JP2007129789A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which can identify inertia with high accuracy on-line, by making it possible to deduce disturbance torque that does not contain inertia error disturbance. <P>SOLUTION: The motor controller comprises a speed controller generating a torque command to a motor, based on speed command from a host controller, and feedback of the difference of positional information, obtained from a position detector of the motor or speed information obtained from a speed detector; a current controller performing conversion into a current command value for controlling the current flowing through the motor, based on the torque command, and an operating unit for identifying the total inertia of the motor and a load. The inertia identification calculating unit calculates the disturbance deduced value from the torque command and the motor speed at a disturbance observer section 41, calculates the disturbance torque deduced value from a disturbance deduced value and the motor speed at a disturbance torque deducing section 43, and identifies inertia from the disturbance deduced value, the motor speed and the torque command at an inertia identifying section 42. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device for online identification of disturbance torque and inertia.

  Conventionally, when a motor is driven in a motor control device, a disturbance estimated value by an observer is regarded as a disturbance torque as it is in order to identify an inertial current online by an adaptive identification side (see, for example, Non-Patent Document 1). .

FIG. 1 is a block diagram showing the configuration of a motor control device having a general inertia identification calculation device, and is shown as an explanatory diagram common to the present invention to be described later and later.
In FIG. 1, 1 is a motor for moving a load, 2 is a speed controller for controlling the speed of the motor 1, and the speed received from a host controller (not shown) or a position controller (not shown). Based on the command and the difference between the position information obtained from the position detector (encoder; not shown) directly connected to the motor 1 and the feedback of the speed information obtained from the speed detector (tachometer; not shown) Torque command to is generated.
Reference numeral 3 denotes a current controller, which converts the current command value into a current command value based on the torque command obtained by the speed controller 2, and controls the current so that the current flowing through the motor becomes the command value. Reference numeral 4 denotes an inertia identification calculation device that acquires information during operation of the motor and identifies the total inertia of the motor 1 and the load using the information. Kt represents a torque constant representing the relationship between the torque generated by the motor and the current flowing through the motor coil, and J represents the total inertia of the motor and the load.

FIG. 5 is a block diagram illustrating the configuration and processing contents of a conventional inertia identification arithmetic apparatus for identifying inertia.
In the inertia identification computing device of FIG. 5, 41 is a disturbance observer unit, and 42 is an inertia identification unit. First, the disturbance observer 41 calculates a disturbance estimated value. But this

Converges to the value shown in Equation (1) including the inertia error disturbance. T _d represents disturbance torque, a represents acceleration, and J _n represents nominal inertia used in the disturbance observer.

  Next, the inertia identification unit 42 calculates an inertia identification value using the estimated disturbance value.

As described above, in the conventional inertia identification calculation device, the procedure of using the disturbance estimated value by the observer as the disturbance torque is used.
IEEJ Transactions D, Vol. 114, No. 4, 1994, Yoichi Hori and Hiroei Kamei “High-performance control of servo motors using low-precision encoders (identification of instantaneous speed observer and moment of inertia)” (text page 424- 431)

  When identifying the disturbance torque and inertia with the conventional inertia identification calculation device, the disturbance estimation value by the observer is regarded as the disturbance torque as it is, and the inertia identification is performed. Since disturbances are included, there is a problem that if the disturbance torque is used as it is, the nominal inertia used in the observer will be identified. Therefore, a method is adopted in which the inertia is identified at the same time as the disturbance torque and the inertia identification value is updated little by little. However, it is difficult to analyze the convergence and there is a problem that the stability is not guaranteed.

  The present invention has been made in view of such problems, and a motor capable of estimating disturbance torque not including inertia error disturbance and accurately identifying inertia online by using the estimated disturbance torque value. An object is to provide a control device.

  In order to solve the above problem, the invention described in claim 1 is obtained from a motor for moving a load, a speed command obtained from a host controller or a position controller, and a position detector directly connected to the motor. Based on the position information difference or the speed information feedback obtained from the speed detector, a speed controller that generates a torque command to the motor, and the motor flows based on the torque command obtained by the speed controller A current controller for converting into a current command value for controlling the current, an inertia identification calculation device for acquiring information during operation of the motor and identifying the total inertia of the motor and the load using the information; In the motor control apparatus having the above, the inertia identification calculation device calculates a disturbance estimated value from the speed signal output from the motor and the torque command. A disturbance observer unit that outputs, a disturbance torque estimation unit that calculates a disturbance torque estimation value that does not include inertia error disturbance from the motor speed signal and the disturbance estimation value, the motor speed signal, the torque command, and the disturbance torque estimation And an inertia identification unit that calculates the total inertia identification value from the value.

According to a second aspect of the present invention, in the motor control device according to the first aspect, the disturbance torque estimating unit calculates the disturbance torque _Td at the following motor speeds when the motor speed ω is positive and negative. Expressed by a linear expression, the viscosity coefficient Dp when the motor speed ω is positive, the constant term Cp when the motor speed ω is positive, the viscosity coefficient Dn when the motor speed ω is negative, and the motor speed ω are negative The constant term Cn is calculated by an adaptive identification rule.

  According to a third aspect of the present invention, in the motor control device according to the first or second aspect, the disturbance torque estimation unit sets a threshold value, and performs the disturbance torque estimation process only when the absolute value of the motor acceleration is smaller than the threshold value. It is characterized by doing.

    According to the first aspect of the present invention, the inertia identification value can be calculated with high accuracy by calculating the disturbance torque estimated value not including the inertia error disturbance online.

  According to the second aspect of the present invention, it is possible to accurately calculate the estimated disturbance torque that does not include the inertia error disturbance even when there is Coulomb friction.

  According to the third aspect of the present invention, it is possible to calculate a disturbance torque estimated value that does not include an inertia error disturbance by using only information when the ratio of the inertia error disturbance to the observer estimated disturbance value is small. It is possible to calculate a good disturbance torque estimated value.

  Examples of the present invention will be specifically described below with reference to the drawings.

  The configuration of the motor control device according to the embodiment of the present invention is basically the same as that of the conventional device shown in FIG. 1, and therefore the description thereof is omitted. In the configuration of the motor control device, inertia different from that of the prior art is used. Only the processing of the identification computing device will be described.

FIG. 2 is a block diagram showing a configuration of an inertia identification arithmetic apparatus for identifying an inertia and its processing contents according to an embodiment of the present invention.
In the figure, 43 is a disturbance torque estimating unit.

The present invention is different from the prior art as follows.
That is, the inertia identification calculation device 4 includes a disturbance observer 41 that calculates a disturbance estimated value from the speed signal output from the motor 1 and the torque command, and an inertia error disturbance from the speed signal of the motor 1 and the disturbance estimated value. A disturbance torque estimating unit 43 that calculates a disturbance torque estimation value that is not present, and an inertia identification unit 42 that calculates a total inertia identification value from the speed signal of the motor 1, the torque command, and the disturbance torque estimation value. The inertia identification method will be briefly described below based on the configuration shown in FIG.
First, when calculating the estimated disturbance value by the disturbance observer unit 41,

Converges to the value shown in Equation (1) including the inertia error disturbance.

  Next, a disturbance torque estimation unit 43 obtains a disturbance torque estimated value that does not include inertia error disturbance. Details of this part will be described later.

Next, the inertia identification unit 42 calculates an inertia identification value using the estimated disturbance torque. Various methods for identifying the inertia have been devised. For example, the following adaptive identification formula can be used. However, γ is a constant and is adjusted appropriately. For example, γ = 1 × 10 ⁻⁸ may be set. T _dm is a disturbance torque estimated value obtained by the disturbance torque estimating unit 43, T _ref is a torque command, and a is an acceleration. k is an integer with an initial value of 0 and increases by 1 for each identification period.

  The processing from the disturbance observer unit 41 to the inertia identification unit 43 is repeated for each period of the adaptive identification rule. The cycle of the adaptive identification rule may not be the same as the motor control cycle, and may be, for example, 10 times the motor control cycle.

FIG. 4 is a graph showing a disturbance torque model showing an embodiment of the present invention. This is a model that combines the generally assumed viscous friction, Coulomb friction, and constant disturbance. The disturbance torque _Td is expressed by a linear expression of the motor speed when the motor speed ω is positive and negative, respectively, a viscosity coefficient Dp when the motor speed is positive, a constant term Cp when the motor speed is positive, Using the viscosity coefficient Dn when the motor speed is negative and the constant term Cn when the motor speed is negative, modeling is performed as in Expression (3). The viscosity coefficient may be Dp = Dn.

FIG. 3 is a flowchart showing a detailed procedure of the process of the disturbance torque estimating unit according to the embodiment of the present invention. Details of the processing of the disturbance torque estimation unit 43 shown in FIG. 2 will be described with reference to FIG.
First, 1 is added to k in step ST30. Next, in step ST31, an estimated disturbance value and motor speed by the observer are acquired. Next, in step ST32, motor acceleration is calculated from the difference in motor speed. When the motor speed resolution is low and the difference value fluctuates greatly, a low pass filter may be applied. Next, in step ST33, the motor acceleration is compared with the set threshold value. If the motor acceleration is smaller than the threshold value, the process proceeds to step ST34. If the motor acceleration is larger than the threshold value, the process proceeds to step ST35. As can be seen from the equation (1), when the acceleration a is small, the second term can be regarded as 0, and the disturbance estimated value by the observer coincides with the disturbance torque. Therefore, a certain threshold value is set, and the disturbance torque is adaptively identified from the value of the disturbance observer only when the motor acceleration becomes smaller than that. In step ST34, whether the motor speed is positive or negative is determined. If the motor speed is positive, the process proceeds to step ST36, and if the motor speed is negative, the process proceeds to step ST37. In step ST36 and step ST37, a disturbance torque estimated value that does not include inertia error disturbance is obtained from equations (4) to (8) based on the following adaptive identification rule. Since both are calculated | required by the same type | formula, it demonstrates using D and C below. In step ST36, D = Dp and C = Cp. In step ST37, D = Dn and C = Cn. However, γ ₀ is an appropriate positive constant. For example, γ ₀ = 0.1 may be set.

Finally, in step ST38, in step ST39, D calculated, it calculates a disturbance torque _{T dm} by using a C (3) expression.

Further, in step ST35 when the motor acceleration is larger than the threshold value, positive / negative determination of the motor speed is performed. If the motor speed is positive, the process proceeds to step ST38, and if the motor speed is negative, the process proceeds to step ST39. The disturbance torque _Td is calculated by the equation (3) without performing adaptive identification and using the previous D and C without updating.

  The formula based on the above adaptive identification rule is derived from the following general formula of the fixed trace method. Consider a system where the output y (i) is given by:

  Here, θ represents a parameter vector to be estimated, ζ represents an available signal vector, and w represents noise with an average value of 0. At this time, according to the following general formula of the fixed trace method:

It is known that can be adaptively identified.

  In formula (10) to formula (13),

By setting (estimated value of disturbance torque by observer when acceleration is small), an expression based on the adaptive identification rule of Expression (4) to Expression (8) is obtained.

  Thus, since the inertia identification value is calculated after calculating the disturbance torque estimated value not including the inertia error disturbance, the online identification of the inertia can be performed with high accuracy even when there is a disturbance torque.

  Since the inertia identification value is calculated after calculating the disturbance torque estimated value that does not include the inertia error disturbance, the online identification of the inertia can be performed accurately even when there is a disturbance torque, and the servo motor online inertia identification and the estimated value are obtained. It can be applied to auto tuning of control parameters used and inertia online identification of industrial robots.

It is a block diagram which shows the structure of the motor control apparatus which has a general inertia identification calculation apparatus, and showed as an explanatory view common to the present invention mentioned later and later The block diagram explaining the structure of the inertia identification arithmetic unit which identifies the inertia which shows the Example of this invention, and its processing content The flowchart which shows the detailed procedure of the process of the disturbance torque estimation part which shows the Example of this invention The graph showing the disturbance torque model which shows the Example of this invention The block diagram explaining the structure of the inertia identification arithmetic unit which identifies conventional inertia, and the processing content

Explanation of symbols

1 motor,
2 speed controller,
3 Current controller,
4 Inertia identification calculation device,
41 Disturbance observer section 42 Inertia identification section 43 Disturbance torque estimation section Kt Torque constant,
J Total inertia of motor and load

Claims (3)

A motor for moving the load;
Torque to the motor based on the difference between the speed command obtained from the host controller or position controller and the position information obtained from the position detector directly connected to the motor or the feedback of the speed information obtained from the speed detector A speed controller that generates a command;
A current controller for converting into a current command value for controlling the current flowing through the motor based on the torque command obtained by the speed controller;
An inertia identification computing device that acquires information during operation of the motor and identifies the total inertia of the motor and the load using the information;
In a motor control device comprising:
The inertia identification calculation device includes a disturbance observer unit that calculates a disturbance estimated value from a speed signal output from the motor and the torque command;
A disturbance torque estimating unit for calculating a disturbance torque estimated value not including an inertia error disturbance from the motor speed signal and the disturbance estimated value;
An inertia identification unit that calculates the total inertia identification value from the motor speed signal, the torque command, and the disturbance torque estimation value;
A motor control device comprising: The disturbance torque estimation unit represents the disturbance torque _Td as a linear expression of the following motor speed when the motor speed ω is positive and negative, respectively, the viscosity coefficient Dp when the motor speed ω is positive, and the motor speed 2. A constant term Cp when ω is positive, a viscosity coefficient Dn when the motor speed ω is negative, and a constant term Cn when the motor speed ω is negative are calculated by an adaptive identification rule. The motor control device described in 1.
  3. The motor control device according to claim 1, wherein the disturbance torque estimation unit sets a threshold and performs disturbance torque estimation processing only when the absolute value of the motor acceleration is smaller than the threshold.