JP6605178B2 - POSITION CONTROL DEVICE AND METHOD, PROGRAM, AND RECORDING MEDIUM - Google Patents

Description

  The present invention relates to a position control apparatus and method. The present invention relates to a position control apparatus and method particularly suitable for position control of an actuator having an elastic support mechanism. The present invention also relates to a program for causing a computer to execute processing in the position control apparatus or method, and a recording medium on which the program is recorded.

  In general, feedback control is used as the position control of the movable portion of the actuator having the elastic support mechanism. The feedback control is control for moving the movable part of the actuator to the target position based on the position information of the movable part of the actuator. The performance index of feedback control includes stability and responsiveness. Stability can be obtained by securing a phase margin or gain margin in feedback control. For this purpose, it is necessary to lower the control gain. When the control gain is lowered, the responsiveness deteriorates. Therefore, stability and responsiveness are in a trade-off relationship. Furthermore, it is not easy to perform optimal control design in consideration of variations in actuator characteristics or disturbances acting on the actuator.

  For example, Patent Document 1 describes a disturbance observer that compensates for variations in actuator characteristics or disturbances acting on the actuator. The disturbance observer divides the transfer function of the nominal model unit that simulates the transfer characteristic of the actuator with respect to the position of the movable part of the actuator, thereby estimating the actuator characteristic variation or the disturbance acting on the actuator. The actuator drive voltage (or drive current) is corrected using the signal. The disturbance observer is a kind of loop control because the estimated signal is fed back to the input. This loop control constitutes a minor loop in the feedback control. The disturbance observer compensates for characteristic variations or disturbances below the control band of control in this minor loop.

JP-A-9-128770 (paragraphs 0019 to 0020, FIG. 2)

  In the technique described in Patent Document 1, it is not necessary to consider the variation in the characteristics of the actuator or the disturbance acting on the actuator by using the disturbance observer, but the problem of the trade-off between stability and responsiveness in feedback control is Remain.

  An object of the present invention is to solve the problem of tradeoff between stability and responsiveness in position control of an actuator provided with an elastic support mechanism, and to improve responsiveness.

The position control device according to the present invention includes:
A position control device for controlling the position of a movable part of an actuator having an elastic support mechanism,
A position target signal generator for outputting a position target signal indicating the target position of the movable part in the position control of the movable part;
A DC sensitivity division unit that divides the position target signal by the DC sensitivity of a nominal model that simulates the transfer characteristics of the actuator;
A disturbance compensator that compensates for a variation in characteristics of the actuator and a disturbance acting on the actuator, using the output of the DC sensitivity divider as an input;

  According to the position control device of the present invention, since it is not necessary to use feedback control for position control, it is possible to eliminate the trade-off problem between stability and responsiveness and improve responsiveness.

It is a block diagram which shows roughly the structure of the position control apparatus which concerns on Embodiment 1 of this invention. FIG. 2 is a block diagram schematically showing a configuration of a disturbance compensation unit in the position control device according to the first embodiment. It is a block diagram which shows the transfer function of the actuator shown by FIG. (A) And (b) is a figure which shows the frequency characteristic of the position detection signal act_p with respect to the voltage signal Edro of the actuator in Embodiment 1. FIG. (A) And (b) is a figure which shows an example of the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation part 20 in Embodiment 1. FIG. (A) And (b) shows the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 when the Q value at the primary resonance frequency of the nominal model in the first embodiment is changed. FIG. (A) And (b) shows the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 when the Q value at the primary resonance frequency of the nominal model in the first embodiment is changed. FIG. (A) And (b) shows the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 when the Q value at the primary resonance frequency of the nominal model in the first embodiment is changed. FIG. (A) And (b) is a figure which shows the step response of an actuator at the time of changing Q value in the primary resonance frequency of the nominal model in Embodiment 1. FIG. (A) And (b) is a figure which shows the step response of an actuator at the time of changing Q value in the primary resonance frequency of the nominal model in Embodiment 1. FIG. (A) And (b) is a figure which shows the step response of an actuator at the time of changing Q value in the primary resonance frequency of the nominal model in Embodiment 1. FIG. FIG. 6 is a diagram illustrating a relationship between a Q value at a primary resonance frequency of a nominal model in Embodiment 1 and a target value convergence time in an actuator step response. (A) And (b) is a figure which shows the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation part 20 at the time of changing the direct current sensitivity of the nominal model in Embodiment 1. (A) And (b) is a figure which shows the step response of an actuator at the time of changing the direct current sensitivity of the nominal model in Embodiment 1. FIG. It is a figure which shows the relationship between the direct current sensitivity of the nominal model in Embodiment 1, and the target value convergence time in the step response of an actuator. (A) And (b) is a figure which shows the step response of the actuator in a prior art. (A) And (b) is a figure which shows the step response of the actuator in Embodiment 1. FIG. It is a block diagram which shows roughly the structure of the position control apparatus which concerns on Embodiment 2 of this invention. FIG. 10 is a block diagram schematically showing a configuration of a disturbance compensation unit in the position control device according to the second embodiment. FIG. 20 is a block diagram showing a transfer function of the actuator shown in FIG. 19. (A) And (b) is a figure which shows the frequency characteristic of the position detection signal act_p with respect to the voltage signal Edro of the actuator in Embodiment 2. FIG. (A) And (b) is a figure which shows the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation part 20b in Embodiment 2. FIG. (A) And (b) is a figure which shows the step response of the actuator in Embodiment 2. FIG. It is a block diagram which shows the structure of the computer which performs the process of the position control apparatus of Embodiment 1 and 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram schematically showing a configuration of a position control device 1 according to Embodiment 1 of the present invention. This position control device is used for position control of a movable part of an actuator provided with an elastic support mechanism.

  A position control device 1 shown in FIG. 1 includes a position target signal generation unit 10, a change width signal generation unit 12, a DC sensitivity division unit 14, and a disturbance compensation unit 20, and drives an actuator 30 to position the movable unit. To control. Here, the actuator 30 includes an elastic support mechanism, and the movable portion of the actuator 30 is elastically supported by the elastic support mechanism.

  The position target signal generator 10 outputs a position target signal ref_p. The position target signal ref_p indicates a target position in the position control of the actuator 30.

  The change width signal generation unit 12 outputs a change width of the position target signal ref_p, that is, a signal (change width signal) ref_p_s indicating a desired movement amount. The change width signal ref_p_s receives, for example, the position target signal ref_p output from the position target signal generator 10, and outputs the change width signal ref_p_s indicating the change width when the position target signal ref_p changes stepwise. .

The DC sensitivity divider 14 receives the position target signal ref_p from the position target signal generator 10, receives the change width signal ref_p_s from the change width signal generator 12, and generates and outputs a voltage signal Edr based on these. DC sensitivity divider 14 defines a DC sensitivity DCS _m nominal model based on the change width signal Ref_p_s, in the DC sensitivity DCS _m, and generates a voltage signal Edr by dividing the target position signal REF_P. The transfer function of the DC sensitivity division unit 14 is 1 / DCS _{m when} expressed using the DC sensitivity DCS _m of the nominal model.

The disturbance compensator 20 receives the voltage signal Edr from the DC sensitivity divider 14. The disturbance compensator 20 controls the position of the movable part of the actuator 30 based on the voltage signal Edr. The position of the movable part of the actuator 30 is detected and input to the disturbance compensator 20 as a position detection signal act_p representing a position detection value. A transfer function from the input (voltage signal Edr) of the disturbance compensator 20 to the position of the movable part of the actuator 30 (represented by the position detection signal act_p), that is, the total transfer function of the disturbance compensator 20 and the actuator 30 is expressed as O ( s). Here, s is a Laplace variable.
Control of the position of the movable part of the actuator 30 is affected by the disturbance g from the disturbance source 16.

  In the first embodiment, actuator position control is performed without using feedback control as shown in FIG. The reason will be explained later.

FIG. 2 is a block diagram schematically showing the configuration of the disturbance compensation unit 20 in the first embodiment.
As shown in FIG. 2, the disturbance compensation unit 20 includes an addition unit 21, a nominal model division unit 22, a subtraction unit 25, and an LPF unit 26. The disturbance compensation unit 20 is also called a disturbance observer.

  The adder 21 receives the voltage signal Edr from the DC sensitivity divider 14. Further, the adding unit 21 receives the voltage signal Edr3 from the LPF unit 26. The adder 21 calculates a sum (Edr + Edr3) of the voltage signal Edr and the voltage signal Edr3, and outputs a voltage signal Edr representing this sum.

  The actuator 30 includes an elastic support mechanism. The elastic support mechanism includes an elastic support member that movably supports the movable part. The transfer function of the actuator 30 is P (s).

The nominal model division unit 22 receives a position detection signal act_p indicating the position of the movable part of the actuator 30. The nominal model division unit 22 divides the position detection signal act_p by the transfer function P _n (s) of the nominal model to generate and output a voltage signal Edr1.
The nominal model division unit 22 includes a transfer function generation unit 23 and a division unit 24. The transfer function generation unit 23 generates the transfer function P _n (s) of the above nominal model, and the division unit 24 performs the above division. I do.

  The subtraction unit 25 receives the voltage signal Edro from the addition unit 21. Further, the subtraction unit 25 receives the voltage signal Edr1 from the nominal model division unit 22. The subtractor 25 calculates a difference (Edr−Edr1) between the voltage signal Edr and the voltage signal Edr1, and outputs a voltage signal Edr2 representing this difference.

  The LPF unit 26 receives the voltage signal Edr2 from the subtracting unit 25. The LPF unit 26 generates and outputs a voltage signal Edr3 by performing low-pass filtering on the voltage signal Edr2.

The disturbance compensation unit 20 of FIG. 2 is configured to feed back the voltage signal Edr3 generated by the LPF unit 26 based on the position detection signal act_p of the actuator 30 to the input of the disturbance compensation unit 20.
The disturbance compensator 20 is a minor loop in the position control device 1. The LPF unit 26 determines the control band of the minor loop, and the cutoff frequency of the LPF unit 26 becomes the control band of the minor loop. The transfer function of the LPF unit 26 is represented by F _c (s).

If attention is paid to the transfer function of the actuator 30 in the first embodiment, it can be understood that the actuator 30 has the configuration shown in the block diagram of FIG.
FIG. 3 assumes a case where the actuator 30 is an objective lens actuator in an optical pickup. FIG. 3 further assumes a case where the actuator 30 includes a voice coil motor and drives the objective lens by passing a current through the coil.

  As shown in FIG. 3, the actuator 30 includes a subtractor 301, a voltage / current converter 302, a current force converter 303, a subtractor 304, a movable part mass divider 305, an adder 306, an acceleration / speed converter 307, a speed A back electromotive force conversion unit 308, a speed position conversion unit 309, a movable part viscosity coefficient multiplication unit 310, a movable part elastic coefficient multiplication unit 311, and an addition unit 312 are provided.

  The subtractor 301 receives the voltage signal Edro from the adder 21 of FIG. The subtractor 301 receives the voltage signal Edro4 from the speed counter electromotive force converter 308. The subtraction unit 301 calculates a difference (Ero-Edro4) between the voltage signal Edro and the voltage signal Edro4. Then, the subtraction unit 301 outputs a voltage signal Edro1 corresponding to this difference.

  The voltage-current conversion unit 302 receives the voltage signal Edro1 from the subtraction unit 301. The voltage-current converter 302 outputs a current signal Idro1 based on the voltage signal Edro1. The transfer function of the voltage-current converter 302 is 1 / (Ls + R) when expressed using the resistance R and inductance L of the voice coil.

The current force conversion unit 303 receives the current signal Idro1 from the voltage / current conversion unit 302. The current force conversion unit 303 outputs a force signal Fdro1 based on the current signal Idro1. The transfer function of the current power conversion unit 303 is a force constant (current force conversion coefficient) K _t. The current force conversion unit 303 corresponds to a function in which the voice coil motor converts a current into a force (electromagnetic force) acting on the movable unit.

  The subtractor 304 receives the force signal Fdro1 from the current force converter 303. In addition, the subtraction unit 304 receives the force signal Fdro2 from the addition unit 312. The subtraction unit 304 calculates a difference (Fdro1-Fdro2) between the force signal Fdro1 and the force signal Fdro2. Then, the subtraction unit 304 outputs a force signal Fdro3 corresponding to this difference.

The movable part mass division unit 305 receives the force signal Fdro3 from the subtraction unit 304. The movable part mass dividing unit 305 divides the force signal Fdro3 by the mass m ₁ of the movable part of the actuator 30 to generate and output the acceleration signal Aro3. The transfer function of the movable part mass dividing unit 305 is 1 / m _{1 when} expressed using the mass m _{1 of the} movable part.
The movable part mass division unit 305 corresponds to an action in which electromagnetic force generated by the voice coil motor is converted into acceleration.

The adder 306 receives the acceleration signal Aro3 from the movable part mass divider 305. Further, the adding unit 306 receives the acceleration disturbance g. The adder 306 calculates the sum (AdrO3 + g) of the acceleration signal Adro3 and the acceleration disturbance g, and outputs an acceleration signal Adro4 representing this sum.
The adding unit 306 corresponds to a process in which an acceleration disturbance g is added to the acceleration caused by the electromagnetic force of the voice coil motor.

  The acceleration speed conversion unit 307 receives the acceleration signal Aro4 from the addition unit 306. The acceleration speed conversion unit 307 integrates the acceleration signal Adro4 and outputs a speed signal Vdro4. The transfer function of the acceleration speed conversion unit 307 is 1 / s.

The speed counter electromotive force conversion unit 308 receives the speed signal Vdro4 from the acceleration speed conversion unit 307. Speed counter electromotive force converting unit 308 multiplies the counter electromotive force constant _{K e} generates and outputs a voltage signal Edro4 by the speed signal Vdro4. The transfer function of the velocity counter electromotive force converting unit 308, a counter electromotive force constant K _e. The speed counter electromotive force conversion unit 308 corresponds to a function in which the voice coil motor converts the movement of the movable part into a counter electromotive force generated in the coil.

The speed position converter 309 receives the speed signal Vdro4 from the acceleration speed converter 307. The speed position conversion unit 309 integrates the speed signal Vdro4 and outputs an actuator position detection signal act_p. The transfer function of the speed position conversion unit 309 is 1 / s.
The acceleration speed conversion unit 307 and the speed position conversion unit 309 correspond to the action of converting acceleration acting on the movable part into speed and position.

The movable part viscosity coefficient multiplying unit 310 receives the speed signal Vdro4 from the acceleration speed converting unit 307. Movable portion viscosity coefficient multiplying unit 310 generates and outputs a force signal Fdro4 by multiplying the viscosity coefficient _{c 1} to the speed signal Vdro4. The transfer function of the movable portion viscosity coefficient multiplying unit 310 is a viscosity coefficient c _1. The movable part viscosity coefficient multiplying unit 310 corresponds to an action in which the speed is converted into force by the viscous resistance received by the movable part.

The movable part elastic coefficient multiplier 311 receives the actuator position detection signal act_p from the speed position converter 309. Movable elastic coefficient multiplication unit 311 generates a force signal Fdro5 output by multiplying the elastic modulus _{k 1} to the actuator position detection signal Act_p. The transfer function of the movable elastic coefficient multiplication unit 311 is an elastic coefficient k _1. The movable part elastic coefficient multiplying unit 311 corresponds to an operation in which the elastic support mechanism converts the displacement of the movable part into a restoring force.

  The adder 312 receives the force signal Fdro4 from the movable part viscosity coefficient multiplier 310. In addition, the addition unit 312 receives the force signal Fdro5 from the movable part elastic coefficient multiplication unit 311. The adder 306 calculates the sum (Fdro4 + Fdro5) of the force signal Fdro4 and the force signal Fdro5, and outputs a force signal Fdro2 representing the force given by this sum.

As described above, the output Fdo2 of the adder 312 is subtracted from the output Fdro1 of the current force converter 303 by the subtractor 304.
The processing by the adding unit 312 and the subtracting unit 304 corresponds to a part of the electromagnetic force generated by the voice coil motor being used to resist the restoring force due to viscous resistance and elasticity, and the rest contributing to driving of the movable unit. To do.

As described above, the transfer function generation unit 23 generates a transfer function P _n (s) of a model that simulates the transfer function of the actuator 30. The division unit 24 divides the position detection signal act_p by the transfer function P _n (s) generated by the transfer function generation unit 23.

The nominal model used for generating the transfer function in the transfer function generating unit 23 has generally the same configuration as the actuator 30 shown in FIG. However, the nominal model is different from that shown in FIG. 3 in that the acceleration disturbance g is not input, the adding unit 306 is not provided, and the output Adro3 of the movable part mass dividing unit 305 is input to the acceleration speed converting unit 307 as it is. In the actuator 30, the viscosity coefficient c ₁ multiplied by the movable part viscosity coefficient multiplier 310, the elastic coefficient k ₁ multiplied by the movable part elastic coefficient multiplier 311, the resistance R and inductance L in the voltage / current converter 302, the current force The constant K _t in the conversion unit 303 and the constant K _e in the speed counter electromotive force conversion unit 308 are affected by temperature, but in the nominal model, they are assumed to be constant regardless of the temperature. Further, the viscosity coefficient c ₁ and the elastic coefficient k ₁ can be changed, and by changing them, the DC sensitivity of the nominal model and the Q value at the primary resonance frequency can be adjusted.

Specifically, the change width signal ref_p_s output from the change width signal generation unit 12 is supplied to the transfer function generation unit 23 so that the Q value at the primary resonance frequency of the nominal model is 0 dB or less and this change is performed. In accordance with the width signal ref_p_s, the parameters of the nominal model are adjusted so that the DC sensitivity DCS _m of the nominal model becomes sufficiently small. More specifically, the change width represented by the change width signal ref_p_s is represented by a symbol ref_p_e so that the Q value at the primary resonance frequency of the nominal model is in the range of −6 dB to 0 dB, and the actuator 30 When the maximum value of the voltage that can be applied to V.sub._max is V.sub._max, the DC sensitivity DCS _m of the nominal model is a value given by ref_p_e / V_max or a value slightly larger than this, for example, a value given by ref_p_e / V_max. It is desirable to adjust the parameters of the nominal model so that the value is within the range up to 25 times.
Adjustment of the parameters of the nominal model can be performed, for example, by changing the viscosity coefficient c ₁ and the elastic coefficient k ₁ used in the transfer function generation unit 23.

  FIGS. 4A and 4B are diagrams illustrating frequency characteristics of the position detection signal act_p with respect to the voltage signal Edro of the actuator 30 according to the first embodiment. FIG. 4A shows the frequency characteristic (gain characteristic) of the gain. The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 4B shows the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  In FIG. 4A and FIG. 4B, characteristic curves GA1 and PH1 indicated by chain lines indicate frequency characteristics when the temperature of the actuator 30 is −30 ° C. Characteristic curves GA2 and PH2 represented by broken lines indicate frequency characteristics when the temperature of the actuator 30 is + 20 ° C. Characteristic curves GA3 and PH3 represented by dotted lines indicate frequency characteristics when the temperature of the actuator 30 is + 85 ° C.

As shown in FIGS. 4A and 4B, the frequency characteristic of the actuator 30 is such that the Q value at the primary resonance frequency is greater than 0 dB. Further, the gain characteristic and the phase characteristic change depending on the temperature of the actuator 30. The reason why the gain characteristic and the phase characteristic change depending on the temperature is that the parameter of the actuator changes depending on the temperature. Specifically, viscosity coefficient _{c 1} of FIG. 3, the elastic coefficient _{k 1,} resistor R, inductance L, the force constant _{K t,} the counter electromotive force constant _{K e} is changed by temperature. Since gain characteristics and phase characteristics change depending on temperature, it is not easy to perform optimum position control in consideration of characteristic variations of the actuator 30.

  FIGS. 5A and 5B are diagrams illustrating an example of frequency characteristics of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 in the first embodiment. FIG. 5A shows the frequency characteristic (gain characteristic) of the gain. The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 5B shows the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  In FIG. 5A and FIG. 5B, characteristic curves GA4 and PH4 indicated by chain lines indicate frequency characteristics when the temperature of the actuator 30 is −30 ° C. Characteristic curves GA5 and PH5 represented by broken lines indicate frequency characteristics when the temperature of the actuator 30 is + 20 ° C. Characteristic curves GA6 and PH6 represented by dotted lines indicate frequency characteristics when the temperature of the actuator 30 is + 85 ° C. Characteristic curves GA7 and PH7 represented by solid lines indicate the frequency characteristics of the nominal model.

  As shown in FIGS. 5A and 5B, the gain characteristic and the phase characteristic are not changed depending on the temperature of the actuator 30. Further, the frequency characteristic of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensator 20, that is, the total frequency characteristic of the disturbance compensator 20 and the actuator 30 agrees well with the frequency characteristic of the nominal model. In this way, the disturbance compensator 20 can compensate for variations in the characteristics of the actuator 30.

  Next, the design of the Q value Q1m at the primary resonance frequency of the nominal model will be described with reference to FIGS.

6A to 8B show the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 when the Q value at the primary resonance frequency of the nominal model in the first embodiment is changed. It is a figure which shows a frequency characteristic. However, the temperature is set to 20 ° C.
FIG. 6A, FIG. 7A, and FIG. 8A show gain frequency characteristics (gain characteristics). The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 6B, FIG. 7B, and FIG. 8B show the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  In FIG. 6A and FIG. 6B, characteristic curves GA11 and PH11 represented by chain lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is 4 dB. Characteristic curves GA12 and PH12 represented by broken lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is 2 dB. Characteristic curves GA13 and PH13 represented by dotted lines show frequency characteristics when the Q value at the primary resonance frequency of the nominal model is 0 dB.

  In FIGS. 7A and 7B, characteristic curves GA14 and PH14 represented by chain lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −2 dB. Characteristic curves GA15 and PH15 represented by broken lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −4 dB. Characteristic curves GA16 and PH16 represented by dotted lines show frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −6 dB.

  In FIGS. 8A and 8B, characteristic curves GA17 and PH17 represented by chain lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −8 dB. Characteristic curves GA18 and PH18 represented by broken lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −10 dB. Characteristic curves GA19 and PH19 represented by dotted lines indicate frequency characteristics when the Q value at the primary resonance frequency of the nominal model is −12 dB.

As shown in FIGS. 6A to 8B, when the Q value at the primary resonance frequency of the nominal model changes, the gain characteristics and phase characteristics around the primary resonance frequency f _{0m of the} nominal model change. The smaller the Q value, the smaller the gain in the vicinity of the primary resonance frequency f _{0 m} , and the phase gradually changes from 0 deg to -180 deg.

FIGS. 9A to 11B are diagrams showing the step response of the actuator 30 when the Q value at the primary resonance frequency of the nominal model in the first embodiment is changed. However, the DC sensitivity DCS _m of the nominal model is set to 5.3333e-5, and the temperature is set to 20 ° C. In FIG. 9A to FIG. 11B, the horizontal axis represents the elapsed time [sec] from a certain reference time.

9 (a), 10 (a), and 11 (a), the position target signal ref_p of the actuator 30 is changed from 0 [m] to 1e-4 [m] ("e- “4” represents “× 10 ⁻⁴ ” (the same applies hereinafter), and the change in the position target signal ref_p is shown.
9B, FIG. 10B, and FIG. 11B show the position target signal ref_p of the actuator 30 in FIG. 9A, FIG. 10A, and FIG. The step response of the position detection signal act_p when changed as shown in FIG.

  In FIG. 9A and FIG. 9B, characteristic curves RE21 and A21 represented by chain lines indicate step responses when the Q value at the primary resonance frequency of the nominal model is 4 dB. Characteristic curves RE22 and A22 represented by broken lines show step responses when the Q value at the primary resonance frequency of the nominal model is 2 dB. Characteristic curves RE23 and A23 represented by dotted lines show step responses when the Q value at the primary resonance frequency of the nominal model is 0 dB.

  10 (a) and 10 (b), characteristic curves RE24 and A24 represented by chain lines indicate step responses when the Q value at the primary resonance frequency of the nominal model is −2 dB. Characteristic curves RE25 and A25 represented by broken lines show step responses when the Q value at the primary resonance frequency of the nominal model is −4 dB. Characteristic curves RE26 and A26 represented by dotted lines show step responses when the Q value at the primary resonance frequency of the nominal model is −6 dB.

  In FIG. 11A and FIG. 11B, characteristic curves RE27 and A27 represented by chain lines indicate step responses when the Q value at the primary resonance frequency of the nominal model is −8 dB. Characteristic curves RE28 and A28 represented by broken lines show step responses when the Q value at the primary resonance frequency of the nominal model is −10 dB. Characteristic curves RE29 and A29 represented by dotted lines show step responses when the Q value at the primary resonance frequency of the nominal model is −12 dB.

  As shown in FIGS. 9A to 11B, when the Q value at the primary resonance frequency of the nominal model changes, the overshoot amount in the step response changes and the response changes. As the Q value increases, the response speed increases but the overshoot increases. The smaller the Q value, the smaller the overshoot, but the response speed becomes lower.

  FIG. 12 is a diagram showing the relationship between the Q value at the primary resonance frequency of the nominal model in the first embodiment and the target value convergence time in the step response of the actuator. The horizontal axis represents the Q value [dB] at the primary resonance frequency of the nominal model, and the vertical axis represents the target value convergence time [sec]. Here, the target value convergence time is the time from the start of the step response until the actuator settles at the target position.

  FIG. 12 shows that the target value convergence time is short when the Q value at the primary resonance frequency of the nominal model is between −6 dB and 0 dB. Therefore, the Q value at the primary resonance frequency of the nominal model is set to -6 dB or more and 0 dB or less. When the Q value is set to -6 dB or more and 0 dB or less, the target value convergence time can be suppressed between 0.00481 [sec] and 0.0052 [sec]. The ratio of the error range (variation range) to the minimum value of the target value convergence time 0.00481 [sec] is {(0.0052−0.00481) /0.00481} × 100 = 8.1%, It can be said that it is within about 10%.

  Next, the design of the DC sensitivity of the nominal model will be described with reference to FIGS.

  FIGS. 13A and 13B are diagrams showing frequency characteristics of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20 when the DC sensitivity of the nominal model in the first embodiment is changed. It is. However, the Q value at the primary resonance frequency of the nominal model is set to -4 dB. The temperature is set to 20 ° C.

  FIG. 13A shows the frequency characteristic (gain characteristic) of the gain. The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 13B shows the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  In FIGS. 13A and 13B, characteristic curves GA31 and PH31 represented by chain lines indicate frequency characteristics when the DC sensitivity of the nominal model is 8.00e-5 [m / V]. Characteristic curves GA32 and PH32 represented by broken lines indicate frequency characteristics when the DC sensitivity of the nominal model is 3.20e-5 [m / V]. Characteristic curves GA33 and PH33 represented by dotted lines show frequency characteristics when the DC sensitivity of the nominal model is 2.00e-5 [m / V].

  As shown in FIGS. 13A and 13B, when the DC sensitivity of the nominal model changes, the gain characteristic and the phase characteristic change. As the DC sensitivity decreases, the gain decreases and the phase changes more rapidly from 0 deg to -180 deg.

  FIG. 14A and FIG. 14B are diagrams showing the step response of the actuator 30 when the DC sensitivity of the nominal model in the first embodiment is changed. However, the Q value at the primary resonance frequency of the nominal model is set to -4 dB. The temperature is set to 20 ° C. In FIG. 14A and FIG. 14B, the horizontal axis represents the elapsed time [sec] from a certain reference time point.

  FIG. 14A shows a change in the position target signal ref_p when the position target signal ref_p of the actuator 30 is changed from 0 [m] to 1e-4 [m] after 0.002 seconds have elapsed. FIG. 14B shows a step response of the position detection signal act_p when the position target signal ref_p of the actuator 30 is changed as shown in FIG. 14A.

  In FIG. 14A and FIG. 14B, characteristic curves RE41 and A41 represented by chain lines indicate step responses when the DC sensitivity of the nominal model is 8.00e-5 [m / V]. Characteristic curves RE42 and A42 represented by broken lines show step responses when the DC sensitivity of the nominal model is 3.20e-5 [m / V]. Characteristic curves RE43 and A43 represented by dotted lines indicate step responses when the DC sensitivity of the nominal model is 2.00e-5 [m / V].

  As shown in FIGS. 14A and 14B, when the DC sensitivity of the nominal model changes, the response speed to the target position changes. As the DC sensitivity decreases, the response speed increases and the target value is reached quickly.

  FIG. 15 is a diagram showing a relationship between the DC sensitivity of the nominal model in Embodiment 1 and the target value convergence time in the step response of the actuator. The horizontal axis represents the DC sensitivity of the nominal model, and the vertical axis represents the target value convergence time [sec]. Here, the target value convergence time is the time from the start of the step response until the actuator settles at the target position.

FIG. 15 shows that the target value convergence time is shorter as the DC sensitivity of the nominal model is smaller. When the direct current sensitivity decreases, it is necessary to increase the voltage signal Edr for moving to the target position. If the value after the change of the position target signal is ref_p_e and the maximum value of the voltage that can be applied to the actuator 30 is V_max, the DC sensitivity of the nominal model is
ref_p_e / V_max
Must be set above. If V_max = 5V and ref_p_e = 1e-4 [m] as shown in FIG. 14, the DC sensitivity of the nominal model must be set to 2e-5 [m / V] or more.

Under the constraint that the applied voltage is not more than the maximum value V_max and the target value convergence time is within the range from the minimum value to 1.1 times the value, the DC sensitivity of the nominal model is
ref_p_e / V_max
The best responsiveness can be obtained by setting the value given by. In the case of FIG. 15, since the minimum value of the target value convergence time is 0.002069 [sec], the target value convergence time is set to 0.0023 [sec] (= 0.002069 × 1.1).
Should be within. The direct current sensitivity of the nominal model at this time is 2.5e-5 [m / V]. This is 1.25 times the lower limit of 2e-5 [m / V].
Therefore, the DC sensitivity of the nominal model is
ref_p_e / V_max
Or a value slightly larger than this, for example,
ref_p_e / V_max
It is desirable to design so as to be a value within a range from the value given by 1.25 to a value 1.25 times that value. However, if the target value convergence time in FIG. 15 is within the allowable range, the DC sensitivity of the nominal model is not necessarily set within the above range.
Here, the maximum value V_max of the voltage that can be applied is, for example, the maximum rated value described in the specifications of the actuator 30.

  FIGS. 16A and 16B are diagrams showing step responses of the actuator 30 in the conventional example. In FIG. 16A and FIG. 16B, the horizontal axis represents an elapsed time [sec] from a certain reference time point.

  FIG. 16A shows a change in the position target signal ref_p when the position target signal ref_p of the actuator 30 is changed from 0 [m] to 1e-4 [m] after 0.002 seconds have elapsed. FIG. 16B shows a step response of the position detection signal act_p when the position target signal ref_p of the actuator 30 is changed as shown in FIG.

  In FIG. 16 (a) and FIG. 16 (b), characteristic curves RE51 and A51 indicated by chain lines indicate step responses when the temperature of the actuator 30 is −30 ° C. Characteristic curves RE52 and A52 represented by broken lines indicate step responses when the temperature of the actuator 30 is + 20 ° C. Characteristic curves RE53 and A53 represented by dotted lines show step responses when the temperature of the actuator 30 is + 85 ° C.

  As shown in FIGS. 16A and 16B, it can be seen that the overshoot amount is large in the step response of the actuator 30 in the conventional example.

  FIGS. 17A and 17B are diagrams showing the step response of the actuator 30 according to the first embodiment. In FIG. 17A and FIG. 17B, the horizontal axis represents the elapsed time [sec] from a certain reference time point.

  FIG. 17A shows a change in the position target signal ref_p when the position target signal ref_p of the actuator 30 is changed from 0 [m] to 1e-4 [m] after 0.002 seconds have elapsed. FIG. 17 (b) shows the step response of the position detection signal act_p when the position target signal ref_p of the actuator 30 is changed as shown in FIG. 17 (a).

  In FIG. 17 (a) and FIG. 17 (b), characteristic curves RE61 and A61 represented by chain lines indicate step responses when the temperature of the actuator 30 is −30 ° C. Characteristic curves RE62 and A62 represented by broken lines show step responses when the temperature of the actuator 30 is + 20 ° C. Characteristic curves RE63 and A63 represented by dotted lines show step responses when the temperature of the actuator 30 is + 85 ° C.

  As shown in FIGS. 17A and 17B, it can be seen that the step response of the actuator 30 according to the first embodiment has no overshoot and a good response.

  Conventionally, the characteristic of the nominal model is the same as that when the temperature of the actuator 30 is + 20 ° C. This is because + 20 ° C. is the design center in the position control of the actuator 30. In this case, the Q value at the primary resonance frequency of the nominal model is greater than 0 dB. For this reason, feedback control is required as position control. This causes a trade-off problem between stability and responsiveness in control. On the other hand, in the first embodiment, it is necessary to increase the voltage applied to the actuator 30. However, by setting the Q value at the primary resonance frequency of the nominal model to 0 dB or less, the position can be properly adjusted without performing feedback control. Control can be performed.

  As described above, according to the position control apparatus 1 according to the first embodiment, the Q value at the primary resonance frequency of the nominal model is set to 0 dB or less, and the DC sensitivity of the nominal model is reduced, thereby reducing the actuator The trade-off between stability and responsiveness in 30 position control can be solved, and the step response can be improved.

Embodiment 2. FIG.
In the first embodiment, the position control of the movable part of the actuator 30 has been described on the assumption that the actuator 30 is an objective lens actuator in an optical pickup. In the second embodiment, position control in the case where the actuator 30 is a drive mechanism for a directivity control mirror will be described. The directivity control mirror corrects, for example, the occurrence of directional axis deviation or observation image blur due to vibration of an optical observation device mounted on a high-precision optical observation satellite, and is installed inside the optical observation device. Is.
The position control device according to the second embodiment controls the position in the rotational direction (angular position), but is simply referred to as a position for simplicity. Similarly, the angular velocity and angular acceleration are referred to as velocity and angular velocity for simplicity.

  FIG. 18 is a block diagram schematically showing the configuration of the position control device 1b according to the second embodiment of the present invention. The position control device 1b of FIG. 18 is generally the same as the position control device 1 of FIG. 1, but instead of the DC sensitivity division unit 14 and disturbance compensation unit 20 of FIG. 1, the DC sensitivity division unit 14b and disturbance compensation unit 20b. Is provided.

  FIG. 19 is a block diagram schematically showing the configuration of the disturbance compensator 20b in the second embodiment. The disturbance compensator 20b in FIG. 19 is generally the same as the disturbance compensator 20 in FIG. 2, but a nominal model divider 22b is provided instead of the nominal model divider 22 in FIG.

The actuator 30b in the second embodiment can be grasped as having the configuration shown in the block diagram of FIG. 20 by paying attention to the transfer function.
FIG. 20 assumes a case where the actuator 30b is a drive mechanism for a directivity control mirror. FIG. 20 further assumes a case where the actuator 30b includes an electromagnetic drive mechanism and drives a movable part including a directivity control mirror by causing a current to flow through the coil.

  20, the same reference numerals as those in FIG. 3 denote the same components. The actuator 30b shown in FIG. 20 is generally the same as the actuator 30 of FIG. 3, but the current force converter 303, the movable part mass divider 305, the movable part viscosity coefficient multiplier 310, and the movable part elastic coefficient multiplier of FIG. Instead of the unit 311, a current torque conversion unit 323, an inertia moment division unit 325, a bearing viscosity coefficient multiplication unit 330, and a bearing elastic coefficient multiplication unit 331 are provided.

The current torque converter 323 receives the current signal Idro1 from the voltage / current converter 302. The current torque converter 323 outputs a torque signal τdro1 based on the current signal Idro1. The transfer function of the current torque converter 323 is a torque constant _Kτ .

  The inertia moment division unit 325 receives the torque signal τdro3 from the subtraction unit 304. The inertia moment division unit 325 divides the torque signal τdro3 by the inertia moment J to generate and output an angular acceleration signal Aro3. The transfer function of the inertia moment dividing unit 325 is 1 / J when expressed using the inertia moment J.

The bearing viscosity coefficient multiplier 330 receives the speed signal Vdro4 from the acceleration speed converter 307. Bearing viscosity coefficient multiplication unit 330 generates and outputs a torque signal τdro4 by multiplying the viscosity coefficient _{c 2} on the speed signal Vdro4. The transfer function of the bearing viscosity coefficient multiplying unit 330 is a viscosity coefficient c _2. The “bearing” here is a bearing that rotatably supports the directivity control mirror.

The bearing elastic coefficient multiplier 331 receives the actuator position detection signal act_p from the speed position converter 309. Bearing elastic coefficient multiplication unit 331 generates and outputs a torque signal τdro5 by multiplying the elastic coefficient _{k 2} in the actuator position detection signal Act_p. The transfer function of the bearing elastic coefficient multiplication unit 331 is an elastic coefficient k _2.

The DC sensitivity divider 14b receives the position target signal ref_p from the position target signal generator 10, receives the change width signal ref_p_s from the change width signal generator 12, and generates and outputs the voltage signal Edr based on these. DC sensitivity divider 14 defines a DC sensitivity DCS _m nominal model based on the change width signal Ref_p_s, in the DC sensitivity DCS _m, and generates a voltage signal Edr by dividing the target position signal REF_P. The transfer function of the DC sensitivity dividing unit 14b is 1 / DCS _{m when} expressed using the DC sensitivity DCS _m of the nominal model.

The nominal model division unit 22b receives the position detection signal act_p from the actuator 30b. The nominal model division unit 22b generates and outputs a voltage signal Edr1 by dividing the position detection signal act_p by the transfer function P _n (s) of the nominal model.

The nominal model division unit 22 b includes a transfer function generation unit 23 b and a division unit 24.
The transfer function generation unit 23b generates a transfer function P _n (s) of a model that simulates the transfer function of the actuator 30b. The division unit 24 divides the position detection signal act_p by the transfer function P _n (s) generated by the transfer function generation unit 23b.

The nominal model used for generating the transfer function in the transfer function generating unit 23b has generally the same configuration as the actuator 30b shown in FIG. However, the nominal model is different from that in FIG. 20 in that the acceleration disturbance g is not input, the adder 306 is not provided, and the output Adro3 of the inertia moment divider 325 is input to the acceleration speed converter 307 as it is. In the actuator 30b, the viscosity coefficient c ₂ multiplied by the bearing viscosity coefficient multiplier 330, the elastic coefficient k ₂ multiplied by the bearing elastic coefficient multiplier 331, the resistance R and inductance L in the voltage / current converter 302, and the current torque converter. The constant K _τ in H.323 and the constant K _e in the speed counter electromotive force conversion unit 308 are affected by temperature, but in the nominal model, they are assumed to be constant regardless of the temperature. Furthermore, viscosity coefficient c ₂ and elastic coefficient k ₂ can be altered, Q value is adjustable in the DC sensitivity and the primary resonance frequency of the nominal model by changing them.

Specifically, the change width signal ref_p_s output from the change width signal generation unit 12 is supplied to the transfer function generation unit 23b so that the Q value at the primary resonance frequency of the nominal model is 0 dB or less and this change In accordance with the width signal ref_p_s, the parameters of the nominal model are adjusted so that the DC sensitivity DCS _m of the nominal model becomes sufficiently small. More specifically, the change width represented by the change width signal ref_p_s is represented by a symbol ref_p_e so that the Q value at the primary resonance frequency of the nominal model is in the range of −6 dB to 0 dB, and the actuator 30b When the maximum value of the voltage that can be applied to V.sub._max is V.sub._max, the DC sensitivity DCS _m of the nominal model is a value given by ref_p_e / V_max or a value slightly larger than this, for example, a value given by ref_p_e / V_max. It is desirable to adjust the parameters of the nominal model so that the value is within the range up to 25 times.
Adjustment of the parameters of the nominal model can be performed, for example, by changing the viscosity coefficient c ₂ and the elastic coefficient k ₂ used in the transfer function generation unit 23b.

  FIGS. 21A and 21B are diagrams illustrating frequency characteristics of the position detection signal act_p with respect to the voltage signal Edro of the actuator 30b in the second embodiment. FIG. 21A shows a frequency characteristic (gain characteristic) of gain. The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 21B shows the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  As shown in FIGS. 21A and 21B, the frequency characteristic of the actuator 30b is similar to the frequency characteristic of the actuator 30 in the first embodiment, and the Q value at the primary resonance frequency is greater than 0 dB. Yes.

  FIGS. 22A and 22B are diagrams illustrating frequency characteristics of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20b in the second embodiment. FIG. 22A shows the frequency characteristic (gain characteristic) of the gain. The horizontal axis represents frequency [Hz] and the vertical axis represents gain [dB]. FIG. 22B shows the frequency characteristics (phase characteristics) of the phase. The horizontal axis is frequency [Hz] and the vertical axis is phase [deg].

  In FIGS. 22A and 22B, characteristic curves GA71 and PH71 represented by dotted lines indicate the frequency characteristics of the actuator 30b. Characteristic curves GA72 and PH72 represented by solid lines indicate the frequency characteristics of the nominal model. The Q value at the primary resonance frequency of the nominal model is set to −4 dB.

  As shown in FIGS. 22A and 22B, by providing the disturbance compensation unit 20b, the frequency characteristics of the position detection signal act_p with respect to the input voltage signal Edr to the disturbance compensation unit 20b, that is, the disturbance compensation unit. The overall characteristics of 20b and actuator 30b can be made equivalent to those of the nominal model.

  FIG. 23A and FIG. 23B are diagrams showing step responses of the actuator 30b in the second embodiment. In FIG. 23 (a) and FIG. 23 (b), the horizontal axis represents the elapsed time [sec] from a certain reference time.

  FIG. 23A shows a change in the position target signal ref_p when the position target signal ref_p of the actuator 30b is changed from 0 [rad] to 1e-4 [rad] after 0.2 seconds have elapsed. FIG. 23B shows the step response of the position detection signal act_p when the position target signal ref_p of the actuator 30b is changed as shown in FIG.

  As shown in FIG. 23A and FIG. 23B, it can be seen that the step response of the actuator 30b in the second embodiment has no overshoot and a good response.

  As described above, according to the position control device 1b according to the second embodiment, the step response can be improved with the same configuration as the position control device 1 according to the first embodiment. That is, the same effect as in the first embodiment can be obtained by designing the nominal model similar to that in the first embodiment.

  A part or all of the processing performed by part or all of the configuration of the position control circuit described above, or part or all of the processing performed by the position control method described above can be executed by a computer including a processor. Therefore, a program for causing a computer to execute part or all of the configuration of the position control device described above, a part or all of the processing performed by the position control method, and a computer recording the program A readable recording medium also forms part of the present invention.

An example of the computer is shown in FIG. The computer shown in FIG. 24 includes a processor 51, a program memory 52, a data memory 53, an input interface 54, and an output interface 55, which are connected by a data bus 56.
The processor 51 operates in accordance with a program stored in the program memory 52, and processes each part of the position control device of the first or second embodiment on the position detection signal act_p input via the input interface 54. The voltage signal Edro obtained as a result of the processing is output from the output interface 55.

The contents of the processing by the processor 51 are the same as those described in the first and second embodiments. Data generated in the course of processing is held in the data memory 53. The data memory 53 is also used to store data necessary for processing, for example, a transfer function P _n (s).
The voltage signal Edro output from the output interface 55 is supplied to the actuator 30.

  In addition, a plurality of computers shown in FIG. 24 may be provided, and each unit may perform processing of each part of the position control device. The same applies to the case where the computer executes part or all of the processing of the position control method.

Modified example.
The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist of the present invention.

  For example, in the above-described embodiment, the case where the actuator is an objective lens actuator in an optical pickup and the case where the actuator is a driving mechanism for a directivity control mirror are exemplified. However, the present invention is not limited to this, and can be applied to actuators other than the above as long as the actuator includes an elastic support mechanism.

DESCRIPTION OF SYMBOLS 1 Position control apparatus, 10 Position target signal generation part, 14, 14b DC sensitivity division part, 20, 20b Disturbance compensation part, 21 Adder part, 30, 30b Actuator, 22, 22b Nominal model division part, 23, 23b Transfer function generation Part, 24 division part, 25 subtraction part, 26 LPF part, 16 disturbance source, 301 subtraction part, 302 voltage current conversion part, 303 current force conversion part, 304 subtraction part, 305 movable part mass division part, 306 addition part, 307 Acceleration speed conversion section, 308 Speed counter electromotive force conversion section, 309 Speed position conversion section, 310 Movable section viscosity coefficient multiplication section, 311 Movable section elastic coefficient multiplication section, 312 Addition section, 323 Current torque conversion section, 325 Inertia moment division section 330 bearing viscosity coefficient multiplication unit, 331 bearing elastic coefficient multiplication unit, ref_p position target signal, E dr voltage signal, g acceleration disturbance, act_p position detection signal, Edr voltage signal, Edr1 voltage signal, Edr2 voltage signal, Edr3 voltage signal, Edro1 voltage signal, Idro1 current signal, Fdro1 force signal, Fdro2 force signal, Fdro3 force signal, Fdro3 force signal Force signal, Fdro5 force signal, Adro3 acceleration signal, Adro4 acceleration signal, Vdro4 speed signal, Edro4 voltage signal, τdro1 torque signal, τdro2 torque signal, τdro3 torque signal, τdro4 torque signal, τdro5 torque signal, DCS _m coil sensitivity, DCS _m coil sensitivity Resistance, L coil inductance, K _t force constant, m ₁ movable part mass, Ke counter electromotive force constant, c ₁ movable part viscosity coefficient, k ₁ movable part elastic modulus, K _τ torque constant, J moment of inertia, c _Two- bearing viscosity coefficient, k _Two- bearing elastic coefficient, O (s) Total transfer function of disturbance compensator and actuator, P (s) Actuator transfer function, P _n (s) Nominal model transfer function, F _c (s) LPF transfer function.

Claims (10)

A position control device for controlling the position of a movable part of an actuator having an elastic support mechanism,
A position target signal generator for outputting a position target signal indicating the target position of the movable part in the position control of the movable part;
A DC sensitivity division unit that divides the position target signal by the DC sensitivity of a nominal model that simulates the transfer characteristics of the actuator;
A position control device comprising: a disturbance compensator that compensates for a variation in characteristics of the actuator and a disturbance acting on the actuator, using the output of the DC sensitivity divider as an input. The position controller according to claim 1, wherein the disturbance compensation unit includes a nominal model division unit that divides the position detection value of the movable unit by a transfer function of a nominal model.   The position control device according to claim 2, wherein a Q value at a primary resonance frequency of the nominal model is set to a value within a range of -6 dB to 0 dB. When the desired moving amount of the movable part of the actuator is ref_p_e and the maximum value of the voltage that can be applied to the actuator is V_max, the DC sensitivity of the nominal model is 1.25 times the value given by ref_p_e / V_max. Set to a value within the range up to
The direct current sensitivity division unit performs the division using the direct current sensitivity,
The position control device according to claim 2, wherein the nominal model division unit performs the division using a nominal model having DC sensitivity. A position control method for controlling the position of a movable part of an actuator provided with an elastic support mechanism,
Generating a position target signal indicating a target position of the movable part in the position control of the movable part;
The position target signal is divided by the DC sensitivity of a nominal model that simulates the transfer characteristics of the actuator,
A position control method comprising: compensating for a variation in the characteristics of the actuator and a disturbance acting on the actuator based on a result of division by the DC sensitivity.   6. The position control method according to claim 5, wherein the compensation of the disturbance includes dividing a position detection value of the movable part by a transfer function of a nominal model.   The position control method according to claim 6, wherein a Q value at a primary resonance frequency of the nominal model is set to a value within a range of −6 dB to 0 dB. When the desired moving amount of the movable part of the actuator is ref_p_e and the maximum value of the voltage that can be applied to the actuator is V_max, the DC sensitivity of the nominal model is 1.25 times the value given by ref_p_e / V_max. Set to a value within the range up to
Division by the DC sensitivity is performed using the DC sensitivity,
The position control method according to claim 6 or 7, wherein division by the nominal model is performed using a nominal model having the DC sensitivity.   The program for making a computer perform the process in the position control method of any one of Claim 5 to 8.   A computer-readable recording medium on which the program according to claim 9 is recorded.

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