JPH0739174A - Drive controller for ultrasonic motor - Google Patents

Abstract

PURPOSE:To control ultrasonic motors in such a manner that a required difference in output is produced between them. CONSTITUTION:The drive controller for ultrasonic motors comprises first and second ultrasonic motor driving means 110, 120 for driving first and second ultrasonic motors 101, 102, and output difference detecting means 104 for detecting a difference of the outputs of the first and second ultrasonic motors, and output difference control means 105 for setting a predetermined output difference at the outputs of the first and second ultrasonic motors and so controlling both or one of the first and second ultrasonic motor driving means as to generate a difference set at the outputs of the first and second ultrasonic motors based on a detected result of the means 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor drive controller for driving and controlling a plurality of ultrasonic motors.

[0002]

2. Description of the Related Art Conventionally, a plurality of ultrasonic motors have been used.
When driving a rotating body such as two rotating shafts or a rotating cylinder,
The relationship between the generated torque (output) and the rotation speed may vary depending on the ultrasonic motors. Therefore, the generated torques from the ultrasonic motors may differ at a certain rotation speed.

This will be described with reference to FIG. FIG. 2 is a diagram showing a torsion moment generated in each part of the output shaft of each ultrasonic motor (hereinafter, the ultrasonic motor is shown as USM in the drawings). The first ultrasonic motor 201 and the second ultrasonic motor 202 are connected by a shaft 203, and a load means 204 is attached to the shaft 203. In the case as shown in FIG. 2, the generated torques T1 and T2 with respect to the rotation speed are set to the respective ultrasonic motors 20.
When they are the same, the generated torques from the ultrasonic motors 201 and 202 are equal.

[0004]

However, the generated torques T1 and T2 with respect to the rotational speed are different from those of the ultrasonic motors 201 and 2, respectively.
02, the ultrasonic motors 201, 2
The generated torques T1 and T2 from No. 02 are different as shown by the broken line, and the share ratio of the load torque TL is different (the sum of the generated torques T1 and T2 is the load torque TL). To this end, both ultrasonic motors 201, 202
There was a problem that he could not fully exercise his ability.

In order to solve such a problem, the applicant of the present invention can control the output of both ultrasonic motors by controlling the drive of the ultrasonic motor (Japanese Patent Application No. 4-2330).
92) has already been proposed.

However, due to design considerations, when two or more ultrasonic motors having different capabilities are connected, if the outputs from the respective ultrasonic motors are the same, a load may be applied to the ultrasonic motor having a small capability. The load may be too small or the load may be too small for an ultrasonic motor having a large capacity. Therefore, there has been a problem that the load sharing of each ultrasonic motor has to be changed depending on the ability.

When two or more ultrasonic motors are used as driving sources for wheels to move a moving body (see FIG. 11)
In addition, the method of adjusting the output of each ultrasonic motor is a very effective method when going straight in the traveling direction. However, there is a problem that the output (generated torque and rotation speed) from each ultrasonic motor has to be changed when the vehicle turns right and left.

In order to solve such a problem, the present invention provides a drive control device for an ultrasonic motor that can positively control the output difference when the output difference is required for each ultrasonic motor. The purpose is to provide.

[0009]

In order to solve the above-mentioned problems, a first solution means of a drive control device for an ultrasonic motor according to the present invention is a first drive means for driving a first and a second ultrasonic motor.
And a second ultrasonic motor driving means, an output difference detecting means for detecting a difference between outputs of the first and second ultrasonic motors, an output of the first ultrasonic motor and an output of the second ultrasonic motor. Is set to a predetermined output difference, and based on the detection result of the output difference detection means, the first or the second ultrasonic wave is generated so that the difference set in the outputs of the first and second ultrasonic motors is generated. Output difference control means for controlling both or one of the sonic motor drive means is provided.

The second solving means includes an output difference setting means for setting a predetermined output difference between the output of the first ultrasonic motor and the output of the second ultrasonic motor, and the output difference control means. Is based on the detection result of the output difference detection means and the set value of the output difference setting means, so that the difference set in the outputs of the first and second ultrasonic motors occurs, Two or more ultrasonic motor driving means are controlled.

In a third solution means, the output difference control means controls the frequency of a drive signal input to the first or second ultrasonic motor. In a fourth solution means, the output difference control means controls an input voltage of a drive signal input to the first or second ultrasonic motor. In a fifth solution means, the output difference control means controls a frequency and an input voltage of a drive signal input to the first or second ultrasonic motor.

[0012]

According to the present invention, the output difference control means controls the first and second ultrasonic motors so that a predetermined output difference is generated between the first and second ultrasonic motors.
Alternatively, the second ultrasonic motor driving means is controlled. Further, the output difference setting means sets a predetermined output difference, and the output difference detection means detects the output difference between the first and second ultrasonic motors, and outputs the detection result and the set value of the output difference setting means. Based on the output difference control means, the first or second ultrasonic motor drive means is controlled so that a predetermined output difference is generated between the first ultrasonic motor and the second ultrasonic motor.

[0013]

EXAMPLES (First Example) The present invention will be described in more detail below with reference to the drawings and the like. Figure 1
1 is a block diagram showing a first embodiment of a drive control device for an ultrasonic motor according to the present invention. The first drive means 110 outputs the drive signal to the first oscillating means 113 and the drive signal to the second oscillator means 113.
First phase shifting means 114 for dividing into two and first amplifying means 115a, 11 for amplifying the driving signal divided into two, respectively.
5b and. The first ultrasonic motor 101 has a first
Piezoelectric body 111a and its piezoelectric body 111 excited by the input of the amplification drive signal from the amplification means 115a and 115b.
a first stator 111 having an elastic body 111b joined to a and generating a progressive vibration wave on the drive surface by its excitation;
The first moving element 112 is in pressure contact with the driving surface of the elastic body 111b and is driven by the progressive vibration wave.

Similarly, the second drive means 120 outputs the drive signal to the second oscillating means 123 and the drive signal to the second drive means 123.
The second phase shifting means 124 which divides into two and the second amplifying means 125a and 12 which respectively amplifies the driving signal divided into two.
5b and. The second ultrasonic motor 102 has a second
Piezoelectric body 121a and its piezoelectric body 121 excited by the input of the amplification drive signal from the amplifying means 125a and 125b.
A second stator 121 having an elastic body 121b joined to a and generating a progressive vibration wave on the driving surface by the excitation.
And a second moving element 122 which is brought into pressure contact with the driving surface of the elastic body 121b and is driven by the progressive vibration wave.

The first moving element 112 and the second moving element 122 are
They are connected by the output shaft 103. The output difference detection means 104 is means for detecting a difference in output value between the first ultrasonic motor 101 and the second ultrasonic motor 102. The output difference control means 105 determines the first ultrasonic motor 101 and the second ultrasonic motor 1 according to the result of the measurement value of the output difference detection means 104.
02 is a means for controlling the drive signal of the second oscillating means 123 so as to cause a predetermined output difference with respect to 02.

Next, the operation of the first embodiment will be described. The drive signal from the first oscillating means 113 is the first phase shifting means 11
4 and the first amplifying means 115 to be transmitted to the first stator 111. As a result, a progressive vibration wave is generated on the drive surface of the first stator 111, and the first mover 112 is driven. The drive signal from the second oscillating means 123 is also transmitted to the second stator 121 via the second phase shifting means 124 and the second amplifying means 125. As a result, a progressive vibration wave is generated on the drive surface of the second stator 121, and the second mover 122 is driven.

At this time, the output difference detecting means 102 has the first
The output difference between the ultrasonic motor 101 and the second ultrasonic motor 102 is detected. The output difference is detected by Japanese Patent Application No. 4-23309.
There is a method of detecting the difference in the amount of twist of the shaft shown in FIG. 2 and a method of detecting the difference in the voltage of the vibration signal from the mechanical-electrical conversion element provided on the stator, which will be described in detail in the second embodiment. .
The output difference control means 103 controls the drive signal of the second oscillating means 123 so that the outputs detected by the output difference detection means 102 have a predetermined difference.

In the first embodiment, the second oscillating means 12
The drive signal of No. 3 is controlled, but the first oscillating means 1
13 may be controlled (see the broken line in FIG. 1), or both the first and second oscillating means 113 and 123 may be controlled.

(Second Embodiment) FIG. 3 is a block diagram showing a second embodiment of the drive control apparatus for the ultrasonic motor according to the present invention. The first driving means includes a first oscillating means 13 which emits a driving signal and a first phase shifting means 1 which divides the driving signal into two.
4 and first amplifying means 15a and 15b for respectively amplifying the two divided drive signals. The first ultrasonic motor 1 is joined to the piezoelectric body 11a and the piezoelectric body 11a which are excited by the input of the amplification drive signal from the first amplifying means 15a and 15b, and the progressive vibration wave is generated on the drive surface by the excitation. First stator 11 having elastic body 11b
And a first moving element 12 that is pressed against the driving surface of the elastic body 11b and is driven by the progressive vibration wave.

Similarly, the second driving means respectively outputs the second oscillating means 23 which emits a driving signal, the second phase shifting means 24 which divides the driving signal into two, and the driving signal which is divided into two. It has the 2nd amplification means 25a, 25b which amplifies. The second ultrasonic motor 2 includes the second amplifying means 25a and 2a.
A piezoelectric body 21a excited by the input of an amplified drive signal from 5b and a second stator 21 having an elastic body 21b joined to the piezoelectric body 21a and generating a progressive vibration wave on the drive surface by the excitation; The second moving element 22 is in pressure contact with the driving surface of the body 21b and is driven by the progressive vibration wave.

The first moving element 12 and the second moving element 22 are connected by the output shaft 3. The output difference detection means 4 is provided on the piezoelectric body 21 a of the second ultrasonic motor 2 and the vibration signal voltage value output from the mechanical-electrical conversion element 11 ap provided on the piezoelectric body 11 a of the first ultrasonic motor 1. It is means for detecting the difference between the vibration signal voltage value output from the mechanical-electrical conversion element 21ap. The output difference setting means 6 is means for setting a predetermined output difference between the two ultrasonic motors 1 and 2. The output difference control means 5 causes the first ultrasonic motor 1 and the second ultrasonic motor 2 to have the output difference set by the output difference setting means 6 according to the result of the measurement value of the output difference detection means 4. It is a means for controlling the drive signal of the second oscillating means 23.

Next, the operation of the second embodiment will be described. The drive signal from the first oscillating means 13 is transmitted to the first stator 11 via the first phase shifting means 14 and the first amplifying means 15. As a result, a progressive vibration wave is generated on the drive surface of the first stator 11, and the first mover 12 is driven. Driving of the moving element by the progressive vibration wave is described in, for example, Japanese Patent Publication No. 1-173.
Since it has been described by No. 54, etc., the description is omitted here. The drive signal from the second oscillating means 23 is also transmitted to the second stator 21 via the second phase shifting means 24 and the second amplifying means 25. As a result, a progressive vibration wave is generated on the drive surface of the second stator 21, and the second mover 22 is driven.

At this time, the output difference detecting means 4 detects the vibration signal voltage value output from the mechanical-electrical conversion element 11ab provided on the piezoelectric body 11a of the first ultrasonic motor 1 and the second ultrasonic motor 2. The difference between the vibration signal voltage value output from the mechanical-electrical conversion element 21ab provided on the piezoelectric body 21a is detected.

FIG. 4 is a diagram showing the relationship between the drive signal frequency, the vibration signal voltage from the mechanical-electrical conversion element provided on the piezoelectric body, and the rotation speed. The rotation speed of the ultrasonic motor under a predetermined load can be obtained from the vibration signal voltage from the mechanical-electrical conversion element provided on the piezoelectric body of the ultrasonic motor. FIG. 5 is a diagram showing the relationship between the torque generated by the ultrasonic motor and the rotation speed. The relationship between the torque generated at a certain frequency and the rotation speed is also schematically shown in FIG.
The generated torque for a certain rotation speed can also be obtained from the vibration signal voltage from the mechanical-electrical conversion element. Therefore, by measuring the difference between the two vibration signal voltages,
It is possible to detect the output difference between the two ultrasonic motors 1 and 2. The output difference control means 5 sets the output difference set by the output difference setting means 6 according to the output difference detection result of the two ultrasonic motors 1 and 2 of the output difference detection means 4,
The drive signal of the oscillation means 23 is controlled.

As shown in FIG. 5, the ultrasonic motors 1, 2
The relationship between the generated torque and the rotation speed at a certain drive frequency changes depending on the frequency of the drive signal. Therefore, if you want to increase the generated torque, lower the frequency of the drive signal,
To reduce the generated torque, the frequency of the drive signal may be increased. By doing so, a predetermined output difference can be automatically obtained even if the adjustment steps of the ultrasonic motors 1 and 2 are omitted, and even when the rotation speed is changed to a desired value, It is possible to automatically adjust to a predetermined output difference according to the rotation speed at that time.

First ultrasonic motor 1 and second ultrasonic motor 2
In the case of controlling not only the torque generated by and the rotation speed of the connecting shaft 3, the vibration of the voltage non-applied portion of the first piezoelectric body 11ap is disclosed, for example, as disclosed in JP-A-61-251490. By detecting the phase difference between the signal voltage waveform and the input voltage waveform and correcting the frequency of the drive signal of the oscillating means 13 by the output control means (not shown) according to the detected output value so as to control the rotation speed and the like. Good. In addition, an encoder is provided on the connecting shaft 4 to measure the rotation speed,
A method may be used in which the frequency of the drive signal of the oscillating means 13 is corrected by the output control means (not shown) based on the measured value.
By doing so, both the rotation speed and the generated torque can be controlled.

Next, a method from detecting the output difference to controlling the oscillating means will be described with reference to FIG. First, the terminal is the piezoelectric body 11a of the first ultrasonic motor 1.
The mechanical-electrical conversion element 11 ap provided above is connected to the mechanical-electrical conversion element 21 ap provided on the piezoelectric body 21 a of the second ultrasonic motor 1, and the terminal thereof is the stator 12 of the first ultrasonic motor 1. , And the terminal obtains the vibration signal voltage of the stator 2 of the second ultrasonic motor 2.

The difference between these vibration signal voltages V1 and V2 is
As described with reference to FIG. 4, it can be regarded as the difference in the output (generated torque) between the first ultrasonic motor 1 and the second ultrasonic motor 2. Therefore, the difference between the generated torques of the first and second ultrasonic motors 1 and 2 can be adjusted to the set value by the difference between the voltage V2 and the voltage V1.

The difference between the voltage V2 and the voltage V1 is calculated by the output difference detecting means 4 (Vd = V1-V2). The resulting voltage Vd (= V1-V2) is positive when the vibration voltage of the first ultrasonic motor 1 is large, and is negative when the second ultrasonic motor 2 is large. The value of the voltage Vd indirectly indicates the relative difference between the current generated torques of the two ultrasonic motors 1 and 2, and the larger the generated torque difference, the larger the absolute value thereof.

On the other hand, the output difference setting unit 6 sets the output difference value of the two ultrasonic motors 1 and 2, and the value is the voltage Vp.
Is output to the first calculation unit 51. The voltage Vp is also set to a positive value when the output of the first ultrasonic motor 1 is set larger than that of the second ultrasonic motor 2 and a negative value when the output of the first ultrasonic motor 1 is set small.

The first calculation unit 51 detects the voltage V of the detected difference.
The difference between d and the set difference voltage Vp is calculated, and is multiplied by a coefficient (−1 × a) to boost the voltage to the control voltage.
The value Vrr (= -1 * a * (Vd-Vp)) indicates the relative correction amount between the current output difference between the first and second ultrasonic motors 1 and 2 and the set value. The larger the amount to be corrected, the larger the absolute value.

Next, the second calculation unit 52 adds the correction amount Vrr by the voltage Vf from the feedback unit 54, and an absolute correction amount Vr (= Vrr + Vf) with respect to the reference voltage Vo. Decide. Next, the third calculation unit 53 adds the voltage Vr and the reference voltage Vo from the terminal, and the value Vi (= Vo + Vr) is output to the voltage controlled oscillator 23a constituting the oscillating means 23.

The voltage controlled oscillator 23a generates a signal having a frequency corresponding to the Vi value and outputs it from a terminal to a waveform shaping section (not shown). As a result, the torque generated by the second ultrasonic motor 2 and the rotation speed characteristic change. Then, the difference between the vibration signal voltages of the ultrasonic motors 1 and 2 at that time is input again from the terminal, and Vrr is calculated.

On the other hand, the feedback section 54 receives the voltage Vi from the third operation section 53, obtains the difference from the reference voltage Vo, and returns the value Vf (= Vi-Vo) to the second operation section 52. . Then, the second arithmetic unit 52 adds the voltage Vf and the re-input voltage Vrr, and further the third arithmetic unit 53 adds the reference voltage Vo to output the voltage Vi.

Next, the operation of correcting the output difference between the first ultrasonic motor 1 and the second ultrasonic motor 2 will be described based on the second embodiment. First, it is assumed that the torque generated by the second ultrasonic motor 2 with respect to the first ultrasonic motor 1 is smaller than the set value. In this case, the frequency of the drive signal of the second ultrasonic motor 2 may be reduced and the generated torque for a certain rotation speed may be increased. Here, since the voltage Vd becomes larger than the voltage Vp, the voltage Vrr becomes negative, the voltage Vr and the voltage Vi are acted so as to become small, and the frequency of the drive signal from the voltage controlled oscillator 23a becomes small.

On the contrary, the second ultrasonic wave for the first ultrasonic motor 1
It is assumed that the generated torque of the ultrasonic motor 21 is larger than the set value. In this case, the second ultrasonic motor 21
The correction of increasing the frequency of the drive signal and decreasing the generated torque for a certain rotation speed may be performed. Here, since the voltage Vd is smaller than the voltage Vp, the voltage Vrr becomes positive, the voltage Vr and the voltage Vi are increased, and the frequency of the drive signal from the voltage controlled oscillator 23a increases.

In the second embodiment, the oscillating means is controlled by changing the frequency of the drive signal, but a method of changing the voltage of the drive signal may be used. FIG. 7 is a diagram showing the relationship between the torque generated by the ultrasonic motor and the rotation speed. The relationship between the generated torque and the rotation speed of the ultrasonic motors 1 and 2 at a certain drive frequency changes depending on the voltage of the drive signal. Therefore, when the generated torque is desired to be increased, the voltage of the drive signal is increased, and when the generated torque is desired to be decreased, the voltage of the drive signal is decreased.

(Third Embodiment) FIG. 8 is a diagram for explaining a voltage control method of an ultrasonic motor drive controller according to a third embodiment. In each of the embodiments described below, only characteristic parts are shown, and parts having the same functions as those in the second embodiment are designated by the same reference numerals, and duplicated description will be omitted.
First, the terminal is the piezoelectric body 11 of the first ultrasonic motor 1.
The mechanical-electrical conversion element 11ap provided on the a and the mechanical-electrical conversion element 21ap provided on the piezoelectric body 21a of the second ultrasonic motor 2 are connected to each other, and the terminals are the stator of the first ultrasonic motor 1. The vibration signal voltage of 12 and the vibration signal voltage of the stator 22 of the second ultrasonic motor 2 are obtained at the terminals.

The difference between these vibration signal voltages V1 and V2 is
As described with reference to FIGS. 4 and 5, it can be regarded as a difference in output (generated torque) between the first ultrasonic motor 1 and the second ultrasonic motor 2. Therefore, the difference between the generated torques of the first and second ultrasonic motors 1 and 2 can be adjusted to the set value by the difference between the voltage V2 and the voltage V1.

The difference between the voltage V2 and the voltage V1 is calculated by the output difference detecting means 4 (Vd = V1-V2). The resulting voltage Vd (= V1-V2) is positive when the vibration voltage of the first ultrasonic motor 1 is large, and is negative when the second ultrasonic motor 2 is large. The Vd value indirectly indicates the relative difference between the current generated torques of the two ultrasonic motors 1 and 2, and the larger the generated torque difference, the larger the absolute value thereof.

On the other hand, the output difference setting unit 6 sets the output difference value of the two ultrasonic motors 1 and 2, and the value is the voltage Vp.
Is output to the first calculation unit 61. The voltage Vp is also set to a positive value when the output of the first ultrasonic motor 1 is set larger than that of the second ultrasonic motor 2 and a negative value when the output of the first ultrasonic motor 1 is set small.

The first calculation section 61 detects the voltage V of the detected difference.
The difference between d and the set difference voltage Vp is calculated, and is multiplied by a coefficient a to boost the control voltage. Its value Vrr
(= A × (Vd−Vp)) indicates the relative correction amount between the current output difference between the first and second ultrasonic motors 1 and 2 and the set value, and the amount to be corrected is The larger the value, the larger the absolute value.

Next, the correction amount V
rr is added by the voltage Vf from the feedback section 64 to determine an absolute correction amount Vr (= Vrr + Vo) with respect to the reference voltage Vo. Next, in the third calculation unit 63, the voltage Vr and the reference voltage Vo from the terminal are added, and this value Vi (= Vr + Vo) is added to the A / D conversion unit 65.
Is output to the feedback unit 64.

The A / D converter 65 transmits the digital signal Sd corresponding to the Vi value to the amplification amount controller 66. The amplification amount control unit 66 sends the control signal Ss corresponding to the Sd value to the amplification unit 23b.

The second oscillating means 23 is composed of an oscillating section 23a and an amplifying section 23b, amplifies the drive signal from the oscillating section 23a to the amplification amount selected by the amplifying section 23b, and then the phase shifting means. Communicate to. The amplification section 23b amplifies the drive signal from the oscillation section 23a in the second oscillating means 23 by the amplification amount corresponding to the control signal Ss. When the Va value is large, the amplification amount in the amplification unit 23b is controlled to be large, and when the Va value is small, the amplification unit 2 is controlled.
The amplification amount in 3b is controlled to be small.

On the other hand, the feedback section 64 receives the voltage Vi from the third calculating section 63, obtains the difference from the reference voltage Vo, and obtains the voltage value Vf (= Vi-Vo) from the second calculating section 62. Return to. Then, in the second calculation unit 62, the voltage Vf and the re-input voltage Vrr are added, and the third calculation unit 6 is further added.
The reference voltage Vo is added by 3 and the voltage Vi is output.

FIG. 9 is a diagram for explaining a method of selecting the amplification amount of the drive signal. The amplification amount control unit 66 is composed of a control signal generation unit capable of selecting a signal like a multiplexer and generating a control signal, and switching devices Q1 to Q8 such as MOS field effect transistors which can be turned on and off by the control signal. Has been done. The control signal generator of the amplification amount controller 66 receives the digital signal Sd from the A / D converter 65, and switches the switching elements Q1 to Q1 according to the signal Sd.
Q8 is selected, and the selected switching elements Q1 to Q8
The ON signal is transmitted to. Switching element Q turned on
1 to Q8 open the feedback section of the operational amplifier A1 to which the resistors Rf1 to Rf8 are connected.

In the feedback section of the operational amplifier A1, resistors Rf1 to Rf8 having different resistance values are connected in parallel, and the resistors Rf1 to Rf8 are switching elements Q1 to Q8 respectively connected in series. When the control signal is turned on, the amplification amount of the operational amplifier A1 can be determined.

In the third embodiment, in order to make the explanation easy to understand, the digital signal from the A / D converter 65 is set to 8 bits, and the switching element Q and the resistor Rf are each set to 8 bits.
The number of digital signals from the A / D converter 65 is 4
The number of bits may be four, and the number of switching elements Q and the number of resistors Rf may be four. The digital signal from the A / D converter 65 may be 16 bits, and the switching elements Q and the resistors Rf may be 16 in number, respectively, or more. The larger the number of bits, the number of switching elements, and the number of resistors, the finer the control becomes.

Next, the operation of correcting the output difference between the first ultrasonic motor 1 and the second ultrasonic motor 2 will be described based on the third embodiment. First, it is assumed that the torque generated by the second ultrasonic motor 2 with respect to the first ultrasonic motor 1 is smaller than the set value. In this case, the voltage of the drive signal of the second ultrasonic motor 2 may be increased and the generated torque for a certain rotation speed may be increased. Where voltage V
Since d becomes larger than the voltage Vp, the voltage Vrr becomes positive and the voltage Vr and the voltage Vi are acted so as to become large, and a signal for increasing the amplification amount by the A / D conversion unit 65 is transmitted to the amplification amount control unit 66. To be done. The amplification amount control unit 66 controls the resistors Rf1 to Rf of the operational amplifier A1 for increasing the amplification amount.
Turning ON switching elements Q1 to Q8 connected to 8
To As a result, the voltage of the drive signal from the oscillator 23a increases.

On the contrary, the second ultrasonic wave for the first ultrasonic motor 1
It is assumed that the generated torque of the ultrasonic motor 2 is larger than the set value. In this case, the voltage of the drive signal of the second ultrasonic motor 2 may be reduced and the generated torque for a certain rotation speed may be reduced. Where voltage Vd
Becomes smaller than the voltage Vp, the voltage Vrr becomes negative, the voltage Vr and the voltage Vi are reduced, and a signal for reducing the amplification amount in the A / D conversion unit 65 is transmitted to the amplification amount control unit 65. The amplification amount control unit 65 turns on the switching elements Q1 to Q8 connected to the resistors Rf to Rf8 of the operational amplifier A1 for reducing the amplification amount. As a result, the voltage of the drive signal from the oscillation unit 23a becomes small.

(Fourth Embodiment) In the second and third embodiments, the frequency and voltage of the drive signal from the oscillating unit 23 are controlled respectively, but in the fourth embodiment, the oscillating unit 23 is controlled.
The voltage and the frequency of the drive signal from are controlled. The control method will be described with reference to FIG. Fourth
The control method of the embodiment is the same as the method shown in FIG. 6, but the part ahead of the third calculation unit 53 is changed as follows. The output value Vi from the third calculation unit 53 is set to the oscillation unit 23 and A
Input to both of the / D conversion units 75. The oscillator 23 is
In the same way as described above, it is transmitted to the voltage controlled oscillator 77,
Controls the frequency of the drive signal. On the other hand, the A / D converter 75
1 is transmitted to the amplification amount control unit 76 in the same manner as described above, and controls the voltage of the drive signal.

When increasing the output of the ultrasonic motor to be controlled, the frequency f1 is lowered and the voltage is raised.
Further, when the output of the controlled ultrasonic motor is decreased, the frequency f1 is increased and the voltage is decreased. In this way, the frequency and voltage controls are opposite for each Vi value. Therefore, in the fourth embodiment, the Vi value is = Vo +
Since it is Vr, Vi input to the A / D conversion unit 75
The value is calculated as follows: b * (-1 * Vi + 2Vo) = b * (Vo-Vr) (b: coefficient), and A / D conversion is performed according to the calculated value.

The method of controlling the driving frequency of the oscillating means by using FIG. 6, the method of controlling the driving signal voltage of the oscillating means by using FIG. 8, and the driving frequency and driving of the oscillating means by using FIG. Although the method of controlling the signal voltage has been described, the control of the drive frequency and the drive signal voltage is not limited to the methods of these embodiments, and it is within the scope of the present invention if the drive frequency and the drive signal voltage can be controlled by other methods. .

(Fifth Embodiment) In the first to fourth embodiments, the case where a plurality of ultrasonic motors are connected by one connecting shaft or the like is taken as an example, but the plurality of ultrasonic motors are not connected by a connecting shaft or the like. The present invention can be applied to the case of driving by. 11 and 1
FIG. 2 is a diagram illustrating a fifth embodiment of the ultrasonic motor according to the present invention. There is a carrying device 330 as shown in FIG. 11, and the drive sources of the two drive wheels 331 and 332 are composed of two ultrasonic motors 301 and 302, respectively. These drive wheels 331, 332 have shafts 331a, 3
32a is not connected. This carrier 330
When going straight, the torques and rotational speeds generated from the two drive wheels 331 and 332 must be the same.
Therefore, the torques and the rotational speeds generated from the two ultrasonic motors 301 and 302 must be the same. Further, when turning, for example, when turning left, the torque and rotation speed generated from the right drive wheel 331 must be greater than those of the left drive wheel 332. Therefore, the torque and rotation speed generated from the right ultrasonic motor 301 must be larger than those of the left ultrasonic motor 302.

Here, in the case of going straight, as shown in FIG. 12, by setting the output difference of the output difference setting means 306 to zero, the torque generated from the two ultrasonic motors 301 and 302 and The rotation speeds can be made substantially the same, and the torques generated from the two drive wheels 331 and 332 and the rotation speeds become substantially the same. Further, in the case of bending, by setting the output difference of the output difference setting means 306 to a predetermined value, it is possible to give a difference in the torque and the rotational speed generated from the two ultrasonic motors 301 and 302, Two
Differences occur in the torque generated from the three drive wheels 331 and 332 and the rotational speed.

(Sixth Embodiment) FIG. 13 is a view for explaining a sixth embodiment of the drive control device for the ultrasonic motor according to the present invention. In the sixth embodiment, the second ultrasonic motor 402 is designed to have a larger outer diameter than the first ultrasonic motor 401. Also in this case, similarly to the second embodiment described above, it is possible to control so as to have the output difference between the ultrasonic motors 401 and 402. According to the sixth embodiment, even if the sizes of the two ultrasonic motors 401 and 402 are different due to the structure of the incorporated device, the small first ultrasonic motor 40
The second ultrasonic motor 4 which is large and has no load on 1
It is possible to perform control to exert the ability of 02.

(Seventh Embodiment) FIG. 14 is a diagram for explaining a seventh embodiment of the drive control apparatus for the ultrasonic motor according to the present invention. In the seventh embodiment, the first ultrasonic motor 501 includes the piezoelectric body 511a and its piezoelectric body 51 which are excited by the input of the amplification drive signal from the first amplification means 515a, 515b.
A first stator 511 having an elastic body 511b joined to 1a and generating a progressive vibration wave on a driving surface by its excitation.
And a moving element 542 which is brought into pressure contact with the driving surface of the elastic body 511b and is driven by the progressive vibration wave. On the other hand, the second ultrasonic motor 502 is joined to the piezoelectric body 521a excited by the input of the amplification drive signal from the first amplification means 525a, 525b and the piezoelectric body 521a, and a progressive vibration wave is generated on the drive surface by the excitation. It is composed of a first stator 521 having an elastic body 521b to be generated, and a mover 542 which is in pressure contact with the driving surface of the elastic body 521b and is driven by the progressive vibration wave. That is, in the seventh embodiment, the first and second ultrasonic motors 50
1 and 502 share one moving element 542, and the moving element 542 is provided with an output shaft (not shown).
Also in the case of the seventh embodiment, the first and second ultrasonic motors 50
It is possible to control by giving an output difference to 1 and 502.

(Modification) The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also included in the present invention. For example, in the above-described embodiment, the method of controlling the output of the ultrasonic motor by detecting the vibration signal from the mechanical-electrical conversion element provided in the elastic body has been described. Current, a method of detecting the phase difference between the drive signal input to the ultrasonic motor and the vibration signal from the mechanical-electrical conversion means installed in the vibrator of the ultrasonic motor, elasticity of the connecting shaft, etc. The method of detecting the deformation amount and other methods can also detect the output of the ultrasonic motor, and the method of controlling the output of the ultrasonic motor by the detected amount is within the scope of the present invention.

Further, in the above-mentioned embodiment, the piezoelectric body is attached to the electro-mechanical conversion element for changing the electrical energy into the mechanical energy, which is joined to the elastic body to generate the progressive vibration wave. Although used, an electrostrictive element may be used.

[0061]

As described above, according to the present invention,
In a case where a plurality of ultrasonic motors require an output difference between the ultrasonic motors, the outputs from the first ultrasonic motor and the second ultrasonic motor are detected, and the detection signals from the output detecting means are detected. Based on the result, the output difference can be generated in the first and second ultrasonic motors.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a drive control device for an ultrasonic motor according to the present invention.

FIG. 2 is a diagram showing a twisting moment generated in each part of the output shaft.

FIG. 3 is a diagram showing a second embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 4 is a diagram showing a relationship between a drive signal frequency, a vibration signal voltage from a mechanical-electric element, and a rotation speed.

FIG. 5 is a diagram showing a relationship between torque generated by an ultrasonic motor and rotation speed.

FIG. 6 is a diagram illustrating output control of the second embodiment.

FIG. 7 is a diagram showing the relationship between the torque generated by the ultrasonic motor and the rotation speed.

FIG. 8 is a diagram showing a third embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 9 is a diagram illustrating a method of selecting an amplification amount of a drive signal.

FIG. 10 is a diagram showing a fourth embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 11 is an external view showing an apparatus using a fifth embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 12 is a diagram showing a fifth embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 13 is a diagram showing a sixth embodiment of the drive control device for the ultrasonic motor according to the present invention.

FIG. 14 is a diagram showing a seventh embodiment of the drive control device for the ultrasonic motor according to the present invention.

[Explanation of sign]

1, 101, 201, 301, 401, 501 First ultrasonic motor 2, 102, 202, 302, 402, 502 Second ultrasonic motor 3, 103, 203, 403 Connecting shaft 4, 104, 304, 404, 504 Output difference detection means 5, 105, 305, 405, 505 Output difference control means 6, 401, 501 Output difference setting means 11ap, 21ap Mechanical-electrical conversion element

Claims (5)

[Claims] 1. A first and second ultrasonic motor driving means for driving the first and second ultrasonic motors, and an output difference detecting means for detecting a difference between outputs of the first and second ultrasonic motors. A predetermined output difference is set between the output of the first ultrasonic motor and the output of the second ultrasonic motor, and the outputs of the first and second ultrasonic motors are based on the detection result of the output difference detecting means. And an output difference control means for controlling both or one of the first or second ultrasonic motor drive means so that the difference set in (1) is generated. 2. The output of the first ultrasonic motor and the second ultrasonic motor
The output difference setting means for setting a predetermined output difference to the output of the ultrasonic motor, the output difference control means, based on the detection result of the output difference detection means and the set value of the output difference setting means, First
2. The ultrasonic wave according to claim 1, wherein both or one of the first or second ultrasonic motor drive means is controlled so that a difference between the outputs of the first and second ultrasonic motors is set. Motor drive control device. 3. The drive control device for an ultrasonic motor according to claim 1, wherein the output difference control means controls a frequency of a drive signal input to the first or the second ultrasonic motor. . 4. The ultrasonic motor drive control according to claim 1, wherein the output difference control means controls an input voltage of a drive signal input to the first or second ultrasonic motor. apparatus. 5. The ultrasonic motor according to claim 1, wherein the output difference control means controls a frequency and an input voltage of a drive signal input to the first or second ultrasonic motor. Drive controller.