JP4475963B2 - Position detection device - Google Patents

Description

  The present invention relates to a position detection apparatus using an incremental encoder having an A phase, a B phase, and a Z phase.

  In the conventional example, the width of the Z-phase pulse of the incremental encoder that outputs a B-phase pulse that has the same number of A-phase pulses and a plurality of A-phase pulses and a 90-degree phase per rotation and outputs one Z-phase pulse, The period is one cycle or less of the A-phase or B-phase pulse (see, for example, Patent Document 1).

  Correction of the origin position of the count value of the counter that counts up and down by the A phase signal and the B phase signal using the Z phase pulse having a width of one cycle or less of the A phase pulse or the B phase pulse is shown in the prior art. As shown, this is performed when the up-edge of the Z-phase signal is detected.

  Also, a Z-phase pulse is input when an up-edge of the A-phase signal (or an up-edge of the B-phase signal) is detected while the Z-phase signal is high and the B-phase signal (or A-phase signal) is high. The origin position is corrected based on the determination.

  FIG. 3 shows the A phase signal, the B phase signal, the Z phase signal, and the count value by the A phase signal and the B phase signal at the time of forward rotation. The Z phase signal includes false values due to noise in the period from t1 to t2. In this example, when the Z-phase pulse appears and the original Z-phase pulse appears in the period from t3 to t4, the conventional origin position correcting means by detecting the up-edge of the Z-phase pulse is applied.

  Prior to t1, the count value is up-counted by the A-phase signal and the B-phase signal. At t1, an up-edge of a false Z-phase pulse due to noise is detected in the Z-phase signal, and the count values based on the A-phase signal and the B-phase signal are corrected to the origin position. However, the count value based on the A-phase signal and the B-phase signal corrected to the origin position at t1 becomes position information different from the original position. When the original edge of the Z-phase pulse is detected at t3, the count value based on the A-phase signal and the B-phase signal is corrected to the origin position again, and the original position matches the count value based on the A-phase signal and the B-phase signal. To come. Therefore, in the period from t1 to t3, position information different from the actual position continues to be output.

  Even in the conventional example, when noise is mixed in the Z-phase signal with the B-phase signal (or A-phase signal) being in the high level and sandwiching the up-edge of the A-phase signal (or the up-edge of the B-phase signal), An erroneous origin position correction is performed by erroneously detecting the Z-phase pulse input, and position information different from the actual position is output.

Further, in a counter that performs quadruple counting using an A-phase signal and a B-phase signal, for example, even if short-pulse noise that is equal to or less than a half cycle of the A-phase pulse is mixed in the A-phase signal, the A-phase signal and the B-phase signal It does not affect the count value of the counter by the signal. When short pulse noise of 1/2 cycle or more of the A phase pulse is mixed, it affects the count value by the A phase signal and the B phase signal, but it is an effect corresponding to the short pulse noise width and does not cause a large error.
Japanese Patent No. 3413053

  The problem to be solved is that when short pulse noise is mixed in the Z-phase signal, the origin position is corrected incorrectly, and the position detector generates a large error in the position information.

  The present invention provides a Z-phase pulse edge detector for determining whether the Z-phase pulse has a width of two or more of an A-phase pulse or a B-phase pulse, and after detecting an up-edge or a down-edge of the Z-phase pulse. A counter after the Z-phase up-edge that starts up / down-counting of the A-phase pulse and the B-phase pulse after detecting the up-edge of the Z-phase pulse, and the counter value of the counter after the Z-phase up-edge and the Z phase A Z-phase pulse input determination device is provided for comparing the output of a setting device in which a numerical value less than the count value of the A-phase pulse and the B-phase pulse corresponding to the pulse width is set in advance to determine the input of the Z-phase pulse. , A data storage for storing the correction value of the A-phase B-phase counter at the up-edge position of the Z-phase pulse, the output of the Z-phase input determination unit, and the post-Z-phase up-edge Wherein the the output of the printer comprises a position correction unit 1 to perform the origin position correction of the A-phase B-phase counter.

  Further, a rotation direction discriminator for discriminating the rotation direction based on the A phase pulse and the B phase pulse is provided, and the setter is less than the count value of the A phase pulse and the B phase pulse corresponding to the width of the Z phase pulse. Is set according to the output of the rotational direction discriminator, and the data storage unit stores the correction value of the A-phase B-phase counter at the up-edge position of the Z-phase pulse in the rotational direction discriminator. A data storage device that stores data in accordance with the output is provided.

  Further, a single numerical value that is ½ of the count value of the A-phase pulse and the B-phase pulse corresponding to the width of the Z-phase pulse is set in the setting device, and the code is determined by the output of the rotation direction discriminator. The data storage device according to claim 1 is configured to store a correction value of the A-phase / B-phase counter at the center position of the Z-phase pulse, and the Z-phase pulse input determination device includes: The output of the setter having a sign corresponding to the output of the rotation direction discriminator is compared with the count value of the counter after the Z-phase up-edge, and when the input of the Z-phase pulse is determined, the A-phase B-phase counter is It is characterized by resetting to the value of the data memory.

  Further, when the count value of the A-phase / B-phase counter exceeds the count value corresponding to one rotation of the incremental encoder, it is within the count value corresponding to one rotation of the incremental encoder according to the output of the rotation direction discriminator. And a position corrector 2 for correcting the count value of the A-phase / B-phase counter.

  Even if noise is mixed in the Z-phase signal of the incremental encoder having the A-phase, B-phase, and Z-phase, it is possible to provide highly reliable position information to the controller without erroneously correcting the origin position.

  The purpose of providing highly reliable position information to the controller even if short pulse noise is mixed in the Z-phase signal is realized without causing a delay due to the filtering process to the Z-phase signal.

  FIG. 1 shows an embodiment combining claim 1, claim 2 and claim 4 of the present invention, and the present invention will be described in detail based on FIG.

  Incremental encoder 1 outputs a plurality of A-phase pulses and a B-phase pulse having the same number of A-phase pulses and a phase of 90 degrees per rotation, and one Z-phase pulse having a width of two or more A-phase pulses. Output. The rotation direction discriminator 2 discriminates the rotation direction of the encoder based on the A phase signal and the B phase signal of the incremental encoder 1.

  The A phase B phase counter 3 counts the A phase signal and the B phase signal of the incremental encoder 1 by 4 times. In this embodiment, the input order of the up edge and the down edge of the A phase signal and the B phase signal is 90 degrees behind the A phase pulse, and the A phase (up) → B phase (up) → When A phase (down) → B phase (down). When A phase (up) → B phase (down) → A phase (down) → B phase (up)..., It is determined that the rotation is reversed, and the A phase B phase counter 3 performs a down count operation.

  The Z-phase pulse edge detector 4 outputs 1 when the up-edge of the Z-phase pulse output from the incremental encoder 1 is detected, outputs 0 when the down-edge is detected, and then outputs the up-edge or The value is maintained until a down edge is detected.

  When the up edge of the Z phase pulse is detected and the output of the Z phase pulse edge detector 4 becomes 1, and the switch 91 of the position corrector 9 described later is connected to 0, the output of the EXOR 51 in the switch 5 Becomes 1, and the switch 52 switches to the input of the A-phase signal and the B-phase signal, and the counter 7 starts counting after the Z-phase up edge. When the down edge of the Z-phase pulse is detected and the output of the Z-phase pulse edge detector 4 becomes 0, or when the switch 91 in the position corrector 9 described later is connected to 1, the switch 5 The output of the EXOR 51 becomes 0, the switch 52 switches to the input of 0, and the counter 7 is cleared to 0 after the Z-phase up edge. The switch 91 in the position corrector 9 is not connected to 1 when the output of the Z-phase pulse edge detector 4 is 0.

  The setter 6 has a forward rotation comparison value and a reverse rotation comparison value, and a positive numerical value smaller than the count values of the A phase pulse and the B phase pulse corresponding to the Z phase pulse width is set as the forward rotation comparison value. The reverse comparison value is set to a value obtained by inverting (negative) the sign of the forward rotation comparison value.

  When the output of the rotation direction discriminator 2 is normal rotation, the Z-phase pulse input determination unit 8 has the count value of the counter 7 after the Z-phase up edge coincides with or becomes larger than the normal rotation comparison value of the setting unit 6. In this case, it is determined that the Z-phase has been input, and 1 is output. If the count value of the counter 7 after the Z-phase up edge is smaller than the forward rotation comparison value of the setting device 6, 0 is output. When the output of the rotation direction discriminator 2 is reverse rotation, it is determined that the Z phase is input when the count value of the counter 7 after the Z-phase up edge coincides with or becomes smaller than the reverse rotation comparison value of the setting device 6. 1 is output, and 0 is output when the count value of the counter 7 after the Z-phase up-edge is larger than the comparison value for reverse rotation of the setter 6.

  When the output of the Z-phase pulse input determiner 8 becomes 1, the position corrector 9 adds the count value of the counter 7 after the Z-phase up edge to the data memory 92, the switch 93 is turned ON, and the A-phase B-phase The count value of the counter 3 is corrected, and the switch 91 is connected to 1, and the switch 5 clears the count value of the counter 7 after the Z-phase up edge to 0.

  The data storage device 92 stores the correction value of the A-phase / B-phase counter 3 at the Z-phase up-edge position as the correction value for normal rotation and the correction value for reverse rotation, and is selected by the output of the rotation direction discriminator 2. Note that the correction value for forward rotation and the correction value for reverse rotation have a difference between the count values of the A-phase signal and the B-phase signal corresponding to the Z-phase pulse width.

  When the count value of the A-phase / B-phase counter 3 exceeds the count value corresponding to one rotation of the incremental encoder, the position corrector 10 counts corresponding to one rotation of the incremental encoder of the encoder when the output of the rotation direction discriminator 2 is normal. When the output of the rotation direction discriminator 2 is reversed, the count value corresponding to one rotation of the incremental encoder is added and the count value of the A-phase / B-phase counter 3 is within the count value corresponding to one rotation of the incremental encoder. Modify to be.

  The count value of the A phase B phase counter 3 is transmitted to the controller 11 using the position information.

  FIG. 2 shows the A-phase signal, the B-phase signal, the Z-phase signal, and the count value by the A-phase signal and the B-phase signal at the time of forward rotation, and a false Z-phase pulse appears in the period from t1 to t2. This shows a case where an original Z-phase pulse appears in the period t6 to t6.

  It is assumed that 8 is set as the forward rotation comparison value of the setting device 6. Before t1, the switch 91 of the position corrector 9 is connected to 0, the output of the Z-phase pulse edge detector 4 is 0 after detecting the down edge, and the counter 7 after the Z-phase up edge is cleared to 0. It is assumed that

  At t1, the Z-phase up edge is detected, and the counter 7 starts counting the A-phase signal and the B-phase signal after the Z-phase up edge. At t2, the count value of the counter 7 after the Z-phase up edge is 2, the Z-phase down edge is detected before exceeding the 8 set in the setting device 6, and the counter 7 after the Z-phase up edge is cleared to 0. The Therefore, position correction by a false Z-phase pulse is not performed during the period from t1 to t2.

  Since the count value of the A-phase / B-phase counter 3 exceeds the count value corresponding to one incremental encoder rotation at t3, the position corrector 10 counts from the count value of the A-phase / B-phase counter 3 to one incremental encoder rotation. The value is subtracted and the counter value of the A phase B phase counter 3 is corrected.

  At t4, the Z-phase up edge is detected, and the counter 7 starts counting the A-phase signal and the B-phase signal after the Z-phase up edge. At t5, the count value of the counter 7 after the Z-phase up-edge becomes 8, which coincides with the forward rotation comparison value of the setting device 6, so that it is determined that the Z-phase pulse is input by the Z-phase pulse input determiner 8, and the position corrector 9 The count value of the A-phase / B-phase counter 3 is corrected by adding the counter value of the counter after the Z-phase up edge to the data memory 92. At the same time, the position corrector 9 switches the switch 52 in the switch 5 to 0, and the counter 7 after the Z-phase up edge is cleared to 0.

  As described above, erroneous detection of the Z-phase pulse input due to noise mixed in the Z-phase signal can be prevented, and appropriate position correction by the Z-phase pulse input can be performed. Thereby, highly reliable position information can be provided to the controller.

  According to the present invention, even if noise is mixed in the Z-phase signal, highly reliable position information can be provided to the controller, so that the electric motor with the position detector attached is operated with a power converter such as an inverter that is a source of noise. Can be applied, and there is great potential for industrial use.

It is the block diagram which showed the Example which combined Claim 1, Claim 2, and Claim 4. FIG. Example 1 The operation at the time of applying Claim 1, Claim 2, and Claim 4 is shown. Example 1 The operation | movement at the time of applying background art is shown.

Explanation of symbols

1 Incremental Encoder 2 Rotation Direction Discriminator 3 A Phase B Phase Counter 4 Z Phase Pulse Edge Detector 5 Switch 51 EXOR
52 Switch 6 Setter 7 Counter after Z-phase up edge 8 Z-phase pulse input determiner 9 Position corrector 1
91 Switch 92 data storage unit 93 switches 10 of location corrector 2
11 Controller

Claims (4)

An A-phase pulse generator that outputs a plurality of pulses per rotation, attached to a rotating body that rotates, and a B-phase pulse generator that outputs the same number of pulses as the A-phase pulses with a phase of 90 degrees; Using an incremental encoder composed of a Z-phase pulse generator that outputs one pulse, the position of the rotating body is detected by an A-phase B-phase counter that counts up and down the A-phase pulse and the B-phase pulse, and the Z-phase In the position detection device for correcting the origin position of the counter value of the A-phase B-phase counter with a pulse
The Z-phase pulse has a width of two or more pulses of the A-phase pulse or the B-phase pulse, and a Z-phase pulse edge detector is provided for determining whether the Z-phase pulse has been detected after the up-edge or the down-edge has been detected, A counter after the Z-phase up-edge that starts up / down-counting of the A-phase pulse and the B-phase pulse after detecting the up-edge of the Z-phase pulse is provided. The counter value of the counter after the Z-phase up-edge and the Z-phase pulse A Z-phase pulse input determination unit is provided for comparing the output of a setting device in which a numerical value less than the count value of the A-phase pulse and the B-phase pulse corresponding to the width is set in advance to determine the input of the Z-phase pulse; A data memory for storing the correction value of the A-phase and B-phase counters at the up-edge position of the phase pulse, the output of the Z-phase input determination unit, and the counter after the Z-phase up-edge Position detecting device characterized by comprising a position corrector 1 for origin position correction of the A-phase B-phase counter by the output of the motor. 2. The position detector according to claim 1, further comprising a rotation direction discriminator for discriminating a rotation direction based on the A phase pulse and the B phase pulse, and the setting device according to claim 1, wherein the A phase corresponding to a width of the Z phase pulse is provided. A setting device is provided for setting a numerical value less than the count value of the pulse and the B-phase pulse according to the output of the rotation direction discriminator, and the data storage device of claim 1 has the A at the up-edge position of the Z-phase pulse. 2. The position detection device according to claim 1, further comprising a data storage device for storing a correction value of the phase B phase counter in accordance with an output of the rotation direction discriminator. The position detection device according to claim 2,
The setting device of claim 1 sets a single numerical value that is ½ of the count value of the A-phase pulse and the B-phase pulse corresponding to the width of the Z-phase pulse. The data storage device of claim 1 is configured to store the correction value of the A-phase B-phase counter at the center position of the Z-phase pulse, and the data storage device of claim 1 is configured to store the correction value of the A-phase B-phase counter. The Z-phase pulse input determiner compares the output of the setter having a sign corresponding to the output of the rotation direction discriminator and the count value of the counter after the Z-phase up-edge to determine the input of the Z-phase pulse. Then, the position detection device according to claim 1, wherein the A-phase and B-phase counters are reset to the numerical values of the data memory. When the count value of the A-phase / B-phase counter exceeds the count value corresponding to one rotation of the incremental encoder, the count value corresponding to one rotation of the incremental encoder is within the count value corresponding to the output of the rotation direction discriminator. The position detecting device according to any one of claims 1, 2, and 3, further comprising a position corrector 2 for correcting a count value of the A phase B phase counter.

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