JP3348881B2 - Vehicle mileage calculation 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 vehicle mileage calculating device for calculating the mileage of a vehicle based on pulses from a speed generator.

[0002]

2. Description of the Related Art Heretofore, there has been known a traveling distance calculating device for a vehicle which calculates a traveling distance of a vehicle based on a pulse from a speed generator mounted on an axle. The speed generators of this travel distance calculating device are attached to, for example, non-drive shafts of front and rear wheels of the vehicle, respectively, and generate a predetermined number of pulses per rotation as the shaft rotates. Then, in order to prevent an error due to the sliding of the wheels during traveling, the number of pulses from both speed generators within a predetermined time is compared, and the pulse with the larger number of pulses is extracted.

[0003] This is because, when a wheel slides, the number of revolutions is relatively small, and the number of pulses is small as compared with a normal rotation without a slide. It is because there is less one. For example, assume that the number of pulses from the front wheel axle is 988 and the number of pulses from the rear wheel axle is 990 within the distance measurement time. In this case, 990 pulses from the rear wheel set are used to calculate the traveling distance.

[0004]

However, if the time for comparing the number of pulses is long, the front wheel and the rear wheel may slide many times during the comparison time. For example, 988 pulses from the front axle in the above example,
The number of pulses 990 from the rear axle is the number of pulses resulting from the presence of several runs in the comparison time, and the number of pulses without the run is 1000 in the comparison time.
Suppose it was an individual. In this case, even if the number of pulses from the rear wheel axle of 990 is used, an error of 10 pulses occurs.

On the other hand, for example, the comparison time is set to 1/100, and the number of comparisons is set to 100.
It is also considered to take out the pulse with the larger number of pulses from the front wheel axle and the pulse number from the rear wheel axle and integrate the number of pulses for 100 times. This is done by shortening the comparison time,
This is to make it easier to extract the pulse number of the person who is not running.

However, when the comparison time is shortened, a calculation error greatly affects the comparison time. This is because since the “number” of pulses within the comparison time is integrated, an error of the minimum unit of the pulse, that is, one pulse is expected in the integrated pulse number. In the case where the above-described about 1000 pulses are integrated and compared, one out of 1,000 pulses needs only an error of 0.1%, but in the case where about 10 pulses are integrated and compared, One out of ten results in a 10% error.

For this reason, an error of up to about 10% occurs in each of the 100 comparison sections, and a calculation error of 10% as a whole results in a calculation error of, for example, 1 km for 10 km. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problem, eliminate a running error due to gliding as much as possible, and make a calculation error hard to occur, and a vehicle running distance that can accurately calculate a running distance of a vehicle. It is to provide a calculation device.

[0008]

According to the present invention, there is provided a vehicle mileage calculating apparatus for generating a pulse corresponding to the rotation of each of a plurality of non-driving wheels. A pulse cycle measuring means for measuring a cycle of each pulse inputted from the pulse generating means, and a correction pulse cycle calculation for calculating a correction pulse cycle based on the latest pulse cycle and the corresponding wheel diameter which have been measured. Means, comparing the calculated correction pulse periods corresponding to the plurality of non-driven wheels with each other, and selecting the shortest one; and a vehicle based on the output pulse having the selected shortest correction pulse period. And a travel distance calculating means for calculating the travel distance of the vehicle.

[0009]

According to the vehicle mileage calculating device of the present invention having the above-described configuration, the pulse generating means generates a pulse corresponding to each rotation of the plurality of non-driving shafts, and the pulse period measuring means outputs the inputted pulse. Are measured respectively.
Then, the correction pulse cycle calculating means calculates the correction pulse cycle based on the latest pulse cycle whose measurement has been completed and the corresponding wheel diameter, and the selecting means corresponds to the calculated plurality of non-driving wheels. The correction pulse periods to be compared are compared with each other and the shortest one is selected. The calculating means calculates the traveling distance of the vehicle based on the output pulse having the selected shortest correction pulse cycle.

For example, it is possible to calculate the running distance by counting the number of output pulses over a predetermined distance measuring time and multiplying the number of output pulses by the running distance corresponding to one output pulse. As described above, since the rotation pulse of the non-driven wheel is detected, there is no influence due to the idling of the wheel. Also,
Pulses from a plurality of non-driving shafts often have different periods and phases due to slightly different wheel diameters, but according to the present invention, the pulse periods from each shaft are measured individually regardless of the phase. When the correction pulse cycle used for distance measurement is determined, the latest correction pulse cycle whose measurement has been completed is compared with each other and the shortest one is selected. Therefore, although the sections of the corrected pulse cycle to be compared do not exactly match, even if they are shifted, the cycle comparison within one pulse section is possible. In addition, since the shortest correction pulse period is selected, the vehicle travel distance can be calculated based on the pulse period from the axis where the gliding has not occurred or the gliding has occurred, even if the gliding has occurred. Accuracy can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram schematically showing a vehicle mileage calculating device according to an embodiment of the present invention. As shown in FIG. 1, the vehicle mileage calculating device of the present embodiment includes front and rear non-driving wheels (hereinafter simply referred to as front wheels and rear wheels) not shown.
Pulse generating means 1a, 1b attached to the axle of the vehicle and generating pulses corresponding to the rotation of the axle; pulse cycle measuring means 3a, 3b for measuring the cycle of the pulse output from the pulse generating means 1a, 1b; Correction pulse cycle calculating means 5a, 5 for calculating a correction pulse cycle based on a diameter or the like;
b, selection means 7 and travel distance calculation means 9. The suffix a indicates a component for a front wheel, and the suffix b indicates a component for a rear wheel.

The structure of the pulse generating means 1a, 1b will be described. Since the configuration for the front wheel is the same as that for the rear wheel, the pulse generating means 1a for the front wheel will be described below. A timing gear 11a made of a magnetic material is provided on the front wheel, and a number of timing teeth 13a are formed around the timing gear 11a at equal intervals.

A magnetic sensor 15a is provided opposite to the timing gear 11a. The magnetic sensor 15a is formed using a permanent magnet and a coil, and detects rotation of the timing gear 11a as a change in magnetic resistance. Therefore, when the timing gear 11a rotates with the rotation of the front wheels, an AC signal is output from the magnetic sensor 15a every time each timing tooth 13a passes, and the waveform shaping circuit 17b
Thus, the pulse is shaped into a pulse having a predetermined waveform, and then output to the pulse period measuring means 3a.

The rear wheel pulse generating means 1b also includes a rear wheel timing gear 11b, a magnetic sensor 15b, and a waveform shaping circuit 17b, and the input pulses Pia and Pib whose waveforms have been shaped are subjected to pulse period measurement. It is configured to output to the means 3b.

In the pulse period measuring means 3a, 3b, the period T of the input pulses Pia, Pib corresponding to the rotation of each axle is
ia and Tib are individually measured regardless of the phase difference.
The correction pulse cycle calculating means 5a and 5b calculate a correction pulse cycle A, which will be described later, based on the latest pulse cycles Tia and Tib for which measurement has been completed and the corresponding wheel diameters Da and Db.
Calculate Tia and ATib.

On the other hand, the selection means 7 corrects the correction pulse cycle ATi input from the correction pulse cycle calculation means 5a, 5b.
a, ATib are compared with each other, and the shorter one of them is selected. Then, the output pulse generation means 8 outputs a pulse corresponding to the short cycle selected by the selection means 7 to the output pulse Po.
Is output to the travel distance calculation means 9 as

The traveling distance calculating means 9 is constituted by a counter or the like, counts output pulses supplied from the output pulse generating means 8 over a predetermined distance measuring time, and counts the number of output pulses input within the distance measuring time. It is configured to be able to calculate. The operation of the thus configured vehicle mileage calculating device of this embodiment will be described with reference to the time chart of FIG. 2 in addition to FIG.

When the wheels rotate during traveling of the vehicle, input pulses Pia and Pib corresponding to the rotations of the front wheels and the rear wheels are generated by the pulse generating means 1a and 1b, and the pulse cycle measuring means 3a and 3b output the respective axles. Are individually measured. In FIG. 2, as shown in FIG. 2A, input pulses corresponding to the axles of the front wheels are represented in time series as Pia1, Pia2,..., And as shown in FIG.
a1, Tia2,... Similarly, as shown in (C), the input pulse is similarly applied to the rear wheel axle by Pib.
, 1, Pib2,..., And the corresponding pulse periods are represented by Tib1, Tib2,.

Next, the correction pulse period calculating means 5a, 5b
, The correction pulse periods ATia and ATib are calculated based on the latest pulse periods Tia and Tib whose measurement has been completed at the time of calculation and the corresponding wheel diameters Da and Db. First, there is a relationship as shown in the following equation between the input pulse cycle Tia for the front wheel axle and the correction pulse cycle ATia, and the correction pulse cycle ATia is obtained as in the following equation (3).

[0020]

(Equation 1)

Where, Lia: the distance of one input pulse corresponding to the front wheel axle Lo: the distance of one output pulse Nr: the number of pulses per rotation corresponding to the front wheel axle Da: the wheel diameter of the front wheel On the other hand, the input pulse to the rear wheel axle The relationship between the period Tib and the correction pulse period ATib has a relationship as shown in the following expression, and the correction pulse period ATib is obtained as in the following expression (6).

[0022]

(Equation 2)

Here, Lib: the distance of one input pulse corresponding to the rear wheel axle Lo: the distance of one output pulse Nr: the number of pulses per rotation corresponding to the rear wheel axle Db: the wheel diameter of the rear wheel The wheel diameter Da , Db may be different between the front wheel and the rear wheel, but the number of pulses in one rotation is the same regardless of the wheel diameter if the same number is set first.

The correction pulse period AT calculated as described above
ia and ATib are selected by the selection means 7 in a shorter cycle, and a pulse corresponding to the shorter cycle is selected as shown in FIG.
As shown in (E), the output pulse Po is output to the traveling distance calculating means 9. Here, when the correction pulse periods ATia and ATib are compared with each other in the selecting means 7 when the distinction is made in chronological order, a description will be given.

FIG. 2F shows the result in the case of this embodiment. For example, the first output pulse P in FIG.
correction pulse period calculating means 5a, 5a
When the calculation is started at b, the latest pulse periods for which the measurement has been completed at that time are Tia1 and Tib1. Therefore, their correction pulse periods ATia1, A
Tib1 becomes a comparison target cycle in the selection means 7,
The shorter of them is selected.

Similarly, when the second output pulse Po2 is determined, the latest pulse periods for which the measurement has been completed are Tia1 and Tib1, so that those correction pulse periods ATia1 and ATib1 are the comparison target periods. Become. Also, for example, when determining the fourth output pulse Po4, the latest pulse cycle for which measurement has been completed is Tia2 corresponding to the front axis, and Ta2 is the one corresponding to the rear axis.
ib3, and their correction pulse periods ATia2, A
Tib3 is the comparison target cycle. As described above, the same correction pulse periods ATia and ATib are not always to be compared.

Then, in the traveling distance calculating means 9,
The output pulse Po is counted over a predetermined distance measurement time, and the output pulse Po input during the distance measurement time is counted.
Is calculated. By multiplying the number of pulses by the travel distance Lo corresponding to one output pulse, the travel distance within the distance measurement time is calculated.

It has already been described that the sections of the pulse periods compared by the selection means 7 do not exactly match, and there is a delay of up to one pulse. The error is examined based on the following equation.

[0029]

(Equation 3)

Here, Vn: current speed Vf: speed one pulse before T: current pulse period a: acceleration Nr: number of pulses per rotation D: wheel diameter ε: speed error Expression (9) The speed error ε is an instantaneous speed error, for example, Vn = 50 km / h, a = 2 km / h /
Assuming that s, D = 810 mm and Nr = 60, the speed error ε
Is 0.01%.

The distance error E when the vehicle travels for a time t seconds from the stop state (initial speed 0 km / h) with the acceleration a is:
From the time average of the time integration of the above equation (9), it is obtained as in the following equation.

[0032]

(Equation 4)

In the equation (10), a = 2 km / h
/ S, t = 25 s (the reaching speed is 50 km / h), the distance error E is 0.01%. Thus, in the practical range, both the speed and the distance are sufficiently accurate. As described above, according to the vehicle mileage calculating device of the present embodiment,
Since the pulse from the non-drive wheel is detected, there is no influence due to the idling of the wheel. Also, the pulses from a plurality of (two in this embodiment) non-driving shafts often have different periods and phases due to minute differences in the wheel diameters Da and Db. Independent measurement,
When the correction pulse periods ATia and ATib used for distance measurement are determined, the latest correction pulse periods ATia and ATib whose measurement has been completed are compared with each other to select the shortest one.

Accordingly, the correction pulse period ATi to be compared is
The intervals of a and ATib do not exactly match, but even if they are shifted, the period can be compared within one pulse interval. Also, the shorter correction pulse period ATia, ATib
In order to select, it is possible to calculate the traveling distance of the vehicle based on the output pulse Po obtained from the axle in which no gliding has occurred, or even if gliding has occurred, which has less gliding, thereby improving the calculation accuracy. it can.

In the above embodiment, the calculation is performed based on input pulses from the front and rear two axes. However, the calculation may be performed based on input pulses from three or more axes if the axle is a non-driven wheel. In that case, the shortest one among the three or more correction pulse periods to be compared may be selected.

[0036]

As described above in detail, according to the vehicle mileage calculating apparatus of the present invention, even if the section of the corrected pulse cycle to be compared is shifted, the cycle can be compared within one pulse section. . In addition, since the shortest correction pulse period is selected, the vehicle travel distance can be calculated based on the pulse period from the axis where the gliding has not occurred or the gliding has occurred, even if the gliding has occurred. The error in running due to is eliminated as much as possible and the error in calculation hardly occurs,
There is an effect that the traveling distance of the vehicle can be calculated with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the present embodiment.

[Explanation of symbols]

ATia, ATib ... correction pulse period, Da, Db ...
Wheel diameter, Pia, Pib ... input pulse,
Po: output pulse, Tia, Tib: input pulse cycle,
1a, 1b: pulse generating means, 3a, 3b: pulse cycle measuring means, 5a, 5b: correction pulse cycle calculating means, 7: selecting means, 8: output pulse generating means,
9: Travel distance calculation means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-312303 (JP, A) JP-A-5-249127 (JP, A) JP-A 1-153909 (JP, A) 5165 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60L 3/00 G01C 22/02

Claims (1)

(57) [Claims] 1. A pulse generating means for generating a pulse corresponding to the rotation of each of a plurality of non-driving wheels; a pulse cycle measuring means for measuring a cycle of each pulse inputted from the pulse generating means; The correction pulse cycle calculating means for calculating the correction pulse cycle based on the latest pulse cycle and the corresponding wheel diameter, and comparing the calculated correction pulse cycles corresponding to the plurality of non-driving wheels with each other. And a travel distance calculating means for calculating a travel distance of the vehicle based on the selected output pulse having the shortest correction pulse cycle. Calculation device.