximated by twisting elements, as shown in FIG. A model in which the friction element 14 and the torsion element 16 are connected in series is obtained. The equation of motion of this system is as follows.

Iz (dγ / dt) = − Kcθ (7) where Kc is a spring constant, θ is a rotation angle of the vehicle about the rotation axis of the yawing motion, and Kcθ is expressed by the following equation (8). The restoring force of the torsion element composed of the represented tire and suspension is shown. Note that the left side of Expression (7) indicates an inertial force with respect to the yawing motion of the vehicle.

[0019] -Kcθ = -2 (LfKf-LrKr) β -2 (Lf 2 Kf + Lr 2 Kr) {γ- (dθ / dt)} / V + 2LfKfδ ··· (8) , where the right side of the equation (8) The first term is the difference in cornering force between the front and rear wheels caused by the vehicle body skidding, that is, the yaw moment caused by the vehicle body skidding, the second term on the right side is the drag from the road surface against yawing motion, and the third term on the right side. Represents the yaw moment generated by the actual steering angle in the input term.

Next, a model in which a small vibration moment for vibrating the vehicle body with a small amplitude around the rotation axis of the yawing motion in the model of FIG. 4 is considered. At a certain operating point, a small excitation moment to be applied is Δfm, a small displacement from an operating point with each of the variables γ, θ, β at that time is Δγ, Δθ, Δβ, and a small displacement from a certain operating point with a front slip angle βf. Is represented by Δβf, the following equations (9) and (10) are derived from the equations (7) and (8).

Iz {d (γ + Δγ) / dt} = − Kc (θ + Δθ) (9) −Kc (θ + Δθ) = − 2 (LfKf−LrKr) β−2 (LfKf−LrKr) Δβ−2 (Lf ^{2 Kf + Lr 2 Kr) {} γ- (dθ / dt)} / V -2 (Lf 2 Kf + Lr 2 Kr) {Δγ- (dΔθ / dt)} / V + 2Lf {Kf + (∂Kf / ∂βf) Δβf) δ + Δfm · (10) The terms of second order or higher of the small displacements Δγ, Δθ, and Δβ are ignored here. Kf and Kr are cornering powers for a slight change in the sideslip angle around the operating point of the front and rear wheels, and correspond to the inclination of the cornering force at the operating point.

Next, since Δβ and Δβf are not directly affected by the minute excitation moment Δfm, and their coefficients are small, terms relating to Δβ and Δβf are ignored.
The following equation is obtained when the equation of motion around the operating point is determined in consideration of the equations (7) and (8).

Iz (dΔγ / dt) = − KcΔθ (11) −KcΔθ = −2 (Lf ² Kf + Lr ² Kr) ｛Δγ− (dΔθ / dt)｝ / V + Δfm (12) , Eq. (11), the following equation is obtained by eliminating Δθ in Eq. (12).

2Iz (Lf ² Kf + Lr ² Kr) (d ² Δγ / dt ² ) / VKc + Iz (dΔγ / dt) +2 (Lf ² Kf + Lr ² Kr) Δγ / V = Δfm (13) The transfer function from the vibration moment to the yaw rate is a second-order lag system of the following equation (14).

[0025]

(Equation 1) And the natural angular frequency is ωn = √ (Kc / Iz) (15) The attenuation coefficient is

Ζ = V√ (Iz) / {4 (Lf ² Kf + Lr ² Kr) √ (Kc)} (16) This is a model of the yawing motion vibration system when a minute excitation moment is applied around the rotation axis of the yawing motion.

Next, the principle of the present invention will be described based on the model of the yawing motion vibration system. In Expression (16), Kf and Kr indicate the cornering power of the front and rear wheels with respect to the slight change in the sideslip angle around the operating point, as described in Expression (10), and correspond to the inclination of the cornering force at the operating point. .

Since the cornering forces Cf and Cr show saturation characteristics as shown in FIG. 1 with respect to the sideslip angle, the cornering powers Kf and Kr substantially coincide with the cornering power at the origin, that is, the so-called cornering stiffness when the sideslip angle is small.

On the other hand, as the cornering forces Cf, Cr become saturated, the cornering powers Kf, Kr decrease, and become zero at the time of saturation.

Since the grip force of the tire decreases with the saturation of the cornering forces Cf and Cr, the cornering powers Kf and Kr also indicate the grip state of the tire. That is, the cornering powers Kf, Kr
When both show values close to the cornering stiffness, it indicates that the tire is firmly gripping the road surface. On the other hand, when it becomes approximately 0, it indicates that there is a dangerous state in which spin occurs due to slight disturbance.

On the other hand, the damping coefficient of the yawing motion vibration system becomes smaller when the cornering powers Kf and Kr are large according to the equation (16).
Since f and Kr become large when they are small, it can be seen that they change in inverse proportion to the cornering powers Kf and Kr. On the other hand, as shown in FIG. 5, the attenuation coefficient of the second-order lag system has a large effect on the gain at the natural angular frequency (normalized for clarity).
That is, when the damping coefficient is a small value, the gain is large, and the yaw rate exhibits resonance characteristics with respect to a minute excitation moment, and vibrates greatly. On the other hand, when the damping coefficient increases, the yaw rate does not exhibit resonance characteristics with respect to the minute excitation moment, and hardly vibrates.

Therefore, when the yawing vibration model shows resonance characteristics at the natural angular frequency, it indicates that the tire is in a grip state, and when the resonance characteristics decrease, the grip force of the tire decreases. It indicates that you are doing. That is, if the resonance characteristics are detected, the grip state of the tire, in other words, the risk of spin or drift out can be determined.

The present invention is based on the above-mentioned principle. The tire grip state, that is, the inertial body of the yawing motion vibration system is obtained from the resonance characteristics when the inertial body is slightly vibrated at the yaw moment of the natural angular frequency of the yawing motion vibration system. It detects a spin limit state. This yawing motion vibration system differs depending on the object on which the vehicle travels, but when the vehicle travels on a road surface, an inertia body composed of a vehicle body, a torsion element around a yaw rotation axis composed of tires and a suspension system, a road surface, Will be composed by

In the present invention, it is preferable that a yaw moment vibrated at the natural angular frequency of the yawing vibration model is added around the rotation axis of the yawing motion, and a resonance component of the yaw rate responding to the added yaw moment is detected. . In this case, the resonance characteristic is calculated based on the ratio of the resonance component responding to the excitation component. If the ratio is large, it is determined that the tire is in a grip state. Is decreased, that is, the risk of spin or drift-out is increased.

The correspondence between the ratio of the resonance component in response to the excitation component (referred to as a vibration gain) and the grip state of the tire is uniquely determined if the specifications of the system are determined. Therefore, the risk is determined in advance by calculation or actual measurement, and the risk is determined based on the corresponding relationship from the vibration gain during traveling.

The inertial body can be minutely vibrated by slightly turning the wheel. In this case, it is effective to slightly steer the front wheels and the rear wheels in opposite phases.

In addition, a rotary vibration system including a flywheel and a torsion spring is provided, and the inertia is generated by a reaction of the continuous vibration of the rotary vibration system or a reaction of providing the flywheel and applying a torque to the flywheel. The body may be slightly vibrated.

As described above, according to the present invention, the ground contact state of each wheel is not detected individually, but the ground contact state of the entire vehicle is comprehensively estimated from the resonance characteristics of the yawing vibration model. The amount of calculation is also small. Therefore, it is economically advantageous and highly reliable. The obtained result also directly indicates the degree of safety of the vehicle motion at that time (the risk of spin or drift-out), and is extremely responsive and effective alarm information.

Further, since the vibration is excited by each of the natural frequency components of the yawing vibration model and only the natural angular frequency component in response to the vibration is detected, it is hardly affected by road surface disturbance generated like white noise. There is also a merit that the sensitivity is high. As a result, the detection accuracy also increases.

The target yaw rate is calculated from the steering angle, the spin is determined based on the difference between the target yaw rate and the actual yaw rate, and the resonance characteristic of the yawing motion vibration system calculated by the spin limit detecting device, and the anti-spin moment is calculated. If it occurs, the running stability of the vehicle can be improved.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of estimating the contact state of a tire using a device for actively turning the front and rear wheels, determining the risk of spin or drift out, and issuing an alarm will be described. .

FIG. 6 shows the system configuration of the first embodiment. A front wheel steering device 20 that steers two front wheels in the same direction is attached to a front wheel axle of the vehicle,
A rear wheel steering device 22 for steering two rear wheels in the same direction is attached to the rear wheel axle. These steering devices are 4
A steering device used in a wheel steering device can be used. A yaw rate sensor 24 for detecting a yaw rate is attached to the center of rotation of the yawing motion. The vehicle is provided with a vehicle speed sensor 34 for detecting the vehicle speed.

The front wheel steering device 20, the rear wheel steering device 22, the yaw rate sensor 24, and the vehicle speed sensor 34 are connected to a control device 26 composed of a microcomputer.
Further, an alarm device 36 including a buzzer or the like is connected to the control device 26. The microcomputer is a CP
U, RO storing program of control routine to be described later
M and a RAM.

When the control device 26 is represented by functional blocks, it can be represented by a vibration yaw moment generating means 28, a vibration response detecting means 30, and a resonance characteristic calculating means 32.

The vibration yaw moment generating means 28 generates a vibration yaw moment for vibrating the vehicle at the natural angular frequency ω1 of the yawing motion model. Wave signal, and a natural angular frequency ω1 having a phase different from that of the sine wave signal to the front wheel steering device 20 by 180 degrees.
And the front wheels and the rear wheels are minutely steered in opposite phases.

The vibration response detecting means 30 detects a resonance component of the yaw rate in response to the vibration yaw moment applied to the vehicle by the vibration yaw moment generating means 28.

The resonance characteristic calculation means 32 calculates the ratio of the amplitude of the resonance component of the yaw rate detected by the vibration response detection means 30 to the amplitude of the steering amount of the front and rear wheels steered by the vibration yaw moment generation means 28. From this ratio, the resonance characteristics of the yawing motion model are estimated, the degree of decrease in the grip force of the tire, that is, the risk of spin or drift-out is determined, and an alarm is issued by the alarm device 36.

That is, the excitation yaw moment generating means 2
8, the amplitude of the vibration yaw moment generated with respect to the amplitude of the turning of the front and rear wheels slightly steered decreases as the grip force of the tire decreases. Also, the amplitude of the resonance component of the yaw rate generated as a response to the amplitude of the applied vibration yaw moment decreases as the grip force of the tire decreases from the resonance characteristics of the yawing motion model. Therefore, the yaw rate amplitude with respect to the steering amplitude monotonously decreases as the grip force of the tire decreases. Therefore, the degree of decrease in the grip force of the tire can be determined from the ratio of the amplitude of the resonance component of the yaw rate to the amplitude of the minute steering.

Therefore, the resonance characteristic calculation means 32 determines the degree of reduction in grip force from the ratio of the amplitude of the resonance component of the yaw rate to the amplitude of the minute steering, and warns the determination result as the risk of spin or drift out. The correspondence between the ratio of the amplitude of the resonance component of the yaw rate to the small steering amplitude and the degree of reduction in the grip force is uniquely determined if the specifications of the system are determined. The risk is determined online based on the map during traveling.

Next, a control routine executed by the vibrating yaw moment generating means 28, the vibrating response detecting means 30, and the resonance characteristic calculating means 32 of the control device 26 will be described with reference to FIG. This control routine is started when the ignition switch is turned on. In step 100, it is determined whether the vehicle speed is equal to or higher than a predetermined value. When the vehicle speed is equal to or higher than a predetermined value, that is, when the vehicle is running at a speed at which drift-out or spin may occur, the front wheels and the rear wheels are minutely steered in opposite phases in step 102 as described above.

In the next step 104, the resonance component of the yaw rate in response to the vibrating yaw moment applied to the vehicle is detected based on the output of the yaw rate sensor 24.

In the next step 106, the reciprocal of the ratio of the small steering amount of the front and rear wheels to the amplitude of the resonance component of the yaw rate (the amplitude of the resonance component of the yaw rate / the small steering amount of the front and rear wheels) is calculated as the spin or drift out. Determined as risk, step 10
It is determined whether or not the risk obtained in step 8 is equal to or greater than a predetermined value. When the risk is equal to or higher than the predetermined value,
Step 1 due to risk of spin and drift out
At 10, an alarm is generated from the alarm device 36.

In step 112, it is determined whether or not the ignition switch has been turned off. If the ignition switch has been turned off, this routine ends.

In the above description, the degree of danger is obtained by the reciprocal of (the amount of small steering of the front and rear wheels / the amplitude of the resonance component of the yaw rate), but the ratio itself may be used.

As described above, in the present embodiment,
Since the grounding state of each wheel is not individually detected, but the grounding state of the entire vehicle is comprehensively estimated from the resonance characteristics of the yawing vibration model, the system configuration is simple and the amount of calculation is small.

Therefore, the present invention is economically advantageous and has high reliability. The obtained result also directly indicates the degree of safety (spin or drift-out risk) of the vehicle motion at that time, and becomes extremely responsive and effective alarm information.

In addition, since vibration is caused by the natural angular frequency component of the yawing vibration model and only the resonance component responsive to the vibration, that is, only the natural angular frequency component, is detected, it is hardly affected by road surface disturbance generated as white noise. Further, there is an advantage that sensitivity is high because the resonance phenomenon is used. As a result, the detection accuracy also increases.

Further, in the present embodiment, the front and rear wheels are minutely steered in opposite phases at the natural angular frequency of the yawing vibration model to generate an exciting yaw moment, and in this case, the grip force of the tire is reduced. As a result, the ratio of the amplitude of the steering to the amplitude of the yaw rate greatly changes in a synergistic manner.
Therefore, the detection sensitivity is further improved.

In the present embodiment, the vibration yaw moment is generated using all four wheels. However, the present invention is not limited to this.
Only the wheels, only two wheels, or only three wheels may be steered to similarly generate an exciting yaw moment. In this case as well, the yawing motion vibration system exhibits the same resonance characteristics as described above, so that the present invention can be realized. In this case, although there are problems such as a reduction in excitation efficiency and generation of a lateral force component, the system is simpler and advantageous in terms of economy and reliability. (Second Embodiment) Next, a second system for exciting a yaw moment using a vibration system composed of a flywheel and a torsion spring and having a natural angular frequency equal to the natural angular frequency of the yawing vibration model is used. An embodiment will be described.

FIG. 8 shows a system configuration according to the second embodiment. One end of the rotating shaft of the flywheel 40 is attached to the roof side via a bearing with little friction so that the rotating shaft can rotate around the center of yawing motion of the vehicle body, and the other end of the rotating shaft of the flywheel 40 is twisted. It is fixed to the floor via 42.

An output shaft of a drive unit 44 for slightly rotating the flywheel 40 around the yawing motion rotation center by the excitation moment generating means 28 is connected to one end of the rotation shaft of the flywheel 40. As the driving device 44, a motor or the like whose torque can be easily controlled is preferable.

Here, if twisted with the flywheel 40,
The natural angular frequency of the vibration system composed of 2 is designed to be equal to the natural angular frequency of the yawing vibration model.
The other configuration is the same as that of the first embodiment, and the description is omitted.

In this system, the vibrating yaw moment generating means 28 includes a flywheel 40 and a spring 42
The driving device 44 is controlled to apply a vibration torque to the flywheel 40 so that the vibration system including At this time, an exciting yaw moment is generated in the vehicle body as a reaction of the rotational vibration of the vibration system.

On the other hand, the vibration response detecting means 30 detects a resonance component of the yaw rate in response to the yaw moment applied to the vehicle by the vibration yaw moment generating means 28.

The resonance characteristic calculating means 32 obtains a ratio between the resonance component of the yaw rate detected by the vibration response detecting means 30 and the amplitude of the rotational vibration of the vibration system rotationally vibrated by the vibration yaw moment generating means 28. The resonance characteristic of the yawing motion system is estimated from this ratio, the degree of reduction in the grip force of the tire, that is, the risk of spin or drift-out is determined, and an alarm is issued by the alarm device 36.

In the above configuration, the rotational amplitude of the vibration system vibrated by the vibration yaw moment generating means 28 is proportional to the vibration yaw moment acting on the vehicle body as a reaction of the vibration. On the other hand, the amplitude of the resonance component of the yaw rate generated in response to the generated vibration yaw moment decreases as the grip force of the tire decreases, based on the resonance characteristics of the yawing motion system. Therefore, the yaw rate amplitude with respect to the rotation amplitude of the vibration system including the flywheel and the torsion spring decreases as the grip force of the tire decreases, and the degree of the grip force decrease of the tire is determined from the ratio of the yaw rate resonance component amplitude to the rotation vibration amplitude. Can be determined.

Therefore, the resonance characteristic calculating means 32 determines the degree of reduction in grip force from the ratio between the amplitude of the rotational vibration and the amplitude of the resonance component of the yaw rate, and warns the determination result as the risk of spin or drift out. The correspondence between the amplitude ratio and the degree of reduction in grip force is calculated in advance from vehicle specifications or obtained as a map by actual measurement.
When driving, the danger of spin or drift out is determined online based on this map and a warning is issued.

It should be noted that the control routine of this embodiment is the first
Since this is the same as the control routine of the embodiment, the description is omitted.

As described above, in this embodiment, since the grounding state of each wheel is not individually detected but the grounding state of the entire vehicle is comprehensively estimated from the resonance characteristics of the yawing vibration system, the system configuration is simple. Thus, the amount of calculation is reduced. Therefore, it is economically advantageous and has high reliability. The obtained result also directly indicates the degree of safety (spin or drift-out risk) of the vehicle motion at that time, and becomes extremely responsive and effective alarm information. Also, since only the natural angular frequency component of the yawing vibration system is vibrated and responding to the natural angular frequency component, it is hardly affected by road surface disturbances that occur like white noise. There is also a merit that the sensitivity is high.
As a result, the detection accuracy also increases.

Further, in this embodiment, since the rotating vibration system is vibrated and the reaction produces a vibrating yaw moment, the vibrating torque does not necessarily have to be sinusoidal, and the continuous vibration is reduced. Sometimes it is sufficient to apply a step-like excitation torque intermittently. Therefore, it is possible to obtain an effect that the configuration of the vibration yaw moment generating means is simplified and the control is facilitated.

In this embodiment, only the flywheel may be provided, and the driving device may be used to perform minute reciprocating rotation to apply vibration. (Third Embodiment) Next, by utilizing the reaction when the flywheel is driven, the vehicle is vibrated around the axis of the yaw moment motion at the natural angular frequency of the yawing vibration system, and stabilized during spinning. A third embodiment for generating a yaw moment for the third embodiment will be described.

FIG. 9 shows a system configuration of the third embodiment. In the center of rotation of the yawing motion of the vehicle body, both ends of the rotating shaft of the flywheel 40 are connected via bearings with little friction. Installed on the roof side and floor side. The output shaft of a driving device 44 composed of a motor or the like whose torque can be easily controlled is connected to the rotation shaft of the flywheel 40. Further, a yaw rate sensor 24 is attached to the center of rotation of the yawing motion of the vehicle body. A steering angle sensor 50 that detects the steering angle of the front wheels from the steering angle of the steering is mounted on the steering column.

The control device 26 constituted by a microcomputer is represented by functional blocks as in the first embodiment, and the same reference numerals are given to the same functional blocks as in the first embodiment, and the description will be made. Although omitted, in the present embodiment, a target yaw rate calculating means 52 and an anti-spin moment generating means 54 are newly provided.

The steering angle sensor 50 is connected to a target yaw rate calculating means 52 for calculating a target yaw rate by applying a primary filter process to the detected steering angle. The target yaw rate calculating means 52 is connected to the anti-spin moment generating means 54, and the anti-spin moment generating means 54 is connected to the yaw rate sensor 24 and the driving device 4.
4 and the resonance characteristic calculating means 32.

In this system, the excitation yaw moment generating means 28 controls the driving device 44 to apply the excitation torque to the flywheel 40 in the forward and reverse directions at the natural angular frequency of the yawing motion system. At this time, a vibration yaw moment is generated in the vehicle body, which vibrates minutely around the rotation axis of the yawing motion as a reaction of the vibration torque applied to the flywheel.

The vibration response detecting means 30 detects a resonance component of the yaw rate in response to the vibration yaw moment applied to the vehicle by the vibration yaw moment generating means 28.

The resonance characteristic calculating means 32 calculates the ratio between the amplitude of the resonance component of the yaw rate detected by the vibration response detecting means 30 and the amplitude of the vibration yaw moment generated by the vibration yaw moment generating means 28. The resonance characteristic of the yawing motion model is estimated from this ratio, the degree of decrease in the grip force of the tire, that is, the risk of spin or drift-out is determined, and an alarm is issued via the alarm device 36.

In the above configuration, the exciting torque applied to the flywheel 40 by the exciting yaw moment generating means 28 matches the exciting yaw moment generated in the vehicle body as a reaction of the exciting torque. On the other hand, the amplitude of the resonance component of the yaw rate generated as a response to the amplitude of the generated vibration yaw moment decreases with a decrease in the grip force of the tire according to the resonance characteristics of the yawing motion system. Therefore, the degree of reduction in the grip force of the tire can be determined from the ratio of the amplitude of the resonance component of the yaw rate to the amplitude of the excitation torque.

Therefore, the resonance characteristic calculation means 32 determines the degree of grip force reduction from the ratio of the amplitude of the excitation torque to the amplitude of the resonance component of the yaw rate, and warns the determination result as the risk of spin or drift out. The correspondence between the amplitude ratio and the degree of reduction in grip force is calculated in advance from vehicle specifications or obtained as a map by actual measurement, and during driving, the risk of spin or drift out is determined online based on this map. Alert.

The reaction when the flywheel is driven can also be used as an anti-spin moment during spin. Therefore, the anti-spin moment generating means 54
Calculates the yaw rate error from the target yaw rate from the target yaw rate calculation means 52 and the actual yaw rate detected by the yaw rate sensor 24, and calculates the resonance characteristic calculation means 32
Enter the risk of spin or drift out. That is, when the risk of spin or drift-out is high and the yaw rate error is large, it is determined that the vehicle is in the spin state, and the flywheel is driven to generate an anti-spin moment as a reaction so that the actual yaw rate follows the target yaw rate.

Next, a control routine executed by each means of the control device 26 will be described with reference to FIG. In addition,
In FIG. 10, portions corresponding to those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.

After a warning is issued due to the high risk of spin or drift-out, in the next step 114, the target yaw rate calculation means 52 performs a primary filter process on the steering angle detected by the steering angle sensor 50 to obtain the target value. The yaw rate is calculated, and in step 116, the actual yaw rate detected by the yaw rate sensor 24 is fetched.

At step 118, a yaw rate error which is a difference between the target yaw rate and the actual yaw rate is calculated.
If the yaw rate error is equal to or larger than a predetermined value, that is, the risk of spin or drift out is high (step 10).
8) If the yaw rate error is large, the spin state is determined, and the flywheel is driven by the antispin moment generating means 54 to generate the antispin moment as a reaction. As a result, a moment is generated in a direction to cancel the spin or the drift out, and the running stability of the vehicle is improved.

As described above, in the present embodiment, the contact state of each wheel is not individually detected, but the contact state of the entire vehicle is comprehensively estimated from the resonance characteristics of the yawing vibration model. Thus, the amount of calculation is reduced. Therefore, it is economically advantageous and has high reliability. The obtained result also directly indicates the degree of safety (spin or drift-out risk) of the vehicle motion at that time, and becomes extremely responsive and effective alarm information. In addition, since the vibration is excited by the natural angular frequency component of the yawing vibration model and only the natural angular frequency component corresponding to the vibration is detected, it is hardly affected by road surface disturbance generated like white noise, and the resonance phenomenon is used. Therefore, there is an advantage that the sensitivity is high. As a result, the detection accuracy also increases.

Further, in this embodiment, since the flywheel for generating the excitation yaw moment is used as a means for generating the anti-spin moment, the anti-spin control can be performed without adding a special device. Can be realized. Therefore, an effect is obtained that the system configuration from the spin warning to the spin suppression control is simple and the control is easy.

Although the present invention has been described above using the equations (11) to (16) and the model shown in FIG. 4, these are one of approximate models, and the present invention uses these models. The present invention is not limited to this case, and the present invention can be realized even if a more complicated approximation model or a simpler approximation model is used as long as the resonance phenomenon can be expressed.

[0087]

As described above, according to the spin limit detecting device and the spin preventing device of the present invention, since the ground contact state of the entire vehicle is comprehensively estimated from the resonance characteristics of the yawing vibration model, the system configuration is simple. Therefore, the amount of calculation can be reduced, and the effect of being able to provide an economically advantageous and highly reliable spin limit detecting device and spin preventing device can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a cornering force and a side slip angle.

FIG. 2 is a schematic diagram for explaining input of a yawing motion.

FIG. 3 is a schematic diagram showing a road surface model represented by friction elements.

FIG. 4 is a schematic view showing a model approximated by twisting elements of a tire and a suspension.

FIG. 5 is a diagram illustrating a relationship between an attenuation coefficient of a second-order lag system and a gain at a natural angular frequency.

FIG. 6 is a block diagram showing the first embodiment.

FIG. 7 is a flowchart illustrating a control routine according to the first embodiment.

FIG. 8 is a block diagram showing a second embodiment.

FIG. 9 is a block diagram showing a third embodiment.

FIG. 10 is a flowchart illustrating a control routine according to a third embodiment.

[Explanation of symbols]

 24 Yaw rate sensor 40 Flywheel 42 Twist 44 Drive

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-230472 (JP, A) JP-A-63-73132 (JP, A) JP-A-6-249655 (JP, A) 71244 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01M 17/06 G01M 17/007

Claims (6)

(57) [Claims] An inertial body in a yawing motion vibration system including an inertial body composed of a vehicle body and a torsion element around a yaw rotation axis composed of a tire and a suspension system is subjected to minute vibration at a natural angular frequency of the yawing motion vibration system. Vibration yaw moment generating means for microvibrating the inertial body by adding a yaw moment to generate, and a vibration response for detecting a response component generated by the microvibration of the vibration yaw moment generating means from the state quantity of the yawing motion vibration system A spin limit detecting device, comprising: a detecting unit; and a resonance characteristic calculating unit that calculates a resonance characteristic of the yawing motion vibration system and detects a spin limit state of the vehicle body from the resonance characteristic. 2. The spin limit detecting device according to claim 1, wherein the excitation yaw moment generating means slightly excites the inertial body by slightly turning the wheel. 3. The spin limit detecting device according to claim 1, wherein the excitation yaw moment generating means slightly excites the inertial body by slightly steering the front wheel and the rear wheel in opposite phases. 4. The vibrating yaw moment generating means includes a rotary vibration system including a flywheel and a torsion spring, and minutely vibrates the inertial body by the reaction of the continuous vibration of the rotary vibration system. Item 6. A spin limit detecting device according to Item 1. 5. An apparatus according to claim 1, wherein said vibrating yaw moment generating means comprises a flywheel, and minutely vibrates the inertial body by a reaction generated by applying a torque to said flywheel. The spin limit detector according to the above. 6. A spin limit detecting device according to claim 1, wherein a target yaw rate is calculated from a steering angle, a target yaw rate is calculated, and a difference between a target yaw rate and an actual yaw rate is calculated. An anti-spin moment generating means for determining a spin based on a resonance characteristic of the yawing motion vibration system calculated by the limit detecting device and generating an anti-spin moment.