JPS60194827A - Pulse counter - Google Patents

Abstract

PURPOSE:To attain high-speed counting by adoting the design that a mean value between the present and preceding count values is adopted when the difference between the said mean value and the present count value is smaller than + or -1 and the present count value is adopted when the difference is larger to eliminate an error of + or -1 without increasing the resolution of a pulse transmitter. CONSTITUTION:An output pulse of a pulse oscillator 1 is counted by a prescribed sampling period by a counter 2, the count value is fetched to a controller main body 3 and fed to a control variable 4. In case of the sampling, a mean value is obtained at the 1st time while regarding the same value for the preceding time, and since the mean value is equal to the count value in this case, the value is adopted. A mean value N between the preceding count value N1 and the present count value N2 is obtained at the 2nd and succeeding operation and when the difference between the value N and the present value N2 is smaller than + or -1, the count value N is brought into count values N1, N2 after correction, and when the present mean value is larger, both the preceding and present count values are adopted. As a result, the error is halved, the instability of the control system is eliminated and the control with good response is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a pulse counting device that counts the number of pulses per unit time.

(Prior art and problems) Pulse counting is used for many measurement controls such as speed detection and numerical control using pulse pickups for feedback speed control of electric motors, as well as process control using simple analog-to-digital conversion that accumulates analog signals as pulse numbers. used for. This count is counted every time, and the counted value is taken into the control device body 3, such as a microcomputer, as a digital quantity. The counting time of the counter λ is set as a sampling periodic signal from the main body 3 by its reset, and the counted value of the caran tacho immediately before the reset is taken into the main body 3 as a digital quantity.

The main body 3 controls the two control objects according to data such as pulse count values, and is provided with a pulse transmitter/as one of the control amount detection means for the control object l.

In such a pulse counting device, an error of 11 Hals occurs in the count value of the counter depending on the sampling period and sampling timing at which the counter 2 is reset. For example, as shown in FIG. 2, the sampling period T and the sampling timing t for the output pulse of the pulse generator/. ,tl.

The count value due to t is the period t0 in pulse rising counting.
~t□ and t1~t both have the same count value 12N, but
The period t is used for counting the falling edge of the pulse. −70 and count value I21
l/(On the other hand, the count value becomes 1fi31 during the period t1 to t. Such errors appear irregularly depending on the sampling timing and sampling period, and when a differential component exists in the control loop as shown in Fig. 1, It may make the control system unstable, and it remains as an error even when applied to an oven-loose control system.

In order to reduce the influence of this error, the sample data can be smoothed using a moving average of several terms, or the resolution of the pulse oscillator can be increased (higher frequency). There is a known method to relatively reduce the error. However, the former method causes a detection delay, that is, a control delay in the control system, due to data smoothing, and cannot be applied to high-speed control.

On the other hand, the resolution of the latter is limited by control from the transmitter/mechanism (for example, limiting the number of slits in the rotating body).

(Object of the Invention) An object of the present invention is to provide a complete pulse counting device that can perform high-speed counting without reducing the resolution of the pulse oscillator and eliminating an error of ±1.

(Summary of the Invention) The present invention provides an average value of the count value before the 1t sampling period and the count value in the current Templing period. When the difference between this average value and the count value in the current sampling period is less than ±1, the average value is used as the count value in the current sampling period and the previous sampling period. By using the count value as it is and setting the count value in the previous sampling period at the next sampling time as the count value from the time before the previous one, +:
It is characterized by correcting a counting error of 1.

(Embodiment) In the counting device of the present invention, when the control device main body 3 in FIG. Perform correction processing before using as a. Further, when the control device main body 3 does not have enough room for correction processing, a new correction processing means is provided between the counter 2 and the main body J. In either case, the count value of the caran taco is corrected as a preprocessing (front process) to be used as count value data in the control device main body 3. The 70-chart for this correction process is the 8th
As shown in the figure.

In Figure 3, the data (count value) in the current sampling cycle is compared to the count value in the first sampling cycle.
Nta: Take in (step Ell), and since data N1 from the previous sampling period one sampling period ago does not exist, the current data Ni--1'' is set as the previous data N8 (step s2).

For the count values in the second and subsequent sampling cycles, data N in the current sampling cycle is loaded (step S3), and the process in step S2 is omitted because data N in the previous sampling cycle exists. do. After importing or setting such data N*+Nl, the current data N
, and the previous data N.

Calculate the forward and backward moving average data N using (step s4
).

N--(N, 10N,) ・・・・・・・・・・・・(
1) To determine whether there is a difference of 11 or more between this average data N and the current data N (step 85), IN-N
, l (1...... (2), the average data N is set as the corrected data bird of the current data N, and is also made the t data bird' of the previous data N, (step 86).

+N-N, +≧1 ・・・・・・・・・・・・When (3), the current data N is set as the corrected data, and the previous data N is set as the corrected data. (step 87). The modified data NI+Ni obtained in step 86°S7 is used as data for the control device main body 3. Then, the current data N is transferred as the previous data N1 (step S8), and the process is repeated to return to step S8.

Through such correction processing, if there is a difference of 1 between the previous data N1 and the current data N, the average value N is set as the corrected data Nl + N1.
, Since the previous data N1 is used in all the next processing (step SS), an error of +:1 due to differences in sampling period or sampling timing is corrected to the moving average value N of the previous data and current data, and the error is is halved. Then, the next average value N is determined in step S8 because the previous data N1 is N, so the error is zero.
The change in the data used in the control device main body 3 (correction data C) does not result in a change of + or l:! : Changes in increments of 0.5 will eliminate unstable control of the control system. For example, if the previous data N is 1551 and the current data N is 15 (3N), the average data N is 155.51. In the next sampling, the previous data N is 1561 and the current data M is 15 (31). Even if the data used is 1
5 (becomes 3N. At this time, the data used for main body 3 is the current data 155# → #5551 → 15 (3N previous data 155# shout 15 residence l → 15 (changes like 3g, etc.)
Even if there is an error of 21 in the counted value, it is 155' to 15f31
The previous data and the current data always match, and the arithmetic control using them will not include an error of 2L.

In addition, the correction process requires a lot of processing that uses the previous data N This improves responsiveness.

Note that if there is a difference of 12 or more between the previous data N□ and the current data N, the husband's data N is changed in step S7.
By using 1+Nl as is, it is possible to perform control that follows changes in the number of output pulses (changes in detected values) of the pulse generator/itself with good responsiveness.

(Effects of the Invention) As described above, according to the present invention, it is possible to eliminate counting errors of +1 due to the sampling period or timing, and to perform count value processing with improved responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a control device for explaining a pulse counting device, FIG. 2 is a time chart for explaining pulse counting errors, and FIG. 3 is a flow chart for explaining an embodiment of the present invention. . /...Pulse transmitter, λ...Kakunta, 3...Control device main body, Hiro...Controlled object.

Claims (1)

[Claims] In a pulse counting device that obtains output pulses from a pulse oscillator as a count value of a counter that counts at a predetermined sampling period, data N at the current sampling period obtained as the count value, and data N1 at the previous sampling period one sampling period ago. and a first processing means for calculating an average value N of the data N, and when the difference between the average value N and the data N is smaller than ±l, the average value N is calculated from the corrected data set in the current sampling period and the previous data set. a second processing means for converting the data in the current sampling cycle into a corrected data set; and an eighth processing unit for processing the data in the current sampling cycle as data in the previous sampling cycle with respect to the data in the next sampling cycle. - Characteristic pulse counting device.