JPH10197547A - Vehicle speed measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sense accurate speed information with good response regardless of period variation in velocity pulses. SOLUTION: A period measuring part 1 and speed calculation part 3 determine the car speed on the basis of velocity pulses generated for each period. An average speed calculation part 4 calculates the mean of the car speed for three periods. A speed comparing part 5 compares the current car speed given from the speed calculation part 3 with the averaged car speed given from the part 4, and if the difference is over a certain value, for example 0.5km/h, judgment is passed that the car speed itself has changed, and speed information to show the current car speed is emitted. If the difference is below 0.5km/h, judgement is passed that a period variation is generated in velocity pulses even if the car speed remains constant, and the averaged speed information is emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed measuring device which is preferably provided in a display system for a running speed of a normal automobile or the like, and more particularly to a device capable of stably displaying a vehicle speed and the like irrespective of fluctuations in the period of a speed pulse. The present invention relates to a vehicle speed measurement device.

[0002]

2. Description of the Related Art A conventional vehicle speed measuring device comprises a period measuring unit 51, a speed calculating unit 52, and a speed output unit 53 as shown in FIG. 4, and measures a current vehicle speed in accordance with each routine shown in a flowchart of FIG. It is designed to detect.

That is, the flowchart shown in FIG.
For example, when the ignition key of the vehicle is turned on, the process starts and the process proceeds to step S11.

In step S11, the cycle measuring unit 51
The cycle of a speed pulse from a speed sensor that detects the running speed of the vehicle is measured, and the cycle measurement data is used as the speed calculation unit 52
And the process proceeds to step S12.

More specifically, for example, FIG.
Assuming that a speed pulse is supplied from the speed sensor as shown in (a), the period measuring unit 51 calculates the time t1, time t2, and time t3 from the falling edge of the speed pulse to the next falling edge. Is supplied to the speed calculation unit 52 as the cycle measurement data.

Next, in step S12, the speed calculation unit 5
2 calculates the vehicle speed according to each cycle data as shown in FIG. 6 (b), and calculates the speed data V1, V2, V3,.
Is supplied to the speed output unit 53, and the process proceeds to step S13.

Then, in step S13, the speed output unit 53 outputs each speed data V as shown in FIG.
, V2, V3,... Are supplied to the speed meter, and all the routines shown in this flowchart are terminated.

The routines of steps S11 to S13 are repeatedly executed until the operation of turning off the ignition key is detected. Thereby, the traveling speed of the vehicle can be displayed on the speed meter.

[0009]

Here, the conventional vehicle speed measuring device measures the period of the speed pulse and detects the vehicle speed based on the measured period. Therefore, when the vehicle speed is constant. In addition, if the period of the speed pulse fluctuates at any time, erroneous speed data is output.

This problem can be solved by displaying the detected speed data without averaging the data and displaying the averaged data. The greater the number of speed data to be averaged, the more the above-mentioned periodic fluctuation can be absorbed, so that more accurate speed display can be performed.

However, if the number of speed data to be averaged is increased, the time required for this calculation is prolonged in proportion to this, so that it takes time to display the speed and the response to the actual vehicle speed is poor. New problems arise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a vehicle speed measuring device capable of detecting accurate speed information with good responsiveness irrespective of a period variation of a speed pulse. I do.

[0013]

According to the present invention, there is provided a vehicle speed measuring apparatus for solving the above-mentioned problems, based on speed information supplied from outside according to the vehicle speed, at predetermined intervals of the speed information. A periodic speed calculating means for calculating the speed information for each cycle calculated by the periodic speed calculating means, and averaging speed calculating means for averaging by adding a predetermined number of the speed information, and a current speed from the periodic speed calculating means. Speed information indicating vehicle speed,
Compare the averaged speed information from the averaged speed calculation means, if these speed differences are greater than or equal to a predetermined speed difference, select the speed information indicating the current vehicle speed, and Speed information selecting means for outputting as a vehicle speed value, selecting the averaged speed information when the speed difference is equal to or less than a predetermined speed difference, and outputting the averaged speed information as a current vehicle speed value. .

In such a vehicle speed measuring device, the speed difference between the speed information indicating the current vehicle speed from the periodic speed calculating means and the averaged speed information from the averaging speed calculating means is equal to or greater than a predetermined speed difference. Means that the vehicle speed itself has changed, not the periodic fluctuation of the speed information.
For this reason, in this case, the speed information selecting means selects the speed information indicating the current vehicle speed from the periodic speed calculating means, and outputs this as the current vehicle speed value.

The fact that the speed difference is equal to or less than the predetermined speed difference means that the vehicle speed itself does not change,
Indicates that the speed information has undergone periodic fluctuations for some reason. For this reason, in this case, the speed information selecting means selects the averaged speed information from the averaged speed calculating means and outputs this as the current vehicle speed value.

That is, when the periodic fluctuation of the speed information is detected, the speed information formed in such a manner that the periodic fluctuation is absorbed by the averaging is output, and when the change of the vehicle speed itself is detected, the current vehicle speed is detected. Output the indicated speed information.

As a result, speed information corresponding to the case can be output, so that accurate and accurate responsive speed information can be output.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle speed measuring device according to the present invention will be described below in detail with reference to the drawings.

A vehicle speed measuring device according to an embodiment of the present invention detects a period of a speed pulse indicating a current vehicle speed of the vehicle detected by a speed sensor as shown in FIG. 1, and outputs this period data. It comprises a cycle measuring section 1 and a speed calculation processing section 2 for calculating a current speed value of the vehicle based on the cycle data from the cycle measuring section 1.

A speed calculation processing unit 2 calculates a current speed of the vehicle based on the cycle data from the cycle measurement unit 1 to form current speed data, and a current speed calculated by the speed calculation unit 3. The averaged speed calculation unit 4 calculates the average speed of the previous speed calculated in the previous calculation and the previous speed calculated in the previous calculation and the speed before the previous calculation calculated in the previous calculation, and forms average speed data. A speed comparison unit 5 for switching and outputting the current speed data and the average speed data in accordance with a difference value between the current speed data and the average speed data from the averaged speed calculation unit 4, and each speed from the speed comparison unit 5 Speed output unit 6 that outputs speed value data corresponding to data
It is composed of

Next, the operation of the vehicle speed measuring apparatus according to the present embodiment having such a configuration will be described with reference to the flowchart shown in FIG.

The flowchart shown in FIG. 2 is started by, for example, turning on an ignition key, and proceeds to step S1.

In step S1, the period measuring unit 1 determines the time t1, time t2, and time t1 required from the falling edge of the speed pulse supplied from the speed sensor as shown in FIG. t3, time t4, time t5... are detected and supplied to the speed calculation unit 3 of the speed calculation processing unit 2 as cycle data, and the process proceeds to step S2.

In step S2, the speed calculation unit 3 determines whether the speed
As shown in (b), based on the cycle data, speed data V1, V2, V3, V4, V5 indicating the current vehicle speed.
.. Are calculated and supplied to the averaging speed calculation unit 4 and the speed comparison unit 5.

In step S3, the averaging speed calculating section 4
Is the speed data V of the current speed as shown in FIG.
1. The average speed data is formed by averaging the speed data V2 of the previous speed calculated at the previous calculation and the speed data V3 of the speed before the last calculated at the time of the last calculation (average speed data = (V1 + V2 + V3) ) / 3), which is supplied to the speed comparison unit 5 and proceeds to step S4.

In step S4, the average speed data is calculated, and the current speed data used in this calculation is used as the previous speed data in the next calculation. The current speed data is set as the previous speed data, and the speed data of the previous speed is set as the speed data two times before, and the process proceeds to step S5. Such updating of the speed data is performed every time the calculation of the average speed data is completed.

Next, at step S5, the speed comparison unit 5
Compares the average speed data calculated by the averaged speed calculation unit 4 with the speed data of the current vehicle speed calculated by the speed calculation unit 3, and the absolute value of this speed difference is, for example, “0.5 km
/ H ”or more. If the absolute value of the speed difference is 0.5 km / h or more (in the case of Yes), the process proceeds to step S6, and if the absolute value of this speed difference is 0.5 km / h or less (in the case of No, ) Proceeds to step S8.

In step S6, since the absolute value of the speed difference is equal to or greater than 0.5 km / h, the speed comparison unit 5 determines that the current vehicle speed has changed, and as shown in FIG. Among the current speed data supplied from the speed calculation unit 3 and the average speed data supplied from the averaged speed calculation unit 4, "current speed data" is selected and supplied to the speed output unit 6, and step S7 is performed. Proceed to.

The speed output unit 6 supplies the "current speed data" to the speed meter as a speed value. Thereby, the current speed changed from the constant speed can be displayed on the speed meter.

Next, in step S7, since the output of the speed value has been completed, the current speed data is used as the previous speed data at the time of the next calculation. The speed data is set as the previous speed data, and the entire routine shown in the flowchart of FIG. 2 is completed. The entire routine shown in the flowchart of FIG. 2 is repeatedly executed until the ignition key is turned off, for example.

On the other hand, if it is determined in step S5 that the absolute value of the speed difference is equal to or less than 0.5 km / h and the process proceeds to step S8, the speed comparing unit 5 determines that the absolute value of the speed difference is 0.5 km / h. / H or less, it is determined that the current vehicle speed has not changed, and the current speed data supplied from the speed calculator 3 and the current speed data supplied from the averaged speed calculator 4 as shown in FIG. Of the average speed data
"Average speed data" is selected and supplied to the speed meter via the speed output unit 6, and all the routines shown in the flowchart of FIG. 2 are completed.

This makes it possible to supply the speed meter with the average speed data that has absorbed the periodical fluctuation of the speed pulse, and to prevent the inconvenience that the vehicle speed displayed on the speed meter changes even though the vehicle speed is constant. Can be prevented.

When the speed difference between the current speed data and the average speed data is equal to or more than a predetermined speed (in this embodiment, 0.5 km / h or more), the current speed data is selected and output. Since the average speed data is selected and output when the data speed difference is equal to or less than the predetermined speed, the speed data can be output with good responsiveness in each case. Therefore, accurate and stable speed display can be achieved.

In the description of the above-described embodiment, a total of three average speeds of the current speed, the previous speed calculated at the time of the previous calculation, and the speed before last calculated at the time of the previous calculation are calculated and averaged. We decided to form speed data,
This is, for example, of the current speed, the previous speed calculated at the time of the previous calculation, the speed of the previous two times calculated at the time of the previous two-time calculation, and the speed of the two-time before and after calculated at the time of the two-time previous calculation.
Arbitrary changes may be made, such as calculating a total of four average speeds to form average speed data.

The present invention is not limited to the above-described embodiment which has been described by way of example. In addition, various modifications can be made without departing from the technical idea of the present invention. Of course.

[0036]

The vehicle speed measuring apparatus according to the present invention can detect accurate speed information with good responsiveness irrespective of the period variation of the speed pulse.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle speed measuring device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining a speed information detecting operation of the vehicle speed measuring device according to the embodiment.

FIG. 3 is a time chart for explaining a speed information detecting operation of the vehicle speed measuring device according to the embodiment.

FIG. 4 is a block diagram of a conventional vehicle speed measurement device.

FIG. 5 is a flowchart illustrating a speed information detecting operation of a conventional vehicle speed measuring device.

FIG. 6 is a time chart for explaining a speed information detecting operation of a conventional vehicle speed measuring device.

[Explanation of symbols]

 1 cycle measurement unit 2 speed calculation processing unit 3 speed calculation unit 4 averaging speed calculation unit 5 speed comparison unit 6 speed output unit

Claims (3)

[Claims] 1. A periodic speed calculating means for calculating a vehicle speed at predetermined intervals of the speed information based on speed information supplied from outside according to the vehicle speed, and for each cycle calculated by the periodic speed calculating device. Averaged speed calculating means for adding a predetermined number of pieces of speed information to each other to average the speed information; speed information indicating the current vehicle speed from the periodic speed calculating means; and averaged speed information from the averaged speed calculating means. If these speed differences are equal to or greater than a predetermined speed difference, speed information indicating the current vehicle speed is selected and output as a current vehicle speed value, and the speed difference is equal to or less than the predetermined speed difference. A speed information selecting means for selecting the averaged speed information and outputting the selected speed information as a current vehicle speed value. 2. Whenever the averaged speed information is calculated, the averaged speed information is updated while the oldest vehicle speed information used in the calculation is updated to new vehicle speed information. The vehicle speed measurement device according to claim 1, wherein the calculation is performed. 3. The periodic speed calculating means calculates a vehicle speed for each cycle of speed information supplied from outside according to the vehicle speed, and the averaging speed calculating means calculates the vehicle speed by the periodic speed calculating means. 3. The vehicle speed measuring device according to claim 1, wherein speed information obtained by averaging speed information for three cycles is calculated.