JPH11321603A - Estimating device of vehicle side slip angle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the control precision of a vehicle attitude control device by calculating the stability factor on the basis of vehicle speed and estimating the side slip angle of a vehicle on the basis of the calculation result or a rear cornering force. SOLUTION: In the attitude stability control of a bus or truck, the possibility of the vehicle being laid in the side slip state during traveling is detected to control a required brake pressure, whereby occurrence of the slide slip is suppressed. At this time, means for measuring body total weight W, vehicle speed V and yaw rate (y) are provided, and the transmission factor is calculated from expression I wherein (s) is a differential operator, a1, a2, b0, b1, b2 are coefficients} according to the yaw rate (y) and steering angle δ. The vehicle speed V is then read, stability factor A is arithmetically calculated from expression II (wherein L is a wheel base), and side slide angle β is arithmetically calculated from expression III (wherein Lf, Lr are distances from the front wheel axle and rear wheel axle to the center of gravity) by use of the vehicle speed V, the stability factor A, and rear cornering force Kr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to attitude control of an automobile. INDUSTRIAL APPLICABILITY The present invention is used for a device that automatically controls the attitude of a vehicle in a stable direction based on the behavior of a running vehicle such as yaw or roll. The present invention, for example, by automatically detecting and calculating that the vehicle may be in a skidding state while traveling, by automatically controlling the brake pressure of all or some wheels, the vehicle The present invention can be used for an automatic control device that recovers to a state in which a side slip is less likely to occur. The present invention relates to attitude control for automatically restoring a stable state when a vehicle reaches a behavior not intended by a driver due to a driving operation exceeding the characteristics of the vehicle, such as a large steering wheel operation during high-speed running.
INDUSTRIAL APPLICATION This invention is utilized for rollover prevention of commercial vehicles, such as a bus and a truck.

[0002]

2. Description of the Related Art Conventionally, electronic control devices for brakes and vehicle stability control devices (VSC, Vehicle Stability Control) have been used.
Etc. are known. ABS (Antilock Brake System) is a typical system for electronic control devices related to brakes.
It is. This is to provide a rotation sensor on the wheel to detect the wheel rotation, and when the wheel rotation stops when the brake pressure is large, assuming that there was a slip between the wheel and the road surface,
The brake pressure is intermittently controlled. ABS has become widespread in passenger cars and freight cars, and has become widely known as a device that can handle while braking. As a typical device of the vehicle stabilization control device (VSC), a skid prevention device is known. This means that the course the driver is going to travel is read from the steering angle (steering angle) input by the driver, and if the vehicle speed is too high for that course, the driver will automatically enter without having to press the brake pedal. This is a device in which control for deceleration is performed and control such as distributing left and right brake pressures so as not to deviate from the course is performed.

[0003] A known vehicle attitude stabilizing device (VSC) (JP-A-63-279976, JP-A-2-112755, etc.) will be further described. When this is done, the direction of the vehicle changes and the vehicle rolls. At this time, if the tire of the inner wheel turning by steering exceeds the grip limit of the road surface, the inner wheel tends to be a so-called wheel lift, and the vehicle starts to skid. For example, when the driver steers to the left from a straight running state, the vehicle leans to the right. At this time, the vehicle turns in accordance with the steering in a normal state, but if the steering speed is too high relative to the traveling speed, the vehicle leans to the right and the left wheel is in a floating state, so that the driver Will move to the right from the intended direction. Such a behavior of the vehicle causes a deviation from the traveling lane or, in an extreme case, a rollover of the vehicle.

In a normal running state, the magnitude and speed of steering, the speed of the vehicle, the speed of lateral movement of the vehicle, and the speed of change in the direction of the vehicle (yaw rate, rotational acceleration of the vehicle around the vertical axis) are detected. A device has been developed which predicts the starting point of a skid of a wheel or the starting point of a wheel lift of an inner wheel by controlling the brake pressure of the wheel before the skid or the wheel lift starts. The brake pressure control of the wheels does not necessarily apply the same brake pressure to all the wheels, but applies a large or small brake pressure to one wheel to prevent the vehicle from skidding. Such an apparatus has been well studied not only for its basic structure and design, but also for its economy and durability, and has reached the stage of being mounted on a commercial product for a passenger car.

[0005] Such a conventional apparatus calculates a yaw rate from parameters relating to the current driving operation including steering and braking and parameters relating to the current behavior of the vehicle, that is, from the parameters at the current time. When it is determined that the yaw rate having the possibility of the sideslip that has been set and stored is reached, the brake pressure of the vehicle is automatically controlled. The possibility of this side slip is calculated by a transfer function from the vehicle operation data which is a driving operation input and various sensor outputs.

In the conventional transfer function calculation device, the calculation using the transfer function is a calculation method in which fast Fourier calculation is widely used. That is, the frequency of the operation input data and the behavior data is frequency-decomposed, and the response is approximated using a Fourier function. The fast Fourier operation has a convenient point such that a general-purpose analyzer that can be installed and used in a computer device can be easily obtained.

In such an apparatus for controlling the attitude of a vehicle, the position of the center of gravity of the vehicle is a very important parameter. The position of the center of gravity of a large commercial vehicle represented by a large truck changes depending on the state of the cargo. In the case of a bus, particularly in a route bus, the position of the center of gravity of the vehicle changes as passengers get on and off. Regarding the attitude control for preventing the rollover of the vehicle, the height of the center of gravity of the vehicle is an important parameter.

Conventionally, the center of gravity of a vehicle can be statically measured, but there is no method for measuring the center of gravity of a vehicle in real time in a running state. That is, while the vehicle whose center of gravity is to be measured is stopped on a horizontal road surface, the load distribution of each wheel is measured,
Next, the vehicle is moved to a road surface having a gradient in the front-rear direction and a road surface having a gradient in the left-right direction, and the load distribution of each wheel is measured, so that the position of the center of gravity including the height of the center of gravity is three-dimensionally measured. be able to.

A conventional attitude control device will be described with reference to FIGS. FIG. 6 is a diagram showing an example of the overall configuration of conventional attitude control. The vehicle 1 is a controlled object of the attitude control device. The vehicle 1 is provided with steering, braking, acceleration, and other driving operation inputs, and the response thereto is the behavior of the vehicle.
The vehicle 1 has an attitude control device 2 mounted thereon. The attitude control device 2 includes a vehicle stabilization control device (VSC) 3 and an electronic control braking device 4. The electronic control braking device 4 is a device represented by a conventional ABS means.

In order to observe the behavior of the vehicle as data, behavior data is output from sensors 11 mounted on the vehicle 1. The behavior data includes speed, lateral acceleration, yaw rate, roll rate, wheel rotation information, and others.

The vehicle stabilization control device 3 predicts and calculates the behavior of the vehicle using the driving operation input and the behavior data as input, and gives the result to the electronic control braking device 4. The electronically controlled braking device 4 also takes in driving operation input and behavior data, and additionally, a vehicle stabilization control device (VSC) 3
And outputs an automatic control output in a safe direction with respect to the driving operation input and the disturbance input to the vehicle 1, and this is a correction input.

FIG. 7 is a system configuration diagram of a conventional attitude control device. The control circuit 51 is an electronic device mounted on a vehicle including a computer circuit that is controlled by a program, and is a vehicle stabilization control device that receives a driving operation input of the vehicle and behavior data of the vehicle and calculates and outputs a motion state of the vehicle. (VSC) and control means for providing the vehicle with a correction input for correcting the driving operation input and the disturbance input to a safe side in accordance with the calculation output of the vehicle stabilization control device.

The vehicle is equipped with a yaw rate sensor 52, a lateral acceleration sensor 53, a roll rate sensor 60, and a longitudinal acceleration sensor 61. The detection outputs of these sensors are connected to a control circuit 51. Wheel rotation sensors 55 are attached to the front wheels 54f and the rear wheels 54r, respectively, and their detection outputs are also connected to the control circuit 51.
A brake pressure sensor 57 is attached to the brake booster actuator 56, and its detection output is also connected to the control circuit 51. A steering angle sensor 59 is attached to the steering handle 58, and the output is connected to the control circuit 51. A governor sensor 63 is incorporated in the governor 62 that controls the internal combustion engine, detects the state of the governor 62, and outputs the detection output to the control circuit 51. FIG. 8 is a perspective view showing an example of mounting each sensor on a vehicle. Although FIGS. 7 and 8 show a vehicle having a two-axis structure, a three- or four-axis structure is used in the case of a large vehicle.

[0014]

However, in the fast Fourier calculation conventionally used in the transfer function calculation, (1) a long time data is required for a signal with a low frequency, and (2) the number of data. Is a power of 2 (8, 16, 32, 64
..), An appropriate number of data may not be obtained in some cases, and (3) a closed loop in which feedback control is performed cannot be operated. In particular, in commercial vehicles such as trucks and buses, there is a component having a vibration frequency of about 1/100 Hertz in the behavior data, and such behavior data is used to calculate a transfer function by fast Fourier computation. Requires real-time data over 200 seconds, at least twice that period. In this case, it is not possible to obtain a practical device for performing calculations in real time during traveling. This is a serious problem that hinders the realization of a commercial vehicle attitude control device.

In a large vehicle, depending on the state of the cargo,
Alternatively, the physical characteristics of the vehicle greatly vary depending on the number of passengers and the seating position. That is, in the case of a passenger car, even if the number of passengers varies, the weight of the passenger (for example, 50 kg per person) is equal to the total weight of the vehicle (for example, 2000 kg).
And the crew is small. Moreover, since the boarding position of the passenger is fixed at a position with a low center of gravity,
Even when the number of passengers fluctuates, even if the calculation is performed with the vehicle model holding the physical constants of the vehicle fixed, the calculation result of the attitude control device does not have a large effect. However, in the case of a heavy-duty vehicle, in the case of a freight vehicle, the weight of the entire vehicle and the position of the center of gravity greatly change between a case where there is no load and a case where there is a typical load close to the loadable limit. Therefore, since the physical characteristics of the vehicle greatly change, even if the calculation is performed using a fixed vehicle model, it does not become a realistic value.

Further, in a truck, the load is not always loaded in a constant state, and the weight and the position of the load or the position of the center of gravity change each time. Even in the case of a large bus, the number of passengers varies from zero to about 50 people, and the position of the passengers in the vehicle also changes each time. In the case of a regular bus, it will change for each stop. Therefore, if the vehicle model on which the attitude control is based is fixedly set, practical attitude control cannot be performed.

Considering the sideslip angle among the above parameters, conventionally, the vehicle speed in the front-rear direction and the left-right direction is measured, and the sideslip angle is calculated. In particular, it is difficult to measure the vehicle speed in the left-right direction, and an expensive measuring device such as a lateral acceleration sensor is required (Japanese Patent No. 272).
No. 2855, JP-A-9-311042, JP-A-6-2
No. 78628).

The present invention has been made in such a background, and an object of the present invention is to provide an attitude control device suitable for a large vehicle, particularly a commercial vehicle. An object of the present invention is to provide a posture control device for adapting to a large vehicle in which behavior data includes many low frequency components. The present invention
An object of the present invention is to provide a posture control device for adapting to a vehicle in which the state of a load or a passenger changes. An object of the present invention is to provide a posture control device in which a vehicle model automatically follows a change in the state of a load or a passenger. An object of the present invention is to prevent a large vehicle from deviating from a traveling lane and to prevent rollover by driving control that exceeds the characteristics of the vehicle. An object of the present invention is to provide a device capable of estimating a sideslip angle of a vehicle in real time. An object of the present invention is to improve control accuracy of a vehicle attitude control device.

[0019]

The present invention is characterized in that when the sideslip angle is estimated, it is estimated based on the steering angle δ, the yaw rate y, and the vehicle speed V. This eliminates the need to mount complex and expensive sensors on the vehicle,
The sideslip angle can be estimated. Further, by measuring the total weight of the vehicle body using an axle load meter, it is possible to estimate a slip angle that changes due to loading and unloading of the cargo at any time.

That is, the present invention relates to an apparatus for estimating a side slip angle of a vehicle, comprising: means for measuring a total body weight W; means for measuring a vehicle speed V; and means for measuring a yaw rate y. And the steering angle δ input by the driving operation

[0021]

(Equation 4) Where s is a differential operator, a ₁ , a ₂ , b ₀ , b ₁ , b
₂ is obtained as a coefficient, and the stability factor A is obtained by taking in the vehicle speed V.

[0022]

(Equation 5) Here, L is obtained as a wheel base (constant), and the vehicle slip angle β is calculated using the vehicle speed V, the stability factor A, and a preset value of the rear cornering force Kr.

[0023]

(Equation 6) However, Lf is a distance from the front wheel axis to the center of gravity and Lr is a distance from the rear wheel axis to the center of gravity.

The stability factor A is a variable that changes according to the yaw rate y, the steering angle δ, and the vehicle speed V. By using the stability factor A in the calculation for estimating the sideslip angle β, the stability factor A can follow the change of the vehicle with high accuracy. Calculation of the estimated side slip angle β can be performed.

The rear cornering force Kr is originally a parameter obtained by a function of the side slip angle β, but is treated as a preset value in the present invention. As this value, for example, an average value obtained experimentally is used. Thereby, the sideslip angle β can be instantaneously estimated according to the steering angle δ, the yaw rate y, and the vehicle speed V.

Alternatively, a new value of the rear cornering force Kr is calculated from the estimated side slip angle β, and the calculated value is compared with the previously set value of the rear cornering force Kr. Rear cornering force Kr
May be changed. In this case, AR
It is desirable to use the method.

The distance Lr from the position of the center of gravity to the rear axis may be preset as a constant, or the distance Lr from the position of the center of gravity to the rear axis may be set.
May include means for calculating from the weight Wf applied to the front shaft and the weight Wr applied to the rear shaft.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing the operation of the embodiment of the present invention. FIG. 2 is a system configuration diagram of the attitude control device according to the embodiment of the present invention. FIG. 3 is a perspective view showing an example of mounting each sensor of the embodiment of the present invention on a vehicle. FIG. 4 is a diagram showing a dynamic model used in the embodiment of the present invention.

The present invention relates to an apparatus for estimating a vehicle side slip angle, and as shown in FIG. 2, axle meters 64f and 64r for measuring the total weight W of a vehicle, and a vehicle speed for measuring a vehicle speed V. And a yaw rate sensor 52 for measuring the yaw rate y.
And the transfer function taking in the steering angle δ input by the driving operation [Equation 4] where s is a differential operator, a ₁ , a ₂ , b ₀ ,
b ₁ and b ₂ are obtained as coefficients, and the vehicle speed V is taken in, and the stability factor A is obtained by [Equation 5] where L is obtained as a wheel base (constant). Rear cornering force K
The value of r is used to determine the sideslip angle β of the vehicle.
The control circuit 51 is a means for estimating and calculating r as the distance from the rear wheel axle to the center of gravity.

The preset value of the rear cornering force Kr may be updated by an auto-regression method (AR method).

The distance L from the position of the center of gravity to the rear axis is
r may be treated as a constant set in advance, or the distance Lr from the position of the center of gravity to the rear axis may be calculated from the weight Wf applied to the front axis and the weight Wr applied to the rear axis.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a feature of a large vehicle, two axes, three
Since the vehicle is classified into an axle and an axle, and various types of wheelbases are present, the vehicle has different motion characteristics. FIG. 5 is a diagram showing the motion characteristics of the vehicle. The horizontal axis indicates frequency, and the vertical axis indicates gain and phase. When different wheelbases (WB (1) <WB (2) <WB (3)) of the same axle configuration are used, as shown in FIG. 5, as the wheelbase showing a stable state becomes shorter, the steering becomes smaller. This indicates that the sensitivity is increased.

Also, from the viewpoint of the use of the vehicle, the axle load changes greatly when the vehicle is empty or loaded, and the center of gravity changes greatly depending on the type of packing. is there.

An embodiment of the present invention will be described. 2 and 3
From the steering angle sensor 59 and the vehicle speedometer 66 shown in FIG.
And the data of the vehicle speed V are input to the control circuit 51. As shown in FIG. 1, the control circuit 51 takes in the yaw rate y (S2) measured by the yaw rate sensor 52 and the steering angle δ (S1) input by the driving operation measured by the steering angle sensor 59, and transfers the transfer function. [Equation 4] where s is a differential operator, a ₁ , a ₂ , b ₀ ,
b ₁ and b ₂ are obtained as coefficients (S4). Speedometer 66
The stability factor A is obtained by taking the vehicle speed V (S3) measured by Equation (5), where L is obtained as a wheelbase (constant) (S5). The vehicle slip angle β is calculated by using the vehicle speed V, the stability factor A, and a preset value of the rear cornering force Kr [Equation 6] where Lf is the distance from the front wheel axis to the center of gravity, L
r is estimated and calculated as the distance from the rear wheel axle to the center of gravity (S6).

At this time, the rear cornering force Kr
Is a parameter originally determined by a function of the sideslip angle β, but is treated as a preset value in the present invention. As this value, for example, an average value obtained experimentally is used. Thereby, the sideslip angle β can be instantaneously estimated according to the steering angle δ and the vehicle speed V.

Alternatively, a value of the rear cornering force Kr is newly calculated based on the estimated side slip angle β, and a predetermined rear cornering force Kr is calculated.
And the value of the preset rear cornering force Kr may be changed according to the comparison result. In this case, the AR method is used. Further, the transfer function is also obtained by using the AR method.

Here, the AR method is a method in which the past data is multiplied by a weighting factor and the calculation is performed in reverse to obtain the current data. In general, when comparing the AR method and the fast Fourier calculation method (FFT), the FFT has advantages such as that a general-purpose analyzer can be easily obtained, and that when the calculation is started, the calculation is completed in a short time. In order to obtain an appropriate resolution for a low (long period) component, data over twice as long as the period is required. For example, the behavior data of a large vehicle includes a frequency component such as 1/100 Hertz (period of 100 seconds), so that the calculation cannot be performed in real time. On the other hand, in the AR method, a past data is multiplied by a weighting coefficient and the calculation is performed in reverse, so that a corresponding result can be obtained one by one, which is suitable as a calculation for real-time control. In the FFT method, the number of data is a power of 2, that is, 2 ⁿ
However, in the AR method, the number of data is not limited and the calculation can be performed using the data held at each time, so that the degree of freedom is increased. In the FFT method,
In principle, it is impossible to perform a loop, that is, a loop control in which the calculation result is immediately fed back to the behavior data. However, the AR method is suitable for closed-loop calculation, and is suitable for the attitude control of a vehicle. This is advantageous in a device in which loop control is always performed.

At this time, the total weight W of the vehicle is shown in FIG.
And the measured values of the axle meters 64f and 64r shown in FIG. That is, the total body weight W is obtained by adding the weight applied to the front wheels and the weight applied to the rear wheels. Theoretically, even when the vehicle body is greatly inclined, the vehicle total weight W can be obtained by adding the weight applied to the front wheels and the weight applied to the rear wheels. However, in practice, when the vehicle body tilts greatly, the difference between the weight applied to the front wheels and the weight applied to the rear wheels increases, and the measured values of the axle meters 64f and 64r differ greatly. When a large difference occurs in the measured values as described above, it is necessary to provide the axle meters 64f and 64r having high measurement accuracy in a wide range, and the cost becomes high. Therefore, the front wheel axle weight 64
It is preferable to measure the total weight W of the vehicle body within the range of zero or ± 1 degree where the difference between the measured values of f and the rear wheel axle meter 64r is small.

There are a method of treating the distance Lr from the position of the center of gravity to the rear axis as constant, and a method of calculating the distance Lr each time. The method of treating the distance Lr as a constant is suitable for use in a type of vehicle in which the position of the center of gravity does not change frequently. For example, it is suitable for the case where the shape of the cargo to be loaded is constant and its loading position is also constant, but only the weight changes. In such a case, by treating the distance Lr as a constant, the procedure for calculating the change in the center of gravity can be omitted, so that the speed of calculating the height of the center of gravity can be increased. Further, the method of calculating the distance Lr each time is suitable for use in a type of vehicle in which the position of the center of gravity frequently changes. For example, when the shape and the loading position of the cargo to be loaded are not constant and change each time, the position of the center of gravity also changes frequently.
Is preferably calculated.

As a very simple example of a method for calculating the distance Lr each time, Wf / (Wf + Wr) = k · Lr /
(Lf + Lr) Here, since k is a constant, Lr = (1 / k) · (Lf + Lr) · [Wf / (Wf +
Wr)].

[0041]

As described above, according to the present invention,
An attitude control device suitable for a large vehicle, particularly a commercial vehicle, can be realized. It is possible to realize a posture control device for adapting to a large vehicle in which behavior data includes many low frequency components. An attitude control device for adapting to a vehicle in which the state of a load or a passenger changes can be realized. Even if the state of the cargo or the passenger changes, it is possible to realize a posture control device in which the vehicle model automatically follows. It is possible to prevent a large vehicle from deviating from the traveling lane and to prevent rollover by driving control that exceeds the characteristics of the vehicle. The slip angle of the vehicle can be estimated in real time. The control accuracy of the vehicle attitude control device can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of an embodiment of the present invention.

FIG. 2 is a system configuration diagram of the attitude control device according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an example of mounting each sensor of the embodiment of the present invention on a vehicle.

FIG. 4 is a diagram showing a dynamic model used in the embodiment of the present invention.

FIG. 5 is a diagram showing the motion characteristics of the vehicle.

FIG. 6 is a diagram showing an example of the overall configuration of a conventional attitude control.

FIG. 7 is a system configuration diagram of a conventional attitude control device.

FIG. 8 is a perspective view showing an example of mounting each sensor on a vehicle.

[Explanation of symbols]

 Reference Signs List 1 vehicle 2 attitude control device 3 vehicle stabilization control device (VSC) 4 electronic control braking device (EBS) 11 sensors 51 control circuit 52 yaw rate sensor 53 lateral acceleration sensor 54f front wheel 54r rear wheel 55 wheel rotation sensor 56 brake booster・ Actuator 57 Brake pressure sensor 58 Steering handle 59 Steering angle sensor 60 Roll rate sensor 61 Front-back direction acceleration sensor 62 Governor 63 Governor sensor 64f, 64r Axle weight meter 65 Gradient sensor 66 Vehicle speedometer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B62D 101: 00 113: 00 137: 00

Claims (4)

[Claims] 1. A means for measuring the total weight W of a vehicle, and a vehicle speed V
And a means for measuring the yaw rate y. The transfer function is obtained by taking the yaw rate y and the steering angle δ input by the driving operation. Here, s is obtained as a differential operator, and a ₁ , a ₂ , b ₀ , b ₁ , and b ₂ are obtained as coefficients. Here, L is obtained as a wheel base (constant), and the vehicle slip angle β is calculated by using the vehicle speed V, the stability factor A, and a preset value of the rear cornering force Kr. However, Lf is a distance from the front wheel axis to the center of gravity, and Lr is a distance from the rear wheel axis to the center of gravity. 2. The vehicle slip angle estimation device according to claim 1, wherein the preset value of the rear cornering force Kr is updated by an autoregressive method (AR method). 3. The apparatus for estimating the height of the center of gravity of a vehicle according to claim 1, wherein the distance Lr from the position of the center of gravity to the rear axis is preset as a constant. 4. A distance Lr from the position of the center of gravity to a rear axis.
2. The apparatus for estimating the height of the center of gravity of a vehicle according to claim 1, further comprising means for calculating from a weight Wf applied to the front shaft and a weight Wr applied to the rear shaft.