JPS601566A - Speed detector - Google Patents

Abstract

PURPOSE:To enable accurate detection of average speed even when the rotating direction varies by determining the rotating direction by a two-phase pulse to compute the difference between the average rotational speed in the positive direction and that in the negative direction resulting in the average rotational speed. CONSTITUTION:The sampling period Stau of positive and negative pulse counters 19 and 20 is controlled with a timer counter 17 for counting the specified number of clocks. Pulses are counted with counters 18 and 19 respectively according to the positive and negative rotational speeds depending on the decision on a two- phase pulse with a pulse generator 2A and a rotating direction detector 13 and counts NP and NN are latched with latch circuits 22 and 23. The period PN from the final pulse to the end of the time Stau is latched with the time counter 18 and a latch circuit 21. A device 28 computes the difference V between the average rotational speeds in the positive and negative directions based on the formula depending on the contents of these circuits 21-23 and the period PN-1 prior to one cycle of a memory 29 to make the average rotational speed. Thus, accurate detection of the average speed can be done regardless of change in the rotating direction.

Description

Detailed Description of the Invention [Technical Field to Which the Invention Pertains] The present invention relates to a method for controlling the repetition period of output pulses from a pulse generator that is driven by a rotating shaft such as a motor shaft and outputs pulses. The present invention relates to a speed detection device that detects the rotational speed of the rotating shaft.

[Prior art and its problems]

FIG. 1 is a block diagram showing a conventional example of this type of speed detection device. In the same figure, ■ is a reference clock pulse generator, and 2 is a pulse generator (tachogenerator PG) driven by a rotating shaft (not shown). , 3 is the frequency division counter 0
Here, the frequency division counter 3 is the reference clock pulse generator 1
Counts the clock pulses from 1 to 4 corresponding to the sampling period TO, and outputs a pulse every time the counting is completed.

4 is a T counter. Note that the T counter 4 receives and counts clock pulses from the reference clock generator 1, and is a counter that is reset each time an output pulse from the pulse generator 2 is input. 5 is an N counter for counting output pulses from the pulse generator 2, 6.11 are delay circuits, 7, 9.10 are buffer counters, and 8 is an arithmetic unit.

FIG. 1A is a chart showing the timing relationship of each part in the circuit of FIG. In the figure, a indicates the clock pulse generated from the reference clock pulse generator 1, b indicates the sampling pulse output from the frequency division counter 3 at each sampling period TO, and C indicates the output from the pulse generator 2. Indicates pulse.

The output pulses from the O pulse generator 2, the operation of which will be explained with reference to FIGS. 1 and 1A, are counted by the N counter 5. The T counter 4 counts the clock pulses from the reference clock pulse generator 1, is reset by the output pulse from the pulse generator 2, and then starts counting again.The zero frequency divider counter 3 counts the sampling pulses every sampling period TO. Output.

When the buffer counter 9 receives a sampling pulse with a slight time delay via the delay circuit 11, the buffer counter 9 receives the sampling pulse T.
Load the contents of counter 4. The buffer counter 7 is
When a sampling pulse is input, the contents of the N counter 5 are taken in. When the N counter 5 receives a sampling pulse with a slight time delay via the delay circuit 6, it is reset and starts counting again. The buffer counter 10 holds the contents of the buffer counter 9 in the previous sampling period.

As a result of the above, it will be understood that the buffer counter 9 holds a value corresponding to the period length T in FIG. 1A, and the buffer counter 10 holds a value corresponding to T. Also, the content N of the buffer counter 7 is
In the current example, it is 3. Also, the value of (T, +T-T) is
It will also be seen from the first AIJ that one time corresponds to the length of three periods of the output pulse.

Therefore, in the arithmetic unit 8, the value F obtained by performing the calculation N/(To + T-T) is the average value in one sampling period of the repetition period of the output pulses generated from the pulse generator 2 (not shown). It can be seen that the average speed of the shaft is

The conventional speed detection device as explained above has no problem when the rotating shaft rotates only in one direction (either the forward direction or the reverse direction), but within one sampling period, the rotation direction is in the forward direction. There was a problem when there was a change in the opposite direction or vice versa.

In other words, for example, if the rotating shaft rotates in the forward direction in the first half of one sampling period and rotates in the opposite direction in the second half, the average speed of the rotating shaft should be zero after subtraction, but the conventional speed detection device Since the N counter 5 unilaterally counts and adds up the pulses output from the pulse generator 2 regardless of the rotational direction of the rotating shaft, the average speed of the rotating shaft never becomes zero.

When trying to control the motor speed near zero, the motor shaft may repeat minute rotations in the forward and reverse directions, but in such cases, the rotation speed detected by a conventional speed detection device will never reach zero. [Objective of the Invention] The present invention has been made to solve the above-mentioned disadvantages in the prior art. An object of the present invention is to provide a speed detection device capable of detecting an average speed that takes into account the positive and negative directions of rotation, regardless of how the direction of rotation changes within a sampling period. The invention focuses on the fact that a pulse generator outputs two-phase pulses with a phase difference of 90 degrees from each other.The two-phase pulses are used to determine whether the rotation direction is positive or negative, and the average rotation speed in the positive direction and the average rotation speed in the negative direction are determined. The difference between the average rotational speed and the difference between the two is taken as the average rotational speed.

[Example of practical invention h1] The present invention will now be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 1A is a time chart of various signals in FIG. In these figures, 2 are pulse generators, 12.12 is a two-phase pulse signal, 13 is a rotation direction detector, 14 is a time counter reset signal, 1 is a positive direction pulse signal, 16
is a reverse pulse signal, 17 is a timer counter, 18 is a time counter, 19 is a forward pulse counter, 20 is a reverse pulse counter, 21 to 23 are latches, and 24
is a counter reset signal, 25 is a hold and interrupt signal, 2
6 is a reference clock, 27 is a bus, 28 is an arithmetic unit, 29
is a storage device.

Referring to FIGS. 2 and 2A, a reference clock 26 outputted from a clock source built into the 0 arithmetic unit 28 is a holding and interrupt signal 25 outputted by the timer counter 17 at each sampling time ST interval, and a counter reset signal. signal 2
h1° at the counter 18 at 31°
counted.

On the other hand, the two-phase Hals 12°12(
90 degrees out of phase with each other) is the rotation direction detector 13
is converted into a clock force unreset h fi1 14, a forward direction pulse signal 15, and a reverse direction pulse signal 16,
The reset signal 14 is applied to a time counter 18, and the pulse signals 15 and 16 are counted by a forward pulse counter 19 and a reverse pulse counter 20, respectively.

The latches 21, 22.23 are activated by the holding and interrupt signals 25 to control the counters Is, 19. The contents of zo are held and the counters 19 and 20 are reset by the reset signal 24. Each time the arithmetic unit 28 receives the holding and interrupt signals 25, the contents of the latches 21t22t23 are calculated as the time Pn1, the number of pulses in the forward direction, Np1, the number of pulses in the backward direction, from the counted pulse position immediately before the sampling time elapses to the sampling pulse position (sampling time elapsed). From a similar value Pn-1 taken in as pulses iI & NN and stored in the storage device 29 one sampling period earlier than Pn, calculation is performed according to the following equation (1) to calculate the rotational speed (2).

FIG. 3 is a block diagram showing another embodiment of the present invention, FIG.
This figure is a chart showing the timing relationship of signals of various parts in the own path of FIG. 3.

In these figures, the same elements as in FIGS. 2 and 2A are given the same reference numerals. In addition, 30 is a timer, 31 is a frequency divider, 32 and 32A are each a forward direction pulse counter, 33 and 33A are each a reverse direction pulse counter, 34 and 34A are each a time counter, 35.36
are counter selection signals, and 37 is an interrupt signal.

Please refer to FIG. 3 and FIG. 3A. The reference clock 26 outputted from the clock source built into the arithmetic unit 28 is transmitted to the frequency divider 3.
1, it is converted into a counter selection signal 35, 36 which is output every time during the sampling time ST, and the counter 32,
33.34.32A.

33A and 34A.

On the other hand, the two-phase pulse 12°12 from C/' It is used to reset the time counters 34, 34A, and the pulse signals 15, 16 are counted by the counters 32.degree. 32A, 33.33A.

The counters 32, 33, and 34 are set when the counter selection signal 36 is high.
A clock count at level is performed, a clock count at L level is prohibited, and resetting of the counter 34 is also prohibited. Counter 32A.

33A and 34A operate in the same manner as the counters 32#33 and 34 described above in response to the counter selection signal 35.

Each time the arithmetic unit 284 receives an interrupt signal 37 from the timer 30, it reads the contents of the counter 34 several times and determines the magnitude of these values, thereby knowing which counter group is prohibited from counting. For example, counters 32, 33, 34
If counting is prohibited, the value of the counter 34 is calculated as the time Pn1 from the counted pulse position immediately before the sampling time elapses to the sampling pulse position (sampling time elapsed).
The value of the counter 32 is converted to the number of positive direction pulses Np1 counter 33
The value of Pn is read as the number of backward pulses NN, and then the counters 32, 33, and 34 are reset to zero, and the previous value Pn of Pn stored in the storage device 29 is read.
−1 and calculate the rotational speed according to equation (1) above.
I put it on.

According to this embodiment, all the required counters are prepared in two sets and are used by switching them alternately, thereby eliminating the need for the latch required in the embodiment of FIG. 2.

FIG. 4 is a block diagram showing still another embodiment of the present invention, and FIG. 4A is a chart related to the timing of various signals in the circuit of FIG. 4.

In these figures, the same elements as in FIGS. 2 and 2A are given the same reference numerals. In addition, when the pulse signal 41 outputted from the rotational direction detector 13 is inputted to the time counter 18, it becomes the reset signal, and when inputted to the addition/subtraction counter 40, the pulse signal 41 outputted from the rotational direction detector 13 also becomes a reset signal for the addition/subtraction counter 40. This is a signal that becomes an addition pulse or a subtraction pulse according to the rotation direction (No. 8 42 polarity level (H level for forward rotation, L level for reverse rotation). 21 and 21A are latches, respectively.

The operation will be explained with reference to FIG. 4 and FIG. 4A.

A reference clock 26 from a clock source built into the arithmetic unit 28 is converted by the timer counter 17 into a holding and interrupt signal 25 and a counter reset signal 24 that are output at each sampling time ST interval, and is also sent to the time counter 18. is counted.

On the other hand, the two-phase pulse from two pulse generators is 12°12
is converted into a pulse signal 41 and a rotation direction signal 42 by rotation direction detection 81% M13. The pulse signal 41 is counted in the addition/subtraction counter 40 according to the polarity of the rotation direction signal 42 and resets the time counter 18. The contents of the counters 18 and 40 are maintained by the latches 21 and 21A and by the holding and interrupt signals 25.

The addition/subtraction counter 40 is reset by the counter reset signal 24 after the contents are held in the latch 21A. The arithmetic unit 28 saves the contents of the lunches 21 and 21A each time it receives the hold and interrupt (No. 3 25), and stores the contents of the lunches 21 and 21A, respectively, for the time Pn1 from the counted pulse position immediately before the sampling time elapses to the sampling pulse position (sampling time elapsed). 3] Calculate the rotational speed V by calculating the rotation speed V from the previous PIT value 1)n-, which was taken in as several pulses ilN and stored in the storage device 29, according to the equation (1). Honest f
According to ffiH, since the counter used is an addition/subtraction counter, there is an advantage that only one counter is required.

〔Effect of the invention〕

According to this invention, the rotational direction of the rotary shaft is detected using the two-phase pulse outputted from the pulse generator, and the rotational direction is thereby detected.

By making it possible to count the number of pulses to 8 using a separate counter depending on the direction of rotation, and calculating the rotation speed from the counted value, the speed in all directions, forward and reverse, can be detected.
As a result, even if the rotation direction changes during the sampling cycle, the correct average speed can be detected.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional speed detection device, Fig. 1A
Figure 2 is a block diagram showing an embodiment of the present invention, and Figure 2A is a diagram showing the timing relationship between signals of each part in the circuit of Figure 2. 3 is a block diagram showing another embodiment of the present invention, and FIG. 3A is a chart showing the timing relationship of each part signal in the circuit of FIG. 3.
'iPush-drawing showing a further embodiment of the invention, No. 4A
This figure is a chart showing the timing relationship of the signals of each part in the circuit of FIG. 4. Symbol explanation l...Reference clock pulse generator, 2, 2A.
...Pulse generator, 3...Divide counter, 4...T counter, 5...N counter, 6...Delay circuit, 7...t...buffer counter, 8...performance W equipment L 9 Flo...
...Buffer counter, 11...Delay circuit,
12.12... Two-phase pulse signal, 13...
...Rotation direction detector, 17...Timer counter, 18...Time counter, 19...Forward pulse counter, 20...Reverse direction pulse counter , 21-23... Latch, 26...
...Reference clock, 27...Pass, 28...
...Arithmetic device, 29...Storage device, 30...
...Timer, 31... Frequency divider, 32, 32
A...Forward direction pulse counter, 33, 33A・
...Reverse direction pulse counter, 34, 34A...
...Time counter, 35°36...Counter selection signal, 37...Interrupt signal, 40...
・Addition/subtraction counter Figure 2A

Claims (1)

[Scope of Claims] 1) A speed detection device that determines the rotational speed of the rotary shaft by taking the average value over a predetermined period of the repetition period of pulses generated by a pulse generator driven by a rotary shaft, the pulse generator means for detecting the rotational direction of the rotary shaft using output pulses from the device; a timer for creating and outputting a sampling time sT as the predetermined period; a first counter that counts the number of output pulses from the pulse generator within a sampling time sT (this is referred to as NP);
Similarly, a second counter counts the number of output pulses when the rotation direction is in the opposite direction (this is assumed to be NN), and a second counter counts the number of output pulses (this is assumed to be NN), and a second counter that counts the number of output pulses (this is assumed to be NN) and the time from the output pulse position immediately before the sampling time elapses to the sampling time elapsed. Let be Pn,
The rotation of the rotation axis is determined by the average value V of the repetition period of the output pulses calculated by the calculation device according to the following formula. A speed detection device characterized in that the speed is detected. 2. The speed detection device according to claim 1, wherein the two counters, the first counter and the second counter, are comprised of -1 addition/subtraction counters. Device.