JP3072938B2 - Position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device used for a control device for synchronously controlling a plurality of axes of a machine tool or the like.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing an example of a conventional position detecting device, FIG. 7 is a block diagram showing a detailed example of an exciting voltage generating circuit 8 as a main part thereof, and FIG. It is a chart. The clock f1 generated by the oscillator 6 is counted by the counter circuit 81 of the excitation voltage generating circuit 8, and the counted value is stored in the ROM 82 and the decode circuit 85.
Sent to A sign table is stored in the ROM 82 in advance, and the data of the address of the ROM 82 corresponding to the count value from the counter circuit 81 is converted into an analog value by the D / A converter 83, amplified by the amplifier 84, and amplified by the AC excitation signal Vex. Is transmitted to the resolver 16. Further, the phase setting value PHI set by the phase setting circuit 7 is sent to the decoding circuit 85 of the excitation voltage generating circuit 8, and when the phase setting value PHI matches the count value from the counter circuit 81, the excitation synchronization signal EXT is sent to the timing synchronization circuit 9. When an external periodic position request signal SQ is input to the timing synchronization circuit 9, a hold signal SH synchronized with the excitation synchronization signal EXT immediately thereafter is sent to S / H (sample and hold) circuits 18s and 18c. Sent out.

On the other hand, when the coil on the primary side of the resolver 16 is excited by the AC excitation signal Vex from the excitation voltage generating circuit 8, the AC amplitude modulated to the sine and cosine values of the deviation angle θ from the reference position is obtained. Detection signals Vs and Vc are output from both ends of the two secondary windings, amplified by amplifiers 17s and 17c, and sent to S / H circuits 18s and 18c. The AC detection signals Vs and Vc are held by the S / H circuits 18s and 18c at the timing of the hold signal SH, are digitized by the A / D converters 19s and 19c, and are converted into sine signals Ds and cosine signals Dc by the interpolation circuit 20. Sent out. Then, the rotation angle θ of the rotor is calculated and output by the interpolation circuit 20 by the calculation of Expressions 1 to 8 using the sine signal Ds and the cosine signal Dc.

[0004]

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

(Equation 5)

(Equation 6)

(Equation 7)

(Equation 8)

[0005]

A position detecting device used in a control device for controlling a plurality of axes in a machine tool or the like in synchronization with each other has the same time for detecting the position of each axis. It is necessary that the interval of time to do so is constant. However, in the conventional position detecting device, the time when the position request signal is input and the time when the position is actually detected are represented by t1 and t in FIG.
There is a problem that the control does not go smoothly because of the variation as shown at 2 and t3. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a position detecting device capable of detecting a position synchronized with a position request signal.

[0006]

According to the present invention, an AC excitation signal is input to output an AC detection signal whose amplitude is modulated in accordance with a measurement position with respect to the AC excitation signal. was converted to a value, it relates a position detecting device for calculating a measuring position by interpolating the digital value, the object of the present invention, the position detection
A period measuring means for measuring a period of a periodic position request signal from the outside of the device; and a 1 / N (N is an integer) period of the measurement period measured by the period measuring unit, Excitation means for generating the synchronized AC excitation signal.

[0007]

According to the present invention, the period of the position request signal is measured by the period measuring means, and the period of the AC excitation signal is reduced to 1 / N of the measurement period by the exciting means. Since the synchronized AC excitation signal is generated, the position synchronized with the position request signal can be detected.

[0008]

FIG. 1 is a block diagram showing an example of a position detecting device according to the present invention in correspondence with FIG. 6, and the same components are denoted by the same reference numerals. 2 is a block diagram showing a detailed example of a period measuring circuit 11 which is a main part thereof, FIG. 3 is a block diagram showing a detailed example of a variable oscillator 13, and FIG. 4 is a detailed example of an excitation voltage generating circuit 15. FIG. 5 is a block diagram and FIG. 5 is a time chart of signals in the device of the present invention. The clock f0 generated by the oscillator 10 is counted by the counter circuit 111 of the cycle measuring circuit 11, and the counted value is sent to the latch circuit 112. Here, the counter circuit 111 is a timer whose period is longer than the input interval of the periodic position request signal SQ from the outside. When an external periodic position request signal SQ is input to the latch circuit 112, the count value N2 at that moment is held. When a periodic position request signal SQ from the outside is input to the latch circuit 113, the count value N1 held by the latch circuit 112 at that moment is held. Therefore, the count value N1 is equal to the count value N2.
Is the time when the position request signal SQ immediately before the position request signal SQ at the time of holding is input. Then, the count values N1 and N2 are sent to the subtraction circuit 114, and the period Tsq of the position request signal SQ is calculated according to Equation 9, and
2 is sent. Note that the number of bits of the counter circuit 111 is n.

[0009]

(Equation 9) Position request signal SQ sent to frequency setting circuit 12
The ratio (N: 1) between the measurement period and the excitation period is calculated according to Equation 10 according to the period Tsq, and then the frequency set value M is calculated according to Equation 11 and transmitted to the variable oscillator 13.

(Equation 10) Here, Tex is a target excitation cycle having the cycle of the oscillator 10 as a basic unit. INT (X) is a function meaning taking an integer of X.

[Equation 11] Here, k is a counter circuit 151 of the excitation voltage generation circuit 15.
Is the number of bits of the counter used for. m is the number of bits of a counter used for the counter circuit 131 of the variable oscillator 13.

On the other hand, the clock f0 generated by the oscillator 10
Is counted by the counter circuit 131 of the variable oscillator 13,
Carry fx is generated at the next clock f0 at which the count value becomes 2 ^k -1. Then, the carry fx is used as a clock for excitation generation and a load signal of the frequency set value M. The loaded frequency set value M is used as the initial value of the count, and a desired excitation generation clock fx is generated by repeating the above-described operation, and is sent to the excitation voltage generation circuit 15. The excitation generation clock fx is counted by the counter circuit 151 of the excitation voltage generation circuit 15,
When an external periodic position request signal SQ is input to the excitation voltage generating circuit 15, the phase setting value PHI set by the phase setting circuit 7 is loaded. The loaded phase setting value PHI is used as the initial value of the count, and the above-described operation is repeated.

A sine table is stored in the ROM 82 in advance. Data of the address of the ROM 82 corresponding to the count value from the k-bit counter circuit 151 is converted into an analog value by the D / A converter 83 and amplified by the amplifier 84. Then, it is sent to the resolver 16 as an AC excitation signal Vex having a cycle of Tsq / N and synchronized with the position request signal SQ. When the coil on the primary side of the resolver 16 is excited by the AC excitation signal Vex, the sine value of the deviation angle θ from the reference position,
AC detection signals Vs and Vc whose amplitudes are modulated to cosine values are output from both ends of the two secondary windings, and the amplifiers 17s and 17c are output.
c and is sent to the S / H circuits 18s and 18c. The AC detection signals Vs and Vc are held by the S / H circuits 18s and 18c at the timing of the position request signal SQ.
/ D converters 19s and 19c to convert the sine signal Ds
And the cosine signal Dc to the interpolation circuit 20. Then, the sine signal Ds and the cosine signal Dc are output by the interpolation circuit 20.
Is used to calculate the rotation angle θ of the rotor and output.

[0012]

As described above, according to the position detecting device of the present invention, the position can be detected from a detector such as a resolver in synchronization with a periodic position request signal from the outside.
When used in a control device for controlling a plurality of axes in synchronization with each other, such as a machine tool, smooth control can be performed. In addition, since the cycle of the AC excitation signal is repeated during the cycle of the position request signal, the quotient obtained by dividing the cycle of the position request signal by the target excitation cycle is rounded to an integer. It can be synchronized with the position request signal without changing the frequency of the excitation signal much, and there is no adverse effect due to the frequency characteristics of the detector and the circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a position detection device according to the present invention.

FIG. 2 is a block diagram showing a detailed example of a cycle measuring circuit of the device of the present invention.

FIG. 3 is a block diagram showing a detailed example of a variable oscillator of the device of the present invention.

FIG. 4 is a block diagram showing a detailed example of an excitation voltage generating circuit of the device of the present invention.

FIG. 5 is a time chart of signals in the device of the present invention.

FIG. 6 is a block diagram illustrating an example of a conventional position detection device.

FIG. 7 is a block diagram showing a detailed example of an excitation voltage generation circuit of a conventional device.

FIG. 8 is a time chart of signals in a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Oscillator 11 Period measurement circuit 12 Frequency setting circuit 13 Variable oscillator 15 Excitation voltage generation circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34

Claims (1)

(57) [Claims] 1. An AC excitation signal is input to output an AC detection signal which is amplitude-modulated in accordance with a measurement position with respect to the AC excitation signal, and converts the AC detection signal into a digital value. the position detecting apparatus for calculating a measuring position by interpolating the, the position detecting device
A period measuring means for measuring a period of a periodic position request signal from the outside of the apparatus, and a period which is 1 / N (N is an integer) of the measurement period measured by the period measuring unit and which is synchronized with the position request signal. And an exciting means for generating the AC exciting signal.