JPS60216260A - Speed detection method - Google Patents

Abstract

PURPOSE:To detect a speed over a wide range with good accuracy while suppressing ripple, by detecting only the inclinations of multi-phase output signals displaced by 90 deg. in the phase of an alternating wave form and differentiating the same by a single differentiation circuit. CONSTITUTION:Reversal circuits 301, 302, which input A- and B-phase signals and output A'- and B'-phase signals being reversal signals, and an analogue switch group 303, which takes out inclinations in the vicinity of zero crosses of A'- and B'-signals in the same direction to output an AB signal, are provided. Further, a switch control signal generation circuit 307, which consists of compartors 308, 309 and a switch selection circuit 301 respectively inputting A- and B- phase signals, and A'- and B'-phase signals, is provided. Furthermore, a single differentiation circuit 304 for performing the differentiation of signals A, B and a slit removing circuit 305 are provided. By this mechanism, ripple caused by the irregularity of parts is suppressed and a speed can be detected over a wide range with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a speed detection method, in particular an analog speed signal by differentiating an original signal (sine encoder output) of a position detection device, for example, an encoder. This invention relates to a speed detection method suitable for detecting speed over a wide range with high accuracy.

[Background of the invention]

Recently, servo motors are often used in NC devices, robots, etc., but the problem here is the speed detection method.

Conventionally, a DC tachometer generator has been used, but since a pulse encoder is required for position control, two components, a pulse encoder and a DC tachometer generator, are required, making the detector complex.

Therefore, it has become important to detect speed using only encoders.

Conventionally, as an example of this, for example, Japanese Patent Application Laid-Open No. 57-7645
There is a rotational speed detection method described in Publication No. 6.

This conventional example uses a sine encoder to detect the speed from its differential waveform, and FIG. 1 shows an operation time chart thereof.

That is, a sine encoder is used as a position detection device to generate A and B phase signals having alternating waveforms whose phases are shifted by 90 degrees and the amplitudes are the same, and a zero cross circuit is used to generate the A and B phase signals. From the phase signals, switch control signals SA, SA, SB.

While generating SB, the above-mentioned A
, generate A and B phase signals which are inverted signals of the B phase signal,
The A, A, B, and B phase signals mentioned above are supplied to respective differentiating circuits consisting of resistors and capacitors, and each differential signal dA is
, dA, , dB, dB.

And each of the above-mentioned differential signals dA, dA, dB.

The vAB signal is obtained by selectively switching dB in the analog switch circuit, and the analog speed detection signal E8, which is an output signal corresponding to the rotational speed, is obtained by adding, inverting and amplifying each of the signals. It is a method.

FIG. 2 shows a circuit configuration for realizing the operation shown in FIG. 1 described above.

That is, 201 and 202 are circuits that invert the A and B phase signals and output the A and B phase signals, and the respective differentiating circuits that differentiate these A, B, A and B phase signals are 203-206.

Then, the differentiated signals are sent to the analog switch 21.
1 performs synchronous rectification, and an analog speed detection signal E8 is obtained by an inverting amplifier 213 via resistors 207 to 210. Here, the switch control signals SA, SA, SB, and SB related to the analog switch control signals are output from the selection circuit 212.

By the way, in speed detection, what is important is ripple reduction.

In the system shown in FIGS. 1 and 2, the differentiating circuits 203 to 2
06 is provided for each phase signal, the magnitude of the differential signal for each phase varies due to variations in capacitors and resistors that are elements of the differential circuit, and the speed detection signal has ripples.

Additionally, since the analog switch 211 is used, the magnitude of the differential signal becomes small at low speeds, which may be affected by the on-resistance of the analog switch.

In this way, it can be said that the above-mentioned conventional example still has some points to be improved.

[Purpose of the invention]

The present invention is a speed detection method using the original signal of a position detection device, such as an encoder, which suppresses ripples in the speed detection signal caused by variations in parts, etc. in conventional methods, and enables speed detection over a wide range with high accuracy. provide,
That is the purpose.

[Summary of the invention]

A first invention related to a speed detection method of the present invention is a speed detection method using a position detection device connected to a moving body, in which a polyphase output signal whose alternating waveform is deviated at a constant phase and has the same amplitude is generated. A speed detection signal is obtained by differentiating a single output signal from a group of analog switches, which take out signals having the same phase and inclination in the same direction, using a single differentiating circuit.

In addition, the following is a supplement to this.

In a method that detects speed by differentiating the output of a sine encoder that outputs an alternating waveform with a phase deviation of 90 degrees and the same amplitude, a differentiating circuit, which causes ripples in the speed detection signal, is installed for each phase. This method uses a single differential circuit to detect the difference, and in order to achieve this, it is necessary to detect only the slope of each phase signal in the same direction.
Furthermore, since the signal is not a differentiated signal at the stage of the circuit that detects only the slope, the amplitude is large, which is advantageous for the use of an analog switch.

Further, a second invention related to the speed detection method of the present invention is a speed detection method using a position detection device connected to a moving object, in which an alternating waveform deviates at a constant phase and has a polyphase output having the same amplitude. Each output signal from a group of analog switches that takes out signals with the same phase and slope in the same direction is differentiated by each differentiating circuit, and each differentiated signal is used to selectively synthesize the signals by removing the slit. This is how the speed detection signal is obtained.

In addition, the following is a supplement to this.

When the signals with the same direction of inclination are taken out separately for the A phase and the B phase, which have different phases, and each of them is differentiated, the differentiated signal has a discontinuous part in the signal with the same direction of inclination, so the slit is arise.

However, the differential signal is two differential signals of A phase and B phase,
The position of the slit is also different. Therefore, by using an analog switch to selectively combine the A-phase differential signal and the B-phase differential signal so as to eliminate the slits, it is possible to obtain a speed detection signal without slits. This is what I did.

[Embodiments of the invention]

Embodiments of the speed detection method according to the present invention will be described with reference to the figures.

First, FIG. 3 is a circuit configuration diagram of a speed detection device used to implement a speed detection method according to an embodiment of the present invention, and FIG. 4 is an operation time chart for speed detection.

In the figure, 301 and 302 are inverting circuits, 303 is a group of analog switches, 304 is a differentiation circuit, 305 is a slit removal circuit, 306 is an inverting amplifier circuit, 307 is a switch control signal generation circuit, 308 and 309 are comparators, and 310 is a This is a switch selection circuit.

That is, first, velocity is detected using a sine encoder related to a position detection device that outputs A and B phase signals of alternating waveforms whose phases are shifted by 90 degrees and have the same amplitude.

In the alternating waveform shown in Figure 4, the part where speed information can be extracted as an analog quantity is the zero cross (
This is the part where the slope is large near the point where the waveform intersects the zero line.

Therefore, the amplitude A of the physiognomy signal can be expressed as shown in the following equation.

A = Ksin (2rr f-t) −・−・−,
-, (1) where K is the maximum value of the amplitude.

Here, in order to extract the frequency f of the encoder, the above amplitude A is differentiated to obtain the following equation.

dA/d t==2yrf , KCO3(2πf −t
) -(2) Since the differential waveform near the zero crossing is actually extracted as the detection signal, when 2πf-i=-Q, it is as follows.

(d A/d t )2. ,,, −f −( for o=2π
3) This makes it possible to obtain an analog signal proportional to the frequency f.

Furthermore, since the frequency f of the encoder is proportional to the speed of the rotating body, the above equation (3) can be used as an analog speed detection signal.

In order to realize the speed detection described above, not only the A and B phase signals but also the A and B phase signals, which are inverted signals of the A and B phase signals, are required.

The inverting circuits 301 and 302 in FIG. 3 are one circuit that receives A and B phase signals as input and outputs inverted signals A and B phase signals of each phase.

Further, the analog switch group 303 in FIG. 3 is a switch group for extracting slopes in the same direction near the zero cross of each phase signal, and the output of the switch group 303 is AB.

Here, each switch in the analog switch group 303 is selectively controlled by a control signal from the switch control signal generation circuit 307.

Therefore, the analog switch group 303 extracts the range of -45 degrees to +45 degrees near the zero cross of each phase.
The switch control signal generation circuit 307 includes comparators aos and M that receive A and B phase signals as inputs.

The SC shown in FIG. 4 has a configuration including a comparator 309 that receives an A-phase signal as input, and a switch selection circuit 310.

SD, Sl, S2. S3. In S4, each switch of the analog switch group 303 is controlled.

As described above, the signal AB obtained by extracting the slopes of the A, E, A, and B phase signals in the same direction is differentiated through a single differentiating circuit 304 consisting of a capacitor and a resistor in order to detect the speed. The output of the differentiating circuit 304 is the illustrated differential signal dAB.

As can be seen from FIG. 4, this differential signal dAB has a portion where the slope before differentiation is obtained, and the signal AB changes discontinuously, so a slit occurs as shown in FIG. 4.

Even if this slit is removed, it has nothing to do with speed detection. Therefore, the slit removal circuit 305 removes the slit, and the inverting amplifier circuit 306 inverts and amplifies the analog signal Eo, which is proportional to the speed. It's something you get.

However, since the above-mentioned slit is momentary, there may be no practical problem even if it is not removed, and in this case, the slit removal circuit 306 is not required.

According to this embodiment, since there is only one differentiating circuit that determines the magnitude of the speed detection signal, there is no influence of variations in the capacitor and resistance of the differentiating circuit, and ripples in the speed detection signal can be suppressed. Furthermore, since the differentiated signal does not pass through an analog switch, the speed can be accurately detected even at low speeds. Also,
The alternating waveform of the sine encoder is not a sine wave, but -45
It is sufficient to maintain linearity in the range of degrees to +45 degrees, and there is also the effect that there are fewer restrictions on the waveform, such as a sine wave shape.

Next, FIG. 5 is a circuit diagram of a speed detection device used to implement a speed detection method according to another embodiment of the present invention, and FIG. 6 is a time chart of speed detection.

In the figure, 401 and 402 are inverting circuits, 403 is a first switch control signal generation circuit, 404 is a second switch control signal generation circuit, 405 is a group of human phase analog switches, 406 is a group of B phase analog switches, 407. 408 is a differentiation circuit, 409 is a group of analog switches for removing slits, 410
is an inverting amplifier circuit.

In the first embodiment, not only the A and B phase signals but also the A signal which is the inverted signal of the A and B phase signals.

We explained that a π-phase signal is also required. However, in the embodiments shown in FIGS. 3 and 4, slits occur in the speed detection signal, so it may be necessary to remove these slits. In this case, the phase deviation of the A and B phases is utilized.

That is, 401 and 402 are inverting circuits that generate inverted signals A and B of the A and B phase signals, and here, for each phase, portions having slopes in the same direction are extracted.

As shown in the figure, for the A phase, the A phase signal A and the A phase inverted signal A are inputted via the analog switch group 405, and the portions of the same slope of the signals A and A are extracted. The output of the analog switch group 405 becomes the A-phase slope signal AA shown in FIG.

Regarding the B phase, similarly to the human phase, the B phase signal B and the B reciprocal inverted signal color are inputted via the analog switch group 406.
This is to extract the same slope portion of the signals B and B, and the output of the analog switch group 406 is B as shown in FIG.
This becomes a phase slope signal BB.

In order to detect the speed, these A and B phase slope signals AA,
BB, each differentiating circuit 407 consisting of a capacitor and a resistor,
Differentiate by 408.

The outputs of those differentiating circuits 407 and 408 are the differential signals d
AA, dBB.

However, as shown in FIG.
, dBB has a slit.

To remove this slit, each differential signal dBB.

Only the 90 degrees near the peak of dAA is taken out via the slit removal analog switch group 409 and synthesized.
Amplified by the inverting amplifier circuit 410, the speed detection signal Eo
The purpose is to obtain the following.

In this case, the slit portions of the differential signals dAA and dBB do not pass through due to the OFF control of the slit removal analog switch group 409, so the speed detection signal E is not passed. No slits occur.

The analog switch group 405 for physiognomy is controlled by the output signals sp and F3- of the first switch control signal generation circuit 403.
The output signals SF, SF are generated by comparing the B-phase signal B and the B-phase inverted signal B.

Furthermore, the control of the B-phase analog switch group 406 is controlled by the first
Output signals SE and SE of the switch control signal generation circuit 403
and this output signal SE.

SE is generated by comparing the A-phase signal A and the A-phase inverted signal A.

Furthermore, the slit removal analog switch group 409 compares the A-phase signal A and the B-phase signal B, and the A-phase signal A and the inverted signal B of the B-phase, and determines the exclusive logic of each output. Sum (Exclusive OR)
It is controlled by the output signals SG and SG of the second switch control signal generation circuit 404.

According to this embodiment, slits unrelated to speed can be removed from the differential signal of the slope signal, and a speed detection signal with less ripple can be output over a wide range of speeds.

Since only the slope in the same direction near the zero cross of the sine encoder is extracted, the alternating waveform of the sine encoder is not sinusoidal, but only needs to maintain linearity in the range of -45 degrees to +45 degrees, and the waveform may be sinusoidal, etc. This has the effect of not requiring any restrictions.

However, each of the above embodiments relates to physiognomy.

Although the present invention is related to the B phase, the present invention is not limited to this, but is general-purpose and relates to more than one phase.

Furthermore, the present invention is not limited to the encoder, and does not preclude the use of other position detection devices.

〔Effect of the invention〕

According to the present invention, it is possible to provide a speed detection method that can suppress ripples in speed detection signals caused by variations in parts, etc. in conventional methods, and can detect speeds over a wide range with high accuracy, and is practical. It can be said that this invention is highly effective.

[Brief explanation of the drawing]

FIG. 1 is an operation time chart of a speed detection method according to a conventional example, FIG. 2 is a circuit diagram thereof, and FIG. 3 is a diagram for implementing a speed detection method according to an embodiment of the present invention. FIG. 4 is a circuit configuration diagram of the speed detection device, FIG. 4 is an operation time chart for speed detection, and FIG. 5 is a circuit diagram of the speed detection device used to implement a speed detection method according to another embodiment of the present invention. The configuration diagram and FIG. 6 are operation time charts for speed detection. 301.302,401,402...inversion circuit, 30
3...Analog switch group, 304,407°408
... Differentiation circuit, 305 ... Slit removal circuit, 30
6.410... Inverting amplifier circuit, 307... Switch control signal generation circuit, 308, 309... Comparator, 31
0... Switch selection circuit, 403... First switch control signal generation circuit, 404... Second switch control signal generation circuit, 405... Analog switch group for physiognomy, 4
06...B phase analog switch group, 409...Slit removal analog switch group. Agent: Patent attorney Kosaku Fukuda (and 1 other person) 1st day, 2nd day, 3rd day, 4th day, 5th day 01

Claims (1)

[Claims] 1. In a speed detection method using a position detection device connected to a moving body, the alternating waveforms are deviated at a constant phase, and polyphase output signals having the same amplitude have the same phase and the same direction. A speed detection method characterized in that a single output signal from a group of analog switches for extracting a slope signal is differentiated by a single differentiating circuit to obtain a speed detection signal. 2. In the device described in claim 1, a signal obtained by differentiating a single output signal from a group of analog switches,
A speed detection method in which a speed detection signal is obtained through a slit removal circuit. 3. In a speed detection method using a position detection device connected to a moving object, an analog method for extracting signals with the same phase and the same direction inclination of multiphase output signals whose alternating waveforms are deviated at a constant phase and have the same amplitude. Each output signal from the switch group is differentiated by each differentiating circuit, and each of the differentiated signals is used to selectively combine them so as to remove the slit to obtain a speed detection signal. A speed detection method characterized by: