JPS5927845B2 - Position and speed detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position and speed detection method, and more particularly to a position and speed detection method for obtaining position and speed signals of a motor or an object driven by the motor.

2. Description of the Related Art A method using a rotary encoder, a linear encoder, or the like is known as a method for detecting the position and speed of a motor and an object driven by the motor. For example, a rotary encoder is attached to the rotating shaft of a motor,
It generates two-phase sine wave signals, A phase and B phase, which have a phase difference of 7C//2 from each other in accordance with the rotation of the shaft, and the frequency of the sine wave signal is proportional to the rotational speed of the motor wave. ing.

From this A, B, two-phase sine wave signal, a position (displacement) signal,
The speed signal is typically detected as follows. Figure 1 is a diagram of a conventional circuit that generates position and velocity signals from the sine wave signal, and Figure 2 is a waveform diagram of each part thereof, where M is the motor, RE is the low tide encoder, and PG is the two-phase sine wave signal. A pulse generator that generates a pulse every time wave signals A and B cross zero volts, PD determines which of the sine wave signals A and B is leading or not, and determines whether the A phase signal is leading or not. A phase detector provides an addition signal if delayed, and a subtraction signal if delayed, to an up/down counter UDC. UDC is an up/down counter, which is generated from a pulse generator PG in response to addition and subtraction signals from the phase detector. UP THE PULSE
DA is a DA converter that performs digital-to-analog conversion (referred to as DA conversion) of the contents of the up/down counter and generates a position signal PS.FVC receives pulses generated from the pulse generator PG and converts the pulses This is an FV converter that converts frequency to voltage and generates a speed signal.

A motor, for example, is rotating clockwise and gradually decelerates until time T.

If we reverse the direction of rotation, the mouth-to-tooth encoder RE initially generates two sine wave signals in which the phase of the A-phase signal leads that of the B-phase by '2', as shown in Figure 2 A and B. do. The phase detector PD detects this and provides an addition signal AD to the up/down counter UDC. On the other hand, the pulse generator PG generates an up pulse UPP every time the A-phase and B-phase sine wave signals cross zero volts, and inputs it to the up/down counter UDC and the FV converter FVC. The up/down counter UDC counts up by 1 each time an up pulse UPP arrives, and its contents are input to the DA converter and DA converted.

Therefore, time T. Until now, the position signal PS advances stepwise as shown in FIG. 2, while the speed signal S attenuates stepwise. Time T
. After that, the direction of rotation of the mole tide is reversed, so the A-phase signal lags behind the B-phase signal, and therefore the subtraction signal S is output from the phase detector PD.
B is generated, and a down pulse DNP is generated from the pulse generator PG, and the contents of the up/down counter are subtracted. Therefore, time T. After that, the position signal PS becomes a signal that decreases stepwise, and the speed signal VS increases stepwise in the negative direction. As described above, according to the conventional method, the position signal PS and the speed signal VS have a step-like shape, and it is not possible to obtain position and speed signals that change smoothly.

Incidentally, even in the flat portions of PS and VS, the motor is actually rotating and the speed is changing. That is, the conventional method described above has the disadvantage that instantaneous and accurate position and velocity signals cannot be obtained. The purpose of the present invention is to eliminate such conventional drawbacks, and the purpose of the present invention is to generate two-phase sine wave signals A and B having a phase difference of V2 according to the movement or rotation of an object. a detector for generating pulses, a means for generating pulses each time each of the sine wave signals crosses zero volts, a counting means for adding or subtracting the pulses depending on the direction of movement or rotation of the object, and a digital/analog converter for outputting the output of the counting means. In an object position detection system equipped with a DA converter for conversion, means for calculating a sum signal and a difference signal of the two-phase sine wave signals A and B, respectively, and outputting the DA converter as appropriate with the sum signal and the difference signal. Provide a means to interpolate
A position detection method that obtains a position or displacement signal from the interpolation means, a means for generating a speed signal by integrating a current that moves or rotates an object, and a position signal obtained from the speed signal and a position obtained from the interpolation means. This is achieved by a speed detection method in which a means for comparing the position signals is provided, the speed signal is corrected so that the difference between the position signals becomes zero, and the corrected signal is used as the speed signal.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The principle of the present invention is that the position signal P which is the DA conversion output shown in FIG.
S is the two-phase sine wave signal A, B of the rotary encoder output.
Interpolate using . Now, rotary encoder R
Sum signal of A and B phase sine wave signals A and B from E (A+
B) and a difference signal (A-B), either of these signals becomes a nearly linear signal with respect to positional displacement between two adjacent up pulses UPP or down pulses DNP. Therefore, this sum signal (A+B) or difference signal (A-
B) is appropriately attenuated so that, for example, the amplitude of the straight line portion is DA
If it is attenuated to be equal to the voltage of one step of the converter output and added to the position signal PS which is the signal obtained by this attenuation, that is, if the position signal PS is interpolated with the signal obtained by the attenuation. A smoothly changing position signal PSS is obtained. Fig. 3 is an embodiment for realizing position signal detection of the present invention, Fig. 4 is a waveform diagram of each part, and SL is a rectangular signal obtained by slicing the sine wave signals A and B from the rotary encoder RE at zero volts. Slicer to convert to P, Q, EOR
is an exclusive OR circuit (hereinafter referred to as EQR circuit) that calculates the exclusive OR (P4Q) of P and Q, AAD is an adder that adds analog sine wave signals A and B, and ASB is sine wave signal A and B. A subtractor that takes the difference between , MPXl is P4Q
? If P4Q=XO, the multiplexer outputs (A+B) in synchronization with the pulse generated from the pulse generator PG, and (A-B) if P4Q=XO. The voltage is attenuated to the voltage value of one step, IN is the inverter, and M is the inverter.
PX2 is a multiplexer that converts the sine wave signal B into a rectangular wave and outputs the output of the attenu output as it is or inverts it using the signal Q obtained.
When =ゞO〃, it is output without inversion, INP is an interpolator, and DA converter output PS and multiplexer MPX
This is an interpolator that removes discontinuity in the stepped position signal PS and converts it into a continuous position signal PSS by adding the outputs 1NPS of 2.

In the figure, the same parts as in FIG. 1 are given the same numbers. Outputs of adder AAD and subtracter ASB (A+B), (A
-B) for either one of Figure 4 11-14, 21-
As shown in Figure 24, when the object is moving at a constant speed, there is a nearly straight line between adjacent up pulses or adjacent down pulses generated from the pulse generator PG, and as the speed decreases, the slope becomes 15. , 16, it becomes smaller,
Furthermore, when the speed changes, a curve deviates from a straight line appears.

Therefore, the interpolated signal 1NPS, which is the output signal of the multiplexer MPX2, becomes as shown in FIG. In addition, in Fig. 3, it initially rotates at a constant speed clockwise, gradually decelerates, and reaches time T.
At O, the direction of rotation is reversed, the speed gradually increases, and it rotates at a constant speed. The interpolation signals 1NPS and DA
If the converter output PS is added by the interpolator 1NP, the PS shown in Fig. 4 is obtained.
A smooth position signal without discontinuities like S can be obtained.

In FIG. 4, A and B are two-phase sine wave outputs of the rotary encoder RE, P and Q are slicer outputs, UPP is an up pulse, and DNP is a down pulse. FIG. 5 is a circuit block diagram for realizing the speed detection method according to the present invention, where Ii is a signal proportional to a current value 1 for driving an object such as a motor, ADl to AD3 are adders, and INTGl to
INTG2 is an integrator, APl to AP2 are amplifiers, PSS
is the position signal obtained from FIG.

Now, the speed signal is changed to the position signal PSS obtained from Fig. 4.
If you try to obtain it by differentiating it, the high-frequency noise component will increase,
Furthermore, if a filter is inserted to cut out the noise, a phase lag will occur.

Therefore, in the present invention, when using a DC motor as a drive motor, attention is paid to the fact that the armature current 1 of the motor is proportional to the angular acceleration, and the current 1 is integrated by an integrator 1NTG1 to obtain a speed signal VSS. , further integrates the speed signal VSS by an integrator 1NTG2 to obtain a position signal P.
SS' is obtained, and then the position signal PSS' is compared with the smooth position signal PSS obtained in FIG.
This is to get SS.

According to this method, a smooth speed signal VSS without time lag and without discontinuities can be obtained. That is,
The angular velocity and angular displacement of the actual servo system and the angular velocity and angular displacement obtained from Fig. 5 can be calculated by making the transfer characteristics of the circuit system shown in Fig. 5 the same as those of the actual servo system. Delays can be eliminated.

Also, the characteristic polynomial of the circuit in FIG. 5 is H(S)=S2+Gl
S+G2, and for the output of the adder/subtractor AD3, H(S) is in the denominator of the transfer function to the angular velocity VSS, so the pooling is performed, and the position signal P
Some noise included in the SS is removed, and a smooth angular velocity signal can be obtained.

As described above, according to the present invention, smooth position signals and velocity signals without time delay can be obtained, and the effect is great.

In addition, when the DA conversion output of FIG. 1 or 3 is inputted to the adder/subtractor AD3 of FIG. 5 instead of the position signal PSS obtained from FIG. 3, the above-mentioned H
Even with the filter function of (S), this cannot be sufficiently attenuated, and ripples occur in the angular velocity signal VS. Although the present invention has been described above in detail with reference to the drawings, the present invention is not limited to the embodiments and can be modified in various ways.

[Brief explanation of the drawing]

Figure 1 is a conventional position and speed detection circuit, Figure 2 is a waveform diagram of each part thereof, Figure 3 is a position detection device according to the present invention, Figure 4 is a waveform diagram of each part thereof, and Figure 5 is a diagram of waveforms of each part thereof. It is a speed detection device. EOR...Exclusive OR circuit, INP...
...Interpolator, AAD...Analog adder, AS
B...Analog subtracter, MPXl, MPX2・
...Multiplexer, ATN...Attenuator, RE...Rotary encoder, M...
・Motor, INTGl, INTG2...Integrator.

Claims (1)

[Scope of Claims] 1. A detector that generates two-phase sine wave signals A and B having a phase difference of π/2 according to the movement or rotation of an object, each time each of the sine wave signals crosses zero volts. In the method for detecting the position of an object, the object position detection method includes a means for generating a pulse according to a moving direction or a rotating direction of the object, a counting means for adding or subtracting the pulse according to a moving direction or a rotating direction of the object, and a DA converter for converting the output of the counting means from digital to analog. Means for calculating the sum signal and difference signal of the two-phase sine wave signals A and B, and means for appropriately interpolating the output of the DA converter with the sum signal and the difference signal are provided, and the position or displacement signal is obtained from the interpolation means. A position detection method characterized by obtaining. 2 When the signals indicating whether the two-phase sine wave signal is a positive potential or a negative potential are P and Q, P■Q="1", Q="1"
” (where ■ indicates exclusive OR), the signal obtained by inverting the polarity of the sum signal makes P■Q="1
”, in the case of Q=“0”, P■Q=
In the case of "0" and Q="1", the signal obtained by inverting the polarity of the difference signal causes P■Q="0" and Q="0".
2. The position detection method according to claim 1, wherein in each case, the output of the DA converter is interpolated using the difference signal. 3. A detector that generates two-phase sine wave signals A and B having a phase difference of π/2 according to the movement or rotation of an object, and means that generates a pulse every time each of the sine wave signals crosses zero volts. , a speed detection method for an object comprising a counting means for adding or subtracting the pulses according to a moving direction or a rotating direction of the object, and a DA converter for converting the output of the counting means from digital to analog, the two-phase sine wave signal; Means for calculating the sum signal and difference signal of A and B, means for appropriately interpolating the output of the DA converter using the sum signal and the difference signal to generate a position signal, and means for integrating the current that moves or rotates the object. Means for generating a speed signal and means for comparing a position signal obtained from the speed signal with a position signal obtained from the interpolation means are provided, and the speed signal is corrected so that the difference between the respective position signals becomes zero. A speed detection method characterized in that the corrected signal is used as a speed signal. 4 When the signals indicating whether the two-phase sine wave signal is a positive potential or a negative potential are P and Q, P■Q="1", Q="1"
” (where ■ indicates exclusive OR), the signal obtained by inverting the polarity of the sum signal makes P■Q="1
”, in the case of Q=“0”, P■Q=
In the case of "0" and Q="1", the signal obtained by inverting the polarity of the difference signal causes P■Q="0" and Q="0".
4. The speed detection method according to claim 3, wherein in each case, the output of the DA converter is interpolated using the difference signal.