JP4827016B2 - Rigid identification device and motor control device including the same - Google Patents

Description

  The present invention relates to a stiffness identification device that identifies the stiffness of a motor connected to a load with low stiffness, and a motor control device including the stiffness identification device.

  A conventional stiffness identification apparatus inputs an identification input signal to a robot using a hammer, and identifies the stiffness of the robot using a result of frequency analysis of the acceleration and a known non-rigidity parameter (see, for example, Patent Document 1). ).

  FIG. 4 shows a conventional stiffness identification apparatus. In the figure, 401 is a hammer, 402 is a robot, 403 is a sensor, 404 is a frequency analysis unit, 405 is a memory, and 406 is an identification unit. An identification input signal is input to the robot 402 by the hammer 401. The sensor 403 detects and outputs the acceleration of the robot 402. The frequency analysis unit 404 inputs the acceleration and outputs an analysis result. The memory 405 outputs known non-rigid parameters such as moment of inertia and viscous friction. The identification unit 406 receives the analysis result and the non-rigidity parameter, and calculates and outputs a stiffness parameter that is the stiffness of the speed reducer of the robot 402.

As described above, the conventional stiffness identification apparatus inputs the identification input signal to the robot by the hammer, and identifies the stiffness of the robot using the result of frequency analysis of the acceleration and the known non-rigidity parameter.
Japanese Patent Laid-Open No. 09-123077 (page 5-7, FIG. 1)

The conventional stiffness identification device is configured to identify the stiffness using the frequency analysis result when the input signal for identification is inputted and the known non-rigidity parameter. If the non-rigid parameters such as the moment of inertia and viscous friction are not accurately known, there is a problem that the rigidity identification cannot be performed accurately. In addition, when it is desired to identify the rigidity of the robot without making a large movement, there is a problem that the rigidity cannot be identified only by a small movement.
The present invention has been made in view of such problems, and even when the non-rigidity parameter is not known, the rigidity of the motor in which the load is connected with low rigidity can be identified with high accuracy only by a minute operation. It is an object of the present invention to provide a stiffness identification device and a motor control device including the same.

  In order to solve the above problem, the present invention is configured as follows.

A typical configuration of the present invention drives a speed controller that calculates a torque command based on an input speed command and a motor position detected by a position detector, and a load connected based on the torque command. A motor control device for controlling power supply to a motor, wherein when the speed command, which is a sine wave signal having a specific frequency and amplitude, is input, the torque command is multiplied by the motor position to multiply the position torque command. A position torque command multiplier for calculating a value, a position amplitude calculator for calculating a motor position amplitude value corresponding to the amplitude of the motor position, and one position of the sine wave signal of the position torque command multiplication value Divide twice the time average value for one cycle by the square value of the motor position amplitude value, and add the product of the square value of the specific frequency and the moment of inertia value of the motor Comprising a rigid calculator for calculating the stiffness identification value, the Te.
Another typical configuration of the present invention is based on a position controller that calculates a speed command based on an input position command and a motor position detected by a position detector, and on the speed command and the motor position. A speed controller that calculates a torque command and a motor control device that controls power supply to a motor that drives a load connected based on the torque command, the sine wave signal having a specific frequency and amplitude When a position command is input, a position torque command multiplier that calculates a position torque command multiplication value by multiplying the torque command and the motor position, and a position that calculates a motor position amplitude value corresponding to the amplitude of the motor position The amplitude calculator and the position torque command multiplication value, which is twice the time average value for one period corresponding to one period of the sine wave signal, is divided by the square value of the motor position amplitude value. Further comprising a rigid calculator for calculating the stiffness identification value by adding the multiplied value of the inertial moment value of the the square value of the specific frequency motor.

According to a typical configuration of the present invention or another typical configuration of the present invention , even when the non-rigidity parameter is not known, a constant torque disturbance can be obtained with only a minute operation of the rigidity of a motor connected to a low-rigidity load. Therefore, it is possible to identify with high accuracy and in a short time without being affected by noise, nonlinear dynamics, transient response, etc. In addition, using any periodic command, the rigidity of the motor connected to the load with low rigidity can be adjusted to a high degree of accuracy with almost no influence from constant torque disturbance, noise, nonlinear dynamics, transient response, etc. It can be identified in a short time.

In addition, even if the non-rigidity parameter is not known, using arbitrary periodic commands, the rigidity of the motor connected to a low-rigidity load can be adjusted only with a minute motion, such as constant torque disturbance, noise, nonlinear dynamics, transient response, etc. It is possible to identify with high accuracy in a short time with almost no influence.

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

    FIG. 1 shows a stiffness identification device based on speed control according to a first embodiment of the present invention. In the figure, 101 is a speed command generator, 102 is a speed controller, 103 is a torque controller, 104 is a control target, 105 is a position detector, 106 is a differentiator, 107 is a stiffness identifier, and 108 is a position torque command multiplier. , 109 is a position amplitude calculator, and 110 is a rigidity calculator.

  The speed command generator 101 outputs a speed command. The speed controller 102 inputs the speed command and the motor speed and outputs a torque command. The torque controller 103 receives the torque command and outputs a motor drive signal. The control object 104 is driven by the motor drive signal, and the position of the motor is detected and output by the position detector 105. The differentiator 106 inputs the motor position and outputs the motor speed.

The stiffness identifier 107 inputs the torque command and the motor position, calculates and outputs a stiffness identification value. In the stiffness identifier 107, the position torque command multiplier 108 inputs the torque command and the motor position, and outputs a position torque command multiplication value which is a multiplication value thereof. A position amplitude calculator 109 receives the motor position and outputs a motor position amplitude that is the amplitude. The stiffness calculator 110 receives the position torque command multiplication value and the motor position amplitude, and calculates and outputs the stiffness identification value that is the stiffness of the control object 104.
The present invention is different from the prior art in that it includes a stiffness identifier 107 having a position torque command multiplier 108, a position amplitude calculator 109, and a stiffness calculator 110. Without using a certain non-rigidity parameter, the rigidity of a motor connected with a low rigidity by only a minute operation is identified with high accuracy.

  Hereinafter, a mechanism in which the stiffness identifier 107 calculates the stiffness identification value will be described.

  It is assumed that the control object 104 is connected to the motor with low rigidity, the motor inertia moment is Jm, the load inertia moment is Jl, the motor viscous friction is D, the load viscous friction is cl, and the load between the motor and the load is Stiffness between motor loads, which is rigidity, k, viscous friction between motor loads, which is viscous friction between the motor and the load, c, torque command, Tref, motor position, θm, load position, θl, constant torque disturbance Assuming that w, the equation of motion of the open loop system including the torque controller 103, the controlled object 104, and the position detector 105 is expressed as Expression (1) and Expression (2).

  In the identification formula derivation up to the following equation (8), the speed command is a sine wave that is a periodic signal of the speed command frequency ω, and the motor position θm, the load position θl, and the torque command Tref are among the frequency components. Consider only the fundamental frequency component that is at frequency ω. When the speed command frequency is set to be sufficiently larger than the natural frequency of the open loop system, the relationship θl << θm is established, and equation (1) can be approximated to equation (3).

  In the steady state, the motor position is expressed by Equation (4).

  Where A is the motor position amplitude and ω is the speed command frequency. When equation (4) is substituted into equation (3), torque command Tref is expressed by equation (5).

  A position torque command multiplication value, which is a multiplication value of the motor position θm and the torque command Tref, can be obtained from Expression (4) and Expression (5) as Expression (6).

  The average value for 1 period of Formula (6) becomes a constant term in Formula (6), and is represented by Formula (7). Here, the average value for one period is a time average value for one period.

  However, the bar indicates the average value for one period. When equation (7) is rewritten, equation (8) is obtained.

  The stiffness calculator 110 calculates the stiffness identification value using equation (8). Since the equation (8) does not include the load inertia moment Jl, the rigidity identification value can be calculated without knowing the load inertia moment Jl. Further, since the equation (8) uses the torque command Tref and the motor position θm, it can be applied when arbitrary linear control is used. For example, the speed controller 102 may be P, PI, IP, and PID control.

  Further, since the fundamental frequency components of the torque command Tref and the motor position θm are used, the influence of a disturbance having a frequency component other than the speed command frequency and a constant torque disturbance due to noise, gravity, etc. is suppressed, and a short time without waiting for a steady state. The stiffness identification value can be calculated.

  FIG. 2 is a stiffness identification device based on position control according to a second embodiment of the present invention. In the figure, 102 is a speed controller, 103 is a torque controller, 104 is an object to be controlled, 105 is a position detector, 106 is a differentiator, 107 is a stiffness identifier, 108 is a position torque command multiplier, and 109 is a position amplitude calculation. , 110 is a stiffness calculator, 201 is a position command generator, and 202 is a position controller.

  The position command generator 201 outputs a position command. The position controller 202 inputs the position command and the motor position and outputs a speed command. The speed controller 102 inputs the speed command and the motor speed and outputs a torque command. The torque controller 103 receives the torque command and outputs a motor drive signal. The controlled object 104 is driven by the motor drive signal, and the position of the motor is detected and output by the position detector 105. The differentiator 106 inputs the motor position and outputs the motor speed. The stiffness identifier 107 inputs the torque command and the motor position, calculates and outputs a stiffness identification value.

  The first embodiment and the second embodiment differ depending on whether they are based on speed control or position control, and the configuration of the stiffness identifier 107 used is the same. Then, the detailed explanation is omitted. Further, although the command output from each command generator differs depending on whether it is a speed command or a position command, the stiffness identifier 107 calculates a stiffness identification value based on the torque command and the motor position. Since they are the same, the derivation of the identification expression up to the above-described expression (8) is the same, and can be applied to the first and second embodiments.

  Hereinafter, the simulation results of this example are shown.

The numerical values used in this simulation are as follows.
Jm = 2.09 × 10 ^ -4 [kg · m ^ 2], Jl = 1.90 × 10 ^ -4 [kg · m ^ 2], D = 0.01 [N · m · s / rad] , Cl = 0.01 [N · m · s / rad], c = 0.001 [N · m · s / rad], ωn = 20 (2π) [rad / s], Kp = 40 [s ^ − 1], Kv = 40 (2π) [s ^ −1], Kvj = Kv · Jm, Ti = 0.020 [s], r0 = 0.1 [rad], ω = 80 (2π) [rad / s ], Trat = 1.27 [N · m]
However, the position controller 202 is P-controlled and the speed controller 102 is PI-controlled, ωn is the natural frequency of the load, Kp is the position proportional control gain, Kv is the normalized speed proportional control gain, Kvj is the speed proportional control gain, Ti Is the speed control integration time, r0 is the position command amplitude, and Trat is the rated torque. The true stiffness value k * is expressed as k * = ωn ^ 2 * Jl using the natural frequency ωn of the load.
These numerical values used in the simulation are in accordance with the application to the actual machine, and even when the present invention is applied to the actual machine, the effect equivalent to the simulation result is obtained.

  FIG. 3 shows the rigidity identification result when the constant torque disturbance is changed according to the second embodiment of the present invention. In the figure, the stiffness identification error ek (%) was calculated by the equation (9) using the stiffness identification value k and the stiffness true value k *.

(9)

  When the constant torque disturbance rated torque ratio w / Trat is changed from 0% to 50%, the rigidity identification error calculated by the equation (9) is 5% or less, and according to the present invention, it is not affected by the constant torque disturbance. It can be seen that high-precision rigidity identification can be performed.

  In this case, the motor position amplitude A is always about 0.004 rad (about 80 pulses with a 17-bit position detector), and the torque command amplitude is about 20% of the rated torque Trat. (Not shown) Therefore, it can be applied to the rigidity identification of a motor connected with a load having a limited movable range, and can also be applied to a case where the load inertia moment is larger.

  In this case, since the ratio of the load position amplitude to the motor position amplitude is 10% or less (not shown), it can be seen that the assumption θl << θm used to derive the expression (3) is established.

  Furthermore, since the equation (8) uses the torque command Tref and the motor position θm, it can be applied when any linear control is used. For example, the position controller 202 and the speed controller 102 may be P, PI, IP, and PID control.

Thus, a position torque command multiplier that inputs a torque command and a motor position and outputs a position torque command multiplication value, a position amplitude calculator that inputs the motor position and outputs a motor position amplitude, and the position torque command multiplication Because it has a configuration that includes a stiffness calculator that inputs the value and the motor position amplitude and calculates and outputs the stiffness identification value, it can be affected by disturbances with frequency components different from the position command, the influence of constant torque disturbance due to noise, gravity, etc. Even when the load inertia moment is not known, the rigidity of the motor connected to the load can be identified with high accuracy, and high-precision control can be performed using the stiffness identification value.
The frequency and amplitude of the speed command or position command generated from the speed command generator 101 or the position command generator 201 are set so that the load position amplitude is sufficiently smaller than the motor position amplitude. What is necessary is just to set so that it may become 10% of position amplitude.

  Since the rigidity of a motor connected to a load with low rigidity can be identified by only a minute operation, the present invention can be widely applied to automatic control gain adjustment of general industrial machines such as semiconductor manufacturing apparatuses and industrial robots.

Rigidity identification device based on speed control showing a first embodiment of the present invention Rigidity identification device based on position control showing a second embodiment of the present invention Rigidity identification result when constant torque disturbance is changed according to the second embodiment of the present invention Conventional stiffness identification device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Speed command generator 102 Speed controller 103 Torque controller 104 Control object 105 Position detector 106 Differentiator 107 Rigidity identifier 108 Position torque command multiplier 109 Position amplitude calculator 110 Rigidity calculator 201 Position command generator 202 Position control Instrument 401 Hammer 402 Robot 403 Sensor 404 Frequency analysis unit 405 Memory 406 Identification unit

Claims (2)

A speed controller that calculates a torque command based on an input speed command and a motor position detected by a position detector, and a motor control that controls power supply to a motor that drives a connected load based on the torque command A device,
When the speed command that is a sine wave signal having a specific frequency and amplitude is input,
A position torque command multiplier that multiplies the torque command and the motor position to calculate a position torque command multiplication value;
A position amplitude calculator for calculating a motor position amplitude value corresponding to the amplitude of the motor position;
The position torque command multiplication value is divided by twice the time average value for one period corresponding to one period of the sine wave signal by the square value of the motor position amplitude value, and further the square value of the specific frequency. And a rigidity calculator that calculates a rigidity identification value by adding a product of the motor and the inertia moment value of the motor. A position controller that calculates a speed command based on an input position command and a motor position detected by a position detector; a speed controller that calculates a torque command based on the speed command and the motor position; A motor control device that controls power supply to a motor that drives a connected load based on the torque command,
When the position command is a sine wave signal having a specific frequency and amplitude,
A position torque command multiplier that multiplies the torque command and the motor position to calculate a position torque command multiplication value;
A position amplitude calculator for calculating a motor position amplitude value corresponding to the amplitude of the motor position;
The position torque command multiplication value is divided by twice the time average value for one period corresponding to one period of the sine wave signal by the square value of the motor position amplitude value, and further the square value of the specific frequency. And a rigidity calculator that calculates a rigidity identification value by adding a product of the motor and the inertia moment value of the motor.