JP4331631B2 - Ultrasonic motor condition monitoring device - Google Patents

Description

  The present invention relates to an ultrasonic motor condition monitoring apparatus, and more particularly to an ultrasonic motor condition monitoring apparatus for warning the occurrence of an unstable event that inhibits stable driving of an ultrasonic motor.

  In recent years, ultrasonic motors have attracted attention as motors with high torque performance at low speeds and excellent quietness during driving.

  In general, an ultrasonic motor includes a stator (stator) formed by laminating a plurality of piezoelectric vibrators having different vibration directions, and a rotor (rotor) placed in a state where pressure is applied to the stator. ). When a driving AC voltage having the same frequency and different phase is applied to the piezoelectric vibrator of the stator in this type of ultrasonic motor, a natural vibration is excited in each piezoelectric vibrator and an ultrasonic wave is generated. The accompanying resonance vibration of the stator causes the rotor placed in close contact with the stator to rotate in the right or left direction.

Further details of the ultrasonic motor are disclosed in Non-Patent Document 1 below, for example.
Kentaro Nakamura, Minoru Kurosawa, Sadayuki Ueha, 'Characteristics of a Hybrid Transducer-Type Ultrasonic Motor,' IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, May 1991, Vol. 38, No. 3, Pages 188-193.

  However, the above-described ultrasonic motor has a drawback that due to its principle configuration, it easily generates heat during driving, and its characteristics change remarkably in a short time. Moreover, since it is practically impossible to visually determine the state of such heat generation or characteristic change from the appearance of the ultrasonic motor, it remains unaware that the ultrasonic motor has fallen into a dangerous state. It often happens that it leads to destruction.

  In addition, when an ultrasonic motor is actually incorporated into a mechanical product, most of the ultrasonic motor is used in a state of being almost concealed by a structural member of the mechanical product, so the state of the ultrasonic motor is visually confirmed from the outside. As such, it is extremely difficult.

  Here, the main objects to be solved by the present invention are as follows.

  That is, the first object of the present invention is to provide an ultrasonic motor condition monitoring device capable of audibly warning the occurrence of heat generation and other unstable events that hinder the stable drive of the ultrasonic motor. It is.

  The second object of the present invention is to provide an ultrasonic motor ultrasonic motor state monitoring device capable of reliably performing the occurrence of the unstable event without degrading the performance of the ultrasonic motor. is there.

  Other objects of the present invention will become apparent from the specification, drawings, and particularly the description of each claim.

  In the device of the present invention, a physical quantity sensor that measures a physical quantity that is a determination index of occurrence of an unstable event, an acoustic signal storage unit that stores an acoustic signal indicating a warning sound to be emitted when an unstable event occurs, An acoustic signal read control means for reading out an acoustic signal related to a warning sound from the acoustic signal storage means when the value of the physical quantity measured by the physical quantity sensor exceeds a threshold, and modulated by modulating the driving AC voltage using the acoustic signal A modulation means for obtaining a wave signal, and when the modulated wave signal is applied to a piezoelectric vibrator of the ultrasonic motor and an ultrasonic wave is emitted, the ultrasonic motor itself has an ultrasonic self-demodulation phenomenon. The characteristic constitution means for emitting the warning sound directly demodulated from the modulated wave signal is taken.

  More specifically, in order to solve the problem, the present invention achieves the above-mentioned object by adopting a new characteristic configuration means ranging from the superordinate concept listed below to the subordinate concept. .

That is, the first feature of the device of the present invention is that when an AC voltage for driving is applied to the piezoelectric vibrator constituting the ultrasonic motor, an unstable event that inhibits stable driving of the ultrasonic motor is generated. An ultrasonic motor state monitoring device for audibly warning, a physical quantity sensor that is installed on the ultrasonic motor and steadily measures a physical quantity that serves as a determination index for occurrence of the unstable event; and Acoustic signal storage means for storing in advance an acoustic signal indicating a warning sound to be emitted when an unstable event occurs, and the value of the physical quantity measured by the physical quantity sensor exceeds a threshold set in advance for the physical quantity. The acoustic signal reading control means for reading out the corresponding acoustic signal from the acoustic signal storage means, and the driving by the acoustic signal read by the acoustic signal reading control means. Modulation means for modulating the AC voltage for use in a predetermined method to obtain a modulated wave signal, and the ultrasonic motor is configured to transmit the modulated wave signal obtained by the modulation means to the piezoelectric vibrator. When applied, the warning sound directly demodulated from the modulated wave signal without going through the process of electrical demodulation of the acoustic signal due to the self-demodulation phenomenon of the ultrasonic wave emitted from the ultrasonic motor The physical quantity sensor is a current sensor that measures the current generated by the driving AC voltage, a temperature sensor that measures the temperature of the ultrasonic motor, and a rotation that measures the rotational speed of the ultrasonic motor. The acoustic signal indicating the warning sound is measured by the two or more physical quantity sensors, including two or more of a speed sensor and a rotation angle sensor for measuring a rotation angle of the ultrasonic motor. It consists audibly distinguishable different 2 or more acoustic content type of the physical quantity, in the configuration adopted for the ultrasonic motor condition monitoring system.

A second feature of the device of the present invention is that the modulation means includes a plurality of piezoelectric vibrators for the ultrasonic motor to realize multi-degree-of-freedom rotational driving. When a period during which the piezoelectric vibrator of one system in the system does not participate in the drive control of the ultrasonic motor occurs, the driving vibrator having a certain amplitude to be applied to the piezoelectric vibrator of the one system during the period The ultrasonic motor condition monitoring apparatus is configured to selectively modulate an AC voltage.

A third aspect of the present invention apparatus, the modulating means, Ri amplitude modulating means der which modulates the amplitude waveform of the acoustic signal of the driving AC voltage is subjected to the performance control of the ultrasonic motor When the control signal is superimposed on the driving AC voltage, the acoustic signal subjected to the intensity setting for obtaining a modulation rate at a level that can ensure stable control of the ultrasonic motor by the control signal, The ultrasonic motor condition monitoring apparatus is configured to amplitude-modulate the driving AC voltage .

  According to the present invention, a warning sound directly demodulated by a self-demodulation phenomenon of an ultrasonic wave from a modulated wave signal obtained by modulating a driving AC voltage using an acoustic signal is emitted to the ultrasonic motor itself. Therefore, for example, without adding an image display device or a speaker separately, with an extremely simple configuration, an audible warning is given of the occurrence of unstable events such as overcurrent, heat generation, and overspeed that hinders the stable drive of the ultrasonic motor. It becomes possible to do. As a result, even when the ultrasonic motor is used in a state of being concealed by a structural member of a mechanical product, for example, the user can be audibly informed that the ultrasonic motor has fallen into a dangerous state. It becomes possible to make it.

  Further, according to the present invention, amplitude modulation is adopted as the modulation method of the driving AC voltage, and the waveform of the control signal used for performance control of the ultrasonic motor is not distorted at that time. Since the modulation rate is set to a level that can ensure stable control by the control signal, the occurrence of the unstable event can be reliably warned without degrading the performance of the ultrasonic motor.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings with an example of an apparatus.

  FIG. 1 is a diagram showing a configuration of an ultrasonic motor state monitoring apparatus according to an example of the present invention together with its application form.

  As shown in the figure, an ultrasonic motor state monitoring apparatus 1 according to this example of the apparatus includes a driving AC voltage power supply 11, a control signal generation unit 12, an acoustic data storage device 13 (acoustic signal storage means) in its main body. ), An acoustic data read control unit 14 (acoustic signal read control means), a D / A converter (digital / analog converter) 15, and an amplitude modulation circuit 16 ((amplitude) modulation means). Further, each of the ultrasonic motors 2 is used as a physical quantity sensor that steadily measures a physical quantity that serves as a determination index for occurrence of unstable events such as overcurrent, heat generation, and excessive rotation that inhibits stable driving of the ultrasonic motor 2. Current sensor 3, temperature sensor 4, rotation speed sensor 5, and rotation angle sensor 6 installed for stator 2a or rotor 2b (details of each physical quantity sensor will be described later) .

  The ultrasonic motor 2 shown in this example is provided with a plurality of systems of piezoelectric vibrators for realizing multi-degree-of-freedom rotational driving of the rotor 2b so as to apply ultrasonic vibrations having different directions to the stator 2a. The first, second, and third systems of piezoelectric vibrators 21, 22, and 23 are provided, and a load heavy object that is an object to be rotationally driven is provided at the tip of the shaft 7 extended from the rotor 2b. 8 is assumed to be fixed. In addition, it is assumed that the sound pressure of the ultrasonic wave emitted from the ultrasonic motor 2 reaches about 100 dBSPL (SPL: Sound Pressure Level).

  Here, the driving AC voltage power source 11 is an ultrasonic region (about 20 kHz or so) to be constantly applied to the first to third piezoelectric vibrators 21 to 23 constituting the stator 2a of the ultrasonic motor 2. The control signal generator 12 is used for performance control such as rotation start, stop, speed adjustment, and direction change for the rotor 2b of the ultrasonic motor 2. A control signal is generated, and these control signals are respectively applied to three driving AC voltages obtained by system-separating the driving AC voltage supplied from the driving AC voltage power supply 11, and the three driving AC voltages are respectively provided. It functions to change the amplitude or frequency of the two or the phase difference between the two driving AC voltages. As a result, three AC driving voltages for applying three-way ultrasonic vibration to the stator 2a are obtained.

  That is, the drive AC voltage power supply 11 and the control signal generator 12 provide basic functions of an “ultrasonic motor drive device” for performing drive control of the ultrasonic motor 2 and performance control associated therewith. .

  On the other hand, the acoustic data storage device 13 stores in advance an acoustic signal indicating a warning sound for each event to be emitted when the aforementioned unstable event occurs as digital acoustic data. Reference numeral 14 denotes an acoustic data storage device 13 when the value of each physical quantity measured by the current sensor 3, the temperature sensor 4, the rotation speed sensor 5, and the rotation angle sensor 6 exceeds a threshold set in advance for the physical quantity. From the above, it functions to read out sound data that has been converted into data regarding the corresponding sound signal.

  Note that the acoustic signal indicating the warning sound is provided with acoustic contents that can audibly identify the type of the physical quantity measured by the corresponding physical quantity sensor (3 to 6), and preferably the unstable signal. An audible “speech signal” that is a significant expression of the occurrence of an event is preferred. As a specific example of this audio signal, if it is applied to the temperature sensor 4, for example, a message sentence such as “Motor temperature is rising rapidly. It may be expressed by a method such as speech synthesis. In addition to this audio signal, various acoustic signals including natural sounds, musical sounds, synthesized sounds, and the like that are comfortable for humans may be applied.

  On the other hand, the D / A converter 15 converts the digital sound data (sound data) read by the sound data read control unit 14 into analog to obtain a corresponding sound signal (sound signal). The amplitude modulation circuit 16 modulates the amplitude of one driving AC voltage among the three driving AC voltages given from the control signal generator 12 by the acoustic signal obtained by the D / A converter 15. A modulated wave signal is obtained, and the modulated wave signal is applied to the corresponding one of the first to third piezoelectric vibrators 21 to 23 constituting the stator 2a of the ultrasonic motor 2 through the illustrated control line 9. This is applied to one system of piezoelectric vibrators (a driving AC voltage not subjected to amplitude modulation is applied as it is to two piezoelectric vibrators of other systems).

  Here, when the amplitude modulation circuit 16 generates a period in which one of the piezoelectric vibrators 21 to 23 of the first to third piezoelectric vibrators 21 to 23 is not involved in the drive control of the ultrasonic motor 2, In the period, the driving AC voltage having a certain amplitude to be applied to the piezoelectric vibrator of the one system is selectively modulated.

  Further, the amplitude modulation circuit 16 controls the drive AC voltage supplied from the control signal generator 12 to a control signal (for driving the drive AC voltage having an amplitude of about several Hz) used for performance control of the ultrasonic motor 2. When a control signal to be changed according to frequency is superimposed, an acoustic signal subjected to intensity setting to obtain a modulation rate (details will be described later) at a level that can ensure stable control of the ultrasonic motor 2 by the control signal. Any one of the driving AC voltages is selectively amplitude-modulated by (sound signal).

  The amplitude modulation circuit 16 described above modulates the drive AC voltage in an analog manner, but instead of this, for example, a required signal is obtained by digital signal processing using a DSP (Digital Signal Processor) or the like. You may comprise so that a modulation function may be acquired. In this case, since the DSP can directly input and process the digital sound data read by the sound data read control unit 14, the D / A converter 15 is not required in terms of configuration.

  On the other hand, the current sensor 3 constituting the physical quantity sensor steadily measures the current generated by the driving AC voltage on the control line 9, and further, the measured value at that time is transmitted to the acoustic data through the illustrated data line 10. By causing the read control unit 14 to acquire the sound data, the sound data read control unit 14 is made to detect whether or not “overcurrent”, which is one of the unstable events described above, has occurred. As the current sensor 3, for example, a Hall element can be applied.

  Further, the temperature sensor 4 steadily measures the temperature of the ultrasonic motor 2 on the stator 2a, and further causes the acoustic data read control unit 14 to acquire the measurement value at that time through the data line 10. This is for causing the acoustic data reading control unit 14 to detect whether or not “heat generation”, which is one of unstable events, has occurred. As the temperature sensor 4, for example, a thermistor or a thermocouple can be applied.

  Further, the rotational speed sensor 5 constantly measures the rotational speed of the rotor 2b of the ultrasonic motor 2 while using the load heavy object 8 (or the rotor 2b itself or the shaft 7) as a medium, and further measures at that time. By causing the acoustic data read control unit 14 to acquire a value through the data line 10, the acoustic data read control unit 14 can detect whether or not “over-rotation”, which is one of unstable events, has occurred. is there. As the rotational speed sensor 5, for example, an optical or magnetic rotary encoder can be applied.

  Furthermore, the rotation angle sensor 6 steadily measures the rotation angle of the rotor 2 b of the ultrasonic motor 2 using the load heavy object 8 as a medium, and further, the measured value at that time is transmitted through the data line 10 as acoustic data. By causing the read control unit 14 to acquire the sound data, the sound data read control unit 14 is made to detect whether or not the “over-rotation” has occurred. As this rotation angle sensor 6, for example, a laser distance measuring device or the like can be applied. However, since the primary measurement value output from the laser distance measuring device is data representing “distance”, in order to make the acoustic data readout control unit 14 know the required rotation angle, the acoustic data readout control unit 14 What is necessary is just to make itself perform the numerical calculation for converting the measured distance into a rotation angle.

  As described above, when the driving AC voltage is applied to the piezoelectric vibrators 21 to 22 of the first to third systems constituting the ultrasonic motor 2, it is a problem that inhibits stable driving of the ultrasonic motor 2. An ultrasonic motor state monitoring apparatus 1 that can audibly warn of the occurrence of a stable event is obtained.

  Subsequently, the operation of the ultrasonic motor state monitoring apparatus 1 configured as described above will be described with an example.

  First, in a steady state before an unstable event that inhibits stable driving of the ultrasonic motor 2 occurs, the control signal generation unit 12 of the ultrasonic motor state monitoring device 1 is used for performance control of the ultrasonic motor 2. In addition to generating various control signals, these control signals are respectively applied to three driving AC voltages obtained by system-separating the driving AC voltage supplied from the driving AC voltage power source 11, and the three directions obtained as a result are obtained. Three AC driving voltages for applying ultrasonic vibration to the stator 2a are constantly applied to the amplitude modulation circuit 16. On the other hand, the amplitude modulation circuit 16 fixes the ultrasonic motor 2 while passing the three driving AC voltages supplied from the control signal generation unit 12 through the corresponding control lines 9 in an unmodulated state. It is constantly applied to the piezoelectric vibrators 21 to 23 of the first to third systems constituting the child 2a.

  Here, in the above steady state, for example, the temperature measurement value of the temperature sensor 4 that constantly measures the temperature of the ultrasonic motor 2 on the stator 2a is increased, and the change in the temperature measurement value is It is assumed that the data is acquired by the acoustic data read control unit 14 through the data line 10. Then, the acoustic data reading control unit 14 presets the acquired current temperature measurement value with respect to the maximum allowable temperature in order to detect the occurrence of heat generation, which is one of the unstable events. It is determined whether or not the threshold value is exceeded. When it is determined that the current temperature measurement value exceeds the threshold value, the acoustic data reading control unit 14 performs data reading control on the acoustic data storage device 13, and generates heat from the acoustic data storage device 13. Acoustic data (for example, voice data related to a voice signal expressing a message sentence according to an example) that is converted into data regarding an acoustic signal indicating a warning sound for warning the occurrence is read, and the acoustic data is read to the D / A converter 15. give.

  In response to this, the D / A converter 15 converts the given acoustic data into a corresponding analog acoustic signal, and provides the acoustic signal to the amplitude modulation circuit 16. Then, the amplitude modulation circuit 16 modulates the amplitude of one driving AC voltage among the three driving AC voltages supplied from the control signal generation unit 12 with a predetermined modulation rate, according to the given acoustic signal. The modulated wave signal is obtained, and the modulated wave signal corresponds to one of the piezoelectric vibrators 21 to 23 of the first to third systems constituting the stator 2a of the ultrasonic motor 2 through the control line 9. Applied to a piezoelectric vibrator of one system. The amplitude modulation circuit 16 does not perform amplitude modulation on the two drive AC voltages to be applied to the two piezoelectric vibrators of the other systems, and passes them in the original state.

  Here, the amplitude modulation circuit 16 superimposes a control signal for changing the amplitude of the driving AC voltage with a frequency of about several Hz on one driving AC voltage selected to obtain the modulated wave signal. In such a case, the level of the required modulation factor during amplitude modulation is selected to a level that can ensure stable control of the ultrasonic motor 2 by the control signal. Hereinafter, the principle will be described with reference to the drawings.

  FIG. 2 is a diagram showing an example of the waveform of the modulated wave signal obtained by the amplitude modulation circuit 16 shown in FIG.

  As shown in the figure, the mode of the modulated wave signal waveform M indicating the time change of the modulated wave signal obtained by the amplitude modulation circuit 16 is a control signal indicating the time change of the control signal having a frequency component of about several Hz. The waveform C is superimposed as the first envelope, and the acoustic signal waveform S indicating the temporal change of the acoustic signal having a frequency component of several hundred Hz to several kHz is superimposed as the second envelope.

  Here, if the modulation rate at the time of amplitude modulation is increased and the degree of amplitude modulation of the driving AC voltage by the acoustic signal is increased, the amplitude of the acoustic signal waveform S forming the second envelope becomes too dominant. Therefore, the control signal waveform C forming the first envelope is subjected to a large distortion that does not keep its original shape, and the effect as a control signal is almost lost. For this reason, the modulation rate needs to be lowered to a level that can ensure stable control of the ultrasonic motor 2 by the control signal. Specifically, the time variation of the amplitude of the acoustic signal is the modulated wave signal. The intensity of the sound signal may be set so that it is set to a sufficiently small value compared to the amount of time variation of the amplitude of.

  And if the above requirements regarding the modulation rate are satisfied, the frequency component of the acoustic signal is relatively high, such as several hundred Hz to several kHz, whereas the frequency component of the control signal is sufficiently low, about several Hz, The influence of the acoustic signal on the control signal can be almost ignored when viewed on a macroscopic time scale.

  When a period in which one of the piezoelectric vibrators 21 to 23 of the first to third piezoelectric vibrators 21 to 23 is not involved in the drive control of the ultrasonic motor 2 occurs, the amplitude modulation circuit 16 AC voltage for driving having a certain amplitude to be applied to the piezoelectric vibrator of the one system (for example, the frequency is increased to invalidate the generation of ultrasonic vibration by the piezoelectric vibrator of the one system. Alternatively, it is selectively modulated with a constant amplitude driving AC voltage that is shifted downward, or whose phase difference from the others is set to a non-vibration offset value. In this case, the modulated signal waveform M obtained by the amplitude modulation circuit 16 is not superimposed with the control signal waveform C that forms the first envelope, but only the acoustic signal waveform S that forms the second envelope. Therefore, no special consideration is required for the above-described modulation rate.

  Next, the modulated wave signal obtained by the amplitude modulation circuit 16 corresponds to one of the piezoelectric vibrators 21 to 23 of the first to third systems constituting the stator 2 a of the ultrasonic motor 2 through the control line 9. When applied to the piezoelectric vibrator of one system, the process of electrical demodulation of the acoustic signal included in the modulated wave signal is caused by the self-demodulation phenomenon of the ultrasonic wave emitted from the ultrasonic motor 2. The warning sound is directly demodulated from the modulated wave signal, and the warning sound is emitted to the outside, for example, “Motor temperature is rising rapidly. Stop the motor immediately”. The

Details regarding the theory and the like of the self-demodulation phenomenon are disclosed in, for example, the following references.
[References] Shigeaki Aoki, Tomoo Kamakura, Kazuo Ikeya, “Self-demodulation of plane wave -Examination of primary wave modulation method for broadband signal transmission-”, Journal of Acoustical Society of Japan, 1984, Vol. 40, No. 5, pp. . 349-356.

  Here, the sound pressure of the ultrasonic wave emitted from the ultrasonic motor 2 takes a very large value to reach 100 dBSPL, and the self-demodulation phenomenon appears remarkably by the ultrasonic wave having the high sound pressure energy. Therefore, as described above, even if the modulation rate in the amplitude modulation circuit 16 is set sufficiently low to a level at which stable control of the ultrasonic motor 2 by the control signal can be ensured, the required warning sound is generated by the ultrasonic motor. 2 will be released at a sufficient volume. Further, when the amplitude modulation circuit 16 performs amplitude modulation using only the acoustic signal on the driving AC voltage having a constant amplitude, the modulated wave signal obtained thereby causes a slight distortion of the acoustic signal. Since there is no control signal, the ultrasonic motor 2 demodulates and emits a warning sound without any distortion.

  As mentioned above, although an example of the apparatus has been described with respect to the embodiment of the present invention, the present invention is not necessarily limited to the above-described means, and may be appropriately modified within the scope having the above-described effects. Is possible.

  For example, in the present apparatus example, the case where the present invention is applied to an ultrasonic motor including a plurality of systems of piezoelectric vibrators for realizing a multi-degree-of-freedom rotational drive of the rotor is described as an example. The invention can be similarly applied to an ultrasonic motor capable of only rotating the rotor with one degree of freedom except for some invention elements characterized by selective modulation means for the drive AC voltage. .

It is a figure which shows the structure of the ultrasonic motor state monitoring apparatus which concerns on the example of 1 apparatus of this invention with the application form. It is a figure which shows an example of the waveform of the modulated wave signal obtained with the amplitude modulation circuit shown in FIG.

Explanation of symbols

1 ... Ultrasonic motor condition monitoring device (main unit)
DESCRIPTION OF SYMBOLS 11 ... Drive AC voltage power supply 12 ... Control signal generation part 13 ... Acoustic data storage device 14 ... Acoustic data read-out control part 15 ... D / A converter 16 ... Amplitude modulation circuit 2 ... Ultrasonic motor 2a ... Stator 2b ... Rotation Sub-units 21 to 23: Piezoelectric vibrators of the first to third systems 3 ... Current sensor 4 ... Temperature sensor 5 ... Rotational speed sensor 6 ... Rotation angle sensor 7 ... Shaft 8 ... Heavy load 9 ... Control line 10 ... Data line C ... control signal waveform S ... acoustic signal waveform M ... modulated wave signal waveform

Claims (3)

Ultrasonic motor status monitoring to audibly warn of the occurrence of unstable events that impede stable drive of the ultrasonic motor when an AC drive voltage is applied to the piezoelectric vibrators constituting the ultrasonic motor A device,
A physical quantity sensor that is installed with respect to the ultrasonic motor and steadily measures a physical quantity that is a determination index of occurrence of the unstable event;
Acoustic signal storage means for storing in advance an acoustic signal indicating a warning sound to be emitted when the unstable event occurs;
Acoustic signal readout control means for reading out the corresponding acoustic signal from the acoustic signal storage means when the value of the physical quantity measured by the physical quantity sensor exceeds a preset threshold value for the physical quantity;
Modulation means for obtaining a modulated wave signal by modulating the driving AC voltage by a predetermined method by the acoustic signal read by the acoustic signal readout control means,
The ultrasonic motor is
When the modulated wave signal obtained by the modulation means is applied to the piezoelectric vibrator, the process of electrical demodulation of the acoustic signal is caused by the self-demodulation phenomenon of the ultrasonic wave emitted from the ultrasonic motor. Function to emit the warning sound directly demodulated from the modulated wave signal without passing through ,
The physical quantity sensor is
A current sensor for measuring a current generated by the driving AC voltage;
A temperature sensor for measuring the temperature of the ultrasonic motor;
A rotational speed sensor for measuring the rotational speed of the ultrasonic motor; and
Comprising two or more rotation angle sensors for measuring the rotation angle of the ultrasonic motor,
The acoustic signal indicating the warning sound is:
It consists of two or more different acoustic contents that can audibly identify the type of the physical quantity measured by the two or more physical quantity sensors.
An ultrasonic motor condition monitoring device characterized by that. The modulating means includes
When the ultrasonic motor includes a plurality of systems of piezoelectric vibrators for realizing multi-degree-of-freedom rotational driving, one system of the plurality of systems of piezoelectric vibrators drives the ultrasonic motor. When a period of time that is not involved in control occurs
In the period, the drive AC voltage having a certain amplitude to be applied to the piezoelectric vibrator of the one system is selectively modulated.
The ultrasonic motor state monitoring apparatus according to claim 1 . The amplitude modulation means includes
Ri amplitude modulating means der which modulates the amplitude of the driving AC voltage waveform of the acoustic signal,
When a control signal used for performance control of the ultrasonic motor is superimposed on the driving AC voltage,
The drive AC voltage is amplitude-modulated by the acoustic signal subjected to intensity setting for obtaining a modulation rate of a level that can ensure stable control of the ultrasonic motor by the control signal.
The ultrasonic motor state monitoring apparatus according to claim 1 .

Images