JP2017055487A - Driving device, control method therefor, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform drive control of a driven part stably and at high speed.SOLUTION: A driving device comprises: a vibration part 101 which is vibrated in a predetermined direction in response to elongation/contraction displacement of piezoelectric elements 101a and 101b; a drive shaft 103 of which one end is fixed to the vibration part and which is vibrated by the vibrations of the vibration part; and a driven part 104 which is brought into press-contact with a surface of the drive shaft and moved along the drive shaft by the vibrations of the drive shaft. A position detection part 105 detects a position of the driven part on the drive shaft, and a drive control part 106 changes drive parameters for driving the piezoelectric elements in accordance with the position of the driven part detected by the position detection part and performs drive control of the piezoelectric elements based on the drive parameters.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drive device, a control method thereof, and a control program, and more particularly to a drive device using a piezoelectric element.

  In general, some drive devices include a vibration unit that vibrates in a predetermined direction by repeatedly performing the expansion and contraction using a piezoelectric element that generates expansion and contraction displacement when a voltage is applied. In this drive device, one end of the drive shaft is fixed to the drive unit in the vibration direction of the vibration unit, and the driven part is pressed against the drive shaft. Then, a voltage of a driving pulse having a gently rising portion and a rapidly falling portion is applied to the piezoelectric element. As a result, at the gently rising portion, the driven portion that is in pressure contact with the drive shaft is driven in one axial direction together with the drive shaft. On the other hand, since the drive shaft rapidly displaces at the rapid falling portion, the drive shaft is slidingly driven with respect to the driven part. As a result, the driven part stops and only the drive shaft is driven in the other axial direction. And by repeating such driving, the driven part can be driven in one direction.

  Further, there is provided a driving device that includes a movement amount detection unit that detects a movement amount of the driven unit, and changes the number of driving pulses input to the piezoelectric element according to the movement amount detected by the movement amount detection unit. Yes (see Patent Document 1). That is, in Patent Document 1, the driven unit is controlled by feedback control by the movement amount detection unit. By providing such a movement amount detection unit, it is possible to control the drive to the target position and to control the speed of the driven unit.

JP-A-11-356070

  However, in the drive device described in Patent Document 1, the vibration characteristics change according to the distance from the vibration portion of the drive shaft. For this reason, in order to perform feedback control, it is necessary to frequently detect the movement amount, and not only the power consumption increases due to the detection of the movement amount, but also the calculation load increases.

  Furthermore, when driving at high speed, feedback control may not be in time, and the drive position relative to the drive target position may be exceeded. If the drive position is over, the drive shaft must be driven in the opposite direction, and stable drive control cannot be performed. On the other hand, if the amount of movement is frequently detected in order to prevent the drive position from being exceeded, the time required for driving increases, and high-speed driving becomes impossible.

  Accordingly, an object of the present invention is to provide a drive device, a control method thereof, and a control program capable of performing drive control of a driven part stably and at high speed.

  In order to achieve the above object, a driving device according to the present invention is a driving device that drives a driven portion in accordance with expansion / contraction displacement of a piezoelectric element, and vibrates in a predetermined direction in accordance with expansion / contraction displacement of the piezoelectric element. And a drive shaft fixed at one end to the vibration portion, vibrated by vibration of the vibration portion, and pressed against the surface of the drive shaft, and moved along the drive shaft by vibration of the drive shaft. A driving unit, a detecting unit for detecting the position of the driven unit on the driving shaft, and a driving parameter for driving the piezoelectric element are changed according to the position of the driven unit detected by the detecting unit. Drive control means for controlling the drive of the piezoelectric element based on the drive parameter.

  The control method according to the present invention includes a vibration unit that vibrates in a predetermined direction according to expansion / contraction displacement of a piezoelectric element, a drive shaft that is fixed to the vibration unit at one end and vibrates due to vibration of the vibration unit, A method for controlling a driving device having a driven portion that is pressed against a surface and moves along the driving shaft by vibration of the driving shaft, the detection method detecting a position of the driven portion on the driving shaft And a drive control step of controlling the drive of the piezoelectric element based on the drive parameter by changing a drive parameter for driving the piezoelectric element in accordance with the position of the driven part detected in the detection step It is characterized by having.

  A control program according to the present invention includes a vibration unit that vibrates in a predetermined direction according to expansion / contraction displacement of a piezoelectric element, a drive shaft that has one end fixed to the vibration unit and vibrates due to vibration of the vibration unit, A control program for use in a driving device having the driven portion that is pressed against the surface and moves along the driving shaft due to vibration of the driving shaft, the computer having the driving device in the driving shaft A detection step for detecting the position of the driven portion and a drive parameter for driving the piezoelectric element are changed according to the position of the driven portion detected in the detection step, and based on the drive parameter And a drive control step for driving and controlling the piezoelectric element.

  According to the present invention, since the driving parameter is changed according to the position of the driven part, the driving control of the driven part can be performed stably and at high speed.

It is a block diagram which shows the structure about an example of the drive device by embodiment of this invention. It is a figure for demonstrating the press contact state of the to-be-driven part in the drive device shown in FIG. 1, (A) And (B) is a vibration part, a drive shaft, and a to-be-driven part shown in FIG. It is the side view seen from the direction. It is a figure for demonstrating the displacement of the drive shaft by the pulse-form voltage applied to a piezoelectric element by the drive control part shown in FIG. 1, (A) is a figure which shows an example of a pulse-form voltage, (B) is a pulse-form. The figure which shows the other example of a voltage, (C) is a figure which shows the displacement of the axial direction of a drive shaft. 2 is a flowchart for explaining drive control by the drive device shown in FIG. 1.

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

  FIG. 1 is a block diagram showing the configuration of an example of a drive device according to an embodiment of the present invention.

  The illustrated driving device is provided with thin plate-like piezoelectric elements 101a and 101b, which are arranged to face each other with an elastic member 101c interposed therebetween. The vibrating part 101 is configured by a laminated structure of the illustrated piezoelectric elements 101a and 101b and an elastic member 101c. One end of a cylindrical drive shaft 103 is fixed to the piezoelectric element 101 a side in the vibration unit 101, and the driven unit 104 is held in a pressed contact with the surface (outer peripheral surface) of the drive shaft 103.

  When a voltage is applied to the two piezoelectric elements 101a and 101b, the vibration part 101 is driven to expand and contract in the surface (surface) direction. The driven portion 104 can be driven on the drive shaft 103 by repeatedly performing this expansion and contraction drive.

  The drive shaft 103 is formed in a cylindrical shape using a material having wear resistance and self-lubricating properties such as carbon graphite. The drive shaft 103 is fixed at one end surface thereof, and the piezoelectric element 101a is fixed by an adhesive or the like.

  A position detection unit 105 is disposed to face the driven unit 104, and the position detection unit 105 detects the position of the driven unit 104 on the drive shaft 103 and outputs position information. The illustrated position detection unit 105 needs to detect the relative position between the vibration unit 101 and the driven unit 104, and thus has a configuration capable of detecting the absolute position of the driven unit 104.

  As the position detection unit 105, for example, an optical position detection unit including a slit plate and a light projecting / receiving element is used. Furthermore, as the position detection unit 105, for example, a magnetic position detection unit including a magnetic member and a magnetic sensor is used.

  In the case of a configuration in which only the relative position is detected, a driving end is provided on the driving shaft 103 and the driven portion 104 is abutted against the driving end as a reset operation when the power is turned on. Position detection by the detection unit 105 is performed. If the detection is continuously performed by incrementing the drive amount from the drive end, the absolute position can be detected.

  The drive control unit 106 applies a voltage to the piezoelectric elements 101 a and 101 b to drive the driven unit 104. At this time, the drive control unit 106 drives and controls the driven unit 104 based on the drive parameter and the position information obtained by the position detection unit 105. The drive control unit 105 has a storage unit 107, and drive parameters are recorded in advance in the storage unit 107.

  FIG. 2 is a view for explaining a pressing contact state of a driven portion in the driving apparatus shown in FIG. 2 (A) and 2 (B) are side views of the vibrating portion, the drive shaft, and the driven portion shown in FIG. 1 as viewed from the direction of the drive shaft.

  2A, the driven portion 104 includes an upper V-groove member 104a having a V-groove portion with which the drive shaft 103 is engaged, and a pressing member 104b that presses the drive shaft 103 against the V-groove member 104a. . The driven portion 104 includes a hinge shaft 104c that rotatably holds the V-groove member 104a and the pressing member 104b, and a spring member 104d that applies pressure to the V-groove member 104a and the pressing member 104b. .

  As a result, the driven portion 104 is in press contact with the drive shaft 103 in a state where a total of three points of two points of the V groove member 104 a and one point of the pressing member 104 b are in contact. Note that the driven portion 104 has a shape that expands in the depth direction of the paper surface in FIG. 2A, and therefore, in actuality, the driven portion 104 is pressed and contacted with three lines instead of three points.

  FIG. 2B shows a process of attaching the driven part 104 to the drive shaft 103. When the driven portion 104 is attached to the drive shaft 103, the pressing member 104b configured to be rotatable by the hinge shaft 104c is attached to the V groove member 104a in an open state. Thereafter, the driven member 104 can be brought into a pressed contact state as shown in FIG. 2A by rotating the pressing member 104b clockwise and sandwiching the pressing member 104b via the spring member 104d.

  FIG. 3 is a diagram for explaining the displacement of the drive shaft due to the pulse voltage applied to the piezoelectric element by the drive control unit shown in FIG. FIG. 3A is a diagram illustrating an example of the pulse voltage, and FIG. 3B is a diagram illustrating another example of the pulse voltage. FIG. 3C is a diagram showing the axial displacement of the drive shaft.

  3A and 3B, the vertical axis represents voltage, and the horizontal axis represents time. The drive control unit 106 applies a pulse voltage (hereinafter referred to as a pulse wave) 201a illustrated in FIG. 3A to the piezoelectric element 101a. The pulse wave 201a has a waveform in which the first voltage time T1 and the second voltage time T2 are repeated. The pulse wave 201a becomes a negative voltage at the first voltage time T1, and becomes a positive voltage at the second voltage time T2. The first voltage time T1 and the second voltage time T2 are different. Here, T1 <T2. The piezoelectric element 101a shortens (shrinks) when a negative voltage is applied, and expands when a positive voltage is applied.

  On the other hand, the drive control unit 106 applies a pulse wave 201b illustrated in FIG. 3B to the piezoelectric element 101b. The pulse wave 201b has a waveform in which the voltage is opposite to that of the pulse wave 201a. That is, the pulse wave 201a becomes a positive voltage at the first voltage time T1, and becomes a negative voltage at the second voltage time T2.

  The drive control unit 106 applies the pulse waves 201a and 201b to the piezoelectric elements 101a and 101b at a frequency in the ultrasonic region of several tens of KHz to vibrate the vibration unit 101. When the vibration unit 101 vibrates, the drive shaft 103 is fixed to the vibration unit 101 and thus vibrates in accordance with the vibration of the vibration unit 101.

  3C, the horizontal axis indicates time, and the vertical axis indicates the displacement of the drive shaft 103 in the axial direction. As illustrated, the displacement of the drive shaft 103 changes in a sawtooth shape. Now, the first displacement time when the displacement changes in the increasing direction is T3, and the second time when the displacement changes in the decreasing direction is T4. Unlike the first displacement time T3 and the second displacement time T4, T3 <T4.

  In the first displacement time T3, since the drive shaft 103 is rapidly displaced, the drive shaft 103 is slidably driven with respect to the driven portion 104, the driven portion 104 is stopped, and only the drive shaft 103 is the shaft. Move in the direction. On the other hand, in the second displacement time T4, the drive shaft 103 is gradually displaced, so that the drive shaft 103 is frictionally driven with respect to the drive unit 104, and the drive shaft 103 and the driven unit 104 are integrated. Move in the direction of the drive shaft. When the displacement as described above is repeatedly performed, the driven unit 104 is driven.

  By the way, the voltage values applied to the piezoelectric elements 101a and 101b, the ratio between the first voltage time T1 and the second voltage time T2, and the frequencies of the pulse waves 201a and 201b are the main driving parameters. Then, by changing these drive parameters, the speed and movement amount of the driven unit 104 can be controlled.

  The drive parameters are not limited to the above three, and other drive parameters may be used. For example, when a piezoelectric element capable of multi-phase driving is used, the driven unit 104 can be controlled by changing the phase between phases.

  FIG. 4 is a flowchart for explaining drive control by the drive device shown in FIG.

  First, the drive control unit 106 determines whether or not there is a drive instruction from the user (step S301). In the drive instruction, a target position and a drive amount for driving to the target position are set.

  If there is no drive instruction (NO in step S301), drive control unit 106 stands by. On the other hand, when there is a drive instruction (YES in step S301), the drive control unit 106 detects the relative position of the driven unit 104 with respect to the vibration unit 101 by the position detection unit 105 to obtain position information (step S302). .

  Subsequently, the drive control unit 106 determines a drive parameter based on the position information and the drive amount set in step S301 (step S303). A drive parameter corresponding to the relative position of the driven unit 104 with respect to the vibration unit 101 is stored in the storage unit 107 in advance. The driving parameters may be the same regardless of the driving device, or may be determined for each driving device based on actual driving in a production process or the like.

  Subsequently, the drive control unit 106 is required to drive the driven unit 104 from the current position to the target position based on the drive parameter determined in step S303 and the drive amount set in step S301. And pulse waves 201a and 201b to be applied to 101b (step S304). Then, the drive control unit 106 applies the pulse waves 201a and 201b obtained in step S304 to the drive unit 101 to drive the driven unit 104 (step S305).

  Next, the drive control unit 106 obtains the current position information of the driven unit 104 by the position detection unit 105 (step S306). The current position information here indicates the current relative position with respect to the position of the driven unit 104 before driving. Then, the drive control unit 106 determines whether or not the difference between the target position corresponding to the drive amount set in step S301 and the position of the driven unit 104 indicated by the current position information is equal to or less than a predetermined threshold value. . That is, the drive control unit 106 determines whether or not the driven unit 104 has reached the target position (step S307).

  If driven unit 104 does not reach the target position (NO in step S307), drive control unit 106 returns to the process in step S303 and newly determines a drive parameter. On the other hand, when driven unit 104 reaches the target position (YES in step S307), drive control unit 106 ends the drive control.

  As described above, in the embodiment of the present invention, the driving parameter is determined according to the position of the driven unit 104, and the piezoelectric element is controlled by the driving parameter. The drive can be controlled. In other words, unless the drive parameter is changed in accordance with the position of the driven part, the amount of driving at one time must be reduced, and it is necessary to drive to the target position while frequently detecting the position. For this reason, although it is difficult to drive at a high speed to the target position, high-speed drive control can be stably performed if the drive parameters are determined according to the position of the driven part.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above-described embodiment may be used as a control method, and this control method may be executed by the drive device. In addition, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the drive device. The control program is recorded on a computer-readable recording medium, for example.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 101 Vibration part 101a, 101b Piezoelectric element 103 Drive shaft 104 Driven part 105 Position detection part 106 Drive control part 107 Storage part

Claims (7)

A driving device for driving a driven part in accordance with expansion and contraction displacement of a piezoelectric element,
A vibrating portion that vibrates in a predetermined direction according to the expansion and contraction displacement of the piezoelectric element;
One end is fixed to the vibration part, and the drive shaft vibrates by vibration of the vibration part,
The driven portion that is pressed against the surface of the drive shaft and moves along the drive shaft by vibration of the drive shaft;
Detection means for detecting the position of the driven part on the drive shaft;
Drive control means for driving the piezoelectric element based on the drive parameter by changing a drive parameter for driving the piezoelectric element according to the position of the driven part detected by the detection means;
A drive device comprising:   The drive parameter is set according to the position of the driven part, and the drive control means controls the drive of the piezoelectric element based on the drive parameter corresponding to the position of the driven part detected by the detection means. The drive device according to claim 1.   The driving device according to claim 1, wherein the detection unit detects a relative position between the vibrating unit and the driven unit.   The drive apparatus according to claim 1, wherein a plurality of drive parameters are set as the drive parameters, and the drive control unit changes at least one of the plurality of drive parameters. The vibration unit includes an elastic member, and a first piezoelectric element and a second piezoelectric element that are disposed to face each other with the elastic member interposed therebetween.
The plurality of driving parameters include a pulse voltage applied to the first piezoelectric element and the second piezoelectric element, a ratio between a time when the pulse voltage is negative and a time when the pulse voltage is negative, and the pulse voltage. The drive device according to claim 4, wherein the drive device has a frequency. A vibrating portion that vibrates in a predetermined direction in accordance with the expansion and contraction displacement of the piezoelectric element, a driving shaft that is fixed to the vibrating portion at one end, vibrates due to vibration of the vibrating portion, and is in press contact with the surface of the driving shaft; A method of controlling a drive device having the driven portion that moves along the drive shaft by vibration of the drive shaft,
A detection step of detecting a position of the driven part on the drive shaft;
A drive control step for changing the drive parameter for driving the piezoelectric element according to the position of the driven part detected in the detection step and driving the piezoelectric element based on the drive parameter;
A control method characterized by comprising: A vibrating portion that vibrates in a predetermined direction in accordance with the expansion and contraction displacement of the piezoelectric element, a driving shaft that is fixed to the vibrating portion at one end, vibrates due to vibration of the vibrating portion, and is in press contact with the surface of the driving shaft; A control program used in a drive device having the driven part that moves along the drive shaft by vibration of the drive shaft,
In the computer provided in the drive device,
A detection step of detecting a position of the driven part on the drive shaft;
A drive control step for changing the drive parameter for driving the piezoelectric element according to the position of the driven part detected in the detection step and driving the piezoelectric element based on the drive parameter;
A control program characterized by causing

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