JPS6312967A - Angular velocity measuring instrument for vehicle - Google Patents

Abstract

PURPOSE:To measure the angle of a vehicle with high accuracy, by constituting the titled device so that the speed of the right and left wheels, obtained by the output of a wheel revolving frequency sensor can be corrected by the output of a non-contact ground speed sensor. CONSTITUTION:Wheel revolving frequency sensors 1, 2 are attached to left and right rear wheels 3, 4, respectively, and detect its revolving frequency. In such state, for instance, a vehicle is turning at a speed (v) on the periphery whose radius is R, and its advance direction is varied by DELTAtheta extending from the time (t) to the time DELTAt. As a result, a processing circuit 5 counts the output pulses of the sensors 1, 2 within the time DELTAt, and derives the left and right wheel speeds vL', vR', and subsequently, the speed v' of the vehicle. Also, the processing circuit 5 derives an average ground speed (v) within the time DELTAt from the output of a non-contact ground speed sensor 9. Said speed (v) and v' should coincide with each other originally, but they do not coincide because the speed v' derived from the sensors 1, 2 contains a large error due to a slip, etc., of the wheel. The processing circuit corrects the speeds vL', vR' so that the speed v' coincides with the speed (v), and derives the angular velocity by using the corrected speeds vL, vR.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention particularly relates to a vehicle angular velocity measuring device used in a navigation system that displays the current position and traveling direction of a vehicle on a map.

[Conventional technology]

FIG. 3 is a configuration diagram of a conventional vehicular angular velocity measuring device used in a navigation system. In the figure, 1, 2
are wheel rotation speed sensors attached to the left and right rear wheels 3 and 4, respectively, to detect their rotation speed; 5 is a processing circuit that inputs the output signals of these wheel rotation speed sensors 1 and 2 to calculate the angular velocity of the vehicle; and 6 is the rear wheel axle, and 7 and 8 are the left and right front wheels, respectively. The wheel rotation speed sensors 1 and 2 are sensors of the basic air pickup type and generate N pulses per rotation of the wheel. If the length of the wheel is L (nm), the weight C of the pulses of wheel rotation speed sensors 1 and 2 is L/N (w/pulse).
It is.

Next, the operation of the above device will be explained. In FIG. 4, it is assumed that the vehicle is turning at a speed V on a circumference with a radius R, and the geometrical properties are maintained so that neither slip nor skid occurs. Further, it is assumed that the turning center is on an extension of the rear wheel axis 6. When the vehicle changes its traveling direction by Δθ within a time Δ, the left and right wheel rotation speed sensors 1 and 2 within a time Δ
Let the pulse count values of PL and PFI respectively, and the weight of each pulse be C, then the left and right rear wheels
The speed of v5. − is given by the following equation.

v, = (c x PIL) /Δt
filvA=(CxP n)/Δt(2) Also, from Figure 4, (R-d/2)・Δθ=v,・Δt(3)(R+d/2
)−Δθ=v,'Δt(4) holds true. However, d is the rear tread. (3).

By eliminating d/2 from equation (4), the following equation is obtained.

R・Δθ=(vL+yFl)HΔt/2 (
5) Also, since R·Δθ=V·Δt (6), the speed V of the vehicle is given by the following equation from equations (51, +61).

v = (v, + vI) / 2
(7) Next! 31. When R is eliminated from the +41 formula, Δθ= (v, -v,) ・Δt/d
(81 Therefore, if Δt→0, the angular velocity ω
is ω=Δθ/Δt = (v, v, )/d (Δt
→0) Given by (9).

From the above, the processing circuit 5
Obtain the angular velocity of the vehicle by counting the pulses of , and calculating the equations (1), (2), and (9) based on this count value.

[Problem that the invention aims to solve]

The conventional angular velocity measuring device for a vehicle is constructed as described above, and the angular velocity is calculated on the premise that the effective distance of the wheel remains unchanged while the vehicle is running, and that slips, skids, etc. do not occur. However, during actual driving, such fluctuations in wheel height, slips, skids, etc. always occur, and these lead to errors in the measurement of angular velocity, resulting in a problem of extremely low accuracy.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a vehicle angular velocity measuring device that can measure the angular velocity of a vehicle with high precision.

[Means for solving problems]

The angular velocity measuring device for a vehicle according to the present invention includes a wheel rotation speed sensor that detects the rotation speed of left and right rear wheels, a non-contact ground speed sensor that measures the ground speed of the vehicle, and a calculation based on the signals of these sensors. and a processing circuit for obtaining the angular velocity of the vehicle.

[For production]

In this invention, the value obtained from the wheel rotation speed sensor that includes errors due to vehicle running conditions, road surface conditions, etc. is corrected using the output of the non-contact ground speed sensor, and the angular velocity of the vehicle is obtained from this corrected value. .

〔Example〕

FIG. 1 is a block diagram of a vehicle angular velocity measuring device according to an embodiment of the present invention. In the figure, 1 to 8 are the same as the conventional device shown in FIG. The explanation will be omitted. Further, reference numeral 9 denotes an ultrasonic Doppler speed sensor as a non-contact ground speed sensor disposed at the center of the rear axle 6.

Next, the operation of the vehicular angular velocity measuring device having such a configuration will be explained using FIG. 2.

In FIG. 2, it is assumed that the vehicle is turning at a speed V on a circumference of approximately radius, and changes its traveling direction by Δθ within a time Δ from time t. Similar to the conventional example, the processing circuit 5 processes the time Δ
Count the output pulses of the left and right wheel rotation speed sensors 1 and 2 in L, and use equations 1 and 2 to calculate the left and right wheel speed v', .
Find v'.

Then, the vehicle speed V' is determined using Equation 7. Furthermore, the processing circuit 5 determines the average ground speed V within a time period Δ from the output of the ground speed sensor 9. These two speeds V and V'
should originally match, but wheel rotation speed sensors 1 and 2
The speed V' obtained from the above method does not match because it contains a large error due to factors such as the wheel slip mentioned above. The processing circuit 5 adjusts the left and right wheel speeds V' so that the speed V' matches the speed V.

Correct v/8 and use the corrected speed -2v8 (
9) Find the angular velocity from the formula.

Next, an example of the correction method will be described. Generally, when a car is turning, the effective distance of the outer wheels becomes smaller due to lateral acceleration. Therefore, when the car is turning to the right, v, = v', + 2 vt
(14v, = v,
The angular velocity is determined from equation (9) by correcting (11). In the case of left turn, v, = v L(lノv, = v', -2vε (1
1 and calculate the angular velocity from equation (9).

In the above embodiment, the non-contact ground speed sensor 9 was installed at the center of the rear axle 6, but it is not limited to this position, and if the position from the left and right rear wheels 3 and 4 is determined, it can be installed at the center. It doesn't have to be.

〔Effect of the invention〕

As described above, according to the present invention, the left and right wheel speeds obtained by the output of the wheel rotation speed sensor are corrected by the output of the non-contact ground speed sensor to calculate the angular velocity of the vehicle, so that the angular velocity with high accuracy can be calculated. This has the effect of making it possible to measure

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a vehicle angular velocity measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing the operation of a vehicle to which the vehicle angular velocity measuring device is applied when turning, and FIG. 3 is a diagram of a conventional vehicle angular velocity measuring device. FIG. 4 is a block diagram of the angular velocity measuring device for vehicles, and is a diagram showing the operation of the vehicle when turning, to which the angular velocity measuring device for vehicles is applied. 1.2...Wheel rotation speed sensor, 3,4...Rear wheel-
15... Processing circuit, 9... Non-contact ground speed sensor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A wheel rotation speed sensor that detects the rotation speed of the left and right rear wheels of the vehicle, a non-contact ground speed sensor that is installed at a predetermined position on the vehicle and measures the vehicle's ground speed, and these wheel rotation speed sensors and non-contact ground speed sensors. Input the output of the speed sensor and
An angular velocity measuring device for a vehicle, comprising a processing circuit that corrects the output signal of the wheel rotation speed sensor with the output signal of the non-contact ground speed sensor and calculates the angular velocity using the corrected value.