JPS5951006B2 - positioning control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positioning control device for a device that relatively moves movable members, and more particularly to a positioning control device for a carriage feeding mechanism and type selection mechanism in an impact-type serial print printer or the like.

In such an impact-type serial printer device, a carriage as a movable member is equipped with a rotary wheel for printing, a motor for driving the wheel, a hammer for printing, and a ribbon cartridge, and the carriage is moved by the motor for driving the carriage. It is moved parallel to the recording medium and stopped and positioned at the printing position. Also,
The rotary printing wheel mounted on the carriage is rotated by the wheel driving motor described above, and the printed characters selected from among the plurality of printed characters carried on the rotating printing wheel are brought close to the recording medium. It is positioned so that it remains stationary at the printing position. In a device that drives a movable member such as a carriage of a serial printer to a target position using a motor or the like, a signal corresponding to the positional error to the target is applied to the motor, and the motor is operated so that the positional error becomes zero. is moved to move the parts.

This type of control includes a speed control mode in which the speed of the motor is made to follow a variable reference speed corresponding to a position error until a certain distance before the target position, as described in U.S. Pat. No. 3,954,163, and a The motor is moved to the target position and positioned using a combination of two control modes: a position control mode in which the position is controlled from a certain distance before the target position based on the position error itself. In this case, in the speed control mode, the motor speed is controlled by adding or subtracting the analog speed feedback signal corresponding to the motor rotation speed to the analog standard speed signal, and in the position control mode, the motor Motor position control is performed by adding and subtracting analog damping signals corresponding to rotational speed. difference. Furthermore, drive circuits for driving the carriage drive motor and the wheel drive motor are also driven by analog signals corresponding to the distance to the target position. However, in such an analog control system, productivity is hindered due to the need for level adjustment for the offset of the above-mentioned two position detection analog circuits, etc., and maintenance requires a large amount of man-hours. This makes it difficult to miniaturize the device, resulting in an increase in the number of parts and, ultimately, an increase in cost due to an increase in the size of the device.

Therefore, in order to solve the above-mentioned drawbacks, patent applications No. 17810 and No. 70 filed by the same applicant as the present application were filed.
No. 074 proposes a positioning control device in which the control system is digitalized.

However, these digital control devices
When an external force is applied to the rotary shaft of the motor by a brush of the motor or a wire system provided in the carriage feed mechanism, vibration of the motor near the positioning target position, that is, a limit cycle 4 occurs, and as a result, A disadvantage is that unpleasant noise is generated outside the device.
SUMMARY OF THE INVENTION An object of the present invention is to provide a high-speed, high-precision positioning control device having a new digital servo system configuration that eliminates the above-mentioned drawbacks.

The device of the present invention is a positioning control device that positions a movable member at a target position, and includes a motor for driving the movable member, and a mechanical link connected to the motor so that the motor rotates at a fixed angle every time the motor rotates by a fixed angle. a position signal generating means for generating a pair of incremental position signals whose polarities are reversed and mutually different phases; a mode signal indicating that the movable member is a certain distance before the force milestone position; integrating means for positioning the movable member at the target position in response to a position error signal with respect to the target position and then integrating the position error signal to generate an integral signal; and movement of the movable member from the current position to the target position. outputting a control signal corresponding to the movement distance from the current position to the target position in response to the incremental position signal and the integral signal based on an external movement information signal indicating the distance and movement direction; a control means for outputting the position error signal, and a drive means for generating a drive signal for driving the motor in response to the control signal, and after positioning the movable member at the target position, the integration means The movable member is accurately positioned at the target position by integrating the position error signal and adding the integrated signal to the position error signal.

Next, the present invention will be explained in detail with reference to the drawings. Note that in the following description, a signal line and a signal may be expressed using the same term without distinction. In one embodiment of the present invention shown in FIG. 1, a moving distance signal 13 and a direction designation signal 12 are initially set in the positioning control circuit 1 from an external control device 8 such as a computer, and the motor is controlled in accordance with these signals 12 and 13. 3 is controlled.

At this time, the rotational movement of the motor 3 is detected by the incremental encoder 2 and fed back to the positioning control circuit 1 via signal lines 9 and 10. The rotational motion of the motor 3 is transmitted to the carriage 5 via the dry fly 4, the wire 7 and the pulley 6, and drives the carriage 5 to a desired position. The incremental encoder 2 is an encoder that is configured using optical or magnetic components and outputs incremental position signals whose polarity is inverted every time the remoter 3 rotates through a constant rotation angle and whose phases are different from each other. Details of the configuration will be described later with reference to FIG. 15. FIG. 2 is a diagram showing the positioning control circuit 1 of FIG. 1 in detail.

In the speed control mode, a movement distance signal 13 and a direction designation signal 12 corresponding to the target position are transmitted from the external control device 8.
is input to the control circuit 14, and is initially set in a counter therein. Here, if the direction designation signal 12 is positive, the control circuit 14 outputs a positive standard speed signal corresponding to the position error to the signal line 23 and a speed control mode display mode signal to the signal line 22. Ru. At this time, the integrating circuit 15 receives the input signal, that is, the speed reference signal 2, according to the speed control mode display mode signal.
At the same time, the internal integrator is reset and an integral signal of O is output to the signal line 25. Therefore,
The reference speed signal is converted to PWM (
(pulse width modulation) circuit 18. The PWM circuit 18 receives the output signal 30 of the addition/subtraction circuit 16 and the PWM clock 32 from the clock generation circuit 20.
The output signal 30 is pulse width modulated and the output is sent to the signal line 3.
5 and 36. Thereby, the drive circuit 19
and drives the motor 3 in the forward direction via the signal line 11. When the motor 3 starts to move in the forward direction, two incremental position signals, whose polarity is reversed every rotation of a certain angle and whose phases are different from each other, are sent from the incremental encoder 2 mechanically connected to the motor 3 to the signal lines 9 and 10.
are output respectively. The phase relationship and polarity reversal of the two incremental position signals are detected in direction pulse generation circuit 21 by reference clocks 33 and 34 from the clock generation circuit, and a positive direction pulse is applied to signal line 28. In response to this positive direction pulse and the sample clock 31 from the clock generation circuit 20, the speed detection circuit 17 detects the speed of the motor and outputs a speed signal to the signal line 29. Therefore, by subtracting the speed signal from the speed reference signal in the addition/subtraction circuit 16, speed feedback can be provided, and the speed of the motor can be made to follow the reference speed corresponding to the speed reference signal. can. On the other hand, the positive direction pulse is input to the control circuit 14 via the signal line 28, and the initially set moving distance signal is subtracted, and as a result, the reference speed signal corresponding to the position error signal is also set in advance. It decreases along the curve.

As described above, the speed detection circuit 17 and the addition/subtraction circuit 16
With the speed feedback, the speed of the motor 3 can be controlled so as to follow a reference speed that decreases along a preset curve corresponding to the position error.

In this way, when the motor 3 reaches a certain distance before the target position, the control circuit 14 outputs a position error signal to the target position to the signal line 23, and the motor 3 uses this position error signal to reach the target position. controlled. At this time, signal line 2
2, a mode signal indicating the position control mode is output, but the integration circuit 15 is prohibited from performing an integration operation as in the speed control mode, and the integral output becomes O and is output to the signal line 25. At this time, speed feedback is performed by the speed detection circuit 17 and the addition/subtraction circuit 16 as in the speed control mode, but in the position control mode it functions as damping. In this way, when the motor 3 is moved by the input target movement distance and positioned at the target position, the integrating circuit 5 switches from the speed control mode to the position control mode by the mode signal 22. After a certain period of time, the input signal, that is, the position error signal 23, is used to integrate the integral clock 26 from the clock generating circuit 20.

That is, when the position error signal 23 deviates from the target position in the positive direction, it is integrated in the positive direction, and when it deviates in the negative direction, it is integrated in the negative direction, and the integrated signal is sent to the signal line 25. Output. The addition/subtraction circuit 16 receives the integral signal and adds it to the position error signal 23, further subtracts the speed signal 29 from the speed detection circuit 17 from the addition result, and outputs the result to the signal line 30. In this way, the motor 3 is driven via the PWM circuit 18 and the drive circuit 11. By adopting such a configuration, it is possible to suppress so-called limit cycles, which often occur in positioning servo systems including digital position detection, which will be described later with reference to FIG. 3, and to achieve accurate positioning control to the target position. can be achieved.

In the above explanation, an example was shown in which the motor 3 is driven in the positive direction, but when driving the motor 3 in the negative direction, the direction designation signal 12
By outputting a negative direction signal to the signal line 27 by the direction pulse generation circuit 21, positioning to the target position is performed in the same way as in the case of the positive direction described above. FIG. 3 is a diagram for explaining in an easy-to-understand manner the state of the limit cycle, which is a problem in a positioning control system including digital position detection.

That is, when the motor is controlled to be positioned at a certain target position 501, a digital position error signal 503 approximately proportional to the position error 500 of the motor is fed back and applied to the motor. However, because of digital position detection, the target position 501 becomes a dead zone having a certain width 504 (this width is inversely proportional to the number of pulses output from the incremental encoder per revolution). Therefore,
When the motor is driven to the target position 501, the position error signal 503 becomes 0, and no force is applied to the motor from the control system. At this time, an external force is applied to the rotating shaft of the motor by the brushes or wire system of the motor, as indicated by the arrow 502.
is applied in the direction of , the motor is moved in that direction,
It deviates from the target position 501 and a position error signal 503 is generated. Then, the motor is positioned again at the landmark position 501 by the position error signal 503, and the position error signal 503 is used to position the motor again.
03 becomes 0. In this way, in the digital positioning control system, when some external force exists, vibration of the motor in the vicinity of the target position 501 as described above, that is, a limit cycle occurs, and as a result, the vibration is transmitted through the motor to the outside of the device. generates unpleasant noise.

Therefore, even if the position error signal becomes 0, the previous position error signal becomes 0. If the control system generates a force sufficient to counter the external force, positioning can be performed without causing the aforementioned limit cycle. FIG. 4 is a diagram showing in detail the integrating circuit 15 of FIG. 2 for suppressing the occurrence of the limit cycle.

The mode signal 22 is input to a monostable multivibrator (hereinafter referred to as one shot) 151 and simultaneously input to one input of an AND gate 152. The other input of the AND gate 152 has the Q of the one shot 151.
(inverted) output is inputted, and the output of the AND gate 152 is inputted to the reset input of the integral counter 154 via the inverter 153, and at the same time, the AND gate 15
5 and 156 respectively.
On the other hand, the position error signal or the reference speed signal is input to the +1 or higher detector and the -1 or lower detector via the signal line 23, respectively, and the outputs of the two detectors are input to the other inputs of the AND gates 155 and 156. are input respectively. Further, the integrating clock 26 is connected to the AND gate 15.
5 and 156, and the outputs of the two AND gates are input to the count-up and count-down inputs of the integral counter 154, respectively. In the speed control mode, the mode signal 22 is at a low level (logic "0"), so the AND gate 15
The output of 2 also becomes low level, and the integral counter 154 is reset via the inverter 153, and at the same time, the outputs of the AND gates 155 and 156 are prohibited, and the integral counter 154 does not perform a count-up or count-down operation, but serves as an integral output. Outputs 0 to the signal line 25. When the position control mode is entered, the mode signal 22 becomes high level (logic 1''), but the one shot 151 operates and the o output of the one shot 151 remains unchanged for a certain period of time, that is, until it is positioned at the target position. becomes a low level, and the integral counter 154 does not perform an integral operation as in the speed control mode.After a certain period of time after entering the position control mode, that is, after positioning at the target position, the AND gate 152 The output of
56, the gate will also be opened. Here, if the motor causes a positional shift in the positive direction with respect to the target position due to the limit cycle, the position error signal is detected by the +1 or more detector 157, and the integrating clock 26 is output from the AND The integral counter 154 via the gate 155
count up. Conversely, if the motor causes a positional shift in the negative direction, the position error signal will be -l
The integral clock is then detected by the detector 158, and the integral clock is passed to the integral counter 154 via the AND gate 156.
count down. After the motor is positioned at the target position as described above, the integral counter 154 outputs an integral output to the signal line 25 in accordance with the position error signal.

Note that the detection operation by the +l or more detector 157 is performed when the most significant bit of the position error signal 23 is detected as shown in FIG.
(MSB) When the power sum is at one level, the OR of the other bits except the most significant bit is performed by the 0R circuit 157A, and the AND of the output signal of this 0R circuit and the output signal of the inverter 157B indicating the high level is performed. AND circuit 157
This is done by taking C.

Further, the detection operation by the -1 or lower detector 158 is performed by detecting the high level of the MSB of the position error signal 23 on the signal line 15.
This is done by detecting with 8A. FIG. 5 is a diagram showing in detail a second configuration example of the integrating circuit 15 of FIG. 2. In FIG.

The mode signal 22 is input to the reset input of the flip-flop 801, and in the speed control mode, the flip-flop 801 is reset, and its Q (non-inverted) output controls the integrating operation of the integral counter 802 as in the case of FIG. prohibit. When the position control mode is entered, the flip-flop 801 is released from the set operation by the mode signal 22, and enters a state of waiting for input of a set signal. When the motor is positioned at the target position, that is, when the position error signal becomes 0, it is detected by the zero detector 800 and the flip-flop 801 is set. Thus, the fourth
As in the case shown in the figure, the resetting operation of the integral counter 802 is canceled, an integral operation is performed according to the position error signal, and the integral output is outputted to the signal line 25. As a result, positioning of the limit cycle to the suppression target position can be detected quickly and accurately. FIG. 6 shows signal waveforms at various parts of the integrating circuit 15 shown in FIG. 4.

In addition, in the figure, the position error signal 23 and the integral signal 25 are as follows.
This shows a signal converted from digital to analog. When in the position control mode, the mode signal 22 is at reference numeral 15b.
The output of the AND gate 152 becomes a high level signal shown in reference numeral 15C after a certain period of time defined by one shot 51. on the other hand,
The position error signal 23 becomes a signal indicated by a reference numeral 15a that gradually approaches 0, and when the output of the AND gate 152 becomes high level, the target position has already been positioned. In other words, the time constant of the one shot 151 is set in advance so that the one shot 151 is positioned within a certain period of time defined by the one shot.

Once positioned at the target position, a so-called limit cycle occurs as shown in FIG. 3, and the position error signal 23 oscillates between 0 and +1 as indicated by reference numeral 15h.
Therefore, the +1 or more detector 157 is +1 of the reference number 15h.
detects the state of
Send the signal shown in Then, in the AND gate 155, the signal indicated by the reference numeral 15e is inputted to the count-up input of the integral counter 154 by the integral clock 26, and is counted up. As described above, when a limit cycle occurs and the integral force counter 154 counts up,
The output becomes a signal indicated by reference number 15f, and the count-up finally ends at the level indicated by the arrow indicated by reference number 15g, and the force generated by the motor and the external force are balanced by the level indicated by the arrow. The limit signal stops. In this way, limit cycles can be suppressed by integrating the position error signal using the integral counter 154. Next, referring to FIG. 7 which shows details of the control circuit 14 of FIG.
A reference speed signal is output from a memory 46 which is initially set in the counter 142 and register 141 via the memory 46 and whose output signals are given as addresses.

Further, the mode signal 22, which is the output signal of the zero detector 147 to which the output signal of the counter 142 is given, outputs a signal indicating the speed control mode since the counter 42 is not O, and the selector 148 outputs a signal indicating the speed control mode. The reference speed signal is selected and output to the signal line 23. on the other hand,
The output signal of the directional pulse generating circuit 21 is applied to the count-up input and count-down input of the counter 145 via signal lines 27 and 28, respectively. That is, a positive direction pulse is applied to the countdown input, and a negative direction pulse is applied to the countup input. Furthermore, the carry down output signal and carry up output signal of the counter 145 are 0R.
The gate 143 performs a logical sum (0R), and the output signal is applied to the countdown input of the counter 142.
Here, when the motor 3 moves in the positive direction, the positive direction pulse counts down the counter 145 via the signal line 28,
The carry down output signal counts down the counter 142 via the 0R gate 143. In this way, the output signal of the counter 142, which is the position error signal, gradually decreases, and the output signal of the memory 146, that is, the reference speed signal, decreases accordingly. Further, the counter 142 counts down, and when its output signal reaches 0, the zero detector 147 outputs a mode signal indicating the position control mode to the signal line 22, and the selector 148 selects the output of the counter 145. It is output to the signal line 23. At this time, the output signal of the counter 145 indicates a position error signal from a certain distance before the target position to the target position, and the motor is driven to the target position by this signal. As described above, the output signal of the memory 146, that is, the standard speed signal, is used as the signal from a certain distance before the target position, and the output signal of the counter 145, that is, the position error signal, is used as the signal from the certain distance before the target position. They are output to lines 23, respectively. FIG. 8 is a diagram showing the addition/subtraction circuit 16 of FIG. 2 in detail.

In the speed control mode and the position control mode, the reference speed signal and the position error signal are respectively inputted to the multiplier 162 through the signal line 23, multiplied by K1, and inputted to the adder 160. Since the output of the integrating circuit 15 is 0 before the motor is positioned at the target position, the adder 160 adds . The output is input to the subtracter 161.
On the other hand, the speed signal that is the output of the speed detection circuit 17 is input to the multiplier 163 via the signal line 29, multiplied by K2, input to the subtracter 161, subtracted from the output of the adder 160, and output to the signal line 30. It is done. Ru. After the motor is positioned at the target position, the integral signal 25, which is the output of the integrating circuit 15, is sent to the position error signal K by the adder 160.
It is added to the value multiplied by 1. That is, the integral signal 25
is of the form J such that it is added to the lower bits of the position error signal. As described above, in the speed control mode, the speed signal is subtracted from the reference speed signal, and in the position control mode, the integral signal is added to the position error signal, and the speed signal is further subtracted and output to the signal line 30.

In the explanation of FIG. 8, multipliers 162 and 163
is used to set the gains of Kl and K2, but instead of using a multiplier, it is also possible to shift the input bits and set the gains of powers of 2. Yes, in that case the circuit will be simpler. Figure 9 is the second
It is a diagram showing the speed detection circuit 17 shown in the figure in detail.

The positive direction pulse 28 and the negative direction pulse 27, which are the outputs of the direction pulse generation circuit, are input to the count up input and count down input of the counter 170, respectively. The output of the counter 170 is input to the register 171, and the output is output to the signal line 29 as a speed signal.
On the other hand, the sample clock 31 of the clock generation circuit 20
is connected to the set input of the register, and a delay circuit 172 is also connected to the set input of the register.
The output of the delay circuit 172 is input to the reset input of the counter 170. , Now, if the motor is moving in the forward direction, the counter 170 counts up the forward direction pulse 28.

When the sample clock 31 is input, the current value of the counter 170 is first set in the register 171, and the sample clock, which has been slightly delayed by the delay circuit 172, is used to input the counter 170. 17
0 is set. In this way, it is possible to output a signal proportional to the number of positive direction pulses or negative direction pulses generated in a certain time period defined by the sample clock 31, that is, the speed of the motor, to the signal line 29 as a speed signal. I can do it. Next, referring to FIG. 10 showing a second example of the speed detection circuit 17 of FIG.
Although not shown in the figure, a clock 600 with a sufficiently high frequency inputted from the clock generation circuit 20 constantly counts up.

Now, the motor is moving in the positive direction and the positive direction pulse is on the signal line 28.
When inputted to the 0R gate 606 via the 0R gate 606, the positive direction pulse is inputted to the set input of the register 602 through the 0R gate 606, and simultaneously sets the output of the counter 601 to the register 602 via the delay circuit 605. The counter 601 is then reset. Additionally, the forward pulse sets flip-flop 607.
The memory 603 is responsive as an address to the output of said register 602, i.e. the time interval of the positive direction pulse and the negative direction pulse, and more specifically to the reciprocal of the motor speed and the output of the flip-flop 607, i.e. the motor movement direction signal. After performing reciprocal conversion, the selector 60
A speed signal is output to 4. At this time, the selector 604 selects the output of the memory 603, that is, the speed signal, in the speed control mode by the mode signal 22 input from the control circuit 4 (not shown in FIG. 2), and selects the output of the memory 603, that is, the speed signal.
Output to 9. However, in the position control mode, the speed of the motor becomes low and the time interval between the positive direction pulse and the negative direction pulse becomes long, and the counter 601 may overflow, making it impossible to provide an accurate speed signal.
Therefore, in position control mode 1, as in the case of FIG. Therefore, a speed signal is input to the selector 604. , the selector 604 selects the output of the register 609 according to the mode signal 22 indicating the position control mode in the position control mode, and outputs the selected output to the signal line 29 as a speed signal.
That is, in the speed control mode, 5 time intervals of positive direction pulses or negative direction pulses are measured, and the signal is converted into a speed signal and output to the signal line 29, and in the position control mode,
The number of positive direction pulses or negative direction pulses within a certain fixed time interval is sampled and outputted to the signal line 29 as a speed signal. In this way, more accurate speed detection than in the case of FIG. 9 becomes possible in the speed control mode. Figure 11 is the PWM of Figure 2.
It is a diagram showing the circuit in detail.

The PWM clock 32 of the clock generating circuit 20 in FIG. 2 is input to the count-up input of the counter 181 of the PWM circuit 18, and constantly counts up the force counter 181. That is, the output of the counter 181 operates in a sawtooth waveform between the negative maximum value and the positive maximum value. The output of the counter 181 is input to the reference input b of the comparator 180, and the second
The output 30 of the addition/subtraction circuit 16 shown in the figure is input. The comparator 180 compares the output of the counter 81 with the output of the addition/subtraction circuit 16, and when the output of the addition/subtraction circuit 16 is greater than the output of the counter 18, the plus output 35 goes high. level(
The logic becomes 1゛1''), and when it is small, the negative output is 36
becomes a high level novel. That is, during one period of the counter 181, the positive output 35 and the negative output 36 alternately become high level, and when the input 30 is a positive signal, the positive output 35 becomes high level in proportion to the positive signal level. The time it takes for the negative output 36 to reach the high level is longer than the time it takes for the negative output 36 to reach the high level.

Conversely, when the input 30 is a negative signal, the above is reversed, and when it is O, the times at which the plus output 35 and the minus output 36 reach the high level are equal. As described above, pulse width modulated outputs proportional to the input signal 30 are provided to the signal lines 35 and 36. FIG. 12 is a diagram showing a first example of the drive circuit 19.

When positive output 35 is high level, negative output 36
is at a low level, and at this time, the positive output 35
turns on (conducts) transistor 192 via gate 191, thereby turning on transistor 193.
On the other hand, negative output 36 is inverted by gate 194 to turn off transistor 195 (non-conducting), thereby turning off transistor 196. As a result, a drive output 11 having a voltage approximately equal to the power supply voltage +ES is generated.
Further, when the negative output 36 is at a high level, the positive output 35 is at a low level, and in this case, contrary to the operation described above, the transistors 196 and 193 are turned on and off, respectively, and the voltage is approximately equal to the power supply voltage - ES. A drive output 11 is generated.

As a result, a drive output 11 having an average voltage proportional to the output 30 of the adder/subtracter circuit of FIG. 2 is applied to the motor. If the frequency of the drive output 11 is selected sufficiently higher than the cut-off frequency determined by the electrical time constant of the motor 3 shown in FIG. 2, the output 30 of the adder/subtractor circuit shown in FIG.
A current proportional to the current flows through the motor 3. FIG. 13 is a diagram showing a second example of the drive circuit 19.

When positive output 35 is high level, negative output 36
is at a low level, and at this time, the positive output 35
turns on transistor 60 through gate 600 and turns on transistor 609 through gate 600 and inverter 611, thereby turning on transistors 602 and 608. On the other hand, after the negative output 36 is inverted by the gate 605, the transistor 606 is turned off and the inverter 6]
0 to turn off transistor 604 and turn off transistors 607 and 603. As a result, an output voltage approximately equal to the difference 2ES between the positive power supply voltage +ES and the negative power supply voltage -ES appears on the signal line 11. Further, when the minus output 36 is at a high level, the plus output 35 is at a low level, and in this case, contrary to the operation described above, transistors 603 and 607 are turned on, and as a result, transistors 602 and 608 are turned off. -2ES
An output voltage approximately equal to is output to the signal line 11.

As a result, as in the example of FIG. 12, a current proportional to the output 30 of the adder/subtractor circuit of FIG. It is possible to flow twice the current using a power source of
The power supply can be used effectively, and the gain of the control system can be increased, so that the control characteristics can be improved. FIG. 14 is a diagram showing a third example of the drive circuit 19.

In Fig. 1, motor 3 is damaged due to excessive current. When demagnetization occurs or when the acceleration limit of the carriage 5 shown in FIG. 1 is determined, the current flowing through the motor 3 must be limited.

In FIG. 14, the current flowing through the motor 3 of FIG. 2 is detected by a current detection resistor 409, and a positive . In the case of excessive current, the comparator 408 sets the output of the comparator 407 or 408 to a high level by comparing it with the voltage corresponding to the preset current limit value, and in the case of the negative overcurrent, the comparator 407 sets the output to a high level. The output of each comparator is. It is input to NOR gate 406.

The output of NOR gate 406 is input to AND gates 400 and 403.
03 output is prohibited. With the above configuration, if the current flowing to the motor 3 exceeds the set current limit value, AN
D gates 400 and 403 are closed. If the current flowing through motor 3 does not exceed the set current limit value, gates 400 and 403 are open and positive output 35
When is at high level, negative output 36 is low level, positive output 35 turns on transistor 402 by turning on transistor 401, and negative output 36 turns on transistor 405 by turning on transistor 404. off, this results in supply voltage +
A drive output 11 of a voltage approximately equal to ES is generated. When the negative output 36 is at a high level, the positive output 35 is at a low level, and contrary to the above operation, transistors 405 and 402 are turned on and off, respectively, and the power supply voltage -E
A drive output 11 of a voltage approximately equal to S is generated. on the other hand,
If the current flowing through the motor 3 exceeds the set current limit value, AND gates 400 and 403 are closed;
Regardless of the states of the plus output 35 and the minus output 36, both transistors 402 and 405 are off, and neither positive nor negative power supply voltage is applied to the drive output 11.

Therefore, the current flowing through the motor 3 drops to the set current limit value. As described above, in the configuration shown in FIG. 14, a current proportional to the output 30 of the adder/subtractor circuit in FIG. In addition to this, it is possible to prevent an undesirable excessive current from flowing to the motor 3.

Here, the incremental encoder 2 shown in FIG. 2 will be explained in detail with reference to FIG. 15. an opaque disk 201 that is mechanically attached to the shaft of the motor 3 and responds to its rotation;
, is illuminated by a light source 200 and detected by photodetectors 204 and 205 as an increase or decrease in the amount of light transmitted through the slit plate 203. These detection signals are sent to comparators 207 and 208
The signal line 9 is converted into a pulse through comparison with a reference voltage 206 in the digital incremental position signal.
and output to 10. At this time, two photodetectors 2
By shifting the spacing between 04 and 205 and the spacing between the two slits of the slit plate 203 by 1/4 with respect to the spacing between adjacent position information patterns 202, the phase difference between the two slits is equal to 1/4 of the slit spacing. Two different incremental position signals are generated. FIG. 16 is a diagram showing the directional pulse detection circuit 21 of FIG. 2 in detail.

The two out-of-phase incremental position signals are input via signal lines 9 and 10 to the data inputs of flip-flops 210 and 211, respectively, and the outputs of the flip-flops 210 and 211 are input to the address input of memory 212. The two outputs of the memory 212 are provided as data inputs to flip-flops 213 and 214, and the outputs of the flip-flops 213 and 214 are provided as addresses of the memory 212. Furthermore, the tarok generation circuit 20 of FIG.
Two reference clocks having sufficiently high frequencies and different phases are connected via signal lines 34 and 33, one reference clock being connected to the clock inputs of the flip-flops 210 and 211, and the other reference clock being connected to the flip-flops 21.
3 and 214 clock inputs, respectively.
The reference clock 34 samples the two incremental position signals in the flip-flops 210 and 211, and the reference clock 33 samples the two outputs of the memory in the flip-flops 210 and 211.
3 and 214. Here, the outputs of the flip-flops 210 and 211 are respectively A and B, and the outputs of the flip-flops 213 and 214 are
Let the outputs of be X and Y, respectively. Further, the inputs of the flip-flops 213 and 214 are respectively P and Q, and the outputs of the memory 212, a positive pulse and a negative pulse, are F and R, respectively. Therefore, the logical formula F=A-X- is stored in the memory 212.
Y+A・X-Y+B-X-Y+B-X-Y. R=AX
・Y+A-X-Y+B-X-Y+B-X-Y. ．． P=A
．． If the state indicated by Q=B is memorized, a positive direction pulse or a negative direction pulse is sent to the signal line 28 or 27 depending on the rotational direction of the motor 3 at the rising and falling edges of the two incremental position signals, respectively. It is possible to output. Note that in the above description, the memory 212 is used, or the logical expressions described above may be constructed using hard logic. FIG. 17 is a diagram showing the clock generation circuit 20 of FIG. 2 in detail.

A reference oscillator 220 oscillates an accurate clock with a sufficiently high frequency, and the signal line 32 is used as a PWM clock.
and the phase is 18 through the inverter 222.
Signal lines 33 and 34 serve as reference clocks that differ by 0°.
give to Further, the tarot output of the reference oscillator 220 is given to the count-up input of the counter 221.
As a result, the frequency of the clock output is divided, and an integrating clock necessary for the integrating circuit 15 in FIG. 2 is outputted to the signal line 26. The integral clock is further divided by the counter 221, so that a clock having a frequency sufficiently lower than the output of the reference oscillator 220 is provided to a pulsing circuit 223 comprising an inverter, a resistor, a capacitor, and an AND gate. As a result, the sample tarot data necessary for the speed detection circuit 17 shown in FIG. 2 is outputted to the signal line 31. 1st
FIG. 8 is a diagram showing signal waveforms at various parts of the PWM circuit of FIG. 11 and the drive circuit of FIG. 12.

In the figure, the signal input and reference input of the comparator 180 in FIG. 11 are digital-to-analog converted signals. When the signal input of comparator 180 is a positive signal as indicated by reference numeral 18a, it is compared in comparator 180 with a sawtooth varying reference input indicated by reference numeral 18b and reference numerals 18C and 1.
A plus output signal and a minus output signal, respectively indicated by 8d, are output. At this time, since the signal input is positive, the high level time of the plus output signal indicated by reference numeral 18C is longer than the high level time of the minus output signal indicated by reference numeral 8d. When these two signals are input to the drive circuit 19, as described above, the positive power supply voltage and the negative power supply voltage increase in proportion to the high level time of the positive output signal and the negative output signal at the reference numeral 18.
The voltages are alternately applied to the motor as shown in e. Thus, due to the low-pass effect due to the electric time constant of the motor, the current flowing through the motor is a positive, substantially constant current as shown by reference numeral 18f. Further, when the signal input to the comparator 180 is O, the positive power supply voltage and the negative power supply voltage are applied to the motor for an equal period of time, and the current becomes approximately O. Furthermore, when the signal input is negative, the application time of the negative power supply voltage is longer than the application time of the positive power supply voltage, and a negative current flows. In this way, a current proportional to the signal input of comparator 180 can be supplied to the motor. As described above, in the present invention,
The entire control system is constructed with a digital circuit, and the motor and movable member are positioned at the target position via the speed control mode and position control mode.Furthermore, after positioning, the so-called limit cycle is also suppressed, thereby achieving the target position. A positioning control device that achieves accurate positioning can be realized.

Further, by digitizing the entire control system, the device can be made into an LSI, which reduces cost and size.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the positioning control circuit 1 of Fig. 1 in detail, and Fig. 3 explains the limit signal that occurs after the motor is positioned at the target position. 4 and 5 are diagrams showing the integrating circuit of FIG. 2, FIG. 6 is a diagram for explaining the operation of the circuit of FIG. 4, and FIG. 7 is a diagram of the control circuit 14 of FIG. FIG. 8 is a diagram showing an example of the configuration of the adder/subtractor circuit 17 in FIG. 2; FIG. 9 and FIG. 11 is a diagram showing an example of the configuration of the PWM circuit 18 in FIG. 2, FIGS. 12, 13, and 14 are diagrams showing an example of the configuration of the drive circuit 19 in FIG. 2 is a diagram showing an example of the configuration of the incremental encoder 2, FIG. 16 is a diagram showing an example of the configuration of the direction pulse generation circuit 21 in FIG. 2, and FIG. 17 is a diagram showing an example of the configuration of the clock generation circuit 20 in FIG. 2. Figures showing examples and Figure 8 is the PW of Figure 2.
FIG. 3 is a diagram showing signal waveforms of each part of the M circuit 18 and the drive circuit 19. In FIG. 2, 8...external control equipment, 14...
... Control circuit, 15 ... Integral circuit, 17
... Speed detection circuit, 16 ... Addition and subtraction circuit, 20 ... Clock generation circuit, 18 ...
...PWM circuit, 19... Drive circuit, 21...
... Direction pulse generation circuit, 3 ... Motor,
2...Incremental encoder.

Claims (1)

[Claims] 1. A positioning control device that positions a movable member at a target position, a motor for driving the movable member;
a position signal generating means that is mechanically connected to the motor and generates a pair of incremental position signals whose polarities are reversed each time the motor rotates by a certain angle and whose phases are different from each other; a direction pulse generation circuit that responsively generates positive direction pulses and negative direction pulses indicating rotation of the motor in the positive direction and negative direction, respectively; and a direction pulse generating circuit that indicates the moving distance and moving direction of the movable member from the current position to the target position. A variable reference speed signal corresponding to the position error signal is output as a first error signal from the current position to a certain distance before the target position in response to the positive direction pulse and the negative direction pulse based on the external movement information signal. and a control circuit that outputs a position error signal as a second error signal from a certain distance before the target position to the target position, and outputs a mode signal indicating that the position is a certain distance before the target position; a speed detection circuit that detects the speed of the motor in response to the positive direction pulse and the negative direction pulse and outputs a speed signal;
After the movable member is positioned at the target in response to a mode signal indicating that the movable member is a certain distance before the target position and a position error signal of the movable member with respect to the target position, the position error signal is transmitted. an integrating means for integrating and generating an integral signal; and adding the integral signal and the error signal in response to the integral signal, the first or second error signal, and the speed signal, and from the addition result. an addition/subtraction circuit that subtracts the speed signal and outputs a control signal;
a PWM circuit that outputs a pulse width modulation signal proportional to the control signal in response to the control signal; and a drive circuit that drives the motor in response to the pulse width modulation signal; A positioning control device characterized in that after positioning the movable member at the target position, the integrating means adds the integral signal to the position error signal to accurately position the movable member at the target position.