JP2022029503A - Inertia estimation device and motor control device - Google Patents

Abstract

To provide an inertia estimation device capable of accurately estimating in a short time dispensing with specific operation like a periodic motion, even in a condition of the presence of a non-linear load torque like viscous friction.SOLUTION: An inertia estimation device has storage means storing a motor speed as an estimation initiation speed of inertia, when a speed absolute value of the motor driving a mechanical load exceeds a prescribed threshold speed, and when lapse time from the start or direction inversion of the motor exceeds the prescribed threshold time, starting means of numerical integration including at least torque and acceleration of the motor in an integration-target function, and means of finishing numerical integration when the motor is decelerated and the absolute speed thereof drops below the estimation initiation speed. The inertia estimation value of the mechanical driving system is acquired from an arithmetic result of the numerical result integration in an acceleration/deceleration period of the motor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for estimating the inertia of a mechanical drive system formed by connecting a mechanical load to a motor capable of speed control.

In order to satisfactorily control the speed of the motor to which the mechanical load is connected, it is necessary to know the inertia of the entire mechanical drive system including the motor and the mechanical load and reflect this inertia in the speed control conditions.
When a mechanical load whose inertia is unknown is connected to a motor to drive it, it is common practice to estimate the inertia by using information on torque and speed during operation. In this case, it is possible to estimate offline using data in a certain time range, and online estimation using a sequential least squares method or the like has already been put into practical use.

When driving a mechanical load by a motor, it is common that load torque such as Coulomb friction and viscous friction is generated in addition to the acceleration torque due to inertia × acceleration. In order to prevent an erroneous inertia from being estimated due to these load torques, for example, in Non-Patent Document 1, the relationship between the torque applied by the motor and the acceleration is not used as it is, but the torque change from the previous time. By performing online estimation using the relationship with acceleration changes, inertial estimation that eliminates the effects of constant disturbance is realized.
Further, in connection with this, Patent Document 1 discloses an online estimation means in which an inertia estimation error is reduced by reducing an estimation gain during vibration detection of a mechanical load.

Further, in Non-Patent Document 2, the Coulomb friction and the viscous friction coefficient are based on the premise that the load torque is represented by the sum of the speed-independent code-function type Coulomb friction and the viscous friction proportional to the speed. Along with the disclosure of means of estimating inertia. In this document, positive and negative symmetric periodic signals are given as velocity commands, and as shown in FIG. 6 (FIG. 4 of Non-Patent Document 2), the signals _τe , q ₀ , q ₀ ^' , based on the torque command u and the angular velocity ω, The values obtained by multiplying q ₁ with each other are integrated at periodic intervals by the mathematical formulas (Eqs. (37) to (44)) described in the same document, and the elements of the matrix Φ are φ ₁₁ , φ ₁₃ , φ ₂₂ , φ ₂₃ , The parameters v ₁ , v ₂ , v ₃ of φ ₃₃ and the vector V are obtained, and then the operation Φ ^-1 V is performed to identify the parameters including the inertia.

Japanese Patent No. 3796261 ([0009] to [0013], etc.)

Yoichi Hori and Hiroe Kamei, "High Performance Control of Servo Motors Using Low Precision Encoders-Identification of Instantaneous Velocity Observers and Moment of Inertia-", IEEJ Transactions on D114, No. 4 (1994), p. 424-431. Ichiro Awaya et al., "Method for identifying parameters of mechanical motion system on which Coulomb friction acts", Proceedings of the Japan Society of Mechanical Engineers (C), Vol. 59, No. 567 (1993), p. 108-114.

According to the methods described in Non-Patent Document 1 and Patent Document 1, even if the influence of constant disturbance can be removed, if a load torque having a large speed dependence is generated, the acceleration torque is not sufficiently large with respect to the load torque. , Inertia estimation error that cannot be ignored occurs.
Further, according to the method described in Non-Patent Document 2, although there is an advantage that other parameters are estimated together with inertia, in addition to the premise that a speed command is given as a periodic signal, the load torque is a speed. If a non-linear dependency is shown, the correct value including inertia may not be estimated.
Further, while it is desirable that the inertia can be estimated with as high accuracy as possible, there are cases where it is desired to estimate it in a short time, but it is difficult to achieve both improvement in estimation accuracy and reduction in estimation time by the conventional estimation method.

Therefore, the problem to be solved by the present invention is the inertia that can obtain an accurate estimation result in a short time even under the condition that a non-linear load torque such as viscous friction exists without the need for special operation such as periodic motion. An object of the present invention is to provide an estimation device and a motor control device for controlling a motor using the inertia estimation result thereof.

In order to solve the above problem, the inertial estimation device according to claim 1 is used.
A device that estimates the inertia of a mechanical drive system, including a motor and the mechanical load driven by the motor.
When the first condition in which the absolute speed value of the motor exceeds a predetermined threshold speed and the second condition in which the elapsed time from the start or reversal of the direction of the motor exceeds the predetermined threshold time are satisfied. A means for storing the speed of the motor as an estimated start speed of inertia, and
When the first condition and the second condition are satisfied, a means for starting numerical integration including at least the torque and acceleration of the motor in the integrand.
A means for ending the numerical integration when the motor decelerates and its absolute speed falls below the estimated start speed.
Equipped with
It is characterized in that the inertia estimation value of the mechanical drive system is obtained from the calculation result of the numerical integration in the acceleration / deceleration period of the motor.

The inertial estimation device according to claim 2 is the inertial estimation device according to claim 1.
The inertial estimation value is J ₁ , and the inertial estimation value J ₁ is set to J 1.
It is characterized in that the calculation is performed by the mathematical formula A using the acceleration a (t) and the torque T (t) of the motor at the time t during the acceleration / deceleration period.
[Formula A]
J ₁ = ∫T (t) a (t) dt / ∫ {a (t)} ² dt

The inertial estimation device according to claim 3 is the inertial estimation device according to claim 1.
The inertial estimation value is J ₁ , and the inertial estimation value J ₁ is set to J 1.
Acceleration a (t), torque T (t), velocity v (t) of the motor at time t during the acceleration / deceleration period, and estimated load torque T _Let (v (t)) estimated based on the load model. ) Is used to perform the calculation by the mathematical formula B.
[Formula B]
J ₁ = ∫ {T (t) _-T Let (v (t))} a (t) dt / ∫ {a (t)} ² dt

The inertial estimation device according to claim 4 is the inertial estimation device according to claim 2 or 3.
A means for obtaining the inertia estimation value J ₁ for each acceleration / deceleration period of the motor and calculating a weight W ₁ = ∫ {a (t)} ² dt.
The inertia estimation average value J ₂ and the integrated weight W ₂ stored before the acceleration / deceleration period are updated using the inertia estimation value J ₁ and the weight W ₁ , and the updated inertia estimation average value J ₂ is output as the inertia estimation result. And the means to do
It is characterized by being equipped with.

The inertial estimation device according to claim 5 is the inertial estimation device according to claim 4.
The inertia estimation average value J ₂ and the integrated weight W ₂ are set to a predetermined upper limit of the result of adding the W ₂ previous value to the W ₁ current value each time the inertia estimation value J ₁ and the weight W ₁ are newly obtained. After updating the value limited by the value W _max as the W ₂ current value,
It is characterized in that the inertia estimation average value J ₂ is updated as the J ₂ current value by the mathematical formula C.
[Formula C]
J ₂ current value = J ₂ previous value + (W ₁ current value / W ₂ current value) × (J ₁ current value-J ₂ previous value)

In the inertia estimation device according to claim 6, the inertia estimation average value J ₂ and the integrated weight W ₂ are stored in the non-volatile memory and initialized from the outside in the inertia estimation device according to claim 4. It is characterized by being possible.

The motor control device according to claim 7 is characterized in that the motor is controlled by using the inertial estimation value obtained by the inertial estimation device according to any one of claims 1 to 6.

According to the present invention, it is not necessary to perform a special operation like the periodic motion in Non-Patent Document 2, and even under the condition where a non-linear load torque such as viscous friction exists, the inertia of the mechanical drive system can be accurately performed in a short time. Can be estimated.

It is a block diagram which shows the main part of the motor control apparatus which concerns on embodiment of this invention. It is a block diagram which shows the 1st Embodiment of the inertia estimation apparatus in FIG. It is a block diagram of the integration start / end determination unit in FIG. It is a block diagram of the inertia estimation average part in FIG. It is a block diagram which shows the 2nd Embodiment of the inertia estimation apparatus in FIG. It is explanatory drawing which shows the main part of the non-patent document 2 as a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 shows a main part of a motor control device for controlling a motor to which a mechanical load is connected.
In FIG. 1, the speed control unit 100 generates a torque T (t) so that the motor speed v (t) coincides with a speed command, and this torque T (t) is applied to the motor and the mechanical load 200 to cause the motor. Driven. The inertia estimation device 300 calculates the inertia estimation _average value J2 by inputting at least the motor speed v (t), the torque T (t), and the reset command. Here, the torque T (t) may be either a torque command or a torque estimated value obtained by detecting the current applied to the motor for applying the torque.
The inertia estimation average value J ₂ output from the inertia estimation device 300 is used, for example, to adjust the speed control gain in the speed control unit 100 to control the speed and torque of the motor.

FIG. 2 is a block diagram showing a first embodiment of the inertia estimation device 300. Here, the reference numeral 300A is attached to the inertial estimation device.
The motor speed v (t) is input to the integration start / end determination unit 302 and the differential calculation unit 303 via the low-pass filter 301.
The integration start / end determination unit 302 performs start / end determination of the integration operation by a function described later, outputs an integration start / end command, and outputs an update command to the division means 309 and the inertial estimation average unit 310. Further, the differential calculation unit 303 differentiates the motor speed v (t) to calculate the acceleration a (t), and the acceleration a (t) is input to the multiplication means 304 and 307. Further, the output of the multiplication means 304 is input to the integration means 305.
On the other hand, the torque T (t) is input to the multiplication means 307 via the low-pass filter 306 having the same time constant as the low-pass filter 301, and the multiplication result with the acceleration a (t) is input to the integration means 308. ..
The low-pass filters 301 and 306 are for removing white noise and the like included in the input signal, but are not essential components in the present invention.

The integrating means 305 performs an operation of ∫ {a (t)} ² dt, and the integrating means 308 performs an operation of ∫T (t) a (t) dt, and the outputs of these integrating means 305 and 308 are the dividing means. It is input to 309. The output of the integrating means 305, ∫ {a (t)} ² dt, is input to the inertial estimation _average unit 310 as the weight W1. In the dividing means 309, the operation of ∫T (t) a (t) dt / ∫ {a (t)} ² dt is performed to obtain the inertia estimation value J ₁ , and this inertia estimation value J ₁ is the inertia estimation average part 310. Has been entered in.

Here, the start / end timings of the operations in the integration means 305 and 308 follow the integration start / end command output from the integration start / end determination unit 302. Further, the division means 309 divides according to the update command output from the integration start / end determination unit 302, and outputs the latest inertia estimation value J ₁ and the weight W ₁ to the inertia estimation average unit 310 as the respective current values. At the same time, each time the inertia estimation average value J ₁ and the weight W ₁ are input, the inertia estimation average unit 310 performs the update operation described later according to the update command and outputs the inertia estimation average value J ₂ .

Next, the configuration of the integration start / end determination unit 302 will be described with reference to FIG.
First, the motor speed v (t) is input to the absolute value calculation unit 302a, and the absolute speed value | v (t) | is calculated. This absolute speed value | v (t) | is input to the zero speed determination unit 302b to determine whether or not the motor is stopped, and the determination signal is sent to the delay unit 302c of the next stage. The zero speed determination unit 302b and the delay unit 302c are means for determining that a predetermined threshold time has elapsed from the time when the motor is not stopped, that is, the elapsed time from the time when the motor is started or the direction is reversed. After the lapse of time, a “High” level signal is input from the delay unit 302c to one end of the AND calculation unit 302e. In FIG. 3, the output signal of the zero speed determination unit 302b is inverted and input to the delay unit 302c composed of the on-delay circuit, but the output signal of the zero speed determination unit 302b is not inverted and is input from the off-delay circuit. It may be input to the delay part.

Further, the absolute velocity value | v (t) | is compared with the threshold velocity in the comparison unit 302d, and when the absolute velocity value | v (t) | exceeds the threshold velocity, a "High" level signal is output to the AND calculation unit 302e. Is input to the other end of. The output signal of the AND calculation unit 302e is input to the start instruction unit 302f, and the integration start command and the estimated start speed storage command are output from the start instruction unit 302f.
Further, the absolute speed value | v (t) | is input to the storage unit 302g for adjusting the speed control gain at one time, and the estimated start speed detected according to the estimation start speed storage command is input to the comparison unit 302. The comparison unit 302h outputs an integration end command and an update command when the absolute speed value | v (t) | falls below the estimated start speed when the motor is decelerated.

Next, the significance of configuring the inertia estimation device 300A of FIG. 2, particularly the integration start / end determination unit 302 in the inertia estimation device 300A as shown in FIG. 3 will be described.
The load torque generated when driving a mechanical load may show a non-linear dependence on speed, but with respect to speed regardless of acceleration or deceleration, except near zero speed. Many are uniquely determined. Therefore, when the load torque _TL (v (t)) generated from a certain time t ₁ to the time t ₂ while the motor is being driven is multiplied by the acceleration dv / dt and integrated,
_∫TL (v (t)) (dv / dt) dt = _∫TL (v) dv,
When integrating so that the speeds at the integration start time and integration end time are the same,
_∫TL (v (t)) (dv / dt) dt = 0.

Therefore, when estimating the inertia J based on the equation of motion: T (t) = J (dv / dt) + T _L (v (t)), both sides of the equation of motion are multiplied by a = dv / dt for acceleration. The influence of the load torque _TL is removed by integrating under the condition that the speeds at the time and deceleration are equal, and the inertia J is estimated by the following equation 1.
[Formula 1]
J = ∫T (t) a (t) dt / ∫ {a (t)} ² dt
The above-mentioned formula 1 is substantially the same as the above-mentioned formula A.

When driving a mechanical load, load torque with hysteresis often occurs near zero speed. In order to correctly estimate the inertia by Equation 1, it is necessary to exclude the hysteresis region from the integration interval, and one method is that the absolute value of the motor speed exceeds a predetermined threshold speed as a condition for starting the integration. Is possible. In addition, even a mechanical system that can be regarded as one inertial system during normal operation may behave vibratingly immediately after starting, and in order to correctly estimate the inertia, the integration is started after this vibration is attenuated. It is desirable to do.

Therefore, in order to start the integration of the numerator and denominator in Equation 1, first, the absolute speed value of the motor exceeds the above-mentioned predetermined threshold speed, and secondly, the acceleration time after the motor leaves the zero speed state. The condition is that the predetermined threshold time is exceeded, and when these first and second conditions are satisfied, the above integration is started, the absolute speed value at that time is stored as the estimated start speed, and the motor decelerates and speeds. It is effective to end the above integration when the absolute value falls below the estimated start speed and determine the inertia J1 in _a series of acceleration / deceleration periods.

In the integration start / end determination unit 302 in FIG. 3, the logical product calculation unit 302e determines the satisfaction of the first and second conditions and sends a signal to the start instruction unit 302f, and the integration start command and the estimated start speed storage command. By the operation of the temporary storage unit 302g, the comparison unit 302h, and the end instruction unit 302i, the integration end command, the inertia estimation value J ₁ , the weight W ₁ (and the inertia estimation average value J _2, which will be described later, integration) are generated. The update command of the weight W ₂ ) is output.

Next, the inertial estimation _average unit 310 provided in the final stage of FIG. ₂ to which the inertial estimation value J1 and the weight W1 are input will be described with reference to FIG.
When the inertia is small and the acceleration is also small, it is conceivable that the inertia cannot be estimated with sufficient accuracy by only one acceleration / deceleration operation even if the above calculation method is used. When repeating the same acceleration / deceleration operation, the estimation accuracy can be improved by applying a simple moving average to the inertial estimation value obtained for each acceleration / deceleration operation, but let's improve the estimation accuracy in the operation that is not repeated operation. In this case, the reliability of each inertial estimation differs depending on the acceleration / deceleration operation. Therefore, in the present embodiment, the inertia estimation average unit 310 shown in FIG. 4 makes it possible to improve the reliability of the inertia estimation.
Hereinafter, the configuration and operation of the inertia estimation average unit 310 will be described.

That is, the inertia estimation average value J ₂ and the integrated weight W ₂ are defined separately from the inertia estimation value J ₁ and the weight W ₁ for each acceleration / deceleration motion, and J ₂ is obtained every time J ₁ and W ₁ are newly obtained. , W ₂ is updated as follows.
In FIG. 4, the W ₂ previous value output from the previous value holding unit 310c is input to the adding means 310a via the switching unit 310d, and is added to the W ₁ current value. By limiting this addition result with a predetermined upper limit value (maximum value) W _max by the limiting unit 310b, the W ₂ current value is obtained. Further, the division means 310e calculates W ₁ current value / W ₂ current value.
On the other hand, the previous value of the inertia estimation average value J2 _output from the previous value holding unit 310i is input to the subtracting means 310f via the switching unit 310j and subtracted from the J ₁ current value (J ₁ current value-). J ₂ Previous value) is calculated.
Then, (W ₁ current value / W ₂ current value) × (J ₁ current value-J ₂ previous value) is obtained by the multiplication means 310 g, and this value and the J ₂ previous value are added by the addition means 310h. It is output as the current value of the inertia estimation _average value J2.
When the above processing is expressed by a mathematical formula, it becomes as shown in the mathematical formula 2. It should be noted that this mathematical formula 2 is substantially the same as the above-mentioned mathematical formula C.
[Formula 2]
J ₂ current value = J ₂ previous value + (W ₁ current value / W ₂ current value) × (J ₁ current value-J ₂ previous value)

Then, as shown in _FIG . 4, J2 and W2 can be initialized by switching the switching units 310j and 310d to the " ₀ " side by a reset command from the outside. Specifically, J ₂ and W ₂ are initialized when the machine load is replaced, and then J ₂ and W ₂ are updated while being stored in the non-volatile memory. Then, when the system is restarted, the values of J2 and _W2 may be read from the non _- volatile memory before the system is operated.

The above-mentioned update processing of J ₂ and W ₂ will be further described.
In FIG. 4, if the addition result remains below the upper limit value W _max even after the addition of the W ₁ current value to the W ₂ previous value by the addition means 310a, the equation 3 holds.
[Formula 3]
J ₂ current value = J ₂ previous value + {(W ₁ current value / (W ₂ previous value + W ₁ current value)} × (J ₁ current value-J ₂ previous value)
By rearranging this mathematical formula 3, the mathematical formula 4 can be obtained.
[Formula 4]
J ₂ current value = (J ₂ previous value x W ₂ previous value + J ₁ current value x W ₁ current value) / (W ₂ previous value + W ₁ current value)
This is equivalent to performing inertial estimation using all the data of past acceleration / deceleration operation, and the weight is suppressed to be smaller in the case of acceleration / deceleration operation where estimation accuracy is difficult to obtain, so the average value of inertia estimation with high reliability J ₂ can be obtained.

However, if the operation is continued without introducing the limit by the upper limit value W _max , W ₂ will eventually become infinite, and J ₂ will not be updated even if a new acceleration / deceleration operation occurs. Therefore, by limiting W ₂ to a predetermined upper limit value W _max by using the limiting unit 310b, the latest operation result is reflected in the inertia estimation average value J ₂ even if the motor is continuously operated. ..

Here, without defining the weight as in the present embodiment, for example,
[Formula 5]
J ₂ current value = J ₂ previous value + constant × (J ₁ current value-J ₂ previous value) (0 <constant <1)
Let's compare the case of calculating as with the present embodiment.
Even when the J2 value is calculated by the formula ₅ , the inertia estimation accuracy is improved by repeating the acceleration / deceleration motions. However, in this case, J ₂ becomes a value smaller than the true value until the number of acceleration / deceleration movements reaches about (3 / constant) (in other words, while it does not reach about (3 / constant)). .. Further, in the case of this calculation, even if low acceleration or short-time acceleration / deceleration operation that is not suitable for inertia estimation is performed, the inertia estimation value is updated with the result as in the case of other motions.
_On the other hand, in the present embodiment, by initializing J2 and W2 when the mechanical load is changed, an estimated value close to the true value can be obtained from the _time when the number of acceleration / deceleration movements is small, and ∫ { Since a (t)} ² dt is updated with a weight proportional to it, the inertia estimation average value J ₂ is less likely to be disturbed for an operation unsuitable for inertia estimation.

Next, FIG. 5 shows the inertia estimation device 330B according to the second embodiment of the present invention. The main parts of the motor control device other than the inertial estimation device 330B are configured in the same manner as in FIG.
In this inertia estimation device 330B, assuming that the speed dependence T _Let (v) of the load torque is known, the load torque estimation unit 311 determines the load torque T _Let (v (v) based on the speed v (t) at each time t. t)) is estimated and input to the subtraction means 312, and the inertia estimation value J1 is obtained using the equation ₆ .
[Formula 6]
J ₁ = ∫ {T (t) _-T Let (v (t))} a (t) dt / ∫ {a (t)} ² dt
The above-mentioned formula 6 is substantially the same as the above-mentioned formula B.

When the calculation is performed in this way, the integrand of the numerator becomes a value close to J {a (t)} ² , so that the calculation error can be reduced. The T _Rest (v) may be in the form of, for example, D × v + T _f × sign (v), and the parameters D and T _f may be identified by using the method disclosed in Non-Patent Document 2 described above.

100: Speed control unit 200: Motor and machine load 300, 300A, 300B: Inertivity estimation device 301, 306: Low pass filter 302: Integration start / end determination unit 302a: Absolute value calculation unit 302b: Zero speed determination unit 302c: Delay unit 302d, 302h: Comparison unit 302e: Logical product calculation unit 302f: Start instruction unit 302g: Temporary storage unit 302i: End instruction unit 303: Differential calculation unit 304, 307: Multiplication means 305, 308: Integration means 309: Division means 310: Inertial estimation average unit 310a, 310h: Addition means 310b: Limiting unit 310c, 310i: Previous value holding unit 310d, 310j: Switching unit 310e: Division means 310f: Subtraction means 310g: Multiplication means 311: Load torque estimation unit 312: Subtraction means

Claims (7)

A device that estimates the inertia of a mechanical drive system, including a motor and the mechanical load driven by the motor.
When the first condition in which the absolute speed value of the motor exceeds a predetermined threshold speed and the second condition in which the elapsed time from the start or reversal of the direction of the motor exceeds the predetermined threshold time are satisfied. A means for storing the speed of the motor as an estimated start speed of inertia, and
When the first condition and the second condition are satisfied, a means for starting numerical integration including at least the torque and acceleration of the motor in the integrand.
A means for ending the numerical integration when the motor decelerates and its absolute speed falls below the estimated start speed.
Equipped with
An inertia estimation device, characterized in that an inertia estimation value of the mechanical drive system is obtained from the calculation result of the numerical integration in the acceleration / deceleration period of the motor. In the inertia estimation device according to claim 1,
The inertial estimation value is J ₁ , and the inertial estimation value J ₁ is set to J 1.
An inertia estimation device characterized by calculating by a mathematical formula A using the acceleration a (t) and the torque T (t) of the motor at a time t during the acceleration / deceleration period.
[Formula A]
J ₁ = ∫T (t) a (t) dt / ∫ {a (t)} ² dt In the inertia estimation device according to claim 1,
The inertial estimation value is J ₁ , and the inertial estimation value J ₁ is set to J 1.
Acceleration a (t), torque T (t), velocity v (t) of the motor at time t during the acceleration / deceleration period, and estimated load torque T _Let (v (t)) estimated based on the load model. ) Is used to calculate the inertia estimation device according to the mathematical formula B.
[Formula B]
J ₁ = ∫ {T (t) _-T Let (v (t))} a (t) dt / ∫ {a (t)} ² dt In the inertial estimation device according to claim 2 or 3.
A means for obtaining the inertia estimation value J ₁ for each acceleration / deceleration period of the motor and calculating a weight W ₁ = ∫ {a (t)} ² dt.
The inertia estimation average value J ₂ and the integrated weight W ₂ stored before the acceleration / deceleration period are updated using the inertia estimation value J ₁ and the weight W ₁ , and the updated inertia estimation average value J ₂ is output as the inertia estimation result. And the means to do
An inertia estimation device characterized by being equipped with. In the inertial estimation device according to claim 4,
The inertia estimation average value J ₂ and the integrated weight W ₂ are set to a predetermined upper limit of the result of adding the W ₂ previous value to the W ₁ current value each time the inertia estimation value J ₁ and the weight W ₁ are newly obtained. After updating the value limited by the value W _max as the W ₂ current value,
An inertia estimation device characterized in that the inertia estimation average value J ₂ is updated as the J ₂ current value by the mathematical formula C.
[Formula C]
J ₂ current value = J ₂ previous value + (W ₁ current value / W ₂ current value) × (J ₁ current value-J ₂ previous value) In the inertial estimation device according to claim 4 or 5.
An inertia estimation device, characterized in that the inertia estimation average value J ₂ and the integrated weight W ₂ are stored in a non-volatile memory and can be initialized from the outside. A motor control device, characterized in that the motor is controlled by using the inertial estimation value obtained by the inertial estimation device according to any one of claims 1 to 6.

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