JP2010051048A - Motor controller equipped with viscous friction identifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which is equipped with a viscous friction identifier that can remove influence given to accuracy in identification of the viscous friction of noise even in case that motor velocity includes much noise and can identify viscous friction with only small action. <P>SOLUTION: An input command is a cycle signal which includes a plurality of frequency components. A viscous friction identifier 107 computes a viscous friction identified value, based on a torque command in the plurality of frequency components of the input command and the motor position in the plurality of frequency components of the input command. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device including a viscous friction identification device that identifies viscous friction of a machine.

When driving a controlled object that is a motor with a mechanical load connected with high accuracy or high response, the motor control device identifies the viscous friction value of the controlled object that is unclear with high precision and minute operation, and the identification It is necessary to drive the motor based on the value.
A motor control device equipped with a conventional viscous friction identification device calculates input energy, which is energy input to a control target by a torque command that drives the control target based on a position command, a position, and a speed. The viscous friction of the control object is identified by the motor position amplitude (see, for example, Patent Document 1).
FIG. 3 shows a conventional viscous friction identification device. In the figure, 301 is an amplitude calculator, 302 is a first input energy calculator, and 303 is a viscous friction Coulomb friction calculator. The amplitude calculator 301 receives the position and outputs a position amplitude that is the input signal amplitude. The first input energy calculator 302 inputs the speed and the speed command, calculates and outputs input energy to an open loop system including a torque controller, an electric motor, and a position detector. The viscous friction Coulomb friction calculator 303 receives the position amplitude and the input energy, and calculates and outputs a friction identification value that is an identification value of the viscous friction and the Coulomb friction based on the input energy and the position amplitude.
As described above, the motor control device provided with the conventional viscous friction identification device calculates the friction identification value based on the position amplitude and the input energy.
Japanese Patent Laying-Open No. 2007-20318 (page 7-9, FIG. 2)

A motor control device equipped with a conventional viscous friction identification device is configured to perform viscous friction identification using input energy calculated based on a position command, a position, and a speed, and when the speed includes a lot of noise, Since the influence on the noise identification accuracy cannot be removed and the identification accuracy is lowered, it is necessary to improve when the speed includes a large amount of the noise.
The present invention has been made in view of such an improvement, and the viscous friction identification is performed based on the difference between the average values for one cycle of the product of the sign of the two frequency components of the torque command and the two frequency components of the motor speed. However, even when the speed includes a lot of noise, the influence of the noise on the viscous friction identification accuracy can be eliminated, and the motor control device having the viscous friction identification device that can identify the viscous friction identification by only a minute operation The purpose is to provide.

In order to solve the above improvement, the present invention is configured as follows.
The invention described in claim 1

According to the first to fourth aspects of the present invention, even when the torque command and the motor speed include a lot of noise, it is possible to identify the viscous friction of the motor connected with the mechanical load with high accuracy.
According to the fifth aspect of the present invention, it is possible to identify the viscous friction of a motor connected with a small stroke mechanical load with high accuracy only by a minute amplitude corresponding to about one hundredth of a rotary motor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a motor control device having a viscous friction identification device according to a first embodiment of the present invention. In the figure, 101 is a command generator, 102 is a feedback controller, 103 is a feedforward controller, 104 is a current controller, 105 is a control target, 106 is a motor position detector, 107 is a viscous friction identification device, and 108 is a torque. Command frequency component separator, 109 is a motor speed calculator, 110 is a motor speed code calculator, 111 is a torque command motor speed code multiplication value calculator, 112 is a torque command motor speed code multiplication value average value calculator, and 113 is a motor A position frequency component separator 114 is a motor position amplitude calculator, and 115 is a viscous friction calculator.

  The command generator 101 outputs an input command that is a periodic signal including frequency components necessary for viscous friction identification. The feedback controller 102 inputs the input command, the motor position, and the motor speed, and outputs a feedback control signal. The feedforward controller 103 receives the input command and outputs a feedforward control signal. The current controller 104 inputs a torque command that is an added value of the feedback control signal and the feedforward control signal, and outputs a motor current. The control target 105 is a motor connected to a mechanical load, and is driven by the motor current, and the motor position is detected and output by the motor position detector 106. The viscous friction identification device 107 receives the torque command and the motor position, identifies the viscous friction of the control target 105, and outputs it as a viscous friction identification value.

In the viscous friction identification device 107, a torque command frequency component separator 108 receives the torque command and outputs a torque command frequency component that is a frequency component used for viscous friction identification among frequency components included in the input signal. The motor speed calculator 109 inputs the motor position, calculates the motor speed, and outputs it. The motor speed code calculator 110 inputs the motor speed and outputs a motor speed code that is a sign of the input signal. The torque command motor speed code multiplication value calculator 111 receives the torque command frequency component and the motor speed code, and calculates and outputs a torque command motor speed code multiplication value which is a multiplication value of the input signal. The torque command motor speed code multiplication value average value calculator 112 inputs the torque command motor speed code multiplication value, and calculates a torque command motor speed code multiplication value average value that is an average value for one period for each frequency component of the input signal. Calculate and output. The motor position frequency component separator 113 inputs the motor position and outputs a motor position frequency component which is a frequency component used for viscous friction identification among frequency components included in the input signal. The motor position amplitude calculator 114 receives the motor position frequency component, calculates the motor position amplitude that is the input signal amplitude, and outputs it. The viscous friction calculator 115 receives the torque command motor speed code multiplication average value and the motor position amplitude, and calculates and outputs the viscous friction identification value.
Here, the frequency components used for the viscous friction identification are a plurality of frequency components used for calculating the viscous friction identification value. Each frequency is 10 Hz or more and the control object 105 is flexible. It is set sufficiently lower (for example, about 1/10) than the lowest value of the antiresonance frequency.

  The present invention is different from the prior art in that it includes a viscous friction identification device 107 that identifies and outputs a viscous friction value of a mechanical load based on a motor position, a motor speed, and a torque command. Includes a torque command frequency component separator 108 that inputs a torque command and outputs a torque command frequency component, a motor speed code calculator 110 that inputs a motor speed and outputs a motor speed code, the torque command frequency component and the motor A torque command motor speed code multiplication value calculator 111 that inputs a speed code and outputs a torque command motor speed code multiplication value, and inputs the torque command motor speed code multiplication value and outputs an average value of the torque command motor speed code multiplication value. Torque command motor speed code multiplication value average value calculator 112, the motor position is input and the motor position frequency component is Input motor position frequency component separator 113, motor position amplitude calculator 114 for inputting motor position frequency component and outputting motor position amplitude, input torque command motor speed code multiplication value average value and motor position amplitude And a viscous friction calculator 115 that outputs a viscous friction identification value.

  Hereinafter, the details of the mechanism by which the viscous friction identification device 107 calculates the viscous friction identification value will be described. If the controlled object 105 is a motor with a rigid mechanical load connected to it, the equation of motion is expressed by equation (1).

Where J is the moment of inertia of the controlled object 105, D is viscous friction, Tc is Coulomb friction, Tref is a torque command, w is a constant torque disturbance, and θ is a motor position. By multiplying equation (1) by the sign of motor speed, equation (2) is obtained.

Assuming that the frequency component of the motor position at the command frequency ω1 generated from the command generator 101 is the first motor position frequency component, the first motor position frequency component is expressed by Expression (3).

However, A1 is the first motor position amplitude. Substituting equation (3) into equation (2) and taking the average value during period T1 = 2π / ω1, equation (4) is obtained.

However, Tref1 is a first torque command frequency component that is a frequency component of the torque command at the command frequency ω1 generated from the command generator 101. Since the phases of the motor acceleration and the motor speed are shifted by π / 4 [rad], it is used that the average value of the first term on the left side and the second term on the right side of Equation (2) is zero. Similar to Expression (4), the average value during the time T2 = 2π / ω2 of Expression (2) at the command frequency ω2 generated from the command generator 101 is expressed as Expression (5).

However, Tref2 is a second torque command frequency component that is a frequency component of the torque command at the command frequency ω2 generated from the command generator 101. When the Coulomb friction Tc is canceled from the equations (4) and (5), the equation (6) is obtained.

The viscous friction calculator 115 calculates the viscous friction identification value using Expression (6).
Here, it is arranged how each output in the viscous friction identification device 107 according to the present invention obtains each output based on each input.
The torque command frequency component separator 108 receives the torque command and is sufficiently lower than the lowest one of the anti-resonance frequencies of the controlled object 105 from the torque command based on FFT (Fast Fourier Transform) (for example, about 1/10). ) Separate (calculate) frequency components in frequency and output torque command frequency components.
The motor speed code calculator 110 inputs a motor speed, applies a signum function, calculates a motor speed code, and outputs it. The signum function is also called a sign function.
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Against that
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Returns either 1, -1, or 0 depending on
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It is a well-known matter that is a "complex function that extends it".
The torque command motor speed code multiplication value calculator 111 receives the torque command frequency component and the motor speed code, multiplies the input signal, and calculates and outputs a torque command motor speed code multiplication value.
The torque command motor speed code multiplication value average value calculator 112 inputs the torque command motor speed code multiplication value and calculates the torque command motor speed code multiplication value average value based on the left side of the equations (4) and (5). And output.
The motor position frequency component separator 113 receives the motor position, and based on the FFT, the frequency component at a frequency sufficiently lower (for example, about 1/10) than the lowest antiresonance frequency of the controlled object 105 from the motor position. Is separated (calculated) and the motor position frequency component is output.
The motor position amplitude calculator 114 receives the motor position frequency component, calculates the motor position amplitude based on the peak value of the input signal, and outputs it.
The viscous friction calculator 115 receives the torque command motor speed code multiplication average value and the motor position amplitude, and calculates and outputs a viscous friction identification value based on the equation (6).

  Since the equation (6) does not include the constant torque disturbance w, viscous friction identification can be performed without being affected even when the torque due to gravity is applied to the motor of the control target 105. Further, since Equation (6) uses the motor position amplitudes A1 and A2 and the frequency components Tref1 and Tref2 of the torque command, it is accurate even when nonlinear dynamics, transient response, etc. exist without being affected by other frequency components. Can identify viscous friction. Further, since the equation (6) extracts and calculates the frequency component of the motor position, the frequency component used for identification has a waveform even when the motor position waveform detected by the motor position detector 106 is low and the waveform of the motor position is rough. Even when the motor position detector 106 has a low resolution (for example, 15 [bit]) and the movable range of the mechanical load is limited, the viscous friction can be accurately identified. In addition, since the average value is used for Expression (6), even when the torque command includes noise, the influence of the noise can be removed and viscous friction identification can be performed with high accuracy. Also, viscous friction identification can be performed when the gain of the feedforward controller 103 is zero.

The simulation results of the present invention are shown below. The numerical values used for the simulation are as follows.
J = 5.80 × 10 ^ −5 [kg · m ^ 2], D * = 7.5 × 10 ^ −4 [N · m · s / rad], Tc = 7.8 × 10 ^ −4 [ N · m], Kp = 120 [s ^ -1], Kv = 120 (2π) [s ^ -1], J0 = 0.116 × 10 ^ -4 [kg · m ^ 2], Kvj = Kv * J0, Ti = 4 / Kv, T = 125 × 10 ^ −6 [s], Trat = 0.637 [N · m], b = 17 [bit], ω1 = 30 (2π) [rad / s], ω2 = 60 (2π) [rad / s], r0 = 0.005 [rad], d = 0.1 * Trat
Where J is the moment of inertia of the controlled object 105, D * is the true value of viscous friction, Tc is the Coulomb friction, Kp is the position proportional control gain, Kv is the normalized speed proportional control gain, J0 is the nominal inertia moment, and Kvj is the speed proportional. Control gain, Ti is a speed control integration time constant, T is a control period, Trat is a rated torque, b is a resolution of the motor position detector 106, ω1 is a first identification frequency, ω2 is a second identification frequency, r0 is a command amplitude, d is the noise amplitude.

  Here, the nominal moment of inertia J0 is a moment of inertia value used for normalizing the speed proportional control gain Kvj, and the first identification frequency and the second identification frequency are frequencies used for viscous friction identification of the present invention. is there. If the first identification frequency and the second identification frequency are set so as to be separated by 10 [Hz] or more, the denominator of Equation (6) does not become too small, and the calculation error of the numerator of Equation (6) is not amplified. Viscous friction can be identified with high accuracy. Furthermore, since the expression (6) is derived on the assumption of a rigid machine load, when the control target 105 is a multi-inertia machine, the first identification frequency and the second identification frequency are determined as the anti-resonance frequency of the control target 105. By selecting a value sufficiently lower than that of the lowest frequency, viscous friction can be identified with high accuracy without being affected by the flexible vibration mode. Further, in order to show that the present invention is effective even when the torque command includes a lot of noise, white noise having an amplitude of a noise amplitude d is added to the torque command.

  FIG. 2 shows viscous friction identification errors when a constant torque disturbance is changed in the simulation showing the first embodiment of the present invention. In the figure, when the constant torque disturbance is changed from 0 [%] to 50 [%] of the rated torque, the viscous friction identification error eD [%] calculated by the equation (7) is always within −2.3 [%]. Met.

  In this simulation, the motor position amplitude is 0.0069 [rad] (1/910 rotation), and the torque command amplitude is 2.2 [%] or less of the rated torque. Thus, it was shown that viscous friction identification can be carried out with high accuracy and can be applied even when the moment of inertia of the load connected to the motor is larger. In a verification experiment in which a control target 105 is connected to a THK KR4620A + 540L slider and a Yaskawa Electric SGDS-02A01A motor by a UA-35C coupling manufactured by Sakai Seisakusho Co., Ltd., and driven by an SGMAS-02ACA21 driver manufactured by Yaskawa Electric According to the prior art of Document 1, an identification error of −23% occurs, whereas in the present invention, a highly accurate viscous friction identification result of −4% is obtained.

Therefore, the present invention is effective for identifying viscous friction in a noisy environment as compared with the prior art. However, in the verification experiment, the true value of viscous friction D * was obtained by the least square method using a plurality of constant speed commands. The least square method is used to obtain the true viscous friction value D * because the operation amplitude of the control object 105 is large, but the identification accuracy is slightly higher than that of the present invention in which identification is performed only with a minute operation.
As described above, according to the present invention, even when there is a lot of noise, the viscous friction of a motor connected to a mechanical load can be identified with high accuracy only by a minute operation while suppressing the influence of constant torque disturbance, transient response, and nonlinear effect.

  Even if the torque command and the motor speed contain a lot of noise by performing viscous friction identification based on the motor speed sign, the two frequency components of the torque command, and the average value for one cycle of the multiplication value, a minute operation Because it is possible to identify the viscous friction of the control object alone, the control gain setting of general industrial machines such as small stroke industrial equipment, semiconductor manufacturing equipment, interference system mechanisms used in noisy environments such as feedforward control It can be widely applied to parameter setting.

Motor control device having viscous friction identification device showing first embodiment of the present invention Viscous friction identification error when a constant torque disturbance is changed in the simulation showing the first embodiment of the present invention Motor control device with conventional viscous friction identification device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Command generator 102 Feedback controller 103 Feedforward controller 104 Current controller 105 Control object 106 Motor position detector 107 Viscous friction identification device 108 Torque command frequency component separator 109 Motor speed calculator 110 Motor speed code calculator 111 Torque Command motor speed code multiplication value calculator 112 Torque command motor speed code multiplication value average value calculator 113 Motor position frequency component separator 114 Motor position amplitude calculator 115 Viscous friction calculator 301 Amplitude calculator 302 First input energy calculator 303 Viscous friction coulomb friction calculator

Claims (5)

A motor control device that drives a controlled object that is a motor connected to a mechanical load, wherein the motor position or the motor speed is input based on an input command and a motor position or motor speed that is a value detected by a detector. A feedback controller that performs control so as to follow a command; and a viscous friction identification device that identifies the viscous friction of the control target and calculates a viscous friction identification value, and uses the viscous friction identification value to define the control target. In the motor control device to drive,
The input command is a periodic signal including a plurality of frequency components,
The viscosity friction identification device calculates the viscous friction identification value based on a torque command in a plurality of frequency components of the input command and the motor position in a plurality of frequency components of the input command. A motor control device provided with a friction identification device.   The said viscous friction identification apparatus extracts two specific frequency components using FFT (fast Fourier transform) from a plurality of frequency components of the torque command and the motor position. Motor control device. The viscous friction identification device calculates a motor speed code, which is a sign of the motor speed, based on the motor positions of the two specific frequency components,
Multiplying the torque command of the two specific frequency components and the motor speed code in the same frequency component, respectively, and calculating the average value of the multiplied values for one period,
3. The motor control device comprising the viscous friction identification device according to claim 2, wherein the viscous friction identification value is calculated based on the average value. The viscous friction identification device is a torque command frequency component separator that inputs the torque command and outputs a torque command frequency component that is a frequency component used for viscous friction identification among frequency components included in the input signal;
A motor speed code calculator for inputting the motor speed and outputting a motor speed code which is a sign of the input signal;
A torque command motor speed code multiplication value calculator that inputs the torque command frequency component and the motor speed code, calculates and outputs a torque command motor speed code multiplication value that is a multiplication value of the input signal;
Torque command motor speed code multiplication value average value calculator that inputs the torque command motor speed code multiplication value and calculates and outputs a torque command motor speed code multiplication value average value that is an average value for one period for each frequency component of the input signal. When,
A motor position frequency component separator that inputs the motor position and outputs a motor position frequency component that is a frequency component used for viscous friction identification among frequency components included in the input signal;
A motor position amplitude calculator that inputs the motor position frequency component and calculates and outputs a motor position amplitude that is an input signal amplitude thereof;
The viscous friction identification device according to claim 1, further comprising: a viscous friction calculator that inputs the torque command motor speed code multiplication average value and the motor position amplitude, calculates and outputs the viscous friction identification value. A motor control device comprising:   2. The motor control device having a viscous friction identification device according to claim 1, wherein the amplitude of the input command is a minute amplitude corresponding to about one hundredth of a rotation of a rotary motor.