JPH0377067A - Rotating speed measuring instrument - Google Patents

Abstract

PURPOSE:To measure an accurate rotating speed by measuring the time between a pulse signal almost at the end time of a measurement time and a pulse signal almost at last measurement end time and calculating the rotating speed from the number of pulse signal which are outputted within that time. CONSTITUTION:A measuring means 6 measures a specific time Ts asynchronously with a pulse signal (f) from a pickup 8. Then when there is a signal (f) in the measurement time of the time Ts, an arithmetic means 11 calculates the time DELTAT between a signal (f) which is outputted at the time closest to the end time of the time Ts and a signal (f) which is outputted at the time closest to the end time of last time Ts. Then an arithmetic means 12 calculates the rotating speed V of a wheel by using the tie DELTAT and the number N of signal (f) from a counter 9. When a comparing means 10 decides that the number N of the signal (f) is 0, the counted value NP of the counter 13 is increased and an arithmetic means 14 calculates the rotating speed V by using the counted value NP. Therefore, the accurate rotating speed of the wheel can be measured from a fast rotating speed range to a slow rotating speed range.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rotation/speed measuring device, and in particular, it can be used to accurately measure rotation speed over a wide range from a low rotation speed region to a high rotation speed region. The present invention relates to a rotational speed measuring device that can accurately measure rotational speed.

(Prior art) For example, in a vehicle such as a car, a disk with protrusions provided at equal intervals on its outer circumference is attached to the rotating shaft of the wheel, and the protrusions are captured as a pulse signal using a pickup to determine the rotational speed of the wheel. Detection methods are known. This pulse signal will be generated at a period proportional to the rotation speed.

Below, a conventional rotational speed measuring method will be briefly explained.

(A) As shown in FIG. 6, the rotation speed is determined by counting the number n of pulse signals input within a certain time Ta and calculating n/Ta.

(B) As shown in FIG. 7, the period Tb of the pulse signal is measured using a clock pulse, and the rotation speed is determined by calculating 1/Tb.

However, in these methods, since there is an inherent error in digital measurement, that is, the measured value is accompanied by an error of ±1 count, the accuracy deteriorates in the low rotation speed range or the high rotation speed range, which is not preferable.

In other words, in the method (A) above, in the low rotation speed range, the number n of pulse signals manually input within time Ta decreases and the accuracy deteriorates, so either increase the pulse signal frequency or
The measurement interval (time Ta) must be lengthened. However, increasing the pulse signal frequency requires providing a large number of protrusions on the outer periphery of the rotating disk, which is a limit, and increasing the measurement interval is not preferable because it deteriorates the response to the input signal.

Furthermore, in the method (B), the period Tb of the pulse signal becomes short in the high rotational speed range, so the error with respect to the measurement clock pulse becomes large.

In order to solve these shortcomings, for example,
Japanese Patent No. 5265 discloses a rotational speed measuring device in which the measured value does not have an error of ±1 count. The rotational speed measurement method using this device is as shown in Figure 8.
A predetermined time Tc is measured in synchronization with the generation of a pulse signal, and the number of pulse signals generated during this measurement is calculated as a factor, and after the predetermined time Tc has elapsed from the start of measurement of the predetermined time Tc. The rotation speed is determined by measuring the time Td until the first pulse signal is generated and dividing the number n of pulse signals generated during the period Td by the time Td.

(Problems to be Solved by the Invention) The above-described conventional technology had the following problems.

That is, in the rotational speed measuring method described in the above publication, the parameters for calculating the rotational speed (time Td and number of pulse signals n) are determined when a pulse signal is generated for the first time after the elapse of a predetermined time Tc. Therefore, if the generation cycle of the pulse signal is extremely long, that is, if the wheels come to a sudden stop and the pulse signal is not generated for a long time after the predetermined time Tc has elapsed, the response to the human input signal will be extremely poor.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a good response to input signals even in an extremely low rotational speed range without causing an error of ±1 count in the measured value. The object of the present invention is to provide a rotational speed measuring device.

(Means and operations for solving the problem) In order to solve the above problems, the present invention measures a predetermined time Ts asynchronously with the pulse signal f output from the pickup, and
A pulse signal f output at a time before the measurement end time of s and closest to the end time, and a pulse signal f output at a time before the measurement end time of the previous Ts and closest to the end time. Using the time ΔT1 and the number N of pulse signals f output during the time ΔT, the rotational speed V is calculated every time Ts is measured, and when the measurement of Ts ends, ΔT
If it is not possible to determine the maximum expected rotational speed for each measurement of Ts, use the time Ts and the number of times NP when the pulse signal f is not output during the predetermined time Ts. The feature is that the rotation speed is estimated.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of one embodiment of the present invention.

In FIG. 2, reference numeral 7 denotes a protruding disk that is attached to the rotating shaft of a wheel of a vehicle and has protrusions provided at equal intervals on its outer periphery.

The pickup 8 detects the protrusion of the protruded disk 7,
Using this signal as a pulse signal f, the microcomputer 3
Output to 0. This pulse signal f is generated at a period proportional to the rotational speed.

The microcomputer 30 is a control device for a vehicle in which the rotational speed measuring device is mounted, and as is well known,
It is composed of a CPU 31, ROM 32, RAM 33, human output interface 34, and a common bus 35 that connects them. And this microcomputer 30
detects the wheel rotational speed V from the pulse signal f using a method described later, performs various calculations using the wheel rotational speed V, and controls various devices of the vehicle.

FIG. 3 is a flowchart showing the operation of one embodiment of the present invention, and FIG. 4 is a pulse signal t output from the pickup 8.
FIG.

In FIG. 3, first, in step S1, a predetermined time T
Measurement of s is started. The start of measuring Ts is performed asynchronously with the pulse signal f output from the pickup 8.

In step S2, N is set to O.

In step S3, it is determined whether or not the pickup 8 outputs the pulse signal f.

If the pulse signal f is not output, it is determined in step S6 whether or not a predetermined time Ts has elapsed.

If the time has not elapsed, the process returns to step S3.

If it is determined in step S3 that the pulse signal f has been output, the value of N is incremented in step S4. Then, in step S5, the time data at that time or the number of clock pulses TO corresponding to it is stored in the ink capture register (
(hereinafter referred to as ICR). Then step S
Move to 6.

Note that when the clock pulse number TO is taken in step S5, the clock pulse number stored in the previous process of step S5 is reset. That is, I.C.
Every time the pulse signal f of the pickup 8 is output, the current time data or data corresponding thereto is newly stored in R.

If it is determined in step S6 that the time Ts has passed, then in step S7 the pulse signal is sent from the pickup 8 at least once until N is a value exceeding 0, that is, until Ts is measured. It is determined whether f has been output.

If the pulse signal f has been output from the pickup 8 at least once before Ts is measured, in step S8, the value of NP that is incremented in step S13, which will be described later, is reset.

In step S9, the previous step S of this process is
The value of T1 set in IO is set to T2.

Furthermore, in step SIO, the value of TO taken in in step S5 is set to T1.

That is, as shown in FIG. 4, the time To taken into the ICH immediately before the end of the measurement of Ts is set to T1, and the time TI set in this previous process (that is, T s tt in this previous process) is set to T1. TI), which was set immediately before the end of the measurement, is set to T2.

In step S11, ΔT is calculated from the first equation.

ΔT-TI-T2 (L) In step S12, the rotational speed V of the wheel is calculated from the second equation.

-KXN/ΔT (2) Here, K depends on the number of protrusions formed on the protruding disk 7 (Fig. 2) and the diameter of the wheel on which the protruding disk 7 is rotationally driven. It is a constant that is determined.

After the process of step S12, the process ends.

In step S7, if it is determined that N is 0, that is, if the pulse signal f is not output from the pickup 8 even once until Ts is measured, in step S13, NP The value of is incremented. Therefore, if it is determined that N is O again in the next processing, the value of NP will increase.

In step S14, the rotation speed V of the wheels is calculated using the third equation.

V-to-/ (Ts XNP) -(3
) Note that K' is the number of protrusions formed on the protruding disk 7,
and a constant determined according to the diameter of the wheel on which the protruding disc 7 is rotationally driven and the predetermined time Ts.

The rotational speed V of the wheel is calculated after the measurement of Ts is completed, but if there is no output of the pulse signal f within the period of Ts, Iri calculation of the rotational speed V can be performed using the second formula. Can not. However, from the fact that no pulse signal f was output within the period Ts, it is possible to predict that the actual rotational speed is below a certain rotational speed. This third equation estimates the rotational speed V from the above-mentioned fact, and the rotational speed V estimated in this way is the maximum value of the rotational speed at which the NJ is performed.

FIG. 5 is a time chart showing an example of the relationship between the rotation speed V of the wheels and the pulse signal f output from the pickup 8. In FIG. 5, among the graphs showing the rotational speed V, the solid line shows the actual rotational speed of the wheel, and the broken line shows the rotational speed calculated according to an embodiment of the present invention. It is. Further, in the same graph, times t1 to t7 are the times at which the measurement of Ts ends, respectively.

First, at times t1 and t2, the rotational speed V is calculated using the second equation using ΔT and N count values (N-5 and 3) measured immediately before each time.

At time t3, since the pulse signal f has not been output in the immediately preceding Ts (period from time t2 to t3), V is calculated (estimated) using the third equation. At this time t3, NP is 1.

Similarly, time 4. 5. 6, from the third equation, V
is estimated. At this time 4.5.6, N
The value of P is incremented by 2, 3, .
It is 4.

At time t7, since the pulse signal f has been output at Ts immediately before that (period from time t6 to t7), V is calculated using the second equation. This time t7
In , N is 1.

In this way, in this embodiment, when calculating (Ts
(at the end of the measurement), the wheel rotational speed V can be estimated even if the pickup 8 does not output the pulse signal f.

In contrast, the conventional rotational speed calculation method
25265), it takes time to calculate V without inputting the pulse signal f, so when the rotational speed of the wheel is particularly slow, as shown by the two-dot chain line in FIG. The calculation timing is delayed, making it virtually impossible to accurately detect the rotational speed.

FIG. 1 is a functional block diagram of an embodiment of the present invention. In FIG. 1, the same reference numerals as in FIG. 2 refer to the same or equivalent parts.

In FIG. 1, the measurement clock φC for the time clock is F
It is manually input to RC1 and counted.

This count value is manually input to the ICR2.

When the pickup 8 outputs the pulse signal f, the ICR 2 takes in the count value of the input measurement clock φC as TO.

The N counter 9 counts the number of pulse signals f output from the pickup 8.

The Tstt measuring means 6 measures IL7 T s at a predetermined time.

That is, when the measurement of Ts starts, the count value of the N counter 9 is reset, and when the measurement of Ts ends, the count value of the N counter 9 is outputted as N.

Comparison means 10 compares whether the count value N of N counter 9 is greater than or less than 0, and if N is greater than 0, first energizes T2 register 4 and delay means 5.

The T2 register 4 takes in the value of T1 stored in the T1 register 3 (TO taken in from the ICR2 in the previous process) as T2 by the activation.

Due to the energization, the delay means 5 causes the value of T1 in the west of the T1 register 3 to change to the value in the T2 register 4 after the scheduled time has elapsed.
T1 register 3 is activated. As a result, the T1 register 3 receives the T output from the ICR2.
Take O as T1.

The comparison means 10 further resets the NP counter 13 and energizes the ΔT calculation means 11.

The ΔT calculation means 11 calculates the T1 value stored in the T1 register 3.
, and T2 stored in the T2 register 4, ΔT is calculated from the first equation shown above.

The first V calculation means 12 uses the calculated ΔT1 and the count value N output from the N counter 9 to calculate the rotational speed V of the wheel from the second equation.

This calculated ■ is output to various calculation devices.

If the count value N output from the N counter 9 is determined to be 0 by the comparing means 10, NP
The count value NP of the counter 13 is incremented,
Then, the value of NP is output to the second v11f calculation means 14.

The second V calculation means 14 uses the value of NP to calculate the third
The rotational speed V of the wheel is calculated from the formula.

Now, in the above explanation, as shown in Figure 2,
Although the explanation has been made assuming that the pulse signal f output from the pickup 8 is taken into the microcomputer 30 and the rotational speed is measured in the microcomputer 30, the present invention is not particularly limited to this.
It goes without saying that the functions shown in FIG. 1 may be achieved by assembling hardware.

Furthermore, in the above description, the present invention was applied to detecting the rotational speed of wheels of vehicles such as automobiles, but it goes without saying that the present invention may be applied to detecting the rotational speed of any object other than the rotational speed of wheels. It is.

(Effects of the Invention) As is clear from the following explanation, according to the present invention, the following effects are achieved.

That is, when the pulse signal f is output during the measurement period of the predetermined time Ts, the pulse signal f output before the measurement end time of Ts and closest to the end time and the previous Ts The time ΔT between the pulse signal f and the pulse signal f that is output before the measurement end time and closest to the end time.
, and the number N of pulse signals f output during the time ΔT
Since the rotational speed V is calculated using , the measured value (the rotational speed V to be detected) does not have an error of ±1 count. Therefore, it is possible to accurately measure the rotational speed even in the high rotational speed range to the low rotational speed range.

In addition, when the pulse signal f is not output during the measurement period of the predetermined time Ts, prediction is made using the time Ts and the number of times NP when the pulse signal f is not output during the predetermined time Ts. The maximum rotational speed among the rotational speeds to be calculated is calculated. The rotational speed calculated in this way is only an estimated value, but by using this estimated value, a value closer to the actual rotational speed can be used in various calculations than when the rotational speed is not calculated as in the past. It will be used.

That is, even in an extremely low rotational speed region, a relatively accurate rotational speed is detected every predetermined time Ts, and there is no risk that responsiveness to input signals will deteriorate.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of an embodiment of the present invention. FIG. 2 is a block diagram of one embodiment of the present invention. FIG. 3 is a flowchart showing the operation of one embodiment of the present invention. FIG. 4 is a diagram showing the pulse signal f output from the pickup. FIG. 5 is a time chart showing an example of the relationship between the rotation speed V of the wheels and the pulse signal f output from the pickup. 6 to 8 are diagrams for explaining the conventional rotational speed detection method. 1...FRC, 2...ICR, 3...T1 register, 4...T2 register, 5...delay means, 6...
- Ts measuring means, 7... projection disk, 8... pickup, 9... N counter, 10... comparison means, 1
DESCRIPTION OF SYMBOLS 1...ΔT calculation means, 12... 1st V calculation means, 1
3... NP counter, 14... 2nd v calculation means, 3
0...Microcomputer

Claims (1)

[Claims] (1) A pulse generating means that generates a pulse signal according to the rotation speed, and a T that measures a predetermined time Ts asynchronously with the pulse signal.
s measurement means, a pulse signal f outputted at a time before the measurement end time of Ts and closest to the end time, and a pulse signal f outputted at a time before the previous measurement end time of Ts and closest to the end time. ΔT calculating means for measuring the time ΔT between pulse signals f outputted during a predetermined time Ts; pulse signal counting means for counting the number N of pulse signals f output during a predetermined time Ts; a comparison means for determining whether the number N exceeds 0, a first V for calculating the rotational speed V every time a predetermined time Ts is measured using the number N and the time ΔT; a calculation means; when the number N is 0, a predetermined time Ts, and a number N of times when the pulse signal f is not output during the time Ts;
A rotational speed measuring device comprising: a second V calculating means for calculating the maximum rotational speed of the predicted rotational speeds every time a predetermined period of time Ts is measured using P.