JP4797096B2 - Stepping motor rotation angle detection device - Google Patents

Description

The present invention relates to a rotation angle detecting device for a stepping motor capable of detecting the rotation angle of a stepping motor with high accuracy by a rotary encoder.

  For example, a servo drive using a stepping motor is equipped with a stepping motor rotation angle detection device that detects the rotation angle of the motor with high accuracy. Conventionally, an optical rotary encoder is generally used. The rotary encoder includes a disk in which a plurality of slits are formed at equal intervals in the circumferential direction, and an optical sensor that detects light that passes / shields through the slit as the disk rotates and outputs it as a pulse train. A rotational displacement amount of the motor is converted into a pulse train of an electric signal while being connected to the shaft of the motor (for example, there is Patent Document 1).

JP 2003-284391 A

  However, when a high-resolution rotary encoder is used in conjunction with the high-resolution driving of the stepping motor, the slit interval is small, so that a detection error of the slit and a delay of the detection signal occur, and accordingly, advanced encoding processing is performed. It has been pointed out that there is a problem that it is necessary and incurs a large cost as a whole.

  The present invention has been created under the above-described background, and its main object is to provide a rotation angle detection device for a stepping motor capable of achieving both high resolution and low cost. There is.

  In order to solve the above problems, the rotation angle detection device for a stepping motor of the present invention has a rotation angle (minimum step angle: n) of the stepping motor compared to a rotary encoder (angle resolution: m) connected to the motor. An encoder that counts encoder signals of a rotary encoder, an input pulse counter that counts input pulse signals for operating a stepping motor, and resets at the timing indicated by the encoder signals And an angle calculation output unit that calculates and outputs the rotation angle A (A = p · m + q · n) of the stepping motor based on the count value p of the counter and the count value q of the input pulse counter.

  According to the present invention, the encoder signal is counted by the encoder counter, while the input pulse signal is counted by the input pulse counter, and the input pulse counter is reset by the encoder signal. Both count values of the encoder counter and the input pulse counter are converted and added by the angle calculation unit, and as a result, the rotation angle of the stepping motor is obtained.

  As described above, the apparatus is configured to interpolate the measurement value of the rotation angle of the stepping motor using the rotary encoder by the count value of the input pulse signal of the stepping motor. It is possible to detect with higher accuracy than a connected encoder. For this reason, a low-resolution rotary encoder can be used, and unlike the conventional case, an advanced encoding process is not required, so that both high resolution and low cost can be achieved. In particular, when the stepping motor is driven at a high resolution, if the uniformity of the angle division is maintained, the above effect can be further increased.

  For the same device for rotating the stepping motor in both directions, the rotation direction signal indicates the encoder counter that counts the encoder signal of the rotary encoder in the direction indicated by the rotation direction signal, and the input pulse signal for operating the stepping motor. An input pulse counter that counts in the direction and resets at a timing indicated by the encoder signal, and a rotation angle α (α = p · m + q ·) of the stepping motor based on the count value p of the encoder counter and the count value q of the input pulse counter It may be configured to include an angle calculation output unit that calculates and outputs n).

  According to the present invention, the encoder counter and the input pulse counter have exactly the same operational effects as the above apparatus except that the encoder counter and the input pulse counter are different from the above apparatus only in that they are counted in the positive and negative directions according to the rotation direction of the stepping motor.

  The following input pulse counter may be used for the apparatus in the case of using an error signal indicating an abnormal rotation of the stepping motor or an emergency stop command of the motor. That is, in addition to counting the input pulse signal as described above, the counting of the input pulse signal is stopped at the timing when the error signal becomes active, and the count value is held until the error signal returns to inactive. The configuration has a function of resuming counting from the count value.

  According to the invention of this subordinate concept, when the error signal becomes active, the count of the input pulse counter stops. Therefore, even if the input pulse signal is input while the rotation of the stepping motor is stopped, the count value is Retained unchanged. Thereafter, when the error signal becomes inactive, the count is restarted from the held count value.

  Therefore, even when the motor stops due to stepping motor out-of-step or overheating, or due to an emergency stop of the machine drive system, an error may occur in the detection of the rotation angle of the motor. In this respect, it is possible to improve performance.

It is a block diagram of the rotation angle detection device of the stepping motor according to the embodiment of the present invention. 3 is a timing chart of main signals for explaining the normal operation of the apparatus. It is a timing chart of the main signal for demonstrating operation | movement at the time of abnormality occurrence of the apparatus.

  A stepping motor rotation angle detection device (hereinafter simply referred to as a rotation angle detection device) according to an embodiment of the present invention will be described below with reference to FIGS.

  The rotation angle detection device A exemplified here is used as a component of a servo motor using a stepping motor B as shown in FIG. 1, and detects the rotation angle (basic step angle: n) of the stepping motor B. The detection result is output to the host E as a feedback value.

  First, before describing the configuration of the rotation angle detection device A in detail, the host E, the driver D, the stepping motor B, and the rotary encoder C will be briefly described.

  The host E is a servo control device having a function such as negative feedback control of the driving of the stepping motor B. The host E generates the input pulse signal b and the rotation direction signal c to control the stepping motor B, and the stepping motor B An error signal d1 indicating an abnormality in the rotation of the motor B is generated. The host E is supplied with an error signal d2 that is an emergency stop command for the stepping motor B generated by various sensors for detecting an abnormality provided in the drive system of the servo motor, an abnormality notification switch, and the like.

  The input pulse signal b is a command pulse signal relating to the rotational drive of the stepping motor B. In this embodiment, the basic step angle N unique to the stepping motor B is divided into M (basic step angle: n = N / M). This is a 1 / M divided high resolution pulse for driving the stepping motor B in high resolution. That is, the host E drives the stepping motor B with high resolution so that the angular division uniformity of the stepping motor B is maintained. For example, when the stepping motor B is a two-phase stepping motor, the basic step angle N is 1.8 ° at a full step. When the division number M is 1000, the basic step angle n when the stepping motor B is driven with high resolution is 0.0018 °.

  The rotation direction signal c is a command digital signal regarding the rotation direction of the stepping motor B. The error signal d1 is a signal for informing the rotation angle detection device A of the detection result when the host E detects an abnormality such as step out of the stepping motor B, an indication of step out, or overheating.

  The driver D is a well-known stepping motor driving device that generates a motor drive excitation signal g for rotating the stepping motor B with the input pulse signal b and the rotation direction signal c as inputs, and divides the input pulse signal b. A frequency divider 40, a phase distribution circuit 50 that distributes the divided signal in the phase rotation direction indicated by the rotation direction signal c, and a current amplification of each of the phase-distributed signals to generate a motor drive excitation signal g. And a motor drive circuit 60.

  As for the stepping motor B, a two-phase stepping motor is used in this embodiment, and a rotary encoder C is connected to one side of the shaft of the motor.

  The rotary encoder C is a rotation angle sensor that converts the mechanical displacement amount of the rotation of the stepping motor B into an electrical signal, and the circumferential direction of the disk c1 connected to the stepping motor B and the surface of the disk c1 at equal intervals. , A light emitting element c3 disposed opposite to the disk c1, and a light receiving element c4 that receives the light output from the light emitting element c3 through the slit c2 and generates an encoder signal a. Have.

  In the present embodiment, the number of slits c2 is set to a value that is an integral multiple of the number of phases of the stepping motor B. This is for the purpose of facilitating the processing of the motor angular displacement for control in the host E exclusively. For example, if the number of slits c2 is 200, 200 pulse trains are output as the encoder signal a when the stepping motor B makes one rotation, and therefore the angular resolution m of the rotary encoder C is 360 ° / 200 = 1.8. °.

  Next, the configuration of the rotation angle detector A will be described. The rotation angle detection device A is a device that detects the rotation angle of the stepping motor B with higher accuracy than the rotary encoder C, and counts the encoder signal a of the rotary encoder C in the direction indicated by the rotation direction signal c. The counter 10, the input pulse signal 20 for operating the stepping motor B is counted in the direction indicated by the rotation direction signal c, and reset at the timing indicated by the encoder signal a, and the count value p of the encoder counter 10 And an angle calculation output unit 30 that calculates the rotation angle α (α = p · m + q · n) of the stepping motor B based on the count value q of the input pulse counter 20 and outputs it as a position information signal f.

  The encoder counter 10 is a positive / negative counter that receives the encoder signal a and the rotation direction signal c, outputs the counter value p to the angle calculation output unit 30, and generates a clear signal e in relation to the encoder signal a. And output to the input pulse counter 20.

  In the present embodiment, when the rotation direction signal c indicates the H level (meaning a forward rotation command of the stepping motor B), the count is incremented every time a pulse of the encoder signal a is input, while the rotation direction signal c is When the L level is indicated (which means a reverse rotation command for the stepping motor B), the countdown is performed every time a pulse of the encoder signal a is input. The clear signal e is a signal indicating that the encoder signal a has risen.

  The input pulse counter 20 is an M-ary positive / negative counter that receives the input pulse signal b, the rotation direction signal c, and the clear signal e. The counter value q is output to the angle calculation output unit 30 and the clear signal a It will be reset when becomes active. In addition to the input pulse signal b, the rotation direction signal c, and the clear signal e, an error signal d1 and an error signal d2 are input, and the counter value q is held according to the signals.

  In this embodiment, when both the error signal d1 and the error signal d2 are at the L level (indicating no abnormality), the pulse of the input pulse signal b is input when the rotation direction signal c indicates the H level. On the other hand, when the rotation direction signal c indicates the L level, the countdown is performed every time the pulse of the input pulse signal b is input. When at least one of the error signal d1 and the error signal d2 is at the H level (indicating that there is an abnormality), the count value q is held at the timing when the signal rises, and the pulse of the input pulse signal b is The count value q does not change even if it is input.

In order to match the correlation between the count value p of the encoder counter 10 and the count value q of the input pulse counter 20, the encoder counter 10 and the clock counter 20 are cleared to 0 with the rotation angle of the stepping motor B matching the reference position. is doing.

  The angle calculation output unit 30 is a multiplication adder that calculates the rotation angle α (α = p · m + q · n) of the stepping motor B with the count value p of the encoder counter 10 and the count value q of the input pulse counter 20 as inputs. The calculation result is always output to the host E as the position information signal f. For example, as in the above example, the basic step angle n is 0.0018 ° and the angular resolution m is 1.8 °, the count value p of the encoder counter 10 is 10, and the count value q of the input pulse counter 20 is 10,000. If there is, the rotation angle α of the stepping motor B is 10 × 1.8 + 10000 × 0.0018 = 32.0000 °.

  The operation of the rotation angle detection device A configured as described above will be described with reference to FIGS. 2 and 3, for convenience of explanation, the number of pulses between slits MC (MC = rp / sl, rp: the number of pulses of the input pulse signal b required for one rotation of the stepping motor M, sl: the rotary encoder C The number of slits c2 formed) is drawn as 10.

  First, when the stepping motor B is driven in the forward direction according to the input pulse signal b and the rotation direction signal c output from the host E, the encoder counter 10 and the input pulse counter 20 count up as shown in FIG. For example, at time t1, since the count value p of the encoder counter 10 is (r) and the count value q of the input pulse counter 20 is 5, the rotation angle α of the stepping motor B is calculated as (r) · m + 5 · n. The calculated value is transferred to the host E as the position information signal f.

  Thereafter, when the pulse input of the input pulse signal b is stopped, the stepping motor B is stopped. Along with this, the count-up of the encoder counter 10 and the input pulse counter 20 is stopped, and each count value is held. For example, since the count value p of the encoder counter 10 is (r + 1) and the count value q of the input pulse counter 20 is 7 at time t2, the rotation angle α of the stepping motor B is the calculated value of (r + 1) · m + 7 · n. It becomes.

  At time t3, when the stepping motor B is driven in reverse according to the input pulse signal b and the rotation direction signal c output from the host E, the encoder counter 10 and the input pulse counter 20 count down. For example, at time t4, the count value p of the encoder counter 10 is (r) and the count value q of the input pulse counter 20 is 8 (the rotation direction signal c indicates reverse rotation when the input pulse counter 20 is reset. Since q is negative and is represented by 2's complement in the figure, it is equal to -2, and therefore the rotation angle α of the stepping motor B is an arithmetic value of (r) · m−2 · n.

  When the error signal d1 or d2 becomes active (H level) at time t5 as shown in FIG. 3 while the stepping motor B is rotating forward, the input pulse counter 20 counts up the input pulse signal b. The count value q is held regardless of whether or not the operation is stopped. Since the stepping motor B is stopped by the host E when the error signal d1 or d2 becomes active, the count value p of the encoder counter 10 is still held. For example, at time t6, since the count value p of the encoder counter 10 is (r) and the count value q of the input pulse counter 20 is 6, the rotation angle α of the stepping motor B is calculated as (r) · m + 6 · n. Value.

  When the error signal d1 or d2 becomes inactive (L level) at time t7, the count-up of the encoder counter 10 and the input pulse counter 20 is restarted, and thereafter the operation is exactly the same as described above.

  As described above, according to the rotation angle detection device A, the rotation angle α of the stepping motor B can be detected with higher accuracy than the rotary encoder C. Therefore, a low-resolution type rotary encoder C can be used. . Not only the configuration of the apparatus is very simple, but also unlike the conventional case, since the host E does not require an advanced encoding process, both high resolution and low cost can be achieved. In particular, when the stepping motor B is driven at a high resolution, the uniformity of the angle division is maintained, so that there is an advantage that the detection accuracy of the rotation angle α of the stepping motor B is very high. In addition, when the stepping motor B stops due to an abnormality such as a step-out of the stepping motor A and then the drive of the motor is returned to normal, the rotation angle α of the stepping motor B is detected without any special setting. Since this can be resumed, it is possible to improve the performance in this respect as well.

  The stepping motor rotation angle detection device according to the present invention is not limited to the application of only a servo motor, but can be similarly applied to a device that needs to detect the rotation angle of a stepping motor. Of course, the types of stepping motors and rotary encoders are not limited to the above-described embodiments, and the apparatus is not separated from the rotary encoder, host, or driver, but all of the components or the components thereof. A form may be used in which a part is incorporated in a rotary encoder, a host, a driver, or the like. Even if the rotation of the stepping motor is unidirectional, the rotation angle of the motor can be detected in the same manner as described above only by not using the rotation direction signal.

  The encoder counter is not particularly limited as long as it can count the encoder signal of the rotary encoder and detect the rotation angle of the stepping motor with low accuracy. If the rotary encoder is a multi-phase output type, a rotational direction signal may be generated by detecting a phase difference between encoder signals having different phases, and this may be used.

  The configuration of the input pulse counter is not limited as long as it has a function of counting an input pulse signal for operating the stepping motor and resetting at a timing indicated by the encoder signal.

  As for the angle calculation output unit, as long as it has a function of calculating and outputting the rotation angle α (α = p · m + q · n) of the stepping motor based on the count value p of the encoder counter and the count value q of the input pulse counter, The configuration is not questioned.

A rotation angle detector 10 encoder counter 20 input pulse counter 30 angle calculation output section B stepping motor C rotary encoder D driver E host

Claims (3)

  An apparatus for detecting a rotation angle (minimum step angle: n) of a stepping motor with higher accuracy than a rotary encoder (angle resolution: m) connected to the motor, and counting an encoder signal of the rotary encoder Based on a counter, an input pulse signal that counts an input pulse signal for operating the stepping motor and resets at a timing indicated by the encoder signal, a count value p of the encoder counter, and a count value q of the input pulse counter And an angle calculation output unit for calculating and outputting the rotation angle α (α = p · m + q · n) of the stepping motor.   A device for detecting a rotation angle (minimum step angle: n) of a stepping motor with higher accuracy than a rotary encoder (angular resolution: m) connected to the motor, wherein the encoder signal of the rotary encoder is a rotation direction signal. An encoder counter that counts in the direction indicated by the input signal, an input pulse counter that counts an input pulse signal for operating the stepping motor in the direction indicated by the rotation direction signal and resets at a timing indicated by the encoder signal, and the encoder counter And an angle calculation output unit that calculates and outputs the rotation angle α (α = p · m + q · n) of the stepping motor based on the count value p of the input pulse and the count value q of the input pulse counter. Stepping motor rotation angle detection device.   3. The stepping motor rotation angle detection device according to claim 1, wherein the input pulse counter receives the input pulse at a timing when an error signal indicating an abnormality in rotation of the stepping motor or an emergency stop command of the stepping motor becomes active. An apparatus for detecting a rotation angle of a stepping motor, which has a function of stopping signal counting, holding the count value until the error signal returns to inactive, and then restarting the count from the count value.

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