JP2017022938A - Control apparatus and control method for vibration type actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus for vibration type actuator, capable of improving accuracy of torque calculation.SOLUTION: The control apparatus for vibration type actuator, moving a mobile body by a frictional force relative to a vibrator, includes: a frequency command unit (2) for commanding a frequency of an AC voltage; an AC voltage generation part (4, 5) for generating an AC voltage which is applied to an electrical-mechanical energy conversion element and has a frequency commanded by the frequency command unit; a speed detection unit for detecting a speed of the mobile body; vibrator amplitude acquisition units (9, 10) for acquiring a mechanical amplitude of the mobile body; and a torque calculation unit (7) for calculating a torque of the mobile body on the basis of the frequency commanded by the frequency command unit, the speed detected by the speed detection unit and the mechanical amplitude acquired by the vibrator amplitude acquisition unit. The frequency command unit commands a frequency according to a difference between the torque calculated by the torque calculation unit and a torque command value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device and a control method for a vibration type actuator.

  The torque of the vibration type actuator is changed by a frictional force generated between the vibration body and the rotor surface as a moving body. Further, the generated frictional force changes according to the amplitude of the vibration wave excited by the vibrating body. Therefore, the torque can be controlled by changing the amplitude and frequency of the AC voltage applied to the electro-mechanical energy conversion element provided in the vibrating body.

  In order to calculate the generated torque, a method is known in which an electrical equivalent circuit composed of a piezoelectric body and a mechanical vibration body is used, and the torque is obtained using the mechanical arm current flowing in the circuit as a substitute characteristic of the magnitude of the vibration body amplitude. ing. As one of such methods, Patent Document 1 discloses the following technique. First, the mechanical arm current is detected, and the no-load rotation speed at the current value is calculated. The output torque is calculated from the current rotation speed and the no-load rotation speed, and a frequency controller that matches the set output torque is provided to control the required torque to be equal to the actual output torque. .

JP-A-2-101974

  In the method of Patent Document 1 described above, since there is no means for calculating the frictional force generated between the vibrating body and the rotor in torque control of the vibration type actuator, there is a problem in torque calculation accuracy. Further, since mechanical arm current, which is a substitute characteristic, is used to detect mechanical vibration of the vibrating body, there is a problem in accuracy.

  An object of the present invention is to provide a control device and a control method for a vibration type actuator that can control torque with high accuracy by improving calculation accuracy of torque.

  The control device for the vibration type actuator of the present invention is a vibration type actuator in which the vibration body vibrates by applying an AC voltage to the electromechanical energy conversion element, and the moving body moves by the frictional force between the vibration body and the vibration body. A control device that generates a frequency command unit that commands the frequency of the AC voltage and an AC voltage that is applied to the electromechanical energy conversion element and that has a frequency commanded by the frequency command unit. AC voltage generation unit, speed detection unit for detecting the speed of the moving body, vibration body amplitude acquisition unit for acquiring the mechanical amplitude of the vibration body, frequency commanded by the frequency command unit, and speed detection unit A torque calculation unit that calculates the torque of the moving body based on the speed detected by the machine and the mechanical amplitude acquired by the vibration body amplitude acquisition unit, and the frequency Command unit, according to a difference between the torque and the torque command value calculated by the torque calculation unit, characterized in that the command frequency.

  According to the present invention, the torque of the moving body can be calculated with high accuracy, and the torque of the moving body can be controlled with high accuracy.

It is a figure which shows the structural example of a vibration type actuator. It is a block diagram which shows the structural example of the control apparatus of a vibration type actuator. It is a block diagram which shows the structural example of a torque calculation part. It is a figure for demonstrating rotor speed. It is a figure which shows the discrete spring model showing the frictional contact state of a vibrating body and a rotor. It is a figure which shows the relationship between a vibrating body amplitude, the sinking height of a rotor, and a position. It is a figure which shows a sticking area | region and a sliding area | region. It is a figure which shows the mode of the force added to the arbitrary points which the vibrating body and the rotor are contacting.

  FIG. 1A is a diagram illustrating a configuration example of a vibration type actuator according to an embodiment of the present invention. The vibration actuator includes a piezoelectric element 21, a vibrating body 22, a flexible substrate 23, and a rotor 26. The two vibrating bodies 22 sandwich the piezoelectric element 21. The flexible substrate 23 is connected to the piezoelectric element 21 and performs power feeding and voltage detection on the piezoelectric element 21. The rotor 26 is a moving body disposed on the upper surface of the vibrating body 22.

  FIGS. 1B to 1E are diagrams showing temporal changes in vibration of the vibrating body 22 of the vibration type actuator. The vibrating body 22 has a natural vibration mode of bending vibration in two orthogonal directions. When the vibrations of the two natural vibration modes are generated with phases different by 90 ° in time, the upper structure of the vibrating body 22 swings around the constricted portion as shown in FIGS. 1B to 1E. Rotates and vibrates. This vibration force is transmitted via a frictional force to the rotor 26 pressed against the upper portion of the vibrating body 22 by a pressing means (not shown), and is taken out as a rotational torque of the rotor 26. The rotor 26 is a moving body and rotates.

  FIG. 1H is a diagram showing one layer 27 of the piezoelectric elements 21 formed in a laminated structure. The layer 27 has four electrodes a +, a−, b +, b− for feeding. The four electrodes of the first layer 27 are supplied with A-phase and B-phase AC voltages via the flexible substrate 23. The alternating voltages of the A phase and the B phase are 90 ° different phases. The sign of each electrode a +, a−, b +, b− indicates the polarization direction, and the opposing electrodes are each polarized so as to have a polarity in the opposite direction. By applying the same drive voltage to the opposing electrodes, an excitation force in the opposite direction is generated, and vibrations in one natural vibration mode are excited corresponding to the A phase and the B phase, respectively. The piezoelectric element 21 is an electro-mechanical energy conversion element. Thereby, as shown in FIGS. 1B to 1E, the upper structure of the vibrating body 22 is rotationally vibrated.

  FIG. 1I is a diagram showing a piezoelectric element 21 having a laminated structure. Only one of the plurality of layers of the laminated structure of the piezoelectric elements 21 is the sensor layer 28. The sensor layer 28 includes a sensor s for detecting the mechanical amplitude of the vibrating body 22 as a voltage. Based on the phase difference between the voltage applied to the A-phase electrode a + and the output from the sensor s, the correlation between the speed and the frequency can be obtained. By obtaining this correlation, it is possible to acquire a change in the resonance frequency, prevent a rapid speed decrease in speed control, and perform a stable operation. In the present embodiment, the sensor s is used to detect the amplitude of the vibrating body 22 in order to calculate the torque of the rotor 26. The voltage output from the sensor s is output to the mechanical amplitude voltage converter 10 in FIG.

  As described above, the vibration type actuator applies an AC voltage to the piezoelectric element 21 to excite vibrations in the vibration body 22, and generates a frictional force with the rotor 26 that can move relative to the vibration body 22. And the rotor 26 is moved relative to the vibrating body 22.

  FIG. 2 is a diagram illustrating a configuration example of the control device for the vibration type actuator according to the present embodiment. The control device for the vibration type actuator is a torque control device for the vibration type actuator 6. The control device for the vibration type actuator includes a torque control unit 1, a frequency command unit 2, a pulse generation unit 4, a driver 5, a vibration type actuator 6, a torque calculation unit 7, a speed sensor 8, and an analog / digital conversion unit (A / D conversion). Part) 9 and a mechanical amplitude voltage converter 10. The vibration type actuator 6 is the vibration type actuator of FIG. Hereinafter, a control method of the vibration type actuator will be described.

  The frequency command unit 2 outputs a frequency command value 3 to the pulse generation unit 4 and the torque calculation unit 7 in order to command the frequency of the AC voltage. The pulse generation unit 4 generates a pulse signal having a frequency indicated by the frequency command value 3 and outputs the pulse signal to the driver 5. In the driver 5, the internal switching element is turned on by the pulse signal, and an AC voltage is applied to the piezoelectric element 21 of FIG. As described above, the pulse generation unit 4 and the driver 5 are AC voltage generation units that generate an AC voltage having a frequency indicated by the frequency command value 3 that is an AC voltage applied to the piezoelectric element 21. Thereby, in FIG. 1A, the vibrating body 22 vibrates and the rotor 26 rotates. The sensor s in FIG. 1G detects the mechanical amplitude of the vibrating body 22 and outputs a voltage indicating the mechanical amplitude of the vibrating body 22 to the mechanical amplitude voltage converter 10. The sensor s is a mechanical amplitude-voltage conversion element that converts the mechanical amplitude of the vibrating body 22 into a voltage.

  The speed sensor 8 is a speed detection unit that detects the rotation speed of the rotor 26 and outputs the rotation speed of the rotor 26 to the torque calculation unit 7. The machine amplitude voltage converter 10 receives a voltage signal indicating the magnitude of the machine amplitude of the vibrating body 22 from the sensor s, shapes the voltage signal, and is a voltage value suitable for the input range of the A / D converter 9. Convert to The A / D converter 9 converts the voltage signal converted by the mechanical amplitude voltage converter 10 from analog to digital, and outputs the digital voltage signal to the torque calculator 7. As described above, the mechanical amplitude voltage conversion unit 10 and the A / D converter 9 are vibration body amplitude acquisition units that acquire the mechanical amplitude of the vibration body 22 and output the mechanical amplitude to the torque calculation unit 7.

  The torque calculation unit 7 is based on the frequency command value 3 output from the frequency command unit 2, the speed detected by the speed sensor 8, and the voltage signal output from the A / D converter 9. The torque due to the rotation of the rotor 26 is calculated. Based on the torque calculated by the torque calculation unit 7, the torque control unit 1 outputs a control signal to the frequency command unit 2 so that the torque of the vibration actuator 6 becomes a torque command value (requested torque). Specifically, the torque control unit 1 calculates a difference between the torque calculated by the torque calculation unit 7 and the torque command value, and multiplies the difference by a control gain to generate a control signal. Output to the frequency command unit 2. The frequency command unit 2 outputs a frequency command value 3 according to the control signal. Thereby, the torque of the rotor 26 in the vibration type actuator 6 is controlled to a torque command value.

  The torque calculation unit 7 needs to obtain a frictional force generated between the vibrating body 22 and the rotor 26 in order to calculate the torque. The vibration type actuator 6 drives the rotor 26 in the contact area between the vibrating body 22 and the rotor 26 while repeating fixation and sliding. That is, at the contact portion between the vibrating body 22 and the rotor 26, there are a stick region and a slip region at a portion where the vibrating body 22 and the rotor 26 are in contact with each other. In the fixed region, the surface of the vibrating body 22 and the surface of the rotor 26 are gripped, and the speed of the vibrating body 22 and the rotor 26 is the same. On the other hand, in the slip region, slip occurs between the surface of the vibrating body 22 and the surface of the rotor 26, and the speeds of the vibrating body 22 and the rotor 26 are different. The frictional force that the rotor 26 receives in the slip region is different from the frictional force that the rotor 26 receives in the fixed region. Therefore, in order to obtain the frictional force, the torque calculation unit 7 needs to calculate the respective frictional forces in the fixed region and the sliding region in the sinking contact portion.

  FIG. 3 is a block diagram illustrating a configuration example of the torque calculation unit 7 of FIG. The torque calculation unit 7 includes a frequency input unit 11, a speed input unit 12, an amplitude value input unit 13, an adhesion height calculation unit 14, a subduction region calculation unit 15, a slip region adhesion region calculation unit 16, a friction force calculation unit 17, and A torque value output unit 18 is provided.

  The frequency input unit 11 converts the frequency command value 3 output from the frequency command unit 2 of FIG. 2 into a frequency used by the fixing height calculation unit 14, and outputs the converted frequency to the fixing height calculation unit 14. To do. The speed input unit 12 outputs the speed detected by the speed sensor 8 in FIG. 2 to the fixing height calculation unit 14. The amplitude value input unit 13 converts the voltage output from the A / D conversion unit 9 in FIG. 2 into the mechanical amplitude of the vibrating body 22, and converts the mechanical amplitude of the vibrating body 22 into the fixed height calculation unit 14 and the subduction region calculation unit. 15 is output.

  Based on the frequency output from the frequency input unit 11, the speed output from the speed input unit 12, and the machine amplitude output from the amplitude value input unit 13, the fixing height calculation unit 14 is described later with reference to FIG. The fixing height 19 shown in FIG. Then, the fixing height calculation unit 14 outputs the fixing height 19 to the slip region fixing region calculation unit 16.

  The subduction region calculation unit 15 is based on the machine amplitude output from the amplitude value input unit 13 and the mechanical characteristic parameters of the vibrator 22 and the rotor 26, and a subduction height 41 and its position 33 in FIG. Is calculated. Then, the subduction area calculation unit 15 outputs the subsidence height 41 and its position 33 to the slip area fixing area calculation unit 16.

  The slip region fixing region calculation unit 16 is based on the fixing height 19 output from the fixing height calculation unit 14, the subduction height 41 output from the subtraction region calculation unit 15, and its position 33. The slip region and the fixed region at the contact portion of the rotor 26 are calculated. That is, the slip region fixing region calculation unit 16 has a sliding region where the speeds of the vibrating body 22 and the rotor 26 are different from each other at the contact portion between the moving body 22 and the rotor 26 and a fixing region where the speeds of the moving body 22 and the rotor 26 are the same. This is a slip region fixing region detection unit for detecting Here, the slip region fixing region calculation unit 16 refers to the mechanical characteristic parameters of the vibrating body 22 and the rotor 26 and calculates the above-described slip region and fixing region.

  The frictional force calculating unit 17 calculates the frictional force in the sliding region and the frictional force in the fixing region based on the sliding region and the fixing region calculated by the sliding region fixing region calculating unit 16. Then, the frictional force calculating unit 17 adds the frictional force in the sliding region and the frictional force in the fixed region, thereby obtaining the total frictional force between the vibrating body 22 and the roller 26 in the tangential direction of the rotation of the rotor 26. It is calculated as the frictional force acting on. The torque value output unit 18 multiplies the frictional force acting in the tangential direction of the rotation of the rotor 26 calculated by the frictional force calculation unit 17 by the radius of the contact portion between the vibrating body 22 and the rotor 26 (radius of the rotor 26). As a result, the torque of the rotor 26 is calculated. Then, the torque value output unit 18 outputs the torque value of the rotor 26 to the torque control unit 1 of FIG.

  FIG. 1H is a diagram illustrating a state where the vibrating body 22 and the rotor 26 are in contact with each other at the friction contact portion 24. FIG. 1 (i) is an enlarged view of the friction contact portion 24 of FIG. 1 (h). The surface of the vibrating body 22 and the rotor 26 are in contact. The vibrating body 22 and the rotor 26 are in deformation contact and represent a state where a frictional force is generated. In the present embodiment, a metal with relatively little wear is used as the rotor 26 as the elastic body. Therefore, the magnitude of the frictional force applied to the rotor 26 can be calculated by multiplying the elastic coefficient inherent to the metal by the amount of displacement. In the present embodiment, it is assumed that the metal is composed of an assembly of springs, and a value related to the displacement of the rotor 26 in the contact state is calculated using a discrete spring model. Details will be described below.

  FIG. 5 is a diagram illustrating a discrete spring model. A subtraction height 41 calculated by the subduction region calculation unit 15 in FIG. 3 and a method for calculating the position 33 will be described using the discrete spring model in FIG. The rotor base 34 shows the base of the rotor 26 for fixing the linear spring 35, and is applied with a pressure that becomes a load. The rotor surface 31 is the surface of the rotor 26. The vibrating body surface 30 is the surface of the vibrating body 22. The vibrating body surface 30 is pressed by the rotor 26 constituted by a linear spring 35. As the vibrating body 22 is excited and a traveling wave is generated on the vibrating body surface 30, the mechanical amplitude of the vibrating body 22 increases and the linear spring 35 is deformed.

A frictional force corresponding to the deformation amount of the linear spring 35 is generated at the contact portion between the vibrating body 22 and the rotor 26, and the rotor 26 rotates in the direction opposite to the traveling direction of the traveling wave. Since the pressure applied to the rotor base 34 is constant, the amount of displacement of the linear spring 35 is determined according to the magnitude of the mechanical amplitude of the vibrating body 22. Since the force applied to the linear spring 35 is obtained by multiplying the amount of displacement by the spring constant, the sum P _sum of the forces in the normal direction in the contact region is represented by the following formula (1 ).

When the mechanical amplitude of the vibrating body 22 is small, the vibration of the vibrating body 22 is completely submerged in the rotor 26. On the other hand, the rotor surface 31 floats as the amplitude of the vibrating body 22 increases and the total sum P _{sum of the} forces shown in Expression (2) becomes larger than the pressure applied to the rotor base 34.

  FIG. 6 is a diagram illustrating the vibration body amplitude 32, the rotor surface 31, and the sinking height 41 when the rotor surface 31 is floating. The sinking height 41 is a distance from the lower side of the vibration of the vibrating body 22 to the rotor surface 31. A position 33 indicates a position where the vibrating body 22 and the rotor 26 are in contact with each other at a sinking height 41, for example, θ3. Here, the vibrating body 22 is displaced in a cosine wave shape, and the pressure applied to the rotor base 34 is constant. The vertical axis in FIG. 6 represents the amplitude of the vibrating body 22. The horizontal axis of FIG. 6 represents the position, and is represented by 2π radians from −π to + π, where the vibration center of the vibrating body 22 is zero. In the section from θ3 to zero, the vibrating body 22 and the rotor 26 are in contact in the section from the sinking height 41 to the amplitude 32 of the vibrating body 22 and are not in contact in the section from θ3 to −π. The position 33 (θ3) is the position of the boundary between the contact portion between the vibrating body 22 and the rotor 26. The sinking height 41 indicates the mechanical amplitude of the vibrating body 22 at the boundary between the contact portion of the vibrating body 22 and the rotor 26.

Area calculation unit 15 subduction, vibrator amplitude 32 enter a, based on the sum P _sum and the spring constant of the pressurization and normal force exerted on the rotor base 34, the height sinking high sinking of 41 It is a boundary calculation part which calculates the position 33 in 41. FIG. At this time, the subduction region calculation unit 15 may calculate using a conversion table or a calculation formula for reasons of calculation accuracy and calculation load. The contact area is an area from the sinking height 41 to the amplitude 32 of the vibrating body 22.

  Next, a method for obtaining the fixing height 19 calculated by the fixing height calculation unit 14 will be described. As described above, in the fixed region, the surface of the vibrating body 22 and the surface of the rotor 26 are gripped, and the speeds of the vibrating body 22 and the rotor 26 are equal. Therefore, the fixing height calculation unit 14 can calculate the fixing height 19 by inputting the speed of the rotor 26 from the speed input unit 12 and obtaining the ratio between the reference fixing position height and the driving condition. .

  FIG. 4A is a diagram illustrating a relationship between the mechanical amplitude of the vibrating body and the fixing height 19 with respect to the vibration frequency of the vibrating body 22. Here, Fr indicates the resonance frequency of the vibrating body 22, and indicates that the mechanical amplitude of the vibrating body 22 increases as the resonance frequency Fr is approached from a region higher than Fr. As the mechanical amplitude of the vibrating body 22 increases, the fixing height 19 also increases proportionally.

  As shown in FIG. 4B, there is a proportional relationship between the vibration amplitude of the vibrating body 22 and the speed of the rotor 26. Further, as shown in FIG. 4C, the vibration frequency of the vibrating body 22 and the speed of the rotor 26 have an inversely proportional relationship. That is, the speed of the rotor 26 is proportional to the mechanical amplitude of the vibrating body 22 and is proportional to the reciprocal of the vibration frequency of the vibrating body 22. Further, the fixing height 19 increases as the mechanical amplitude of the vibrating body 22 increases, and is proportional to the reciprocal of the vibration frequency of the vibrating body 22. The fixing height calculation unit 14 takes these proportional relationships into consideration, the frequency output from the frequency input unit 11, the speed output from the speed input unit 12, the machine amplitude output from the amplitude value input unit 13, and the coefficient Based on α, the fixing height 19 is calculated. The coefficient α is a coefficient obtained from the machine amplitude, speed, and fixing height at the reference frequency.

  Next, a method for calculating the slip area and the fixed area calculated by the slip area fixed area calculating unit 16 will be described. As described above, in the vibration type actuator 6, the rotor 26 is driven while fixing and sliding are repeated in the contact area between the vibrating body 22 and the rotor 26.

  FIG. 7 is a view showing the fixing region 36 and the sliding region 42. The fixing region 36 has positions 37 and 38 that turn from the fixing region 36 to the sliding region 42 in the positive and negative directions of the fixing height 19 respectively. These positions 37 and 38 are called slip start positions. A section in the zero direction from the slip start position 37 (θ1) is a slip region 42. Similarly, the section from the slip start position 38 (θ2) to the position 33 (θ3) is also the slip region 42. Further, the section from the slip start position 37 (θ1) to the slip start position 38 (θ2) is a fixing region 36. The position 33 (θ3) is the position of the boundary between the contact portion between the vibrating body 22 and the rotor 26. The sinking height 41 indicates the mechanical amplitude of the vibrating body 22 at the boundary between the contact portion of the vibrating body 22 and the rotor 26. The subduction area calculation unit 15 is a boundary calculation unit that calculates the subduction height 41 and the position 33. The slip region fixing region calculation unit 16 can detect the slip region 42 based on the sinking height 41 and the position 33.

  The fixing height 19 is a reference value of the mechanical amplitude of the vibrating body 22 in the fixing region 36. The fixing height calculation unit 14 is a fixing amplitude calculation unit that calculates the fixing height 19. The slip region fixing region calculation unit 16 can detect the fixing region 36 based on the fixing height 19.

  Here, the slip start positions 37 and 38 will be described. When the vibrating body 22 is excited and a traveling wave is generated on the surface of the vibrating body 22, a frictional force is generated in the normal direction at the contact portion as described above. Since the excited traveling wave travels in the tangential direction, a force in the tangential direction is simultaneously generated.

  FIG. 8 is a diagram illustrating a force applied to an arbitrary point in a state where the vibrating body 22 and the rotor 26 are in contact with each other. The force 40 is a force applied in the normal direction and indicates a frictional force. The force 39 is a force applied in the tangential direction. If the force 39 acting in the tangential direction becomes larger than the force 40 acting in the normal direction, it is considered that slip occurs. Therefore, the slip region fixing region calculation unit 16 calculates a position where the forces 39 and 40 in both directions are balanced and fixed. A region 36 and a slip region 42 are calculated. Specifically, the slip region fixing region calculation unit 16 includes a fixing height 18, a sinking height 41 and its position 33, a vibrating body amplitude 32, an elastic coefficient that is a stiffness parameter of the rotor 26, and a contact parameter. Based on the friction coefficient, the slip start positions 37 and 38 are calculated. In addition, since stainless steel is used for the vibrating body 22 and the rotor 26, the longitudinal elastic coefficient and the lateral elastic coefficient specific to the material are used as the stiffness parameters. Also, as a friction coefficient, a typical friction coefficient in the friction between metals is used. Then, the slip region fixing region calculation unit 16 detects a section between the slip start position 37 (θ1) and the slip start position 38 (θ2) as the fixing region 36. Further, the slip area fixing area calculation unit 16 detects a section between the slip start position 38 (θ2) and the position 33 (θ3) as the slip area 42, and detects a section in the + π direction from the slip start position 37 (θ1). It is detected as a slip region 42.

  The frictional force calculation unit 17 in FIG. 3 adds the force generated in the sliding region 42 and the force generated in the fixing region 36, and the frictional force of the entire contact portion is added to the torque value output unit 18 as a frictional force acting in the tangential direction of the rotor 26. Output.

  As described above, the torque calculation unit 7 specifies the sliding region 42 and the fixing region 36 based on the fixing height 19 at the contact portion between the vibrating body 22 and the rotor 26, the sinking height 41, and its position 33. Then, the frictional force in the sliding region 42 and the fixing region 36 is added to calculate the torque.

  The torque value output unit 18 calculates the torque by multiplying the radius of the rotor 26 and the frictional force acting in the rotor tangential direction, and outputs the torque to the torque control unit 1. The torque control unit 1 controls the frequency command unit 2 so that the calculated torque becomes a torque command value. According to the present embodiment, by calculating the frictional force generated in the vibration type actuator 6, the torque of the rotor 26 can be calculated with high accuracy, and the torque of the rotor 26 can be controlled with high accuracy.

  For example, in the control when the robot hand grips an object with the vibration type actuator 6, first, the vibration frequency is used in a region separated from the resonance frequency Fr, and the combination of the speed sensor 8 and a position detection unit (not shown) Detects contact between an object and a robot hand. Thereafter, the gripping force can be calculated by the torque calculator 7. Further, when gripping a heavy object with high rigidity, torque control is performed near the resonance frequency Fr, and when gripping a flexible object with low rigidity, torque control is performed in a region away from the vicinity of the resonance frequency Fr. It is possible to control the gripping force of various objects.

  When the vibration actuator 6 is applied to a robot hand or the like, when the robot hand performs an operation of gripping an object, the torque calculation unit 7 calculates the torque without using a contact sensor that detects a gripping contact force. The gripping force control can be realized. The vibration type actuator 6 is smaller, lighter and higher torque than the electromagnetic motor. The vibration type actuator 6 can perform stable torque control and can be replaced with an electromagnetic motor, so that not only the robot hand can be reduced in size and weight, but also the robot arm can be reduced in size and weight.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Torque control part, 2 Frequency command part, 4 Pulse generation part, 5 Driver, 6 Vibration type actuator, 7 Torque calculation part, 8 Speed sensor, 9 A / D conversion part, 10 Mechanical amplitude-voltage conversion part, 21 Piezoelectric element , 22 vibrator, 26 rotor

Claims (7)

A control device for a vibration type actuator in which an oscillating body vibrates by applying an AC voltage to an electromechanical energy conversion element, and a moving body moves by frictional force with the oscillating body,
A frequency command unit that commands the frequency of the AC voltage;
An AC voltage applied to the electromechanical energy conversion element, an AC voltage generator that generates an AC voltage having a frequency commanded by the frequency command unit;
A speed detector for detecting the speed of the moving body;
A vibrating body amplitude acquisition unit for acquiring a mechanical amplitude of the vibrating body;
A torque calculation unit that calculates the torque of the moving body based on the frequency commanded by the frequency command unit, the speed detected by the speed detection unit, and the machine amplitude acquired by the vibration body amplitude acquisition unit. And
The frequency command unit commands a frequency according to a difference between a torque calculated by the torque calculation unit and a torque command value. The torque calculator
A frictional force calculation unit for calculating a frictional force between the vibrating body and the moving body;
The torque value output unit according to claim 1, further comprising: a torque value output unit configured to calculate a torque of the mobile body based on the frictional force calculated by the frictional force calculation unit and to output a torque value of the mobile body. Control device for vibration actuator. The torque calculation unit includes a sliding region where the vibration body and the moving body have different velocities and a fixed region where the vibration body and the moving body have the same speed at the contact portion between the vibrating body and the moving body. It has a slip area fixing area detection unit to detect,
The frictional force calculation unit calculates a frictional force between the vibrating body and the moving body by adding a frictional force in the sliding region and a frictional force in the fixing region. Item 3. A vibration type actuator control device according to Item 2. The torque calculation unit calculates a position of a boundary between a contact portion between the vibrating body and the moving body and a mechanical amplitude of the vibrating body at the boundary based on the mechanical amplitude acquired by the vibrating body amplitude acquisition unit. A boundary calculation unit;
4. The vibration type actuator control device according to claim 3, wherein the slip region fixing region detection unit detects the slip region based on a position of the boundary and a mechanical amplitude of the vibrating body at the boundary. . The torque calculation unit is based on the frequency commanded by the frequency command unit, the speed detected by the speed detection unit, and the mechanical amplitude acquired by the vibration body amplitude acquisition unit. A fixed amplitude calculating unit for calculating a reference value of the mechanical amplitude of the vibrating body;
5. The vibration type actuator control according to claim 3, wherein the slip region fixing region detection unit detects the fixing region based on a reference value of a mechanical amplitude of the vibrating body in the fixing region. apparatus. The frictional force calculating unit calculates a frictional force acting in a tangential direction of the rotation of the moving body,
The torque value output unit calculates a torque of the moving body by multiplying a frictional force acting in a tangential direction of rotation of the moving body by a radius of a contact portion between the vibrating body and the moving body. The control device for a vibration type actuator according to claim 2, wherein: A control method of a vibration type actuator in which an oscillating body vibrates by applying an AC voltage to an electromechanical energy conversion element, and a moving body moves by a frictional force with the oscillating body,
A frequency command step for commanding the frequency of the AC voltage by a frequency command unit;
An AC voltage generation step for generating an AC voltage of the frequency commanded in the frequency command step, which is an AC voltage applied to the electro-mechanical energy conversion element by an AC voltage generation unit;
A speed detection step of detecting a speed of the moving body by a speed detection unit;
A vibrating body amplitude acquisition step of acquiring a mechanical amplitude of the vibrating body by a vibrating body amplitude acquisition unit;
Based on the frequency commanded in the frequency command step, the speed detected in the speed detection step, and the machine amplitude acquired in the vibrating body amplitude acquisition step, the torque of the moving body is calculated by the torque calculation unit. A torque calculating step for calculating,
In the frequency command step, a frequency is commanded in accordance with a difference between the torque calculated in the torque calculation step and a torque command value.

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