JPH0758202B2 - Vehicle traveling direction detection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle advancing direction detecting method for detecting an advancing direction of a vehicle from a rotational angle difference between left and right wheels of the vehicle.

2. Description of the Related Art Conventionally, in this type of vehicle device, assuming that the diameters of the left and right wheels are constant, the change in the traveling direction of the vehicle is obtained from the difference in the rotation angles of the left and right wheels.

Problems to be Solved by the Invention However, when actually traveling on a road, when the road is inclined to the right or the upper left, or when the traveling direction of the vehicle is changed, a lateral or axial acceleration is applied. As a result, the ground pressure of the left and right wheels changes, one of the left and right wheel diameters increases, and the other decreases, resulting in a dynamic change of the wheel diameters in the conventional method that calculates only the difference in the rotation angles of the two wheels. There was a drawback that an error was caused by.

Means for Solving the Problems In the present invention, in consideration of such a point, the pressure difference applied to the left and right wheels is calculated using the detection value obtained by detecting the acceleration in the axle direction applied to the vehicle, The moving direction of the vehicle is calculated from the rotational angle difference between the left and right wheels so as to eliminate the error by obtaining and guiding the dynamic diameter of the wheel having a functional relationship with the pressure.

That is, according to the present invention, the rotation angle detector 1 that generates a pulse proportional to the rotation angle of the left wheel, the rotation angle detector 2 that generates a pulse proportional to the rotation angle of the right wheel, and the difference and the sum of the pulsations, respectively. A differential pulse counter 5 and a sum pulse counter 6 which are counted and output as digital signals and then converted into analog signals, a tilt detector 9 for taking out an output signal proportional to the acceleration in the axle direction, the tilt detector 9 and the sum. An analog integrating circuit 12 and an error signal integrating circuit 15, which are provided with a signal obtained by analogizing the digital signal of the pulse counter 6 to obtain an angular difference detection error or a correction value of the left and right wheels, and an analog signal of the difference pulse counter 5. And an error signal subtraction circuit 17 to which the output of the error signal integration circuit 15 is given.
When the change in the wheel diameter is obtained from the acceleration in the axle direction by using and, the traveling direction is measured using the obtained dynamic wheel diameter, and when traveling on a sloping road or changing the traveling direction. This is a method for detecting the traveling direction of a vehicle, which is characterized in that the measurement error that occurs in 1) can be removed.

Thus, according to the method of the present invention, the change in the wheel diameter is obtained from the acceleration in the axle direction, and the traveling direction is measured using the obtained dynamic wheel diameter. It is possible to eliminate the measurement error that occurs when changing the traveling direction, and obtain accurate traveling direction measurement accuracy.

EXAMPLE Next, the method of the present invention will be described with reference to the illustrated example.
FIG. 2 is a block diagram of the embodiment apparatus, and FIG. 2 is a vector diagram for explaining changes in wheel pressure.

In the figure, 1 is a rotation angle detector that generates a pulse proportional to the rotation angle of the left wheel, 2 is a rotation angle detector that generates a pulse that is proportional to the rotation angle of the right wheel, and 3 and 4 are rotation angle detectors 1 respectively. , A pulse output proportional to the rotation angle of the left and right wheels extracted from 2, 5 is a differential pulse counter that counts the difference between the pulse numbers of pulse outputs 3 and 4, and 6 is the sum of the pulse numbers of pulse outputs 3 and 4. Sum pulse counter for counting, 7 and 8 are D / A converters that can set conversion factors, 9 is a tilt detector (axle direction acceleration detector) that outputs the amount of tilt in the left-right direction as an analog signal, and 10 is the same tilt detection Output signal of the device 9, 11 is an analog signal proportional to the sum of the left and right pulses from the D / A converter 8, 12 is an analog input circuit for obtaining the product of the analog input of the signals 10 and 11 and a certain coefficient, 13
Is the analog output signal from the analog integration circuit 12 and 14 is D
An analog output signal from the / A converter 7, 15 is an error signal integrating circuit to which the analog output signal 13 is added, 16 is a cumulative error signal from the error signal integrating circuit 15, 17 is an error signal subtracting circuit, 18
Is the output signal from the circuit 17 after error subtraction.

FIG. 2 is a vector diagram for explaining the pressure difference between the left and right wheels due to the acceleration in the axle direction. 19 and 20 are left and right wheels, 21 is the axle, 22 is the center of gravity of the vehicle, and 23 is the size G of the axle. The acceleration vector, 24 is the ground, 25 and 26 are the pressure change vectors of the left and right wheels due to G, and 27 is the radius of the left and right wheels when G = 0 at rest on the horizontal plane.

Here, in order to facilitate the operation of the present invention, the relationship of the pressure difference F between the left and right wheels due to the axle-direction acceleration G will be described.

In Fig. 2, if the distance between the left and right wheels is D, the height from the axle 21 to the center of gravity 22 is H, and the vehicle weight is M, the torque T due to the acceleration G in the axle direction is T = MGH. The pressure difference F between the left and right wheels is F = (MH / 2D) G, which is proportional to the acceleration G in the axle direction. Due to this pressure difference F, one wheel diameter decreases and the other increases. When the amount of change in the wheel radius due to F is Δr, Δr is proportional to G in a practical range, and therefore Δr can be obtained from the value of G.

Here, in order to obtain the rotation angle error of the left and right wheels due to Δr, consider as an example the case where the road travels to the lower right and travels straight for a section of distance L. When the rotation angle of the left wheel and the rotation angle of the right wheel in this section are θ ₁ and θ ₂ , respectively, L = (r + Δr) θ ₁ = (r−Δr) θ ₂ (1) and Δθ = θ ₂ − If θ ₁ is set, Δθ = Δr (θ ₁ + θ ₂ ) / r (2) from the equation (1).

Equation (2) indicates the angle difference detection error or the correction value of the left and right wheels in the section L (the error in the traveling direction is rΔθ / D), and the correct angle difference is obtained by subtracting this value from the detection value. be able to.

Although the case of straight traveling has been described above, the above equations (1) and (2) are also established even in the case of curved traveling.

FIG. 1 shows a block diagram of an embodiment for embodying the above operation. The pulse outputs 3 and 4 from the rotation angle detectors 1 and 2 of the left and right wheels are given to the difference pulse counter 5, and the difference pulse counter 5 outputs the integrated value of the pulse difference as a digital signal, and the D / A converter 7 The angle difference analog signal 14 is converted. The angle difference analog signal 14 is zero at the start of running, and becomes the value of Δθ in the equation (2) at the time when the vehicle runs straight on the right downhill road by the distance L as described above. Meanwhile, pulse output
3, 4 are given to the sum pulse counter 6, and the sum pulse counter 6 outputs the sum of both pulses as a digital signal, and D /
The A converter 8 converts the analog signal 11. The analog signal 11 is zero at the start of traveling, and when traveling the distance L under the above conditions, the analog signal 11 is θ ₁ + θ in the equation (2).
_{It has} a value of ₂ . Since the output signal 10 of the inclination detector 9 is proportional to the acceleration in the axle direction, and is therefore proportional to Δr in the equation (2), the output signal 13 of the analog integrating circuit 12 is selected by selecting the gain of the analog integrating circuit 12 ( Δr (θ ₁
The value of + θ ₂ ) / r can be obtained. The content of the error signal integrating circuit 15 is zero at the start of running, and the output signal 16 of the error signal integrating circuit 15 has the same value as the output signal 13, that is, Δr (θ ₁ +
θ ₂ ) / r. Therefore, in the error signal subtraction circuit 17, Δθ
An operation of −Δr (θ ₁ + θ ₂ ) / r is performed, and in this case, the output signal 18 of the circuit 17 becomes zero.

Although the case where the vehicle travels straight for the distance L from the start of traveling has been described above, the output signal 14 becomes a value obtained by integrating the sum of the angular difference of all traveling sections and the error of all traveling sections during ordinary traveling, and the cumulative error signal 16 becomes all. It becomes the integrated value of the error in the running section,
The error signal subtraction circuit 17 subtracts the integrated value of the error, that is, the accumulated error. Accumulated error resets the sum pulse counter at certain intervals or at certain intervals, and outputs the output signal in that interval.
It can be obtained by adding 13 to the error signal integration circuit 15. The traveling direction α of the vehicle is given by α = Ar / D + B, where A is the value of the output signal 18 and B is the traveling direction of the vehicle at the start of traveling.

As described above, according to the method of the present invention, the change in the wheel diameter is obtained from the acceleration in the axle direction, and the traveling direction is measured using the obtained dynamic wheel diameter. It is possible to eliminate measurement errors that occur when traveling on the road or changing the traveling direction.

By using the method of the present invention and another azimuth detection method (for example, by the geomagnetism) together to make up for weaknesses of both, higher measurement accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a vector diagram for explaining changes in wheel pressure. In the figure, 1 is a left wheel rotation angle detector, 2 is a right wheel rotation angle detector, 3 is a left wheel pulse output, 4 is a right wheel pulse output, 5 is a difference pulse counter, 6 is a sum pulse counter, 7 and 8 are D / A converter that can set conversion coefficient, 9 is horizontal tilt detector, 10 is tilt detector output signal, 11 is sum angle analog signal, 12 is analog integration circuit, 13 is analog integration output signal, 14 is difference Angle analog output signal, 15 is error signal integration circuit, 16 is cumulative error signal, 17
Is an error signal subtraction circuit, and 18 is an angle output signal.

Claims (1)

[Claims] 1. A rotation angle detector 1 for generating a pulse proportional to a rotation angle of a left wheel, a rotation angle detector 2 for generating a pulse proportional to a rotation angle of a right wheel, and a difference and a sum of the pulses. The difference pulse counter 5 and the sum pulse counter 6 which are respectively counted and output as digital signals and then converted into analog signals, a tilt detector 9 for taking out an output signal proportional to the acceleration in the axle direction, the tilt detector 9 and the above An analog integrating circuit 12 and an error signal integrating circuit 15 which are provided with a signal obtained by analogizing the digital signal of the sum pulse counter 6 to obtain an angle difference detection error or a correction value of the left and right wheels, and the difference pulse counter 5 are analogized. Error signal subtraction circuit 17 which receives the signal and the output of the error signal integration circuit 15
When the change in the wheel diameter is obtained from the acceleration in the axle direction by using and, the traveling direction is measured using the obtained dynamic wheel diameter, and when traveling on a sloping road or changing the traveling direction. A method for detecting the traveling direction of a vehicle, characterized in that it is possible to eliminate a measurement error that occurs in