JPH11262289A - Servomotor apparatus and controlling method of servomotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the acceleration and speed of a motor, based on its heat generation and temperature. SOLUTION: A servomotor apparatus has a servo motor 1 repeating its operation and resting each command signal and a servo-controller 3 for computing the acceleration and speed of the servomotor 1. Computing by the servo- controller 3 a necessary resting time required for cooling the servomotor 1 to a predetermined temperature, the actual resting time taken to operate the servomotor 1 by the next command signal is sensed and the necessary and actual resting times are compared with each other to be computed, based on this comparison the acceleration and speed of the servomotor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a servomotor device, and more particularly to a servomotor device capable of speed control and position control and a servomotor control method.

[0002]

2. Description of the Related Art Servo motors are used in automatic changers for automatically changing recording media, industrial robots used in assembly factories or manufacturing factories, and positioning devices such as machine tools.

An example of a conventional servo motor speed control method will be described with reference to FIG. The servomotor repeats operation and pause for each command signal. First the first command signal C1 is input at time t ₁ in. Servomotor, according to a first command signal, to start the rotation from the time t _1, the stop time t _2. After downtime T _B has elapsed, the second command signal C2 of the next time t ₃ is input. Servo motor, likewise, according to a second command signal C2, to start the rotation from the time t _3, and stops at time t _4. Such an operation is repeated every time an external command signal is input.

The operating time T _A of the servomotor has a substantially trapezoidal shape including an initial acceleration period, an intermediate constant speed period, and a final deceleration period as shown in the figure. The area of this trapezoid represents the amount of work. The length of the pause time T _B after workload and operating time T _A of the servo motor is different for each command signal. However,
The acceleration in the acceleration period and the speed in the constant speed period are fixed values set in advance.

In order to operate the servomotor safely, a current must be supplied so as not to exceed an allowable current value. Further, in order to use the servomotor for a predetermined life, it is necessary to operate the motor so that the effective value of the current does not exceed the rating. That is, in the speed control of the servomotor, the acceleration and the speed are set so that the effective current value does not exceed the rating.

[0006]

Heretofore, the heat value and the temperature of the servomotor have not been considered as parameters related to the life of the servomotor. However, parameters that are actually related to the life of the servomotor are the amount of heat generated by the motor and the temperature of the motor. If the motor is sufficiently cooled and used, the life of the motor is prolonged. If the motor is used in a state where the cooling of the motor is insufficient and the temperature is high, the life of the motor is shortened.

For example, referring to the example of FIG. 11, first,
_A first command signal having a long operation time T _A is executed. After a short pause T _B, a second command signal C2 having a relatively short operation time is executed. After a relatively long pause T _B after the second command signal, the third command signal C3 is executed.

[0008] It is generally unknown when the command signal is provided. The second command signal is supplied before the motor is sufficiently cooled, and the third command signal is supplied after the motor is sufficiently cooled. However, regardless of whether the motor is sufficiently cooled, the acceleration and the speed of the motor are set to constant values so that the effective current value does not exceed the rating. Therefore, it has not been possible to efficiently execute the speed control of the conventional servomotor.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to control the speed of a servomotor based on the heat and temperature of the motor.

In view of the foregoing, an object of the present invention is to maximize the life of a servomotor and efficiently execute speed control.

[0011]

According to the present invention, a servo motor device has a servo motor that repeats operation and pause for each command signal, and a servo controller that calculates the acceleration and speed of the servo motor. Calculates the required pause time required for the servo motor to cool to a predetermined temperature, detects the actual pause time until the servo motor is activated by the next command signal, and calculates the required pause time and the actual pause time. It is configured to compare time and calculate the acceleration and speed of the servomotor based on the comparison.

According to the present invention, since the motor is operated in consideration of the heat generation and temperature of the motor, the motor is operated with the set values of the acceleration and speed fixed so that the effective value of the current does not exceed the rating as in the prior art. The motor can be operated more efficiently as compared with the case where the motor has been operated.

According to the servo motor control method of the present invention, the required pause time required for the servo motor to cool to a predetermined temperature when the operation of the servo motor is stopped is calculated, and the servo motor is operated again. When the actual pause time of the servomotor is detected, the actual pause time is subtracted from the required pause time to obtain a deviation between the two, and when the deviation is negative, the acceleration and speed of the servomotor are increased. Decreasing the acceleration and speed of the servomotor when the deviation is positive.

According to the servo motor control method of the present invention, the motor is operated in consideration of heat generation and temperature of the motor, so that the motor can be operated efficiently without sacrificing the life of the motor. Further, the present invention can be applied to all servo motors such as a DC motor, an AC motor, and a step motor.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The servo motor device of the present embodiment includes a servo motor 1 and a drive circuit 2 for supplying a drive voltage to the servo motor.
And a servo controller 3 for supplying acceleration and speed signals to the drive circuit.

The servo motor 1 includes various control motors such as a DC motor, an AC motor, and a step motor. The servomotor may be controlled by an open loop as shown, but is typically controlled by a closed loop.
Note that the case of closed loop control will be described later with reference to FIG.

The servo controller 3 basically performs the following five operations for each command signal. (1) Calculation of the effective value of the current of the motor Instead of directly calculating or measuring the calorific value of the motor, the effective value of the current is measured. It is assumed that the square of the effective value of the motor current is proportional to the heat value of the motor. (2) Calculation of required pause time The required pause time is the motor stop time required to sufficiently cool the motor. When the motor stops, the required pause time increases when the motor temperature is high, and decreases when the motor temperature is low. The method for determining the required pause time will be described in detail later. However, instead of the motor temperature, the required pause time is determined from the above-described current effective value and the previous pause time.

(3) Calculation of actual pause time The actual pause time is the time from when the motor stops to when the motor starts to rotate again by the next command signal. The actual pause time is obtained by actually measuring.

(4) Calculation of deviation of pause time and its integrated value The required pause time is compared with the actual pause time to determine the deviation between the two. If the actual pause time is greater than the required pause time,
That is, when the deviation is negative, the motor is considered to be sufficiently cooled. Conversely, when the actual pause time is shorter than the required pause time, that is, when the deviation is positive, the motor is sufficiently cooled. It is not considered to be.

Further, an integrated value of the deviation is calculated. If the integrated value of the deviation is negative within the predetermined time, it is determined that the motor has been repeatedly used in a sufficiently cooled state within the predetermined time, and if the integrated value of the deviation is positive, the motor is activated. Within the predetermined time, it is generally determined that the battery has been repeatedly used without being sufficiently cooled. (5) Calculation of acceleration and speed The speed and speed are calculated based on the deviation between the required pause time and the actual pause time and the integrated value thereof. For example, when the integrated value of the deviation is negative, the acceleration and speed of the motor are increased, and when the integrated value of the deviation is positive, the acceleration and speed of the motor are reduced.

FIG. 2 shows an example of a servomotor device by closed loop control. In this case, an encoder 4 for detecting the rotation speed of the servomotor is provided. The output of the encoder 4 is fed back to the servo controller 3.
In the case of the closed loop control, the servo controller 3 further performs the following calculation. (6) Calculation of target speed and target position The target speed and target position are calculated based on the acceleration and speed of the motor obtained by the above calculation. (7) Calculation of deviation between target speed and target position and actual speed and position The deviation between the target speed and target position obtained by the above-described calculation and the actual speed and position output from encoder 4 is calculated. A control value is calculated from this deviation and output to the drive circuit 2.

A description will be given with reference to FIG. First, an example of a method for calculating the required pause time will be described. FIG. 3 shows the estimated value of the temperature change of the motor when the rotation and stop of the servo motor are repeated for each command signal. The horizontal axis represents time, and the vertical axis represents the motor temperature. At time t ₁ is supplied first instruction signal C1, the servo motor 1 starts rotating at a predetermined acceleration and velocity. After the operation time T _A has elapsed, and stops at the time t _2. At this time, the temperature of the motor rises from the operation starting temperature M ₁ to a temperature M _2.

Here, the required pause time t _B is a time required for the temperature of the motor to drop to a predetermined low temperature M ₀ . This predetermined temperature, i.e., the reference temperature M ₀ may not necessarily be an operation start temperature M ₁ of the motor.

Next, in this example, the second command signal C2 is supplied to the time t ₃ after a short rest time than the required downtime t _B T _B. During this pause time T _{B, the} motor temperature becomes M ₂
It descends to M ₃ from. Since the pause time T _B is short, the motor starts rotating without being sufficiently cooled. Therefore, in this case, the motor is operated with an acceleration and a speed smaller than the previous acceleration and the speed. After the operation time T _A, and stops at time t _4. The temperature of the motor at this operating time T _A is increased from M ₃ to M _4.

Next, a third command signal C3 is supplied to the time t ₅ after the long quiescent period T _B than the required downtime t _B.
During this pause time T _B, the temperature of the motor falls from M ₄ to M ₅ . Since the idle time is long, the motor starts rotating in a sufficiently cooled state. Thus, in this case, the motor is operated at an acceleration and speed that is greater than the previous acceleration and speed. After the operation time T _A, the operation stops at time t ₆ .

The calorific value of the motor at the operating time T _A and the temperature rise amount is assumed to be proportional to the square of the effective value in between the current. Thus, for example, a temperature rise amount M ₂ -M ₁ of the motor in the first operation time T _A is proportional to the square of the effective value in between of the current, the temperature rise of the motor at the second operation time T _A M ₄ -M ₃ is proportional to the square of the effective value in between the current. The square of the effective value I _RMS of the current is expressed by the following equation.

[0027]

[Number 1] _{^{I RMS 2 = (I 1 2}} t + I 2 2 t + I 3 2 t + ···· + I n 2 t) / (nt) = (I 1 2 + I 2 2 + I 3 2 + ···· + I n ² ) / n

[0028] where n is the sampling number at the operating time T _A, t is one sampling time.

The heat radiation amount and temperature drop amount of the motor at rest time T _B is assumed to be proportional to the downtime. Thus, for example, a first pause time T the temperature drop amount M ₂ -M ₃ of the motor in _B is proportional to the quiescent time t ₃ -t _2,
Temperature drop amount of the motor at the second pause time T _B M ₄ -
M ₅ is proportional to its resting time t ₅ -t _4.

The temperature of the motor rises every operation time T _A, descends every downtime T _B. Thus, the current temperature of the motor, until that time, by adding the temperature increase in each operation time T _A, obtained by subtracting the temperature drop amount for each downtime T _B.

According to the present embodiment, the amount of temperature rise during the operation time T _A is represented as a positive digital value obtained from the square of the effective value I _RMS of the current, and the amount of temperature decrease during the pause time T _B is represented by the pause time T _{B Expressed} as a negative digital value obtained from the length of _B.

[0032] Thus, the current temperature of the motor, until that time, is obtained by integrating the negative digital value in the positive digital value and downtime T _B at the operating time T _A. If the integrated value of the digital value is zero, so that the temperature of the motor is returned to the initial temperature M _1.

The required pause time t _B is obtained at the end of each operation time T _A. First, at the end of the operation time T _A ,
The square of the effective value of the current at the operation time T _A is obtained,
The temperature rise amount is calculated from the value, and a positive digital amount δM corresponding to the temperature rise amount is obtained.

[0034] Temperature M _B of the motor at the end of the operation time T _A is obtained by adding the temperature rise amount δM temperature M _A of the motor at the start of the operation time T _A.

[0035]

## EQU2 ## M _B = M _A + δM

The deviation ΔM temperature M _B and the reference temperature M ₀ of the motor at the end of the operation time T _A is the temperature drop required.

[0037]

## EQU3 ## ΔM = M _B −M ₀

The required rest time t _B is proportional to the required temperature drop ΔM. When the next command signal is supplied, the actual resting time T _B is obtained. Comparing the actual downtime T _B and the required downtime t _B, if the actual pause is greater than the required downtime t _B period T _B, the motor will have been sufficiently cooled, the actual pause time T _B required pause time t _B
If it is smaller, the motor has not been sufficiently cooled.

Next, with reference to FIG. 4, an example of a method for detecting a tendency of a change in motor temperature during a predetermined time will be described. FIG. 4 shows an example of the change of the motor temperature in the case of the repetitive operation of the motor similarly to FIG. In this example, time points t ₁ , t ₃ ,
Each command signal C1, C2, C3 is supplied at t _5, the motor is activated. Motor is stopped at time _{t 2, t 4, t 6} .

In the example shown in FIG. 4A, the command signals C2, C
3. The temperature of the motor at times t ₃ , t ₅ , and t ₇ when C4 is supplied is higher than the reference temperature M ₀ . In the example shown in FIG. 4B, the command signal C2, C3, C4 time t ₃ when being supplied, t _5, the temperature of the motor at t ₇ is lower than the reference temperature M ₀ none. As in the example shown in FIG. 4A, when the temperature of the working start time of the motor is generally higher than the reference temperature M ₀ is detrimental to the life of the motor. As in the example shown in FIG. 4B, when the temperature at the start of the operation of the motor is generally lower than the reference temperature M ₀ , the operation of the motor is not efficient, which is not economically preferable.

In the example shown in FIG. 4C, the command signals C2, C
3. The temperature of the motor at times t ₃ , t ₅ , and t ₇ when C4 is supplied may be higher or lower than the reference temperature M ₀ . Therefore, generally, at the start of operation of the motor,
Temperature of the motor is a value close to the reference temperature M _0. Preferably, the motor temperature is equal to the reference temperature M as in the example shown in FIG. 4C.
The acceleration and speed of the motor are set to operate at a value close to _zero .

Referring to FIG. 5, a first example of a method for setting the acceleration and speed of the motor will be described. First, step S10
Deviation of the actual pause time T _B and required rest time t _B at 1 Δ
t and its integrated value ΣΔt are obtained.

[0043]

Δt = t _B −T _B ΣΔt = ΣΔt + Δt

When the deviation Δt of the pause time is negative, it indicates that the motor temperature is sufficiently low at the present time, that is, at the time of starting the operation of the motor, and the integrated value ΣΔt of the deviation of the pause time is negative. Time indicates that the history of the temperature of the motor repeatedly operated is as shown in FIG. 4B. vice versa,
When the deviation Δt of the pause time is positive,
When the operation of the motor is started, it indicates that the temperature of the motor is still high. When the integrated value ΣΔt of the deviation of the pause time is positive, the history of the temperature of the motor repeatedly operated is shown in FIG.
A indicates that it is as shown in FIG.

When the integrated value 偏差 Δt of the deviation of the pause time is a value close to zero, it indicates that the history of the temperature of the repeatedly operated motor is as shown in FIG. 4C. That is,
This shows that the temperature at the start of operation of the motor that was repeatedly operated was close to the reference temperature on average.

In step S102, it is determined whether the integrated value ΣΔt of the deviation of the pause time is positive or negative. When the integrated value ΣΔt of the deviation of the pause time is negative, step S103
To increase the acceleration and speed from the previous operation. On the other hand, when the integrated value 偏差 Δt of the deviation of the pause time is positive, the process proceeds to step S104, and the acceleration and the speed are decreased from those in the previous operation.

The increase and decrease of the acceleration and speed of the motor are performed by an incremental method of adding or subtracting predetermined increments one by one. In step S105, the motor is rotated at the acceleration and speed set as described above. In this way, the acceleration and speed of the motor are increased or decreased based on the integrated value ΣΔt of the deviation of the pause time.
Δt eventually approaches zero.

The first method, if the operation of the motor is relatively regular, for example, the actual pause fluctuation time T _B is less relatively, the integrated value of the deviation Δt and deviations downtime Σ
There is no problem when Δt is relatively small. However, an irregular operation of the motor, a problem in the case of particularly actual resting time T _B at times extremely long.

Description will be made with reference to FIG. In this example, as shown, operation time T _A for the instruction signal C1 is completed at time t _2, the next command signal C2 is supplied at time t _4. Actual pause time T _B is sufficiently longer than the required rest time t _B. In this case, the pause time deviation Δt has a large negative absolute value. When such an operation is repeated, the integrated value ΣΔt of the deviation of the pause time becomes a value having a large negative absolute value.

Therefore, when the acceleration and the speed are calculated based on the integrated value ΣΔt, the values of the acceleration and the speed become very large, and the motor is overloaded.

[0051] In the above discussion, as indicated by a broken line, it is assumed that the temperature of the motor is lowered in proportion to the length of the pause time T _B. However, the temperature of the motor, in fact, as shown by the solid line, not lowered in proportion to the pause time T _B. For example, when greater than a certain value downtime T _B, the temperature of the motor becomes constant approaches the initial temperature M _1.

Therefore, it is necessary to set a limit value for the integrated value ΣΔt of the deviation of the pause time. When the integrated value 偏差 Δt of the deviation exceeds the limit value, the acceleration and the speed are calculated on the assumption that the values are constant.

A second example of the method for setting the acceleration and speed of the motor will be described with reference to FIG. This is an improvement of the first method. First, a deviation Δt and the integrated value ΣΔt actual downtime T _B requires downtime t _B at step S201, then in step S202, the integrated value ΣΔt of the deviation of the dwell time is positive or negative Judge. Up to this point, it is the same as in the first example of FIG.

In step S202, when the integrated value 偏差 Δt of the deviation of the pause time is negative, the motor is repeatedly operated in a state where the motor is sufficiently cooled on average, and step S20 is performed.
Proceed to 3. In step S203, the integrated value of the deviation ΣΔt
Is determined to have exceeded a predetermined limit period -L. The time limit -L may be, for example, -30 minutes or -1 hour.

The integrated value 偏差 Δt of the deviation is equal to a predetermined limit period -L
If it exceeds, as described with reference to FIG. 6, it is determined that when the actual is than long enough required downtime t _B downtime T _B occurs. Therefore, the process proceeds to step S204, and the integrated value 偏差 Δt of the deviation is replaced with the limit period -L.

In this case, the process proceeds to step S205, where the acceleration and the speed are calculated based on the replaced limit period -L. The acceleration and the speed are set to a first set value. The first set value is selected such that the effective value of the current is greater than the rating when the motor is operated continuously at the assumed average operation.

In step S203, the integrated value of the deviation ΣΔ
If it is determined that t does not exceed the predetermined limit period -L, the process proceeds to step S206, and the acceleration and the speed are calculated based on the integrated value 偏差 Δt of the deviation. The acceleration and speed of the motor are set to a second set value. The second set value is
The rms value of the current is selected to be slightly less than the rating when the motor is operated continuously at the expected average operation.

In step S202, when the integrated value 偏差 Δt of the deviation of the pause time is positive, the motor is repeatedly operated in an averagely not sufficiently cooled state. The acceleration and speed of the motor are set to a third set value. The third set value is selected to ensure that the effective value of the current is less than the rating when the motor is operated continuously at the assumed average operation.

Referring to FIG. 8, an example of a DC motor device according to the present invention will be described. The DC motor device of the present embodiment is an example in which a DC motor based on PWM control is used as a servo motor. The DC motor device of the present embodiment includes a DC motor 11 by PWM control and a rotation detecting device for detecting rotation of the DC motor 11, for example, an encoder 12, a drive circuit 13 for supplying a pulse voltage signal to the DC motor, and a servo controller 20. Having. Servo controller 20 is P
WM signal generator 21, CPU 22, and hard counter 23
And a memory 24. The servo controller 20
Is connected to a host computer 31 for supplying command signals and various setting signals.

Various loads are connected to the DC motor 11, but it is assumed here that a robot arm is connected. The robot arm moves according to a movement plan or a movement procedure stored in the host computer 31. Accordingly, first, a command signal for moving the robot arm is supplied from the host computer 31 to the CPU 22 of the servo controller 20 via an appropriate interface. Of course, the CPU 22 may be configured to be supplied with a command signal by manual input.

On the other hand, the encoder 12
, And supplies a pulse signal to the hard counter 23. The hard counter 23 counts the pulses supplied from the encoder 12, accumulates the pulses, and holds the count.

According to the present embodiment, the detection of the amount of rotation by the encoder 12 and the counting and integration by the hard counter 23 are performed constantly, that is, both when the DC motor 11 is rotating and stopped. . Therefore, the hard counter 12 always holds the current rotational position of the DC motor 11. For example, when the robot arm is stopped by a stop command, the robot arm may slightly move due to its own weight. In this case, the axis of the DC motor 11 also slightly rotates, but the hard counter 23 always keeps the accurate rotational position of the DC motor 11 at the present time.

The CPU 22 determines the required rotational speed of the DC motor 11 based on the command signal from the host computer 31 and the current position of the DC motor 11. Further, a PWM value necessary for obtaining the required rotation speed is obtained, and the obtained PWM value is supplied to the PWM signal generator 21. The PWM signal generator 21 outputs P
A PWM signal is generated from the WM value, and is generated by the drive circuit 1
Supply 3 The drive circuit 13 generates a pulse-shaped voltage signal as shown in FIG.

A description will be given with reference to FIG. FIG. 9 shows a waveform of a pulse-like voltage signal supplied to the DC motor 11.
As shown in FIG. 9A, when a voltage signal having the same positive pulse width T ₁ and negative pulse width T ₂ is supplied, the DC motor 11
Stops. As shown in FIG. 9B, when a voltage signal in which the positive pulse width T ₁ is larger than the negative pulse width T ₂ is supplied,
The DC motor 11 rotates in the forward direction. As shown in FIG. 9C, the positive pulse width T ₁ is negative pulse width T ₂ is less than the voltage signal is supplied, the DC motor 11 is rotated in the reverse direction.

[0065] Rotation speed of the DC motor 11 varies as a positive function of the difference ΔT = T ₁ -T ₂ or duty ratio T ₁ / T ₂ of the pulse width T ₁ and a negative pulse width T _2. When the pulse width difference ΔT is positive and its absolute value is large, the DC motor 11 rotates at a high speed in the positive direction, and when the pulse width difference ΔT is positive and its absolute value is small, The DC motor 11 rotates at a low speed in the forward direction. Conversely, when the pulse width difference ΔT is negative and its absolute value is large, the DC motor 11 rotates at a high speed in the negative direction, and when the pulse width difference ΔT is negative and its absolute value is small. , The DC motor 11 rotates at a low speed in the negative direction.

When a DC motor under PWM control is used as described above, even when the load on the robot arm or the like is stopped, that is, even when the DC motor 11 is not rotating, the DC motor 11 has the configuration shown in FIG. 9A. a voltage of such a duty ratio T ₁ / T ₂ = ₁ indicates an applied, therefore, is always current. The DC motor 11 is provided with a duty ratio T ₁ / T so that the load does not move by its own weight during the stop.
_In some cases, a pulse voltage where ₂ is slightly larger than 1 is applied. Therefore, even when the DC motor 11 is stopped, power is consumed and heat is generated in the DC motor 11.

Referring back to FIG. The CPU 22 calculates the effective value of the current, the required pause time, the actual pause time, the deviation between the required pause time and the actual pause time, the acceleration and the speed, and calculates the target rotational speed and the target rotational position based on the acceleration and the speed. Calculate. Further, a deviation between the target rotation speed and the target rotation position and the current rotation speed and the rotation position output from the encoder 12 is obtained, and a PWM value is calculated based on the deviation. The PWM value is calculated by the PWM signal generator 21.
Supplied to

Here, an example of a method of obtaining the required pause time t _B from the effective value of the current will be described. First, the square of the effective value of the current is obtained. The square of the effective value of the current is a hard counter 2
3 is obtained from the rotation speed of the DC motor 11 obtained from the output. Determining a control parameter u _i which is expressed by the following equation at every predetermined sampling period.

[0069]

[Number 5] _{u i = u-K E w} i

[0070] Here the PWM value u is supplied from CPU22, as shown in FIG. 8 to the PWM signal generator 21, K _E is back electromotive force constant of the motor, w _i is the rotation speed of the DC motor 11, the control parameter u _i is represented by a digital value. The current value I _i is obtained by multiplying the conversion factor k _D to the control parameter u _i.

[0071]

I _i = k _D u _i = (1/512) (E / R) u _i

Here, E is the drive voltage of the motor, and R is the internal resistance of the motor or the like. Numerical value 512 is a conversion rate for converting a digital value into a current value. The square of the effective value of the current is obtained by substituting the current value I _i in Expression 1.

[0073]

Equation 7] _{^{I RMS 2 = (k D 2}} / n A) (u 1 2 + u 2 2 + u 3 2 + ···· + u n 2) = (k D 2 / n A) U S U S = ( _{^{u 1 2 + u 2 2 +}} u 3 2 + ···· + u n 2)

Here, n _A is the number of times of sampling during the operation time T _A. It is assumed that the effective value of the current does not exceed the rated current during the time from one command signal to the next command signal, that is, the total time of the operation time T _A and the required pause time t _B. Assuming that the number of times of sampling at the required pause time t _B is n _B , the following equation holds.

[0075]

Equation 8] _{n A + n B = (k} D / I T) 2 U S

[0076] here _{I T} is the rated current value of the motor. If the control is performed so that the effective current value of the motor does not exceed the rated current value of the motor, a predetermined life of the motor is ensured. The required pause time t _B is one sampling time t
Is obtained by the following equation.

[0077]

Equation 9] _{t B = n B t = [} (k D / I T) 2 U S -n A] t

When the required pause time t _B is long, the value of the sum of squares U _S of the control parameters u _{i on} the left side can be increased. On the contrary, the actual pause time T _B is necessary pause time t _B
Larger than, the effective value of the current flowing through the motor becomes smaller than the rated current I _T.

Referring to FIG. 10, another example of the DC motor device according to the present invention will be described. The DC motor device of this example is also
This is an example in which a DC motor based on PWM control is used as a servomotor. The DC motor device of this example is different from the DC motor device of FIG.
Between the digital signal PWM value and the analog signal PWM value.
The difference is that a DA converter 25 for converting into a value is provided, and the output current i of the drive circuit 13 is fed back to the input side of the PWM signal generator 21. It may be the same as the motor device.

Similarly, a current value is obtained by multiplying the digital control parameter v _i by the conversion coefficient k _F.

[0081]

Equation 10] _{I i = k F v i =} (5/1024) K DR v i

The conversion coefficient k _F is the product of the current feedback gain K _DR and the conversion rate 5/1024. The conversion ratio is a ratio for converting a digital value to a current value. For example, the numerical value 102
4 corresponds to 5 volts. The square of the effective value of the current is obtained by substituting the current value I _i in Expression 1.

[0083]

Equation 11] _{^{I RMS 2 = (k F 2}} / n A) (u 1 2 + u 2 2 + u 3 2 + ···· + u n 2) = (k F 2 / n A) U S U S = ( _{^{u 1 2 + u 2 2 +}} u 3 2 + ···· + u n 2)

Here, n _A is the number of samplings during the operation time T _A. Similarly, assuming that the number of samplings at the required pause time t _B is n _B , the following equation holds.

[0085]

Equation 12] _{n A + n B = (k} F / I T) 2 U S

[0086] here I _T is the rated current value of the motor.
The required pause time t _B is obtained by the following equation, where one sampling time is t.

[0087]

Equation 13] _{t B = n B t = [} (k F / I T) 2 U S -n A] t

Although the embodiments of the present invention have been described in detail above, it will be understood by those skilled in the art that the present invention is not limited to the above-described examples and can adopt various other configurations without departing from the gist of the present invention. Will be easy to understand.

[0089]

According to the present invention, since the rotational acceleration and the rotational speed of the next operation are set depending on whether or not the servo motor is sufficiently cooled, there is an advantage that the servo motor can be operated efficiently. .

According to the present invention, since the rotational acceleration and rotational speed of the next operation are set in consideration of the heat generation amount and temperature of the servo motor, there is an advantage that the life of the servo motor can be maintained long.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining an example of a servomotor device according to the present invention.

FIG. 2 is an explanatory diagram for explaining another example of the servomotor device according to the present invention.

FIG. 3 is a diagram showing a relationship between an operation cycle of a servomotor and a temperature.

FIG. 4 is a diagram showing a state of a change in temperature of a servomotor.

FIG. 5 is a flowchart showing a first example of a process of calculating acceleration and speed.

FIG. 6 is a diagram showing a state of a change in the temperature of a servomotor when a pause time is long.

FIG. 7 is a flowchart showing a second example of the process of calculating the acceleration and the speed.

FIG. 8 is an explanatory diagram showing an example of a DC motor device according to the present invention.

FIG. 9 is a waveform diagram showing a drive voltage waveform of the servo motor device.

FIG. 10 is an explanatory view showing another example of the DC motor device according to the present invention.

FIG. 11 is an explanatory diagram showing a change in rotation speed of a motor.

[Explanation of symbols]

1 servo motor, 2 drive circuit, 3 servo controller, 11 DC motor, 12 encoder, 13 drive circuit, 20 servo controller, 21 PWM signal generator, 22 ‥‥ CPU, 2
3 hard counter, 24 memory, 25 DA
Converter, 31 、 host computer

Claims (7)

[Claims] 1. A servo motor that repeats operation and pause for each command signal, and a servo controller that calculates acceleration and speed of the servo motor, wherein the servo controller cools the servo motor to a predetermined temperature. The required pause time is calculated, the actual pause time until the servo motor is operated by the next command signal is detected, the required pause time is compared with the actual pause time, and the comparison is performed. A servo motor device configured to calculate an acceleration and a speed of the servo motor based on the servo motor. 2. The difference between the required pause time and the actual pause time is subtracted to obtain a deviation between the two. When the integrated value of the deviation is negative, the acceleration and the speed are increased from the acceleration and the speed in the previous operation. 2. The servo motor device according to claim 1, wherein when the integrated value of the deviation is positive, the acceleration and the speed are reduced from the previous operation. 3. When the integrated value of the deviation is negative, and when the integrated value of the deviation exceeds a predetermined limit value, the acceleration and the speed based on the limit value are changed from the acceleration and the speed in the previous operation. 3. The servo motor device according to claim 2, wherein the servo motor device is configured to increase. 4. The system according to claim 1, wherein said servo controller calculates an effective value of a current supplied during operation of said servomotor, and calculates said required pause time based on the effective value of said current. The servomotor device according to the above. 5. When the actual pause time is longer than the required pause time, the acceleration and speed are increased from the acceleration and speed of the previous operation, and when the actual pause time is shorter than the required pause time, 2. The servo motor device according to claim 1, wherein the acceleration and the speed are reduced from the previous operation. 6. Calculating a required pause time required for the servo motor to cool to a predetermined temperature when the operation of the servo motor is stopped, and calculating the pause time when the servo motor is operated again. Detecting the actual pause time, subtracting the actual pause time from the required pause time to obtain a deviation between the two, and increasing the acceleration and speed of the servo motor when the deviation is negative, Reducing the acceleration and speed of the servo motor when the deviation is positive. 7. The required pause time is obtained by calculating an effective value of a current in operation when the operation of the servomotor is stopped, and using the effective value of the current. The control method of the servomotor described in the above.