JP6214480B2 - Frequency response measuring device - Google Patents

Description

  The present invention relates to a frequency response measuring apparatus for measuring a frequency response in an industrial machine.

  In an industrial machine, a frequency response of a mechanical system is measured in order to diagnose a mechanical system state or grasp a vibration characteristic. Further, when adjusting the servo system, the frequency response of a control loop such as a speed loop and a position loop is also measured. The frequency response is the ratio of the amplitude and the phase of the input signal and the output signal with respect to the output signal when an input signal of a specific frequency is given. The frequency and amplitude ratio (gain) and the frequency and phase Expressed in relationships.

  Conventionally, when measuring the frequency response, a sinusoidal input signal was given, and the frequency of the input sine wave was sequentially changed to measure the gain and phase for each frequency. However, the frequency of the input signal was gradually changed. Thus, there is a problem that it takes a long time to measure the frequency response.

  In order to solve such a problem, the conventional technique represented by Patent Document 1 below is obtained by sampling the white noise as an input signal, sampling the speed when the white noise as a speed command is given, and sampling. It is disclosed that a frequency response characteristic from a speed command to a speed is obtained by performing a Fourier transform between the speed data and the speed command. Since ideal white noise is a signal including all frequency components, it is possible to measure frequency responses in all frequency regions in a short measurement time. For the white noise, a pseudo-random signal called an M-sequence signal is used.

JP 2000-278990 A

  In Patent Document 1, a response waveform of a mechanical system, for example, speed feedback data, is measured when white noise including all frequency components is applied to vibrate the mechanical system. However, when there is friction as a disturbance factor in the mechanical system, there is a problem that even if white noise is applied, the mechanical system is not vibrated and the frequency response cannot be obtained correctly. In particular, the response in the low frequency region deteriorates due to the influence of mechanical friction, and the frequency response in the low frequency region cannot be obtained correctly.

  Specifically, when measuring the frequency response from torque to speed feedback, if the mechanical system can be approximated by a rigid system, the frequency response in the low frequency region is linear with a gain diagram of −20 dB / dec. And the phase diagram should be constant at -90 °. On the other hand, when the low frequency region is not vibrated due to the influence of friction, the output is considered not to respond to the input, so the gain becomes smaller than the original value in that region, and the phase Becomes a value close to 0 °.

  If the frequency response measurement result cannot be obtained correctly as described above, a large estimation error occurs when the mechanical system inertia is estimated by reading the gain value in the low frequency region. Further, when reading the gain curve peak or phase curve change to estimate the resonance frequency or damping ratio of the mechanical system, an incorrect value is estimated. Furthermore, when measuring the frequency response to adjust the control system, if the gain in the low frequency region is smaller than the original value, the bandwidth of the control system cannot be determined correctly, and the control system There arises a problem that the gain tuning cannot be properly adjusted.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a frequency response measuring apparatus capable of accurately obtaining a frequency response over a wide frequency range even when subjected to a disturbance.

In order to solve the above-described problems and achieve the object, the present invention provides a frequency response measuring apparatus for measuring a frequency response of a servo system that performs feedback control of a mechanical system, and excites a reference period of a plurality of different pseudo-random signals. From the excitation cycle setting unit that is set as a cycle, the excitation execution unit that vibrates the servo system a plurality of times with the excitation signal of the different excitation cycle, and the servo system that has been subjected to the plurality of excitations, A set of an identification input signal and an identification output signal is acquired for each of the plurality of excitations, the excitation cycle for each of the plurality of excitations, the identification input signal and the identification for each of the plurality of excitations A frequency response calculation unit that calculates the frequency response based on a set of output signals, and a frequency response synthesis unit that calculates a frequency response of the servo system by synthesizing a frequency response for each of the plurality of excitation periods And comprising And wherein the door.

  According to the present invention, by calculating the frequency response using a plurality of different excitation periods, there is an effect that the frequency response can be accurately obtained over a wide frequency range even if a disturbance is received.

FIG. 1 is a configuration diagram of a frequency response measuring apparatus according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram of a servo system to which the frequency response measuring apparatus according to the first embodiment of the present invention is applied. FIG. 3 is a configuration diagram of a mechanical system that is a measurement target of the frequency response measuring apparatus according to the first embodiment of the present invention. FIG. 4 is a configuration diagram of a frequency response measuring apparatus according to Embodiment 2 of the present invention. FIG. 5 is a configuration diagram of a mechanical system that is a measurement target of the frequency response measuring apparatus according to the third embodiment of the present invention.

  Hereinafter, embodiments of a frequency response measuring apparatus according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a frequency response measuring apparatus 100 according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram of a servo system 3 to which the frequency response measuring apparatus 100 according to Embodiment 1 of the present invention is applied. 3 is a configuration diagram of a mechanical system 35 that is a measurement target of the frequency response measuring apparatus 100 according to the first embodiment of the present invention.

  A frequency response measuring device 100 shown in FIG. 1 is a device that measures the frequency response of the servo system 3, and includes an excitation period setting unit 1, an excitation execution unit 2, a frequency response calculation unit 4, and a frequency response synthesis unit 5. Is provided.

  The excitation cycle setting unit 1 sets the excitation cycle T of the excitation signal Vin in the excitation execution unit 2. The excitation execution unit 2 outputs an excitation signal Vin corresponding to the excitation cycle T set by the excitation cycle setting unit 1.

  The vibration signal Vin output from the vibration execution unit 2 is input to the servo system 3, and the vibration is executed in the servo system 3 having a configuration described later. An identification input signal 3 a and an identification output signal 3 b inside the servo system 3 at the time of vibration are sent to the frequency response calculation unit 4.

  The frequency response calculation unit 4 calculates a frequency response between the identification input signal 3a and the identification output signal 3b. Specifically, in the frequency response calculation unit 4, the frequency response of each time is calculated by the identification input signal 3 a and the identification output signal 3 b that are input every time the vibration is performed a plurality of times. The calculated frequency response of each time is input to the frequency response synthesis unit 5.

  Each frequency response calculated by the frequency response calculation unit 4 and the excitation cycle T from the excitation cycle setting unit 1 are input to the frequency response synthesis unit 5. The frequency response synthesizer 5 synthesizes the frequency response corresponding to each excitation period T and outputs the synthesized frequency response.

  The servo system 3 shown in FIG. 2 includes a subtraction unit 31, a position control unit 32, an addition / subtraction unit 33, a speed control unit 34, and a mechanical system 35. The mechanical system 35 is mainly composed of a servo motor 36 and a load 37, and a load 37 is connected to the servo motor 36. Details of the mechanical system 35 will be described later. The addition / subtraction unit 33, the speed control unit 34, and the servo motor 36 constitute a speed control loop, and the subtraction unit 31, the position control unit 32, the addition / subtraction unit 33, the speed control unit 34, and the servo motor 36 constitute a position control loop.

  The position command 6 is commanded by a numerical control device (not shown), and is normally updated every moment according to a G code (EIA code) specified by the NC program. However, it is assumed that a position command 6 having a constant value is given when the excitation is performed by giving the excitation signal Vin.

  In the subtraction unit 31, a deviation 31 a between the position command 6 and the motor position θ is calculated, and the deviation 31 a is input to the position control unit 32. In the addition / subtraction unit 33, the speed deviation e is calculated by subtracting the motor speed v from the sum of the output signal 32a of the position control unit 32 and the vibration signal Vin.

  The speed deviation e is input to the speed control unit 34, the torque command τ is calculated by the speed control unit 34, and the servo motor 36 is driven and controlled according to the torque command τ. In practice, the torque control unit and the power conversion unit exist inside the speed control loop, but the response is very fast and the response delay is negligible, so the description is omitted in FIG. Proportional control is used for position control of the position control unit 32, and proportional-integral control is used for speed control of the speed control unit 34.

  FIG. 3 shows a configuration example of the mechanical system 35. A load 37 that is a load inertia is connected to a servo motor 36 that receives a torque command τ and generates rotational torque via a shaft 39. Further, a rotary encoder 38 as a position detector is attached to the servo motor 36. The rotary encoder 38 detects the rotation angle that is the position of the servo motor 36, and differentially calculates the rotation angle, thereby obtaining a motor speed. Get v.

  Next, the frequency response measurement operation in frequency response measurement apparatus 100 according to Embodiment 1 will be described. The excitation cycle setting unit 1 sets two types of excitation cycles T1 and T2. In Embodiment 1, it is assumed that the excitation cycle T2 is longer than the excitation cycle T1. Specifically, the excitation period T1 is the same as the sampling period of the servo control system, and the excitation period T2 is about several times the excitation period T1, for example, 4 to 8 times.

  The vibration execution unit 2 generates a first vibration signal Vin1 corresponding to the vibration period T1 and a second vibration signal Vin2 corresponding to the vibration period T2. The excitation signal Vin is generated by generating a binary signal of −1 and +1 corresponding to the number of points set according to the generation algorithm of the M-sequence signal, which is a pseudo-random signal, and then multiplying the binary signal by the excitation amplitude. It has been done.

  At this time, the M-sequence signal becomes a discretely changing signal, and the timing of the change, that is, the time interval from when the binary signal changes from one value to the other value until the next change is set. It is an integral multiple of the reference period. The reference period is the excitation period T1 for the first excitation signal Vin1, and the excitation period T2 for the second excitation signal Vin2. Since the vibration period T2 is longer than the vibration period T1, the second vibration signal Vin2 changes less frequently than the first vibration signal Vin1. Note that a method for generating an M-sequence signal is known in the field of signal processing, and thus description thereof is omitted here.

  In the servo system 3, first, the first vibration signal Vin1 is applied as the vibration signal Vin, and the first vibration is performed. At the time of vibration, the position command 6 is a constant value. That is, the mechanical system 35 is vibrated by the vibration signal Vin. In the first embodiment, the frequency response of the mechanical system 35, that is, the frequency response from the torque command τ to the motor speed v is obtained using the frequency response measuring apparatus 100. Therefore, the frequency response calculation unit 4 acquires the first identification input signal 3a that is the torque command τ during vibration and the first identification output signal 3b that is the motor speed v during vibration.

  The frequency response calculation unit 4 calculates a frequency response from the torque command τ to the motor speed v based on the first identification input signal 3a and the first identification output signal 3b. As a method for obtaining a frequency response between input and output from the identification input signal 3a and the identification output signal 3b, a known method such as a periodogram FFT method, ARX model identification, or a subspace method can be used. An example of the details of these methods is described in “System identification for control by MATLAB” (Tokyo Denki Shuppan). Pintelon, J.M. Since it is described in “System Identification” (IEEE Press) by Schukens, description thereof is omitted here. Let the frequency response in the first excitation be G1 (j2πf). f is a frequency and its unit is Hz. The absolute value of G1 (j2πf) becomes the gain, and the declination angle in the complex region of G1 (j2πf) becomes the phase.

  Excitation using the second excitation signal Vin2 is performed in the same manner as the first excitation. Let the frequency response obtained in the second excitation be G2 (j2πf).

  Next, the frequency response calculation procedure in the frequency response synthesis unit 5 will be described. The frequency response synthesizer 5 sets the reciprocal number of the first vibration period T1 to the first vibration frequency F1, and sets the reciprocal number of the second vibration period T2 to the second vibration frequency F2. Since the excitation cycle T2 is longer than the excitation cycle T1, the excitation frequency F2 is lower than the excitation frequency F1. Here, when a frequency lower than 1/2 of the second excitation frequency F2 is defined as the boundary frequency Fb, an example of the boundary frequency Fb is 1/4 of the excitation frequency F2. The frequency response synthesizing unit 5 responds in a frequency region that is equal to or higher than the boundary frequency Fb of the frequency response G1 (j2πf) in the first excitation and a region less than the boundary frequency Fb in the frequency response G2 (j2πf) in the second excitation And the combined frequency response, that is, the frequency response G (j2πf) from the torque command τ to the speed is output. The above composition operation can be expressed by the following equation.

  When excitation is performed with an M-sequence signal that is an example of white noise, a frequency component that is 1/2 or more of the reference frequency is not included in the excitation signal according to the Nyquist theorem. In the frequency region relatively lower than the reference frequency, components in the region are less likely to be included in the excitation signal due to the influence of disturbance such as the S / N ratio of the signal or friction. Therefore, when vibration is performed with a single vibration cycle, it is impossible to correctly obtain the frequency responses in the low frequency region and the high frequency region.

  The frequency response measuring apparatus 100 according to the first embodiment sets a plurality of excitation periods T1, T2, and in the low frequency region, the excitation period T2, which is longer than the excitation period T1, that is, lower than the excitation frequency F1. In the high frequency region, using the frequency response when the vibration is performed at the vibration frequency F2, the vibration period T1 shorter than the vibration period T2, that is, when the vibration is performed at the vibration frequency F1 higher than the vibration frequency F2. Since the frequency response is used, the frequency response can be accurately obtained over a wide frequency range.

  In the first embodiment, the torque command τ as the identification input signal 3a and the motor speed v as the identification output signal 3b are used to acquire the frequency response of the mechanical system 35. These signals may be used. Specifically, when measuring the frequency response of the speed open loop, the speed deviation e may be used for the identification input signal 3a and the motor speed v may be used for the identification output signal 3b. When measuring the frequency response of the speed closed loop, the output signal 32a of the position controller 32 may be used as the identification input signal 3a, and the motor speed v may be used as the identification output signal 3b.

Embodiment 2. FIG.
FIG. 4 is a configuration diagram of the frequency response measuring apparatus 100 according to the second embodiment of the present invention. The difference from the first embodiment is that three types of excitation periods T1, T2, and T3 are set in the excitation period setting unit 1. Hereinafter, the same reference numerals are given to the same parts as those in the first embodiment, and the description thereof is omitted, and only different parts will be described here.

  In the second embodiment, it is assumed that the excitation cycle T2 is longer than the excitation cycle T1, and the excitation cycle T3 is longer than the excitation cycle T2. Specifically, the excitation period T1 is the same as the sampling period of the servo control system, and the excitation period T2 is about several times the excitation period T1, for example, 4 to 8 times. The excitation period T3 is about several times the excitation period T2, for example, 4 to 8 times.

  The vibration execution unit 2 performs the first vibration signal Vin1 corresponding to the vibration period T1, the second vibration signal Vin2 corresponding to the vibration period T2, and the third vibration signal corresponding to the vibration period T3. An oscillation signal Vin3 is generated. The generation method of the excitation signal Vin for each excitation cycle is the same as that in the first embodiment. The vibration executing unit 2 performs vibration in the same manner as in the first embodiment, and the frequency response in the first vibration is G1 (j2πf), and the frequency response obtained in the second vibration is G2 (j2πf). Let the frequency response obtained in the third excitation be G3 (j2πf).

  Next, the frequency response calculation procedure in the frequency response synthesis unit 5 will be described. The reciprocal of the first excitation cycle T1 is the first excitation frequency F1, the reciprocal of the second excitation cycle T2 is the second excitation frequency F2, and the reciprocal of the third excitation cycle T3 is the third addition. The oscillation frequency is F3. Due to the magnitude relationship between T1, T2, and T3, the excitation frequency F3 is lower than the excitation frequency F2, and the excitation frequency F2 is lower than the excitation frequency F1. A frequency lower than ½ of the second excitation frequency F2 is defined as a first boundary frequency Fb1. An example of the first boundary frequency Fb1 is ¼ of the excitation frequency F2. Further, a frequency lower than ½ of the third excitation frequency F3 is set as a second boundary frequency Fb2. An example of the second boundary frequency Fb2 is ¼ of the excitation frequency F3.

  The frequency response synthesizer 5 has a frequency domain response equal to or higher than the first boundary frequency Fb1 in the frequency response G1 (j2πf) in the first excitation and a frequency response G2 (j2πf) in the second excitation. The response in the region of the second boundary frequency Fb2 or more and less than the first boundary frequency Fb1 is synthesized with the response in the region of the frequency response G3 (j2πf) in the third excitation less than the boundary frequency Fb2. The frequency response, that is, the frequency response G (j2πf) from the torque command τ to the speed is output.

  The frequency response measuring apparatus 100 according to the second embodiment sets three types of excitation periods T1, T2, and T3, and in the low frequency region, an excitation period T3 that is longer than the excitation period T2, that is, the excitation frequency In the middle frequency region, using the frequency response when the vibration is performed at a vibration frequency F3 lower than F2, the vibration period T2 is shorter than the vibration period T3 and is longer than the vibration period T1, that is, the vibration frequency F1. In the high frequency region, an excitation cycle T1 that is shorter than the excitation cycle T2, that is, an excitation that is higher than the excitation frequency F2, is used. Since the frequency response when the vibration is applied at the frequency F1 is used, the frequency response can be accurately obtained over a wider frequency range.

Embodiment 3 FIG.
FIG. 5 is a configuration diagram of a mechanical system that is a measurement target of the frequency response measuring apparatus 100 according to the third embodiment of the present invention. The frequency response measuring apparatus 100 of the third embodiment has the same configuration as that of the first embodiment, but the structure of the mechanical system to be measured is different in the third embodiment. FIG. 5 shows an example of the mechanical system. A two-axis machine 40 is shown.

  The biaxial machine 40 includes a first shaft 41 and a second shaft 45 that are movable shafts. The first shaft 41 includes a first shaft motor 42, a first shaft position detector 43, and a first shaft load 44. The first shaft load 44 includes a first shaft 44a and a first table 44b. The first shaft 44a converts the rotational motion of the first shaft motor 42 into linear motion by the first shaft 44a, which is a ball screw. Move straight. The second shaft 45 includes a second shaft motor 46, a second shaft position detector 47, and a second shaft load 48. The second shaft load 48 includes a second shaft 48a and a second table 48b. The second shaft 48a converts the rotational motion of the second shaft motor 46 into linear motion by the second shaft 48a, which is a ball screw, and the second table 48b is linearly converted. Move. Independent servo control is performed on the first axis motor 42 and the second axis motor 46 as in the first embodiment.

  Next, the frequency response measurement operation in the frequency response measurement apparatus 100 according to Embodiment 3 will be described. The excitation cycle setting unit 1 sets two types of excitation cycles T1 and T2. When the first axis 41 is the first axis and the second axis 45 is the second axis, in the servo system 3, the first axis is excited by the excitation cycle T1 and the second axis is rotated by the excitation cycle T2. Excitation is performed at the same time. The frequency response calculation unit 4 simultaneously calculates the frequency response G1x (j2πf) in the first axis excitation period T1 and the frequency response G2y (j2πf) in the second axis excitation period T2.

  Subsequently, in the servo system 3, the first axis excitation with the excitation period T2 and the second axis excitation with the excitation period T1 are performed simultaneously. In the frequency response calculation unit 4, a frequency response G2x (j2πf) in the first axis excitation period T2 and a frequency response G1y (j2πf) in the second axis excitation period T1 are calculated simultaneously.

  The reciprocal of the first excitation cycle T1 is the high-frequency excitation frequency F1, and the reciprocal of the second excitation cycle T2 is the low-frequency excitation frequency F2. A frequency lower than 1/2 of the low-frequency excitation frequency F2 is defined as a boundary frequency Fb. An example of the boundary frequency Fb is 1/4 of F2. For each of the first axis and the second axis, the frequency response synthesizing unit 5 has a response in a frequency region equal to or higher than the boundary frequency Fb of the frequency response in the excitation cycle T1 and less than the boundary frequency Fb of the frequency response in the excitation cycle T2. The response in the region is combined, and the combined frequency response, that is, the frequency response from the torque command τ to the speed is output. When the frequency response from the torque command τ of the first axis to the motor speed v is Gx (j2πf) and the frequency response from the torque command τ of the second axis to the motor speed v is Gy (j2πf), the above composite calculation Can be expressed as:

  When measuring the frequency response of a plurality of axes, if the measurement is performed by exciting one axis at a time, the measurement time becomes long. Therefore, the measurement time can be shortened by simultaneously exciting the plurality of axes. However, in the conventional technique represented by the above-mentioned Patent Document 1, white noise including all frequency components is applied to vibrate the mechanical system. Therefore, when a plurality of axes are simultaneously vibrated, the frequency due to the interference between the axes. There was a problem that the response could not be measured correctly. That is, in a machine having an X-axis and a Y-axis, when white noise is simultaneously applied to the first axis that is the X-axis and the second axis that is the Y-axis, for example, the frequency response of the X-axis The response component resulting from the vibration of the X axis and the response component resulting from the vibration of the Y axis are superimposed, and the frequency response of the single X axis cannot be obtained correctly.

  On the other hand, in the frequency response measuring apparatus 100 according to the third embodiment, when the first axis and the second axis are simultaneously excited, the excitation periods of the first axis and the second axis are changed. Therefore, the frequency response can be measured in a short time while avoiding the influence of interference between the first axis and the second axis. That is, when excitation is performed with an M-sequence signal that is an example of white noise, a frequency component that is 1/2 or more of the reference frequency is not included in the excitation signal according to the Nyquist theorem. In the frequency region relatively lower than the reference frequency, components in the region are less likely to be included in the excitation signal due to the influence of disturbance such as the S / N ratio of the signal or friction. Therefore, when the first axis is vibrated with a long period and the second axis is vibrated with a short period, even if the vibration of the first axis in the low frequency region affects the behavior of the second axis, the first axis is vibrated simultaneously. Since the second axis is an excitation with a short period, the low frequency region component is not included in the excitation result, and the frequency response in the high frequency region of the second axis is not affected by the excitation of the first axis. Can be measured.

  In the third embodiment, a two-axis machine 40, which is an example of a mechanical system, is used. However, the measurement target of the frequency response measuring apparatus 100 according to the third embodiment is limited to a mechanical system having two movable axes. Instead, it may be a mechanical system having three or more movable axes.

  As described above, the frequency response measurement apparatus 100 according to the first to third embodiments includes the excitation cycle setting unit 1 that sets a plurality of different excitation cycles, and the servo system 3 using the excitation signals having different excitation cycles. From the vibration execution unit 2 that vibrates a plurality of times and the servo system 3 that has been subjected to the plurality of times of vibration, a set of the identification input signal 3a and the identification output signal 3b is obtained for each of the plurality of times of vibration. A frequency response calculation unit 4 for calculating a frequency response based on a vibration period for each vibration of the vibration and a set of the identification input signal 3a and the identification output signal 3b for each of the plurality of vibrations, and a plurality of vibrations A frequency response synthesizer 5 that synthesizes the frequency response of each period and calculates the frequency response of the servo system 3; With this configuration, the frequency response measuring apparatus according to Embodiments 1 to 3 cannot be obtained correctly when the vibration is performed with a single excitation cycle, whereas the frequency responses in the low frequency region and the high frequency region cannot be obtained correctly. In 100, since vibration can be performed using an excitation signal having an appropriate excitation period for each frequency range, the frequency response can be obtained with high accuracy over a wide frequency range.

  Further, the frequency response synthesis unit 5 according to the first to third embodiments sets a different frequency range for each of a plurality of excitation cycles based on the excitation frequency that is the reciprocal of the excitation cycle, and performs a plurality of additions. Responses corresponding to different frequency ranges are extracted and synthesized from the frequency responses for each oscillation cycle. With this configuration, all frequency ranges including the low frequency region, medium frequency region, and high frequency region to be measured are divided into a plurality of frequency ranges, and an appropriate excitation period is added to each divided frequency range. Since vibration can be performed using the vibration signal, the frequency response can be obtained with high accuracy over the entire frequency range.

  In addition, the frequency range that is different for each of the plurality of excitation periods set in the frequency response synthesis unit 5 according to the first to third embodiments is a higher frequency range as the excitation frequency that is the reciprocal of the excitation period is higher. . This configuration uses a relatively long excitation period in the low frequency range, that is, a frequency response when excitation is performed at a relatively low excitation frequency, and a short excitation period or high excitation frequency in the high frequency range. Since the frequency response in the case of shaking can be used, the frequency response can be accurately obtained over a wide frequency range.

  In the frequency response measuring apparatus 100 according to the third embodiment, the mechanical system has a plurality of movable shafts, and the vibration execution unit 2 vibrates the plurality of movable shafts simultaneously with different vibration periods. By simultaneously oscillating a plurality of movable axes, the measurement time can be shortened, and the frequency response of each axis can be accurately measured without being affected by the interference between the axes even when simultaneously oscillating.

  As described above, the present invention is useful for a frequency response measuring apparatus that measures a frequency response in order to diagnose the state of an industrial machine.

  1 excitation cycle setting unit, 2 excitation execution unit, 3 servo system, 4 frequency response calculation unit, 5 frequency response synthesis unit, 6 position command, 31 subtraction unit, 32 position control unit, 33 addition / subtraction unit, 34 speed control unit , 35 Mechanical system, 36 Servo motor, 37 Load, 38 Rotary encoder, 39 Shaft, 40 2-axis machine, 41 1st axis, 42 1st axis motor, 43 1st axis position detector, 44 1st axis load, 45 Second axis, 46 Second axis motor, 47 Second axis position detector, 48 Second axis load, 100 Frequency response measuring device.

Claims (4)

In a frequency response measuring device that measures the frequency response of a servo system that performs feedback control of a mechanical system,
An excitation period setting unit that sets a reference period of a plurality of different pseudo-random signals as an excitation period;
A vibration execution unit that vibrates the servo system a plurality of times with vibration signals of the different vibration periods;
From the servo system that has been subjected to the plurality of excitations, a set of identification input signals and identification output signals is obtained for each of the plurality of excitations, and the excitation cycle for each of the plurality of excitations, A frequency response calculation unit for calculating the frequency response based on the set of the identification input signal and the identification output signal for each of a plurality of vibrations;
A frequency response synthesis unit that synthesizes a frequency response for each of the plurality of excitation cycles and calculates a frequency response of the servo system;
A frequency response measuring apparatus comprising:   The frequency response synthesis unit sets a different frequency range for each of the plurality of excitation cycles based on an excitation frequency that is the reciprocal of the excitation cycle, and sets the frequency response for each of the plurality of excitation cycles. The frequency response measuring apparatus according to claim 1, wherein responses corresponding to different frequency ranges are extracted and synthesized from among the plurality of excitation periods.   3. The frequency response measuring apparatus according to claim 2, wherein the frequency range that is different for each of the plurality of excitation periods set in the frequency response synthesis unit is a higher frequency range as the excitation frequency is higher. . The mechanical system has a plurality of movable shafts,
4. The frequency response measuring apparatus according to claim 1, wherein the vibration execution unit vibrates the plurality of movable shafts simultaneously with different vibration periods. 5.

Images