TWI766046B - Vibration system control device and workpiece conveying device - Google Patents

Abstract

Provided is a control device for a vibration system that can stably and efficiently drive devices using vibration such as parts feeders and ultrasonic motors. It is designed to be used when a plurality of vibration systems (1, 2) are driven by a common drive command, and the vibration systems (1, 2) each have a resonance frequency (f1, f2), and the target frequency setting means (31) , set the target frequency (fm) between the resonance frequencies (f1, f2); and the tracking means (32), so that the frequency (fv) of the drive command tracks the target frequency (fm) set by the target frequency setting means (31) ).

Description

Vibration system control device and workpiece conveying device

The present invention relates to a control device and a workpiece conveying device suitable for a vibration system that can drive them stably and efficiently in devices using vibrations such as parts feeders and ultrasonic motors.

Conventionally, devices such as elliptical vibrating parts feeders or ultrasonic motors have a plurality of vibrating systems, and they are driven at a single frequency to perform various functions. Here, the term “plurality of vibrational systems” includes any one of a vibrational system formed by a plurality of structures, a vibrational system having a plurality of vibrational directions, and a plurality of vibrational modes of the same structure.

In such a device, in order to vibrate efficiently, it is often designed and adjusted so as to have a value close to the resonance frequency of the plurality of vibration systems, and is driven at a frequency near their resonance frequency. In addition, there has been proposed a control that adjusts the drive frequency in accordance with the resonance frequency of one vibration system among a plurality of them (for example, refer to Patent Documents 1 and 2).

Patent Document 1 discloses a drive circuit for an ultrasonic motor, which is configured to use a voltage (from a piezoelectric for drive detection) according to a drive state. The driving frequency is controlled so that the phase difference between the voltage obtained from the element) and the voltage applied to the piezoelectric body (the voltage applied to one of the two electrodes) becomes a preset phase difference.

On the other hand, Patent Document 2 discloses a drive control device for an elliptical vibration parts feeder, which is configured to set the output frequency so that the amplitude of one of the horizontal vibration and the vertical vibration is maximized.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 07-2023

[Patent Document 2] Japanese Patent Application Laid-Open No. 11-227926

However, as shown in FIG. 12 , the resonance frequencies of the respective vibration systems do not strictly match, but vary. In addition, when the resonance frequency changes due to a temperature change or the like, the resonance frequency of each vibration system does not necessarily change in the same way, and it is expected that the variation may become larger.

Therefore, in the conventional control for adjusting the drive frequency based on the resonance frequency of one vibration system, the overall efficiency of the device is not maximized due to the influence of the variation in the resonance frequency. In addition, the difference in response magnification of the vibration of each vibration system increases, which is expected to occur in some of the vibration systems. It is necessary to generate the necessary amplitude. There are various problems such as excessive oscillation force or insufficient amplitude in a part of the vibration system.

The present invention aims to effectively solve these problems.

In order to solve this problem, the present invention adopts the following means.

That is, the control device of the vibration system of the present invention is used when a plurality of vibration systems are driven by a common drive command, wherein each of the vibration systems has a resonance frequency, and includes: target frequency setting means, A target frequency is set between the resonant frequencies; and a tracking means is formed to make the frequency of the drive command track the target frequency set by the target frequency setting means.

If configured in this way, each vibration system can be driven at a frequency that achieves overall balance without biasing a part of the resonance frequency. Also, even if the resonance frequency of the vibration system changes due to temperature or the like, the vibration system can be driven by tracking the frequency.

In this case, preferably, the target frequency setting means sets the target frequency such that the phase of each vibration system and the phase of the drive command have a predetermined phase relationship, and the tracking means is Feedback control is performed to set the frequency of the drive command to the target frequency.

In this way, if the target frequency is set by the phase, there is no need to search for the resonance frequency, so that the control can be continued without interruption of the driving.

Specifically, it is preferable that the target frequency setting means includes: a phase difference setter provided in each vibration system; and a phase difference detector for detecting a phase difference between the phase detected in each vibration system and the phase of the drive command and an adder that adds the deviation between the set phase difference of each of the vibration systems and the detected phase difference; and generates the drive command based on the combined deviation added by the adder.

With this configuration, it is not necessary to use the phase search for the resonance frequency, so that the configuration of the control device can be simplified.

Moreover, it is suitable that in each of the vibration systems, the phase difference detector multiplies the signal of the drive command and the detection signal from the vibration detector to extract the DC component, and normalizes it to detect phase difference.

With this configuration, it is not necessary to perform sampling with high resolution such as zero-cross detection, etc., and therefore the phase relationship can be detected reliably (∴ effect of extracting and normalizing the DC component). If configured in this way, even when the amplitudes of the vibration systems are different, the influence of the vibration systems can be removed and the phase difference detection can be performed reliably.

Further, preferably, the target frequency setting means detects the vibration frequencies of the respective vibration systems and sets target frequencies therebetween, and the tracking means performs a process of setting the frequency of the drive command to the target frequency. feedback control.

With this configuration, the target frequency can be relatively easily set through the vibration frequency without depending on the phase, for example, in an object for which phase detection is difficult.

Furthermore, if the above-mentioned control device is applied, it is provided with: a conveying unit for conveying the workpiece in a mounted state; and a traveling wave generating means for generating the deflection of the conveying unit by synthesizing standing waves of different phases. The traveling wave of flexural vibration; the workpiece conveying device is designed to control the traveling wave generating means of the workpiece conveying device by the above-mentioned control device, so that it can exert a stable conveying capability with high efficiency.

According to the present invention described above, when it is applied to a device using vibration such as a parts feeder or an ultrasonic motor, it is possible to provide a novel and useful vibration system control device that can drive them stably and efficiently, and Workpiece transfer device.

1(1x): First Vibration System

2(2x): Second Vibration System

11: First oscillator

12: First Amplifier

14: First Vibration Detector

15: The first phase difference detector

21: Second oscillator

22: Second amplifier

23: Phaser

24: Second vibration detector

25: Second phase difference detector

30: Adder

31: Target frequency setting means

32: Tracking means (drive command generation part)

31A1: The first phase difference setter

32B1: The second phase difference setter

C: Control device for vibration system

f1, f2: resonance frequency

fm: target frequency

fv: drive frequency (frequency of drive command)

T1, t1, t2: conveying part

BZ, LZ: means of generating traveling waves

PF: Workpiece transfer device (parts feeder)

1 is a schematic block diagram of a control device of a vibration system according to an embodiment of the present invention.

[Fig. 2] A part of Fig. 1 is a specific schematic block diagram. [Fig.

[FIG. 3] A part of FIG. 2 is a more specific schematic block diagram.

[ Fig. 4] Fig. 4 is a schematic Bode plot of the relationship between the resonance frequency and the frequency of the drive command in a plurality of vibration systems.

[ Fig. 5 ] A Bode diagram corresponding to a part of Fig. 4 which is the sum of the target frequencies in the embodiment.

[Fig. 6] It is used to explain the case where standardization is not performed in the same embodiment. Below is a comparison chart of the problem.

[ Fig. 7] Fig. 7 is a schematic diagram of a modification of the control device of the vibration system of the present invention.

[ Fig. 8] Fig. 8 is a schematic diagram of another modification of the control device of the vibration system of the present invention.

[ Fig. 9] Fig. 9 is a schematic diagram of a parts feeder as a configuration example of the workpiece conveying device of the present invention.

[Fig. 10] A control block diagram for the bowl feeder constituting the same parts feeder.

[Fig. 11] A control block diagram for the linear feeder constituting the same parts feeder.

[FIG. 12] A diagram for explaining a conventional control in comparison with the present invention.

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

FIG. 1 is a block diagram showing a control device C of the vibration system according to the present embodiment. This control device C includes the first and second vibration systems 1 and 2, and has vibration parts (1x, 2x) such that the resonance frequencies f1 and f2 of the respective vibration systems 1 and 2 are close to each other. As a vibration system in which the resonant frequencies f1 and f2 are close to each other in this way, for example, there can be mentioned parts feeders, etc., which oscillate at a plurality of places having a spatial phase difference in a plurality of vibration modes, thereby generating a traveling wave. Ultrasonic vibration systems, or spring-mass-damping vibration systems such as planar conveying devices that generate elliptical vibrations through vibrations in the XYZ directions.

Specifically, the first and second vibration systems 1 and 2 are oscillated by the first and second oscillators 11 and 21, respectively.

A periodic signal such as a sine wave or a rectangular wave, which is generated by the drive command generating unit 32a of the transmitter or the like, has a variable frequency and is amplified by the first and second amplifiers 12 and 22 and is input to the first and second amplifiers. , the second oscillator 11 , 21 . The second oscillator 21 is input to the phase shifter 23 to shift the phase of the periodic signal from the drive command generation unit 32 and amplify it by the second amplifier 22, so as to give the first vibration system 1 as a The relative phase difference of the reference.

That is, the periodic signal from the driving command generating unit 32 is input to the first amplifier 12 , and is input to the second amplifier 22 with the phase shifted by the phase shifter 23 .

Here, in general control, the first vibration detector 14 is installed at the position where the vibration waveform of the first vibration system 1 is detected, and the first phase difference detector 15 is installed to input the input generated by the drive command. The periodic signal generated by the section 32 and the signal detected by the first vibration detector 14 adjust the frequency by the target frequency setting means 31 in such a way that the phase difference ΔΦ1 here becomes 90°, and control the generation of the drive command Section 32. At the same time, it is configured to drive the second vibration system 2 by changing the phase of the driving frequency by the phase shifter 23 .

However, as described above, the control of driving the whole by the resonant frequency f1 of the first vibration system 1 becomes a drive that deviates from the resonance frequency f2 in the second vibration system 2, so the response is amplified between the first vibration system 1 and the second vibration system 2. The rate gap will become larger, which is expected to occur for the second vibration system 2 To create the necessary amplitude, the second amplifier 22 must have an excessively large oscillation force or insufficient amplitude. The same applies to the case where the whole is designed to be driven by the resonant frequency f2 of the second vibration system 2 .

In view of this, in the present embodiment, also on the side of the second vibration system 2, the second vibration detector 24 is set at the position where the vibration waveform of the second vibration system 2 is detected, and the second phase difference detector 25 is set to input the The drive command generation unit 32 generates a phase difference ΔΦ2 between the periodic signal adjusted in phase by the phase shifter 23 and the signal detected by the second drive detector 24 , and the phase difference is added to the aforementioned first phase. The phase difference of the difference detector 15 is input to the target frequency setting means 31 together.

The target frequency setting means (frequency adjuster) 31 determines the frequencies of the resonance frequencies f1 and f2 of the first vibration system 1 and the second vibration system 2 from the outputs Φ1 and Φ2 of the first and second phase difference detectors 15 and 25 The frequency fv of the drive command generated by the drive command generation unit 32 is adjusted to the target frequency fm.

In this way, when adjusting the frequency fv of the drive command, the target frequency setting means 31 uses the phase difference between the command and the response of each of the plurality of vibration systems 1 and 2 to set the frequency. Then, using the drive command generation unit 32 as a tracking means, the drive frequency fv is made to track the target frequency fm.

More specifically, the target frequency setting means 31 and the tracking means 32 are configured as shown in FIG. 2 .

The target frequency setting means 31 includes first and second phase difference setters 31A1 and 31B1, and uses subtractors 30a and 30b to obtain deviations from the output signals of the first and second phase difference detectors 15 and 25, respectively. for The respective deviations can be adjusted by adjusting the weights of the gain adjustment units 31A2 and 31B2.

Then, a signal obtained by adding the first and second deviation signals by the adder 30c (hereinafter referred to as a composite deviation) is used as a feedback signal as the basis of the driving command, and the feedback signal is output from the target frequency setting means 31 .

The tracking means of the present invention, that is, the driving command generating unit 32, makes the driving frequency fv of the driving command track the intermediate frequency fm in order to input the feedback signal, and automatically adjusts the transmitter 32b (VCO: Voltage controlled oscillator) by the PI controller 32a. ) frequency, and output the drive command.

The phase difference detectors 15 and 25 are configured as shown in FIG. 3 .

That is, the phase difference detectors 15 and 25 are provided with amplitude detectors 15a and 25a for detecting the vibration amplitude from the signals detected by the first and second vibration detectors 14 and 24. In addition, the periodic signals input to the vibration systems 1 and 2 and the signals detected by the vibration detectors 14 and 24 are multiplied by the multipliers 15b and 25b, and are cut off by the low-pass filters 15c and 25c. frequency components. Then, dividers 15d and 25d are provided to normalize the output signals from the low-pass filters 15c and 25c by dividing the output signals from the amplitude detectors 15a and 25a.

In this configuration, for example, assuming that the gains of the gain adjusters 31A2 and 32A2 are each 1, and the settings of the first phase difference setter 15 and the second phase difference setter 25 are both -90°, when the first deviation ΔΦ1 or The second deviation ΔΦ2 is in the relationship that one becomes larger and the other becomes smaller, so as a result, the In other words, the frequency of the drive command will be stable between the frequency at which the first deviation ΔΦ1 becomes 0 and the frequency at which the second deviation ΔΦ2 becomes 0. That is, the first vibration system 1 and the second vibration system 2 can be driven at a frequency fm between the frequency f optimal for the first vibration system 1 and the frequency f optimal for the second vibration system 2 , that is, a balanced frequency. The second vibration system 2 .

In order to illustrate this point, it is assumed that the first and second vibration systems 1 and 2 are represented by a simple spring-mass-damper system, and the vibration detectors 14 and 24 are used to detect vibration displacement as an example. The frequency between the frequencies f1 and f2 is driven.

The set values in the first and second phase difference setting devices 31A1 and 31B1 are set to -90°. That is, it is set so that the deviation becomes 0 at each resonance frequency. In this case, the deviations ΔΦ1 (=-90°-Φ1) and ΔΦ2 (=-90°-Φ2) at a certain frequency become the values shown in Fig. 4 . According to this figure, the frequency fm in which ΔΦ1 and ΔΦ2 are equal in magnitude and opposite in sign exists between the resonance frequencies f1 and f2 of the two vibration systems 1 and 2 . Therefore, if the frequency fv of the drive command is adjusted so that the combined deviation ΔΦ1+ΔΦ2 becomes 0, driving can be performed at the frequency fm between the two resonance frequencies f1 and f2 (see FIG. 5 ). At this time, the driving frequency fv in FIG. 4 will remain stable in the region of the intermediate frequency fm between the resonance frequency f1 of the first vibration system and the resonance frequency f2 of the second vibration system.

The above-described target frequency setting means 31 automatically sets such a frequency, and the drive frequency fv is traced to the target frequency fm by the tracking means 32 . In addition, if the gain for two deviations is adjusted by the gain adjusters 31A2 and 32B2, it is also possible to perform proportional setting so that the two resonance frequencies are It is driven by the frequency of the resonance frequency f1 (f2) which is between f1 and f2 but closer to one.

Here, the operation in the case where the phase difference detectors 15 and 25 are designed as shown in FIG. 3 will be described.

If the first and second driving command signals are respectively set as cosωt and cos(ωt-Φe), the displacement detection signals output by the first and second vibration detectors 14 and 24 are set as v1cos(ωt+ Φ1), v2cos(ωt-Φe+Φ2), the signal obtained by multiplying the driving command signal and the detection signal is as follows.

When only the DC component is extracted by the low-pass filters 15c and 25c, they become (1/2)v1cosΦ1 and (1/2)v2cosΦ2, respectively. Then, it is normalized by the dividers 15d and 25d to obtain a signal which is not dependent on v1 and v2 but proportional to cosΦ1 and cosΦ2. cosΦ1 and cosΦ2 become 0 at the resonance frequencies f1 and f2, respectively, and monotonically change from 1 to -1 in the vicinity of the resonance frequencies f and f2. Therefore, if the target frequency fm is adjusted so that cosΦA+cosΦB=0, the two vibration systems 1 and 2 can be driven at a frequency between the resonant frequencies f1 and f2 of the two vibration systems 1 and 2 (in the middle).

Conversely, assume a case where normalization is not performed, that is, a case where control is performed so that v1cosΦ1+v2cosΦ2 becomes 0. Since the vibration amplitudes v1 and v2 of the two vibration systems take the maximum values according to their respective resonance frequencies, v1cosΦ1 and v2cosΦ2 do not change monotonically. Fig. 6 is a curve drawn by v1cosΦ1, v2cosΦ2, v1cosΦ1+v2cosΦ2. v1cosΦ1+v2cosΦ2, in addition to the frequency fm in the middle of the resonance frequencies f and f2, there is a point at which it becomes 0, and the direction of the change of the value (the slope of the graph) varies depending on the frequency. Therefore, it is easy to drive at a frequency deviating from the intermediate value fm of the resonance frequency, or the control becomes unstable (the drive frequency deviates from the target value and diverges). By standardizing, such problems will be solved, and control will become easier.

As described above, according to the control device C of the vibration system of the present embodiment, the difference in the response magnification ratio of vibration between the first drive system 1 and the second drive system 2 is reduced, and it is difficult to occur in one vibration system f1. (f2) There is a problem that an excessively large oscillation force is necessary, or that the amplitude of one of the vibration systems f1 (f2) is insufficient.

In addition, compared with the case where the whole is driven by one resonance frequency f1 (f2), the advantage that the electric power necessary for the whole is reduced, or the frequency is automatically adjusted, it becomes unnecessary to search for the first, Advantages of time such as resonant frequencies f1, f2 of the second vibration systems 1, 2.

One embodiment of the present invention has been described above, but the specific configuration of each part is not limited to the above-described embodiment.

For example, even when there are three or more vibration systems, by using a signal obtained by adding the deviation signals outputted for each system, it is possible to control a part of the resonance frequency without flattening a part of the resonance frequency. Driven by frequencies that achieve total balance.

In addition, in the above-described embodiment, the outputs of the first and second phase difference detectors 15 and 25 are respectively set at the first and second phase differences. The setter 31A1, 31B1 takes the deviation from the set value, but as shown in FIG. 7, the signal obtained by adding the outputs of the first and second phase difference detectors 15, 25 is taken in the phase difference setting 131a. Deviation from the set value. In this case, only one phase difference setter is required.

In addition, although PI control was used in the said embodiment, it is not limited to this, Various control methods can be employ|adopted for making a synthetic|combination deviation 0.

In addition, the thing detected by the vibration detector may be any of vibration displacement, vibration velocity, and vibration acceleration.

In addition, it may be controlled so as not to drive at the resonance frequency but at a frequency deviated from the resonance frequency by a predetermined amount. For this reason, the set phase difference of the phase difference setters 31A1 and 31A2 can be adjusted.

In addition, the drive command input to the phase difference detectors 15 and 25 may be a signal of any stage as long as the phase difference is the same signal. For example, in FIG. 2 and the like, although the output signal from the transmitter 32 is input to the first phase difference detector 15, the output signal from the first amplifier 12 may also be input.

In addition, in the present invention, although only the control method of the drive frequency is described, it is also conceivable to use a fixed amplitude control or the like for keeping the amplitude of each vibration system at a set value in combination. In this case, by keeping the amplitude constant, more stable driving can be achieved. In addition, in the case of the configuration shown in FIG. 3 , the output signal of the amplitude detector using the normalization can also be used for constant amplitude control.

In addition, in a vibration system that can be regarded as having approximately the same maximum amplitude at the resonant frequency, as shown in FIG. The detectors 215 and 225 detect the vibration frequency of each vibration system and input this to the target frequency setting means 231, the target frequency fm is set by the frequency difference setting means 231a, and the tracking means 232 is configured so that the frequency fv of the drive command is set as the frequency fv of the drive command. Feedback control of target frequency fm.

In this way, when the maximum amplitude can be assumed to be approximately equal, the target frequency can be set relatively simply by the vibration frequency without depending on the phase.

If the above-mentioned control device C is used, a plurality of vibration systems arranged at a plurality of places having a spatial phase difference and oscillated with a phase difference from each other are driven by a common drive command, thereby allowing the traveling wave to travel on a track (track). ) to construct the workpiece conveying device, the reduction of the traveling wave ratio can be prevented, and the device can be operated with high efficiency.

That is, in the case of conveying a workpiece using a traveling wave, it is particularly required to design/adjust such that the driving frequency becomes a value close to the resonance frequency compared to other devices. However, since the frequency band during conveyance using the traveling wave is high frequency (eg, ultrasonic wave), the response of the conventional control method is too late. That is, it is difficult to achieve efficient control.

In addition, piezoelectric bodies are often used as drive sources for conveying devices using such traveling waves. However, due to the influence of the voltage applied to the piezoelectric bodies, the piezoelectric bodies themselves may become heat sources, which may cause temperature changes. sex. Therefore, the variation due to the change of the resonance frequency due to the temperature change or the like becomes large, and the efficiency of the whole device cannot be maximized. In view of this, by applying the present invention, it is possible to exhibit a stable conveying capability with high efficiency.

FIG. 9 shows the parts feeder PF, which is an example of the workpiece conveying device. The parts feeder PF is composed of the bowl feeder Bf that makes the workpieces to be loaded climb up the slope along the screw conveyance portion T1, and the alignment and direction determination of the workpieces discharged from the bowl feeder Bf by the alignment conveyance portion t1. It consists of the linear feeder Lf which passes only the workpiece|work of a correct posture, and returns an inappropriate workpiece|work to the bowl feeder Bf through the return conveyance part t2.

Among them, the bowl feeder Bf, as shown in FIG. 10, is configured as a traveling wave generating means BZ, and is located in the first region and vibrates in a 0° mode in the annular vibration region of the bottom surface of the feeder body. The vibrating portion 1x of the vibration system 1 and the vibrating portion 2x of the second vibrating system vibrating in the 90° mode in the second region are oscillated by the first oscillator 11 and the second oscillator 12 using piezoelectric elements , whereby the standing waves with different phases are synthesized, thereby generating a traveling wave for flexural vibration of the conveying portion T1 . In addition, when the above-mentioned control device C is applied to the bowl feeder Bf, it can be configured that the periodic signal amplified by the first and second amplifiers 12 and 22 also disclosed in FIG. 1 and the like is input. To the first and second oscillators 11 and 21 of the traveling wave generating means BZ, the vibrations of the first and second vibration systems 1 (1x) and 2 (2x) are detected by the first and second vibration detectors 14 and 24. take out. In Fig. 10, the other parts of the control device C (refer to Fig. 1) are omitted, and the control method is the same as that of the above-described embodiment. Also in this case, the control device C can adopt the structure of FIG. 6 or 7 instead of the structure of FIG. 1 .

In the case of driving such a part feeder PF, as a general practice, the resonant frequencies of the oscillating parts 1x and 2x are considered to be almost the same. If the piezoelectric element is attached to the bottom surface of the vibrating parts 1x and 2x, the resonance frequency at a plurality of oscillation points will change by several % due to the heat generation of the piezoelectric element, and the standing wave ratio may decrease, which may significantly impair the transfer efficiency. However, through the control of the control device C, this problem can be effectively solved.

On the other hand, as shown in FIG. 11, the linear feeder Lf in FIG. 9 is configured as a traveling wave generating means LZ, and is located in the first region and at 0° with respect to the oval vibration region of the bottom surface of the feeder body. The vibration part 1x of the first vibration system 1 that vibrates modally, and the vibration part 2x of the second vibration system that is located in the second region and vibrates modally at 90°, through the first oscillator 11 and the second vibration system using piezoelectric elements. The two oscillators 12 are oscillated, whereby standing waves with different phases are synthesized, thereby generating traveling waves for flexing and vibrating the conveying parts t1 and t2. Also, when the above-mentioned control device C is applied to the linear feeder Lf, it can be configured as a periodic signal amplified by the first and second amplifiers 12 and 22 also disclosed in FIG. 1 and the like. are input to the first and second oscillators 11 and 21 of the traveling wave generating means LZ, and the vibrations of the first and second vibration systems 1 (1x) and 2 (2x) are transmitted through the first and second vibration detectors 14 , 24 are taken out. In Fig. 11, the other parts of the control device C (refer to Fig. 1) are omitted, and the control method is the same as that of the above-described embodiment. Also in this case, the control device C can adopt the configuration of FIG. 6 or 7 instead of the configuration of FIG. 1 .

In this way, the same effects as those described above are also exhibited.

In addition, by using the above-mentioned control device, a plurality of vibration systems to be operated in the XYZ directions can be operated in the required manner under a common drive command. Even if it is configured as a workpiece conveying device that conveys the workpiece on the flat conveying section in the XY plane, it can be driven with high efficiency and stable conveying capability.

Other configurations can be variously modified without departing from the gist of the present invention.

1(1x)‧‧‧First Vibration System

2(2x)‧‧‧Second vibration system

11‧‧‧First Oscillator

12‧‧‧First Amplifier

14‧‧‧First Vibration Detector

15‧‧‧First Phase Difference Detector

21‧‧‧Second oscillator

22‧‧‧Second amplifier

23‧‧‧Phase Shifter

24‧‧‧Second vibration detector

25‧‧‧Second Phase Difference Detector

31‧‧‧Target frequency setting method

32‧‧‧Tracking Means (Drive Command Generation Section)

C‧‧‧Control device for vibration system

fm‧‧‧target frequency

fv‧‧‧drive frequency (frequency of drive command)

Claims (6)

A control device for a vibration system, which is used when a plurality of vibration systems are driven by a common drive command, wherein each of the vibration systems has a resonance frequency, and includes: target frequency setting means, in these The target frequency is set between the resonance frequencies; and the tracking means makes the frequency of the driving command track the target frequency set by the target frequency setting means; the target frequency setting means is based on the phase of the vibration system and the phase of the driving command. The target frequency is set in such a way that there will be a predetermined phase relationship between them, and it is provided with: a phase difference setting device, which is provided in each vibration system; and a phase difference detector, which detects the difference between the phase detected in each vibration system and the phase of the drive command. Phase difference; the drive command is generated based on the deviation between the set phase difference of each vibration system and the detected phase difference. The control device for a vibration system according to claim 1, wherein the tracking means performs feedback control for setting the frequency of the drive command to the target frequency. The control device for a vibration system according to claim 1 or 2, further comprising: an adder for adding the deviations; The above-mentioned drive command is generated from the resultant deviation added by this adder. The control device for a vibration system according to claim 3, wherein, in each of the vibration systems, the phase difference detector multiplies the drive command and the detection signal from the vibration detector to extract a DC component , which is normalized to detect the phase difference. The control device for a vibration system according to claim 1, wherein the target frequency setting means detects the resonance frequencies of the respective vibration systems and sets the target frequency therebetween, and the tracking means performs a The frequency of the aforementioned driving command is set as the feedback control of the aforementioned target frequency. A workpiece conveying device, comprising: a conveying part for conveying a workpiece in a mounted state; and a traveling wave generating means for generating by synthesizing standing waves of different phases for flexing the conveying part The traveling wave of flexural vibration; the control device of the vibration system as described in any one of the claims 1 to 5 of the scope of application is applied to the aforementioned traveling wave generating means.

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