JP2693335B2 - Motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling the position of a controlled object by driving a motor according to the amount of command pulses.

[0002]

2. Description of the Related Art A motor control device is known in which a motor is controlled according to the amount of an input command pulse to control the position of a controlled object. FIG. 4 shows a conventional example of such a motor control device. The motor control device shown in FIG.
Broadly divided, a position control unit 50, a speed control unit 70,
The current control unit 80 is included. A command pulse for commanding a counterclockwise or clockwise rotation is input to the position control unit 50. The position control unit 50 includes a first multiplier 51 that multiplies the command pulse by G ₁ times, a second multiplier 65 that multiplies a feedback pulse from a rotary encoder 63, which will be described later, by G ₂ times, and these. A deviation counter 52 that counts the deviation between the command pulse and the feedback pulse multiplied by the multipliers 51 and 65, a divider 53 that makes the deviation amount counted by the deviation counter 52 1 / C, and a divider 53. Digital-to-analog converter 54 for converting the output of the above into an analog command signal B, a feedforward pulse generator 55 for generating a feedforward control pulse according to the above command pulse, and a feedforward pulse for converting the feedforward pulse into a voltage signal. The frequency / voltage converter 56 for the feedforward amount signal A, the feedforward amount signal A and the analog command signal No. B and an adder 57 which outputs the sum as a speed command signal. The multiplication rate of the multipliers 51 and 65 and the division rate of the divider 53 are set in advance by switches.

The speed control unit 70 converts the feedback signal from the rotary encoder 63 into a voltage signal, a frequency / voltage converter 64, the speed command signal, and the converted voltage of the feedback signal by the frequency / voltage converter 64. It has a subtracter 58 that outputs a signal of a difference from the value, and a speed calculation amplifier 59 that calculates the output signal of the subtractor 58 and outputs it as a current command signal.

The current control unit 80 calculates a voltage applied to the motor 62 according to the current command signal and converts the applied voltage into a duty corresponding to the current operation amplifier and a PWM unit 61, and the current calculation amplifier. And a motor 62 driven by the PWM unit 61, and a rotary encoder 63 that outputs a pulse signal according to the rotation speed and the rotation position of the motor 62. The motor 62 drives a controlled body (not shown). The output signal of the rotary encoder 63 is input as a feedback signal to the feedback pulse multiplier 65 and the frequency / voltage converter 64 as described above.

The command pulse multiplier 51, the feedback pulse multiplier 65, the deviation counter 52, the divider 53, and the feedforward pulse generator 55 included in the position control unit 50 are integrated into an application specific integrated circuit (ASIC) 60. It is configured. Therefore, the command pulse multiplication processing and the feedback pulse multiplication processing are performed by hardware.

When a clockwise or counterclockwise command pulse is input, the command pulse is used as a feedforward control pulse in the feedforward pulse generator 55, and is multiplied by G _{1 in the} pulse multiplier 51. . The pulse detected by the encoder 63 is multiplied by G _{2 in the} pulse multiplier 65. The command pulse multiplied by G ₁ times and the output of the encoder 63 multiplied by G ₂ times are input to the deviation counter 52, and both deviations are detected. Deviation counter 52
Outputs by counting the difference between the command pulse and the feedback pulse. The output signal of the deviation counter 52 is reduced to 1 / C by the divider 53, and then the digital-analog converter 5
At 4, the command signal B is converted. The feedforward control pulse is converted by the frequency / voltage converter 56 into a feedforward amount signal A which is a voltage signal. The command signal B and the feedforward amount signal A are added by the adder 57 and output as a speed command signal.

The speed command signal is supplied to the speed calculation amplifier 59.
Is calculated as a current command signal, and the current calculation amplifier and the PWM unit 61 are operated by the motor 62 in accordance with the current command signal.
Drive. The rotation position and rotation speed of the motor 62 are detected by the rotary encoder 63, and this detection signal is input to the deviation counter 52 as a feedback signal and is converted into a voltage signal by the frequency / voltage converter 64. The difference between this voltage signal and the speed command signal is obtained by the subtractor 58, and this difference signal is calculated by the speed calculation amplifier 59 and output as the current command signal. When the controlled object reaches the position instructed by the command pulse, the output of the deviation counter 52 becomes zero, the motor 62 stops, and the controlled object is positioned at the target position. When a command pulse of a high frequency is suddenly input, a large speed command signal is output by the feedforward flow including the feedforward pulse generator 55, whereby the motor 62 is rapidly driven and the controlled object is It will be quickly positioned at the target position.

The motor control device as described above is
It is disclosed in the column of "Small AC Servo Motor" by Kenji Sawai of "Mechanical Design", 1987 11 special edition.

[0009]

According to the above-mentioned conventional motor control device, since the command pulse multiplication processing and the feedback pulse multiplication processing are performed by hardware, there are the following problems. The command pulse multiplication rate G ₁ can be selected only within a narrow range of about 1 to 16 times due to the number of bits and the number of switches. Similarly, the multiplication factor G ₂ of the feedback pulse is 1
Only a narrow range such as double, double, or four can be selected. In some cases, the feedforward amount is not linked to the command pulse multiplication rate G ₁ , and the effect of improving the responsiveness to a sudden change in the command pulse is small. Since the open-loop transfer function of the position control loop is changed by the feedback pulse multiplication factor G _2, the stability of the control by changing the feedback pulse multiplication factor G ₂ is changed.

The present invention has been made in order to solve the problems of the prior art. The command pulse multiplication process and the feedback pulse multiplication process are performed by software, so that the command pulse multiplication factor and The multiplication factor of the feedback pulse can be selected in a wide range such as 1 to 9999 times, and the feedforward amount is linked to the command pulse multiplication factor to improve the responsiveness to a sudden change of the command pulse. By preventing the open-loop transfer function of the position control loop from changing due to the feedback pulse multiplication factor, it is possible to prevent the control stability from changing even if the feedback pulse multiplication factor is changed. An object is to provide a control device.

[0011]

According to the present invention, there is provided a command counter for counting command pulses, a first pulse multiplier for multiplying the output of the command counter by G ₁ , and an encoder for detecting the position of a controlled object. And a feedback counter that counts the detection pulses of the encoder and the output of the feedback counter
And _doubling the second pulse multiplier, the first and deviation counter for counting the multiplied pulses mutual deviation due to the pulse multiplier and the second pulse multiplier, the output of the error counter 1 / G
₂ of the first divider and the second divider that makes the output of the first pulse multiplier 1 / G ₂ , and the output of the first divider and the second divider It is characterized by comprising an adder for adding the output and a speed command, and a drive amplifier for driving the controlled object drive motor according to the speed command output of the adder. A first arithmetic means for multiplying the output of the first divider by a constant and a second arithmetic means for multiplying the output of the second divider by a constant may be provided. The order of the first divider and the first arithmetic means may be reversed. The order of the second divider and the second arithmetic means may be reversed.

[0012]

The deviation counter detects the deviation between the command pulse multiplied by G ₁ by the first pulse multiplier and the detection pulse of the encoder counted by the feedback counter and multiplied by G ₂ by the second pulse multiplier. The output pulse of the deviation counter is reduced to 1 / G ₂ by the first divider. The command pulse multiplied by G ₁ by the first pulse multiplier is made 1 / G ₂ by the _second divider and becomes a feedforward amount, and this feedforward amount and the output of the second divider are adders. Is added, the motor is driven according to the output of the adder, and the position of the controlled object is controlled. When the multiplication rate G ₂ of the feedback pulse is changed, the command pulse is correspondingly changed to 1 / G by the first divider.
_{It is set to 2} and balanced to stabilize the servo system. Further, the feedforward amount is reduced to 1 / G ₂ by the _second divider, and the balance between the feedforward amount A and the command signal B is maintained. By providing the first and second calculating means for multiplying the outputs of the first and second dividers by a constant, the response of the servo system to the command pulse can be set arbitrarily.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motor control device according to the present invention will be described below with reference to FIGS. In FIG. 1, the motor control device is roughly divided into a position control unit 10, a speed control unit 20, and a current control unit 30.
The servo motor 25 included in the current control unit 30 drives a controlled body (not shown). The servo motor 25 has an encoder 26 that detects the rotational position of the servo motor 25. The position of the controlled object can be detected by counting the detection pulse of the encoder 26 with the feedback counter 27. On the other hand, the count value from the command counter 11 is input to the position control unit 10. The command counter 11 and the feedback counter 27 are up / down counters. The command counter 11 is connected so that the value is +1 for each counterclockwise command pulse input and the value is -1 for each clockwise command pulse input. The feedback counter 27 is connected so as to add the detection pulse of the rotary encoder 26 when the motor 25 rotates counterclockwise and subtract it when the motor 25 rotates clockwise.

The position control unit 10 includes a command counter 1
Sampling unit 12 that takes the difference of the output of ₁ every T ₁ seconds
And a sampling unit 28 that takes the difference of the output of the feedback counter 27 every T ₁ seconds. Here, the instruction counter 11 will be described as an example with reference to FIG. When the current sampling value is Cr (n) and the previous sampling value T ₁ second before is Cr (n-1), Cr (n) -C
Let r (n−1) be the “difference for every T ₁ second” and define this value as ΔCr (n). Due to the slope of the straight line shown in FIG. 3, ΔCr (n) becomes a positive value, a negative value or zero. Similarly, in the case of the feedback counter 28, ΔCf (n)
= Cf (n) -Cf (n-1).

The position control unit 50 includes the sampling unit 1 described above.
The number of command pulses per T ₁ seconds sampled in 2 is G ₁
A first multiplier 13 that doubles the frequency, and a sampling unit 28.
A second multiplier 29 that multiplies the number of feedback pulses sampled for every T ₁ seconds by G ₂ times, and a subtractor that finds the deviation between the command pulse and the feedback pulse multiplied by these multipliers 13 and 29. 14 and subtractor 1
The deviation counter 15 that counts the deviation output of No. 4, the first divider 16 that makes the deviation amount counted by the deviation counter 15 1 / G ₂ , and the output of the first divider 16 are multiplied by a constant. The outputs of the first computing means 17, the second divider 19 for making the command pulse multiplied by G ₁ times 1 / G ₂ by the first multiplier 13 and the output of the second divider 19 It has a second arithmetic means 21 for multiplying by a constant to obtain a feedforward amount signal A, and an adder 18 for adding the feedforward amount signal A and the command signal B and outputting it as a speed command signal.

The speed control unit 20 includes a feedback counter 2
A speed detection unit 31 that detects the speed of the motor 25 based on the feedback signal Cf from 7; and a calculation unit 32 that multiples the speed signal detected by the speed detection unit 31 by a constant.
A subtractor 22 for outputting a signal of a difference between the speed command signal and the feedback signal from the calculating means 32;
And a speed calculation amplifier 23 for calculating an output signal of the above and outputting it as a current command signal.

[0017] The current controller 30 includes the above-mentioned current command signal that current operational amplifier and PWM section 24 converts the duty corresponding to and and it calculates a voltage applied to the motor 25 in accordance with, the current calculation amplifier and PWM A motor 25 driven by the unit 24 and a rotary encoder 26 that outputs a pulse signal according to the rotation speed and the rotation position of the motor 25 are included. The speed calculation amplifier 23
And the current calculation amplifier and the PWM unit 24
It constitutes a dynamic amplifier.

The position controller 10 and the speed controller 20 are
It can be constituted by a microprocessor, and the values of the multiplication factors G ₁ and G ₂ of the _first and _second multipliers 13 and 29, the first and second dividers 16, 19 values and first and second arithmetic means 1
The magnification of 7, 21 can be set freely and finely. FIG. 3 shows an example of an operation section for setting such various parameters. The operation panel 40 displays a parameter number display section 41 for displaying the type of the selected parameter by number and a set parameter value. A parameter value display section 42, an up button 43 for changing the numerical value in the up direction, a down button 44 for changing the numerical value in the down direction, and a set button 45 for registering the set numerical value.

Next, the operation of the above embodiment will be described. Now, when a command pulse is input, this is the command counter 1
1 counts, and the difference ΔC of this count value every T ₁ seconds
The sampling unit 12 outputs r (n), and the first pulse multiplier 13 multiplies the sampled value by G ₁ to obtain G ₁
× ΔCr (n). In addition, the sampling unit 28 calculates the difference between the feedback pulses detected by the encoder 26 and counted by the feedback counter 27 every T ₁ seconds.
Is output by the second pulse multiplier 2
9 is multiplied _twice G, and G ₂ × ΔCf (n). The deviation counter 15 has a deviation G ₁ × ΔCr (n) −G ₂ × ΔCf (n) between the outputs of the first and second pulse multipliers 13 and 29.
Is added every T ₁ seconds, or subtracted depending on the sign. The first divider 16 sets the count value of the deviation counter 15 to 1 / G ₂ , and the first arithmetic means 17 multiplies the constant Kpp to generate the command signal B. This command signal B
Accordingly, the motor 25 is driven through the speed control unit 20 and the current control unit 30, and when the output value of the deviation counter 15 becomes zero, the command signal B also becomes zero and the motor 25 also stops. By the above operation, the driven body (not shown) is controlled to the position corresponding to the command pulse.

As described above, the position control section 10 controls the motor 25 so that the value of the deviation counter 15 becomes zero to control the position of the controlled object. For example, it is assumed that two pulses are input as a counterclockwise command pulse, and the multiplication rate G _{1 of} the first pulse multiplier 13 is set to _{2 and} the multiplication rate G _{2 of} the second pulse multiplier 29 is set to G ₂ = 4. Think of if. The output of the deviation counter 15 is 2 × 2 = 4 pulses. The output of the deviation counter 15 is the first divider 16
Is made 1/4 to be 1 pulse, and further, the command signal B is multiplied by Kpp by the first computing means, and the command signal B drives the motor 25 to rotate counterclockwise. By the rotation of the motor 25, one pulse is input to the feedback counter 27 and counted, and this is counted by the second pulse multiplier 29.
Is multiplied by G ₂ (= 4 times) to become 4 pulses, and these 4 pulses are subtracted by the deviation counter 15, the value of the deviation counter 15 becomes zero, and the motor 25 stops. That is, the motor 25 rotates by (number of command pulse inputs) × G ₁ / G ₂ pulses. In the present example, 2 × 2/4 = 1, and the motor 25
Rotates one pulse.

Next, the feedforward will be described. G ₁ × ΔCr (n) × Kff by branching to the feedforward loop after the first pulse multiplier 13 and passing through the second divider 19 and the second calculating means 21.
The feedforward amount signal A which is / G ₂ is the adder 1
At 8 the command signal B is added and the speed command signal is obtained. Since there is a difference every T ₁ seconds before the first pulse multiplier 13, when the frequency of the command pulse input to the command counter 11 is constant, the feedforward amount signal A
Is constant. If the frequency of the command pulse changes, the feedforward amount signal A also changes. For example, the rotation speed is 0
When starting from rpm to 3000 rpm,
Since the frequency of the command pulse changes, the feedforward amount changes from 0 to a certain value, increasing the speed command. Therefore, the rotational position control of the motor 25, that is, the position control of the controlled object with respect to the change of the command pulse is quickly performed, which is effective for improving the position response.

By the way, in the conventional motor control device shown in FIG. 4, in order to avoid the structure of the special purpose integrated circuit including the position control unit 50 and the like from becoming complicated, the feed is performed from before the first pulse multiplier 51. Forked the forward loop. Therefore, the multiplication factor G of the first pulse multiplier 51
_{When 1} is changed, the ratio (A / B) of the feedforward amount A to the command signal B is changed, and in some cases, the responsiveness to a sudden command pulse change cannot be improved.

In that respect, according to the position controller 10 constructed by software as in the embodiment of the present invention,
It is easy to branch the feedforward loop after the pulse multiplier 13 of FIG. 1 and in fact, in the above embodiment, the feedforward loop is branched after the first pulse multiplier 13. Even if the multiplication rate G ₁ by the pulse multiplier 13 changes, the ratio of the feedforward amount A to the command signal B does not change, and it is possible to obtain a motor controller having excellent responsiveness.

When the position control unit 10 is constructed by software, the deviation counter 1 as in the embodiment shown in FIG. 1 is used.
Insert a first divider 16 with a value of 1 / G ₂ after 5,
It is also easy to insert the second divider 19 having a value of 1 / G _{2 in} the feedforward loop. First,
By inserting the second dividers 16 and 19, the multiplication rate G _{2 of} the second pulse multiplier 29 and the value 1 / G _{2 of} the first and second dividers are interlocked. 2 pulse multiplier 29
Even if the multiplication factor G ₂ of change, the rate of feed forward amount A (A / B) and the open-loop transfer function does not change with respect to the command signal B, the position control of the controlled device by the change in the multiplication factor G ₂ It is possible to prevent the performance from changing.

Also in the conventional motor control device shown in FIG. 4, the multiplication factor G ₂ by the second pulse multiplier 65 and the divider 53 are used.
It is desirable that 1 / C = 1 / G ₂ by interlocking with the value 1 / C of 1 / C. By doing so, G ₂ × 1 / G ₂ = 1 and the open-loop transfer function of position control is invariant with respect to G ₂ , and there is no problem that the control performance changes due to a change in G ₂ . However, in the conventional motor control device shown in FIG. 4 in which the position control unit 50 and the like are configured by the special purpose integrated circuit, the multiplication factor G ₂ by the second pulse multiplier 65 and the value of the divider 53 If 1 / C is to be interlocked, the configuration of the special purpose integrated circuit becomes complicated and the cost becomes high. Therefore, the second pulse multiplier 65 and the divider 53 are provided as separate circuits, and Parameter G ₂
And 1 / C were set by the switch. According to such a conventional motor control device, the second pulse multiplier 65
When the multiplication rate G ₂ due to changes in position, the position control performance of the controlled object changes.

The multiplication factors G ₁ and G _{2 of} the first and second pulse multipliers 13 and 29 and the constants Kpp and Kff of the first and second calculation means 17 and 21 are as shown in FIG. This is performed on the operation unit as shown. For example, if G ₁ is the parameter number 1 and G ₂ is the parameter number 2,
With the operation panel 40 shown in FIG. 3, G ₁ = _{1 to} 9999, G ₂ =
It can be set as 1 to 9999. Although it is possible to increase the number of digits displayed on the parameter value display section 42 to set a parameter value of a larger digit,
If both G ₁ and G ₂ can be set to 9999, the values will be sufficiently large for practical use. Further, since the number of position control calculation bits must be increased corresponding to the values of G ₁ and G _2, the number of position control calculation bits should be stopped when practically satisfactory. Since the microprocessor also sets the parameters such as G ₁ and G ₂ and controls the position of the controlled object, the parameters such as G ₁ and G ₂ can be freely used in the position control software.

[0027]

According to the present invention, the feedforward loop is branched after the first pulse multiplier.
Even if the multiplication rate G ₁ by the first pulse multiplier changes, the ratio of the feedforward amount to the command signal does not change, and it is possible to obtain a motor controller having excellent responsiveness.

Further, putting the first divider having a value of 1 / G ₂ after the deviation counter, for containing the second divider having a value of 1 / G ₂ in the feed forward loop, the Two
The multiplication rate G ₂ of the pulse multiplier and the value 1 / G _{2 of} the first and second dividers are interlocked, and the multiplication rate G _{2 of} the second pulse multiplier is
The ratio of the feedforward amount with respect to the command signal does not change even when is changed, and it is possible to prevent the position control performance of the controlled object from being changed by the change of the multiplication rate G ₂ .

Further, since the command pulse multiplication processing and the feedback pulse multiplication processing can be configured by software, the command pulse multiplication rate G ₁ and the feedback pulse multiplication rate G ₂ are as wide as ₁ to 9999 times. You can select a range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a motor control device according to the present invention.

FIG. 2 is an explanatory diagram of the operation of the sampling unit in the above embodiment.

FIG. 3 is a front view showing an example of an operation panel used in the embodiment.

FIG. 4 is a block diagram showing an example of a conventional motor control device.

[Explanation of symbols]

 11 Command Counter 13 First Pulse Multiplier 15 Deviation Counter 16 First Divider 17 First Arithmetic Means 18 Adder 19 Second Divider 21 Second Arithmetic Means 24 Drive Amplifier 26 Encoder 27 Feedback Counter 29 Second pulse multiplier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02P 5/00 H02P 5/00 G

Claims (2)

(57) [Claims] 1. A command counter that counts command pulses and outputs a count value, a first pulse multiplier that multiplies the output of the command counter by G ₁ , and an encoder that detects the position of a controlled object. A feedback counter that counts the detected pulses of the encoder and outputs a count value, a second pulse multiplier that multiplies the output of the feedback counter by G ₂ , a first pulse multiplier and a second pulse multiplier A deviation counter that counts the deviation between the multiplied pulses, a first divider that makes the output of the deviation counter 1 / G _2, and a _second divider that makes the output of the first pulse multiplier 1 / G _2. An adder that outputs the speed command by adding the output of the first divider and the output of the second divider, and for driving the controlled object according to the speed command output of the adder A model including a drive amplifier for driving the motor. Motor controller. 2. A first arithmetic means for multiplying the output of the first divider by a constant, and a second arithmetic means for multiplying the output of the second divider by a constant. The described motor control device.