JPS59106006A - Increment-type detector of driving quantity - Google Patents

Abstract

PURPOSE:To detect an accurate driving quantity even if a count miss occurs in a counter which counts position detection pulses by providing a count error correcting circuit. CONSTITUTION:A microcomputer includes a subtractor 12 and is provided with a count error correcting circuit 28. This count error correcting circuit 28 forecasts a relative driving quantity in the next driving position, which is a prescribed length apart from a current driving position, on a basis of a relative driving quantity in the current driving position of an increment-type encoder 20. Simultaneously, the circuit 28 attains the difference between the forecasted relative driving quantity and the relative driving quantity in the next driving position to calculate an error value corresponding to count miss components of a counter 24, and the relative driving quantity in the next driving position is corrected with this error value. Thus, an accurate driving quantity is detected even if a count miss occurs in the counter 24 which counts position detection pulses.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an incremental drive amount detection device that detects the drive amount of a motor or the like using an incremental encoder.

When servo control of a motor is performed using a feedback loop using digital signals, the amount of drive of the motor is generally detected by an encoder.

As this encoder, an absolute type encoder that can output a position detection pulse that directly corresponds to the amount of drive of a motor etc. is suitable for configuring the device, but absolute and T type encoders are expensive. , which is inconvenient when manufacturing the device at low cost.

Therefore, an incremental encoder has conventionally been used to detect the amount of drive as described below.

In FIG. 1, the position command 10 of the position command generator 1o is
0 (target value) is supplied to one input of the subtracter 12, and the deviation 102 output from the subtracter 12 is converted into an analog by the AD converter 14 and input to the driver 16. And the drive current 104 output from the driver 16
is supplied to the servo motor 18, and the servo motor 1
8 can drive the arm of the robot with this drive current 104.

Here, in this device, as mentioned above, the servo motor 1
Incremental encoder 2 to detect the drive amount of 8.
0 is used. Here, the incremental encoder 20 is of a rotary type, and is rotated by the servo motor 18, and as it is rotated, the number of detection pulses corresponding to the relative drive amount of the servo motor 18 is generated.
06 can be output. That is, when the incremental encoder 20 is rotated, it corresponds to the angle from the current rotation position to the new rotation position, in other words, the angle from the current rotation position to the new rotation position. Detection pulse 10 of the number of pulses corresponding to the drive amount of the servo motor 18
6 can be output.

The incremental encoder 20 of this device uses detection pulses 10 of a phase and b phase that have a phase difference of 90 degrees from each other.
6-1.1.06-2 can be output.

These detection pulses 106-1 and 106-2 are supplied to the direction discriminator 22.

The direction discriminator 22 detects these detection pulses 106-1.1.
06-2, it is possible to determine the rotational direction of the servo motor 18, and when the servo motor 18 is rotated in one direction, the pulse 108-1 is sent to the UP count input of the counter 24, and when the servo motor 18 is rotated in the other direction. J pulse 108 when
-2 can be output to the DOWN count input of the counter 24, respectively.

This counter 24 has a child count value reset to zero when the incremental encoder 20 is at the origin position corresponding to the origin of the servo motor 18, and therefore performs an UP count of the pulse 108-1, or When the DOWN count of IQ8-2 is performed, the count value becomes a value corresponding to the relative drive amount of the servo motor 18 from the origin position to the rotation position.

The relative drive amount 10 output from the counter 24 is supplied to the other input of the subtracter 12. Therefore, the subtracter 12 compares the position command lOO with the relative drive amount 110 and calculates the relative drive amount 11 with respect to the position command 100.
A deviation 102 of 0 can be output.

The conventional device shown in FIG. 1 has the above configuration, and its operation will be explained below.

Before the device is started, the origin of the servo motor 18 and the origin of the incremental encoder 20 are matched, and at this time, the relative drive amount 110 of the counter 24 is cleared.

After that, when this device starts operating, the position command generator 1
A position command 100 is supplied from 0 to the subtractor 12, and initially the servo motor 18 and the incremental encoder 20 are at the origin and the origin position, respectively, so the relative drive amount 110 is zero, so the deviation 102 is the same value as the position command 100. becomes.

When the drive current 104 corresponding to the deviation 102 is supplied to the servo motor 18 in this way, the servo motor 18 rotates and the detection pulse 106-1 or 106-2 corresponding to the amount of rotation, that is, the amount of drive is generated. It is output from the incremental encoder 20.

Then, the direction discriminator 22 detects the detection pulse 106-1.106
-2, the rotation direction of the servo motor 18 is determined, and a pulse 108-1 or 108-2 corresponding to the rotation direction is output.

At this time, when the pulse 108-1 is supplied, the counter 24 counts up the relative drive amount 110, and
When 108-2 is supplied, the relative drive amount 110 is counted down.

The relative drive amount 110 does not immediately match the position command 1.00, so the subtractor 12 outputs this non-zero deviation 102, and the relative drive amount 110 changes to the position command 1.00.
The servo motor 18 is feedback-controlled so as to coincide with 00.

As explained above, this type of device is configured so that the position detection pulses of the incremental encoder driven by the motor are counted by a counter to determine the relative drive amount of the motor. Drive control of the motor is performed based on the deviation from the target value, and feedback control is performed so that the relative drive amount of the motor matches the target value.

However, in the past, when a counting error occurs in the counter 24 due to noise or other causes, the relative drive amount 110 includes an error, and the error due to the counting error is accumulated by the counter 24, so that the device does not operate for a long time. When the servo motor 18 is operated, a problem arises in that the relative drive amount of the servo motor 18 no longer corresponds accurately to the position command 100.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide an incremental drive amount detection device that can accurately detect the drive amount even if a counting error occurs in a counter that counts position detection pulses.

In order to achieve the above object, the present invention provides an incremental drive amount detection device in which position detection pulses of an incremental encoder are counted by a counter to obtain a relative drive amount. Based on the amount, the relative drive amount at the next drive position separated by a predetermined interval from the current drive position is predicted, and the difference between the predicted relative drive amount and the relative drive amount at the next drive position is calculated, which corresponds to the counting error of the counter. The present invention is characterized in that it is provided with a count error correction circuit that calculates an error value and uses the error value to correct the relative drive amount at the next drive position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an incremental drive amount detection device according to the present invention will be described below with reference to the drawings.

FIG. 2 shows a block configuration of a preferred embodiment of the incremental drive amount detection device according to the present invention, and the device of this embodiment has a position command generator 10, a position command generator 10, It has an AD converter 14, a driver 16, a servo motor 18, an incremental encoder 20, a direction discriminator 22, and a counter 24.

This apparatus has a microcomputer 26, and the microcomputer 26 is shown in functional blocks in FIG.

In FIG. 2, the microcomputer 26 includes the subtracter 12, so that the present device is configured to operate in the same manner as the conventional example.

The microcomputer 26 also has a count error correction circuit 28 as described below.

The count error correction circuit 28 receives the C-phase reference detection pulse 106- output from the incremental encoder 2o.
A sequencer 3o to which 3 is supplied is provided. This detection pulse 106-3 is detected by the incremental encoder 2.
The sequencer 3o can output control signals 112-1.112-2.112-3.112-4 in synchronization with this detection pulse 106-3.

Further, the relative drive amount 110 is supplied to the register 32A, and the register 32A stores the relative drive amount 1 at the time of the latest detection pulse 106-3 according to the control signal 112-1.
Can hold 1o. The relative drive amount 110 output from the register 32A is supplied to the register 32B, and the register 32B can hold the relative drive amount 110 at the time of the previous detection pulse 106-3 generation by the control signal 112-2.

The latest relative drive amount 110 of the register 32A is the subtracter 3
4 and the previous relative drive amount 110 of the register 32B are respectively supplied to the adder 36.

Further, the count error correction circuit 28 is supplied with +, N, O, -N (N is the detection pulse 106-1 or the detection pulse 106-2 generated during one rotation of the incremental encoder 20) by the control signal 112-4 of the sequencer 30. A bit pattern generator 38 is provided which outputs a bit 1 pattern 114 (value corresponding to the number of pulses), and this bit pattern 114 is supplied to the adder 36.

The adder 36 can add this bit pattern 114 and the previous relative drive M110 to predict the next predicted relative drive amount 116 when the detection pulse 106-3 is generated next.

Further, the subtracter 34 subtracts the predicted relative drive amount 116 output from the adder 36 from the latest relative drive amount 110 output from the register 32A, and calculates the difference thereof, that is, one revolution corresponding to the count error of the counter 24. Error 118
can be found.

The above-mentioned one-rotation error 118 is generated by the incremental encoder 2.
Since it occurs every rotation of 0, it is supplied to an integrator 40 and integrated. Note that the integrator 40 can integrate and hold the one-rotation error 118 according to the control signal 112-4.

As described above, the count error correction circuit 28 predicts the relative drive amount at the next drive position separated by a predetermined interval from the current drive position based on the relative drive amount at the current drive position of the servo motor 18, and also predicts the predicted relative drive amount. The configuration is such that the error value corresponding to the count error of the counter 24 can be calculated by determining the difference between the relative drive amount at the next drive position and the relative drive amount at the next drive position.

Further, the count error correction circuit 28 includes an adder 42 that adds the total position difference 120 obtained by the integrator 40 to the relative drive amount 110 of the counter 24,
It is configured so that the relative drive amount at the next drive position can be corrected.

The naori runt error correction circuit 28 has a one-rotation error 118.
A discriminator 44 that determines whether or not is within a correctable range.
is provided, and its discrimination signal 122 is supplied to the sequencer 30.

A preferred embodiment of the device according to the present invention has the above configuration, and its operation will be explained below.

When the position command generator 10 outputs a position command of 1.00, the servo motor 18 is driven, and the detection pulse 106-1.106-2 is output from the position command generator 10, and the relative drive amount 110 is output from the counter 24 as a subtracter. 12, and the servo motor 18 is feedback-controlled with the position command 100 as the target by the deviation 102 of the subtractor 12.

If a count error occurs in the counter 24 due to noise or other causes while the above control is being performed, the count error correction circuit 28 corrects it as follows.

FIG. 3 shows a flowchart of this device. First, a C-phase reference detection pulse 1' 06-3 is sent to the sequencer 30.
When is supplied, an interrupt occurs and in step 200, the relative drive amount 110 of the counter 24 is stored in the register 32A.

In the next step 202, the bit pattern generator 38 outputs the bit pattern 114. This bit pattern generator 38 is controlled by a control signal 112-3 to output a detection pulse 1. If it returns to the same position again after the occurrence of 06-3, O is output as the bit pattern 114.

Then, in step 204, the register 32 is
The relative drive amount 110 of B and the bit pattern 114 of the bit pattern generator 38 are added to obtain the predicted relative drive amount 11.
6 is required. That is, since the difference between the relative drive amount 110 of the counter 24 between the old position where the detection pulse 10B-3 is generated and the current position is always 10N, -N, or 0, the relative drive amount 110 of the old position By adding any one of these to , the relative drive amount 110 at the next position can be predicted.

Furthermore, in step 206, the register 32 is
Predicted relative drive of the adder 36 from the relative drive amount 110 of A,
The amount 116 is subtracted to determine the one revolution error 118.

Further, in step 208, the discriminator 44 uses the one-rotation error 11
It is determined whether or not 8 is within a correctable range as follows.

In this embodiment, an error occurs when the count error of the counter 24 is close to ±N. For example, if N'(#N) is missing even though the incremental encoder 20 has made one revolution in the count-up direction, since N'>>N-N', the detection pulse 106
When -3 is detected twice, it is assumed that the noise of the N-N' pulse has been counted extra. As can be understood from this, the count error that can be corrected is ±N/2
limited to cases within the range of

Therefore, the discriminator 44 determines whether the value 118 is within such a range.

If it is determined in step 208 that the one-rotation error 118 is not within the above range, steps 202, 204, and 208
This is repeated, and when this is repeated three times, an emergency stop command is output from the sequencer 30 and the apparatus is stopped (step 212).

Further, when it is determined in step 208 that the one-rotation error 118 is within the above range, the process proceeds to step 214, where the integrator 40 integrates the one-rotation error 118, and in step 216, the relative drive amount of the register 32A is 110 is stored in register 32B.

Thereafter, the microcomputer 26 controls the position command generator 1.
When the position command 100 of 0 changes, this is taken in as an interrupt command, and in step 218, the relative drive fillo of the counter 24 and the total error 120 of the integrator 4o are summed to correct the count error of the counter 24.

In the next step 220, the deviation 10 of the corrected relative drive amount 110 with respect to the position command lOO of the position command generator 10 is
2 is calculated, and in step 212 this deviation 102 is calculated as AD
The signal is supplied to the converter 14, and feedback control of the servo motor 18 is performed using the position command 100 as a target value.

As explained above, according to Kimi-ryu, even if a counting error occurs in the counter 24, it can be corrected by the amount,
Therefore, it is possible to obtain an accurate relative drive amount 110 as a feedback value.

Furthermore, when the above correction is impossible, the device is brought to an emergency stop, making it possible to avoid any inconvenience caused by continued control of the servo motor 18.

Note that it is preferable to use the phase difference between the detection pulses 106-1 and 106-2 to quadruple the number of pulses per rotation of the incremental encoder 20 to increase its resolution.

As explained above, according to the present invention, even if a count error occurs in the counter 24, the amount is corrected, so that an accurate relative drive amount 110 can be obtained, and therefore, the servo motor 18 can be controlled accurately. It becomes possible to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a block diagram of a preferred embodiment of the device according to the present invention, and FIG. 3 is a flowchart explaining the operation of the embodiment shown in FIG. 10...Position command generator, 12...Subtractor, 18...Servo motor, 26I111...Microcomputer, 28...
Count error correction circuit, 34...subtractor, 36...adder. 40...Integrator, 42...Adder. Agent Patent Attorney Atsushi Nakajima

Claims (1)

[Claims] (1) In an incremental l-type drive amount detection device in which the position detection pulses of the incremental encoder are counted by a counter to determine the relative drive amount, the current drive is based on the relative drive amount at the current drive position of the incremental encoder. Predict the relative drive amount at the next drive position separated by a predetermined distance from the position, and calculate the difference between the predicted relative drive amount and the relative drive amount at the next drive position to calculate an error value corresponding to the count error of the counter. An incremental drive amount detection device comprising: a count error correction circuit that corrects the relative drive amount at the next drive position using the error value.