JP4660983B2 - Position detection method or stop position control method by pulse encoder - Google Patents

Description

BACKGROUND OF THE INVENTION
The present invention relates to a position detection method or a stop position control method using a pulse encoder that can perform position detection and stop position control by continuous pulse counting even if the number of pulses per rotation of the pulse encoder is an arbitrary value.
[Prior art]
FIG. 3 is a block circuit diagram showing a conventional example of a position detection method using a pulse encoder that outputs a pulse number of 2 ^N P / R (P / R = number of pulses / 1 rotation). A case where the number of pulses is 2 ¹⁰ P / R = 1024 P / R will be described as an example.
In the conventional circuit of FIG. 3, the A-phase pulse 11 and the B-phase pulse 12 (both 1024 P / R) output from a pulse encoder (not shown) are input to the quadruple circuit 14. Since the A-phase pulse 11 and the B-phase pulse 12 have a phase difference of 90 degrees, the quadrature circuit 14 uses the quadrature circuit 14 as a predetermined multiple of 1024 by using the respective rise and fall points as starting points. , That is, 4096 P / R. Thus, the accuracy of the detection position can be improved by increasing the number of output pulses of the pulse encoder four times (or a predetermined number). The number of pulses multiplied by four is counted by the pulse counter 15. At this time, the Z-phase pulse 13 output once per rotation from the pulse encoder is also input to the pulse counter 15. The count value in the pulse counter 15 is converted into a hexadecimal value by the hexadecimal conversion circuit 16 in the next stage.
FIG. 4 is a positional correlation diagram showing the positional relationship near the origin of the spindle. The point C is an electrical origin (hereinafter simply referred to as the origin) serving as a reference for position detection. A point rotated clockwise by 1 pulse (1/4096 of 1 rotation) in the clockwise direction (hereinafter referred to as reverse rotation) is a point −A, and a point rotated by 2 pulses (2/4096 of 1 rotation). -Point B. A point rotated by one pulse counterclockwise (hereinafter referred to as forward rotation) from point C as the origin is defined as + A point, and a point rotated by two pulses is defined as + B point.
Assume that the output value of the pulse counter 15 at point C (origin) is zero. The output value of the pulse counter 15 when the main shaft rotates in the forward direction from the point C to the point + A is 1 in hexadecimal, and when it rotates to the point + B, 2 in hexadecimal is output. From this point, if the rotation reaches about -B point, the output of the pulse counter 15 at that time is FFE in hexadecimal (4094 in decimal), and if it reaches -A point, it is FFF in hexadecimal (in decimal). 4095). The output value of the pulse counter 15 when the main shaft rotates from the point C in the reverse direction to the point -A is FFF in hexadecimal, and when it rotates to the point -B, FFE in hexadecimal is output. That is, the value of each point exhibits the same value regardless of whether the rotation direction of the main shaft is the forward rotation direction or the reverse rotation direction.
In the mask data generation circuit 17, a value of FFF (2 ¹² -1 = 4096-1 in decimal number) obtained by subtracting 1 from the value of 1000 in hexadecimal number is set, and this becomes mask data. On the other hand, at the point C where the main shaft is rotated by one pulse in the forward direction from the point -A, the output value of the hexadecimal conversion circuit 16 is 1000 obtained by adding 1 to the FFF, and this is the value of the mask data generation circuit 17. If the logical product operation is performed on the set value FFF in the logical product operation circuit 18, the result is zero. That is, every time the spindle rotates once, the output value of the hexadecimal conversion circuit 16 is reset to zero, so that the calculation result of the AND operation circuit 18 indicates the current position of the spindle.
[Problems to be solved by the invention]
For example, when a pulse encoder having a pulse number of 2000 when one rotation is employed and this is multiplied by 4 is used, the number of pulses per rotation is 8000. If the value of point C (origin) is set to zero using a hexadecimal number as in the conventional case, the value of + A point is 001 and the value of + B point is 002. The value at the time is 1F3E, and the value when the point -A is reached is 1F3F. Here, the value of the point C rotated by one pulse in the positive direction from the point -A is 1F40 by adding 1 to 1F3F. Further, the value at the point -A rotated by one pulse in the reverse direction from the point C becomes FFFF when 1 is subtracted from zero and masked with four digits, and the position data will be different.
In other words, when using a pulse encoder in which the number of pulses per rotation is not 2 ^N , different position data is presented as described above, so the processing for clearing to zero at point C is complicated. Have
Accordingly, an object of the present invention is to make position detection easy by avoiding position data discontinuity before and after the origin even when a pulse encoder whose number of pulses is not 2 ^N is used. is there.
[Means for Solving the Problems]
In order to achieve the above object, a position detection method or a stop position control method using a pulse encoder according to the present invention includes:
A division constant obtained by dividing the N-th power value of 2 by the number of pulses output by one rotation of the pulse encoder by a predetermined number is used as a conversion constant, and the pulse encoder coupled to the rotary shaft outputs The number of pulses obtained by multiplying the number of pulses by the predetermined number is counted, and a value obtained by multiplying the counted value by the conversion constant is used as a conversion pulse number. A logical product with mask data obtained by subtracting 1 from the decimal conversion value is calculated, and the logical product calculation result is used as the current position data of the spindle.
Alternatively, the pulse encoder coupled to the rotating shaft may be a conversion constant obtained by dividing the N-th power value of 2 by a value obtained by multiplying the number of pulses output in one rotation of the pulse encoder by a predetermined number, and a conversion constant. The number of pulses obtained by multiplying the number of pulses to be output by the predetermined number is counted, and a value obtained by multiplying the counted value by the conversion constant is defined as the number of converted pulses. The logical product with the mask data obtained by subtracting 1 from the hexadecimal conversion value of the above, and the logical operation result and a value obtained by multiplying the stop position setting value set separately by the conversion constant The spindle is stopped at the stop set position by an adjustment operation for obtaining a deviation and making the deviation value zero.
When obtaining the conversion constant, the value obtained by subtracting 1 from the Nth power of 2 is larger than the value obtained by multiplying the number of pulses output by one rotation of the pulse encoder by the predetermined number. Determine the value of N.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the present invention will be described by taking a pulse encoder having an output pulse number of 30000 P / R as an example.
FIG. 1 is a block circuit diagram showing a first embodiment of the present invention.
In the circuit of the first embodiment of FIG. 1, an A-phase pulse 21 and a B-phase pulse 22 (both 30000 P / R) output from a pulse encoder (not shown) are input to the quadruple circuit 14, so that FIG. Similar to the conventional circuit described above, the quadruple circuit 14 can obtain a pulse number of 120,000 P / R, which is four times 30000. This is counted by the pulse counter 15. At this time, the Z-phase pulse 23 (1P / R) from the pulse encoder is also input to the pulse counter 15. The count value in the pulse counter 15 is input to the conversion constant circuit 24, and the product of the pulse count value and the conversion constant is calculated.
The conversion constant is obtained by the following Equation 1 so that the quadruple value of the pulse encoder is 2 ^N.
[Expression 1]
Conversion constant = 131072 / (30000 × 4) = 1.09226667
The value 131072 for calculating the conversion constant is obtained by determining the value of N so that (2 ^N −1)> (four times the number of pulses of the pulse encoder). That is, in the circuit of the first embodiment of FIG. 1, 2 ^N = 2 ¹⁷ = 131072.
The calculation position data corresponding to each point described in the position correlation diagram of FIG.
+ A point --- 1.09226666 -A point --- 131070.9077
+ B point---2.18545333-B point---131069.8155
Is processed as follows. The position data for calculation is a real number including a decimal point. When position data is converted back to a pulse count value as integer data, in order to perform reverse conversion without causing a calculation error, 6 significant digits are required. If the position data is calculated as such data, calculation without causing a calculation error is possible.
Note that 131072 is 20000 in hexadecimal. In the mask data generation circuit 25, a value of 1FFFF obtained by subtracting 1 from a value of 20000 in hexadecimal is set. If the logical product operation circuit 18 performs an AND operation on the 1FFFF and the output value 20000 of the conversion constant circuit 24 at the C point where the main axis is rotated by one pulse from the -A point in the forward rotation direction, the value becomes zero. That is, every time the spindle rotates once, the output value of the conversion constant circuit 24 is reset to zero, so that the operation result of the AND operation circuit 18 indicates the current position of the spindle. The same as in the case of the example circuit.
FIG. 2 is a block circuit diagram showing a second embodiment of the present invention. The position detector 27 includes a pulse encoder 26 that outputs a pulse of 30000 P / R, a quadruple circuit 14, a pulse counter 15, and a conversion constant circuit. 24, the mask data generation circuit 24 and the logical product operation circuit 18, but their names, uses, and functions have already been described, and thus their descriptions are omitted.
In the circuit of the second embodiment, the stop position is separately set by the stop position setter 31, but the product of the stop position set value and the conversion constant described in Equation 1 is calculated by the conversion constant circuit 32. . By inputting the deviation between the operation value of the conversion constant circuit 32 and the operation value of the logical product operation circuit 18 to the position adjuster 33, a control signal for adjusting the input deviation to zero is given to the motor control circuit 34. Since the electric motor 35 is controlled, the main shaft 36 stops at the set stop position.
【The invention's effect】
Conventionally, when the number of output pulses of the pulse encoder is not 2 ^N P / R, the position data becomes discontinuous before and after the origin, and there is a disadvantage that the calculation of position detection becomes complicated. On the other hand, in the present invention, even if the number of output pulses of the pulse encoder is an arbitrary value, ^{N N} is set so that the value 2 ^N −1 is larger than the number of output pulses or a value obtained by multiplying the output pulse number by four. By adopting the conversion constant with the value of 1 as the product of the number of pulse measurements, the position data can be prevented from becoming discontinuous before and after the origin, so that the effect of easily detecting the position can be obtained.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a first embodiment of the present invention. FIG. 2 is a block circuit diagram showing a second embodiment of the present invention. FIG. 3 is a pulse that outputs a pulse number of 2 ^N P / R. Block circuit diagram showing a conventional example of a position detection method using an encoder [Fig. 4] Position correlation diagram showing the positional relationship near the origin of a spindle
11, 21 A-phase pulse 12, 22 B-phase pulse 13, 23 Z-phase pulse 14 Quadruple circuit 15 Pulse counter 16 Hexadecimal conversion circuit 17, 25 Mask data generation circuit 18 AND operation circuit 24, 32 Conversion constant circuit 26 Pulse encoder 27 Position detector 31 Stop position setter 33 Position adjuster 34 Motor controller 35 Motor 36 Spindle

Claims (3)

The division operation value obtained by dividing the N-th power value of 2 by the value obtained by multiplying the number of pulses output by one rotation of the pulse encoder by a predetermined number is used as a conversion constant.
Counting the number of pulses obtained by multiplying the number of pulses output by the pulse encoder coupled to the rotating shaft by the predetermined number,
The value obtained by multiplying the count value by the conversion constant is the number of conversion pulses,
The logical product of the number of converted pulses and the mask data obtained by subtracting 1 from the hexadecimal converted value of the 2 N power value,
A position detection method using a pulse encoder, wherein the logical product operation result is used as current position data of the spindle. The division operation value obtained by dividing the N-th power value of 2 by the value obtained by multiplying the number of pulses output by one rotation of the pulse encoder by a predetermined number is used as a conversion constant.
Counting the number of pulses obtained by multiplying the number of pulses output by the pulse encoder coupled to the rotating shaft by the predetermined number,
The value obtained by multiplying the count value by the conversion constant is the number of conversion pulses,
The logical product of the number of converted pulses and the mask data obtained by subtracting 1 from the hexadecimal converted value of the 2 N power value,
Obtaining a deviation between the logical product operation result and a value obtained by multiplying the stop position setting value set separately by the conversion constant;
A stop position control method using a pulse encoder, wherein the spindle is stopped at the stop set position by an adjustment operation for setting the deviation value to zero. In the position detection method or the stop position control method by the pulse encoder according to claim 1 or 2,
When obtaining the conversion constant, the value obtained by subtracting 1 from the Nth power of 2 is larger than the value obtained by multiplying the number of pulses output by one rotation of the pulse encoder by the predetermined number. A position detection method or a stop position control method using a pulse encoder, wherein a value of N is determined.

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