JP2007198909A - Rough/fine positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rough/fine positioning device which is inexpensive and easily manufactured. <P>SOLUTION: The rough/fine positioning device is provided with: a rough moving mechanism for moving a moving table; a fine moving mechanism for moving the moving table at high moving accuracy than that of the rough moving mechanism; a position sensor for detecting the position of the moving table; a rough moving controller for control of the rough moving mechanism on the basis of a feedback signal from the position sensor; a fine moving controller for controlling the fine moving mechanism on the basis of the feedback signal from the position sensor; and a signal adjuster intervening in a feedback route. The signal adjuster outputs a first encode signal derived by encoding the detection signal of the position sensor by first resolution to the coarse controller, and also outputs a deviation signal indicating the deviation between a second encode signal derived by encoding the detection signal of the position sensor by second resolution and a command value signal to the fine moving controller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coarse / fine motion positioning device that performs fine positioning with high accuracy in a long stroke range, and more particularly to a coarse / fine motion positioning device that is inexpensive and easy to manufacture.

Conventionally, as a coarse / fine movement positioning device, for example, a technique described in Patent Document 1 is known.
The technique described in Patent Document 1 includes a coarse movement mechanism that moves the table in the axial direction with respect to the base, and a fine movement mechanism that moves the table in the axial direction with respect to the base using expansion and contraction of the piezoelectric actuator after the coarse movement operation ends. And a single displacement detection means that also serves as the coarse movement adjustment displacement detection means and the fine movement adjustment displacement detection means, and a controller that feedback-controls the coarse movement mechanism and the fine movement mechanism based on a detection signal from the displacement detection means. It is. (Paragraphs [0047] and [0053] in the same document)
JP-A-9-192958

However, in the technique described in Patent Document 1, since fine displacement control is performed, displacement detection means with high resolution must be used. On the other hand, since coarse motion control does not require a detection signal with high resolution, If the displacement detection means is also used, an expensive product must be used as a controller, which increases the cost.
Further, when an existing positioning device that does not have a fine movement mechanism is improved and a coarse / fine movement positioning device is manufactured, a controller dedicated to the coarse / fine movement positioning device must be introduced as in the technique described in Patent Document 1, so that the system Had to be rebuilt, requiring a lot of time and effort.
Accordingly, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and an object thereof is to provide a coarse / fine motion positioning device that is inexpensive and easy to manufacture.

  In order to achieve the above object, a coarse / fine motion positioning apparatus according to claim 1 according to the present invention includes a moving part, a coarse moving mechanism for moving the moving part, and the movement with higher movement accuracy than the coarse moving mechanism. A fine movement mechanism that moves a moving part, a coarse movement control device that controls the coarse movement mechanism based on a feedback signal related to the movement result of the moving part, and a fine movement control device that controls the fine movement mechanism based on the feedback signal. A coarse / fine movement positioning device for positioning the moving unit, the position sensor detecting the position of the moving unit, and the coarse signal of the feedback signal of the first resolution based on a detection signal of the position sensor. And a signal adjusting means for outputting the feedback signal having a second resolution higher than the first resolution to the fine movement control device.

  With such a configuration, the coarse movement mechanism is controlled by the coarse movement control device, and the moving unit moves by driving the coarse movement mechanism. Next, the position sensor detects the position of the moving unit, and the signal adjustment unit outputs a feedback signal having the first resolution to the coarse motion control device based on the detection signal from the position sensor. The coarse movement control device controls the coarse movement mechanism based on the input feedback signal.

Also, the fine movement mechanism is controlled by the fine movement control device, and the moving unit moves with high movement accuracy by driving the fine movement mechanism. Next, the position sensor detects the position of the moving unit, and the signal adjustment unit outputs a feedback signal having a second resolution higher than the first resolution to the fine movement control device based on the detection signal from the position sensor. Then, the fine movement control device controls the fine movement mechanism based on the input feedback signal.
Here, the coarse motion control and the fine motion control may be performed independently. However, from the viewpoint of simplifying the control, it is preferable to perform the fine motion control after the coarse motion control is completed.

Furthermore, the coarse / fine motion positioning device according to claim 2 of the present invention is the coarse / fine motion positioning device according to claim 1, wherein the coarse motion control device outputs a coarse motion completion signal indicating that the coarse motion control is completed. The fine movement control device starts fine movement control based on the coarse movement completion signal.
With such a configuration, in the coarse motion control device, when the coarse motion control is completed, a coarse motion completion signal is output to the fine motion control device. In the fine movement control device, when a coarse movement completion signal is input, fine movement control is started.

  Furthermore, the coarse / fine motion positioning device according to claim 3 according to the present invention is the coarse / fine motion positioning device according to any one of claims 1 and 2, wherein the coarse motion control device determines a target position of the moving unit. The command adjustment signal is output to the signal adjustment unit, and the signal adjustment unit outputs an encoded signal obtained by encoding the detection signal of the position sensor with the first resolution to the coarse motion control device as the feedback signal. And outputs a deviation signal indicating a deviation between an encoded signal obtained by encoding the detection signal of the position sensor with the second resolution and the command value signal as the feedback signal to the fine movement control device.

  If it is such a structure, the command value signal which shows the target position of a moving part will be output to a signal adjustment means by the coarse motion control apparatus. Then, the signal adjustment means outputs an encoded signal obtained by encoding the detection signal of the position sensor with the first resolution to the coarse motion control device as a feedback signal. Further, a deviation signal indicating a deviation between the encoded signal obtained by encoding the detection signal of the position sensor with the second resolution and the command value signal is output as a feedback signal to the fine movement control device.

Furthermore, in the coarse / fine movement positioning device according to claim 4 according to the present invention, in the coarse / fine movement positioning device according to any one of claims 1 and 2, the signal adjusting means outputs the detection signal of the position sensor. An encoded signal obtained by encoding at a first resolution is output as the feedback signal to the coarse motion control device, and an encoded signal obtained by encoding a detection signal of the position sensor at the second resolution is used as the feedback signal. To the fine motion control device.
With such a configuration, the encode signal obtained by encoding the detection signal of the position sensor with the first resolution is output to the coarse motion control device as a feedback signal by the signal adjusting means. An encoded signal obtained by encoding the detection signal of the position sensor with the second resolution is output as a feedback signal to the fine movement control device.

Furthermore, the coarse / fine movement positioning device according to claim 5 of the present invention is the coarse / fine movement positioning device according to any one of claims 1 to 4, wherein the feedback signal to the fine movement control device is an analog signal. .
If it is such a structure, a feedback signal will be output to a fine movement control apparatus as an analog signal by a signal adjustment means.

Furthermore, the coarse / fine movement positioning device according to claim 6 of the present invention is the coarse / fine movement positioning device according to any one of claims 1 to 5, wherein the feedback signal to the fine movement control device is a digital signal. .
With such a configuration, the feedback signal is output as a digital signal to the fine movement control device by the signal adjusting means.

  Furthermore, the coarse / fine movement positioning apparatus according to claim 7 of the present invention is the coarse / fine movement positioning apparatus according to any one of claims 1 to 6, wherein the coarse movement mechanism is rotatably supported by a base. A screw shaft, a nut screwed to the screw shaft and fixed to the moving portion, and a motor driven based on a drive signal from the coarse motion control device to rotate the screw shaft, The fine movement mechanism includes two rolling bearing devices arranged opposite to each other and applied with a preload, a housing fixed to the base and fitted with respective outer rings of the rolling bearing device, and a control voltage from the fine movement control device. A piezoelectric actuator that expands and contracts in response, and each inner ring of the rolling bearing device is fitted to the screw shaft, the inner ring is fixed to the screw shaft in the axial direction, and one of the outer rings is fixed to the axial direction. Restrained, It said axial distance between Kigairin was so varied by expansion and contraction of the piezoelectric actuator.

With such a configuration, in the coarse motion mechanism, the motor is driven based on the drive signal from the coarse motion control device to rotate the screw shaft, and the nut fixed to the moving portion moves in the axial direction. Along with this, the moving unit moves.
In the fine movement mechanism, when the piezoelectric actuator expands and contracts according to the control voltage from the fine movement control device, the axial distance between the outer rings changes. At this time, since one of the outer rings is constrained in the axial direction, elastic deformation occurs between the outer ring and the inner ring due to the displacement between the outer rings, and each inner ring is displaced. And a movement part moves with the displacement of an inner ring | wheel. Further, when the piezoelectric actuator is extended, a preload reaction force acts on the piezoelectric actuator, so that a fine movement operation is performed while applying a compressive load.

  Furthermore, the coarse / fine movement positioning device according to an eighth aspect of the present invention is the coarse / fine movement positioning device according to any one of the first to sixth aspects, wherein the coarse movement mechanism is a screw shaft fixed to a base. And a nut that is screwed onto the screw shaft and is rotatably supported by the moving unit, and a motor that rotates based on a drive signal from the coarse motion control device and rotates the nut. The mechanism corresponds to two rolling bearing devices that are arranged opposite to each other and are provided with a preload, a housing that is fixed to the moving part and into which each outer ring of the rolling bearing device is fitted, and a control voltage from the fine movement control device. A piezoelectric actuator that expands and contracts, and engages each inner ring of the rolling bearing device with the nut, fixes the inner ring to the nut in the axial direction, and restrains one of the outer rings in the axial direction. The distance of the axial direction between the outer ring and so as to be changed by expansion and contraction of the piezoelectric actuator.

If it is such a structure, in a coarse motion mechanism, a motor will drive based on the drive signal from a coarse motion control apparatus, a nut will rotate, and a moving part moves to an axial direction in connection with this.
In the fine movement mechanism, when the piezoelectric actuator expands and contracts according to the control voltage from the fine movement control device, the axial distance between the outer rings changes. At this time, since one of the outer rings is constrained in the axial direction, elastic deformation occurs between the outer ring and the inner ring due to the displacement between the outer rings, and each inner ring is displaced. And a movement part moves with the displacement of an inner ring | wheel. Further, when the piezoelectric actuator is extended, a preload reaction force acts on the piezoelectric actuator, so that a fine movement operation is performed while applying a compressive load.

  As described above, according to the coarse / fine movement positioning device according to the first aspect of the present invention, the fine movement can be performed without introducing a controller dedicated to the coarse / fine movement positioning device to an existing positioning device having no fine movement mechanism. Since it can be manufactured only by introducing a mechanism, a fine movement control device, and a signal adjustment means, it is not necessary to reconstruct the system as compared with the conventional case, and the time and labor required for manufacturing can be reduced. Is obtained. In addition, since the coarse motion control device is configured to input a feedback signal with low resolution, an inexpensive product can be used as the coarse motion control device, and the coarse motion control device has a cycle for reading the feedback signal. Since it is not necessary to shorten it, cost can be reduced compared with the past.

Further, according to the coarse / fine movement positioning device according to the second aspect of the present invention, the movements of the coarse movement operation and the fine movement operation overlap, and the controls interfere with each other so that the movement of the coarse movement operation is corrected by the fine movement. As a result, there is an effect that the control can be simplified.
Furthermore, according to the coarse / fine movement positioning device according to the fifth aspect of the present invention, it is not necessary to use an expensive servo control device as the fine movement control device, so that an effect of further reducing the cost can be obtained. .

  Furthermore, according to the coarse / fine movement positioning device according to claim 7 or 8 of the present invention, the opposingly arranged rolling bearing device functions as a highly rigid spring member, and the piezoelectric actuator has a high rigidity in the compression direction and a highly rigid spring. Since the rigidity of the fine movement mechanism can be maintained high by the combination with the member, an effect that a fine movement operation with high responsiveness can be realized is obtained. Further, when the piezoelectric actuator is extended, a preload reaction force acts on the piezoelectric actuator, and a fine movement operation can be performed while applying a compressive load. Therefore, it is possible to prevent the piezoelectric actuator from being damaged due to a tensile load. Is obtained.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 to 8 are views showing a first embodiment of a coarse / fine movement positioning device according to the present invention.
First, the moving mechanism of the coarse / fine movement positioning device 1 will be described.
FIG. 1 is a cross-sectional view of an axial fine movement mechanism 41 with a rotation mechanism.
FIG. 2 is a plan view of the coarse / fine movement positioning device 1.
FIG. 3 is a side view of the coarse / fine movement positioning device 1.

  Reference numeral 2 denotes a linear guide mechanism, which is a linear guide device including a bowl-shaped slider 4 assembled to the rail 3 via a rolling element, and the rail 3 is installed on the base 5 of the coarse / fine motion positioning device 1. The moving table 6 of the coarse / fine movement positioning device 1 is mounted on the moving table mounting surface 4a of the slider 4 with a bolt or the like. The linear guide mechanism 2 includes two rails 3 installed on both sides of the screw shaft 11 in parallel to the longitudinal direction (referred to as the axial direction) of the screw shaft 11 of the coarse motion mechanism 10, and 2 assembled to each rail 3. In total, there are four sliders 4.

  The coarse movement mechanism 10 includes a plurality of illustrated shaft raceway grooves 11 a formed on the outer peripheral surface of the screw shaft 11 and nut raceway grooves (not shown) facing the shaft raceway groove 11 a formed on the inner peripheral surface of the nut 12. A ball screw device 13 as a feed screw device screwed through a non-ball, a drive motor 14 disposed at one end of the screw shaft 11 and capable of rotating in the forward and reverse directions such as a stepping motor installed on the base 5, A coupling 15 that connects the drive motor 14 and the screw shaft 11, and a support bearing 16 such as a deep groove ball bearing that is disposed on the other end of the screw shaft 11 and is installed on the base 5 are configured. .

The nut 12 is fixed to the movable table 6 and is screwed to the screw shaft 11 with no play in the axial direction by preloading with an oversized ball or the like. Moreover, the support bearing 16 supports the screw shaft 11 rotatably, and supports the other end of the screw shaft 11 so as to be movable by play in the axial direction.
Reference numeral 17 denotes a position sensor, which is fixed to the movable table 6 and detects fine irregularities formed at equal intervals on a scale 18 installed in parallel with the screw shaft 11 on the base 5 and detects the detection signal later. It has a function of outputting to the motion control device 45a and the fine motion control device 45b. The coarse motion control device 45 a and the fine motion control device 45 b measure the relative movement amount between the moving base 6 and the base 5 using the detection signal of the position sensor 17.

In FIG. 1, 20a and 20b are angular contact ball bearings as rolling bearing devices, and are formed on the outer ring raceways 22a and 22b formed on the inner peripheral surfaces of the outer rings 21a and 21b and on the outer peripheral surfaces of the inner rings 23a and 23b. It has a plurality of balls 25a and 25b as rolling elements disposed between the inner ring raceways 24a and 24b.
Angular contact ball bearings 20a and 20b are opposed to each other as a front combination, and the inner peripheral surfaces of the inner rings 23a and 23b are fitted to the outer peripheral surface of a fitting shaft 26 formed on the drive motor 14 side of the screw shaft 11. The outer peripheral surfaces of 22a and 22b are fitted to the inner peripheral surface of the housing 27 fixed to the base 5 with bolts or the like, and support the screw shaft 11 together with the support bearing 16 so as to be rotatable.

Reference numeral 29 denotes an inner ring locking portion, which is a large diameter portion having a diameter substantially equal to the outer diameter of the inner rings 23a and 23b formed between the shaft raceway groove 11a of the screw shaft 11 and the fitting shaft 26, One side surface of the inner ring 23a is locked.
Reference numeral 30 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the inner rings 23a and 23b. The inner circumferential surface of the inner ring is fitted to the outer circumferential surface of the fitting shaft 26 and the inner rings 23a and 23b. It is arranged between.

Reference numeral 31 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to the inner rings 23a and 23b, the inner peripheral surface of which is fitted to the outer peripheral surface of the fitting shaft 26, and between the inner rings of the inner ring 23b. It is arranged on the opposite side of the seat 30.
Reference numeral 32 denotes a lock nut, which is screwed into a threaded portion 33 provided on the drive motor 14 side of the fitting shaft 26 and between the inner ring 23a, the inner ring spacer 30, the inner ring 23b and the inner ring spacer. 31 is tightened, and the movement of the inner rings 23a and 23b on the screw shaft 11 is fixed.

Reference numeral 34 denotes a coupling mounting portion, which is a small-diameter portion having a diameter equal to or less than the root diameter of the screw portion 33 provided at the end of the screw shaft 11 on the drive motor 14 side, and the coupling 15 is fitted and attached. The power from the drive motor 14 is transmitted.
Reference numeral 36 denotes a piezoelectric actuator, which is a hollow actuator in which a single or a plurality of piezoelectric elements having a hollow portion 36 a into which the inner ring spacer 31 can be inserted is laminated, and its outer peripheral surface is fitted to the inner peripheral surface of the housing 27. It arrange | positions at the drive motor 14 side of the outer ring | wheel 21b, and is expanded-contracted to an axial direction according to the voltage applied from the outside. The piezoelectric actuator 36 is a stacked cylindrical actuator in which a plurality of annular piezoelectric elements are stacked.

Reference numeral 37 denotes an outer ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the outer rings 21a and 21b. The outer peripheral surface of the cylindrical member is fitted to the inner peripheral surface of the housing 27 and the outer ring 21b and the piezoelectric actuator 36 are connected. Arranged between.
Reference numeral 38 denotes an outer ring locking portion, which is a step portion having a diameter substantially equal to the inner diameter of the outer rings 21a and 21b formed at a position facing the inner ring locking portion 29 on the inner peripheral surface of the housing 27, and the outer ring 21a. Lock one side of the.

  Reference numeral 39 denotes a cover, which is a hollow disk member having an inner diameter into which the inner ring spacer 31 can be inserted and having an outer diameter substantially equal to that of the housing 27, and is formed on the end surface of the housing 27 on the drive motor 14 side. The holes 27a are fastened to the housing 27 by bolts or the like, and the outer rings 21a and 21b, the outer ring spacer 37, and the piezoelectric actuator 36 are pressed between the outer ring engaging portions 38.

As a result, the outer ring 21a is pressed by the outer ring locking portion 38 in the axial direction and the outer ring 21b on the unrestricted side is pressed through the outer ring spacer 37 and the non-energized piezoelectric actuator 36, thereby the angular ball bearing 20a. 20b, a predetermined preload is applied, and a gap 40 is formed as an axial distance between the outer rings 21a and 21b.
The axial fine movement mechanism 41 with a rotation mechanism includes angular ball bearings 20a and 20b, a fitting shaft 26, an inner ring locking portion 29, an inner ring spacer 30, an inner ring spacer 31, a lock nut 32, a housing 27, an outer ring locking portion 38, As shown in FIG. 1, the outer ring spacer 37, the piezoelectric actuator 36, the cover 39 and the like are arranged on the same axis of the screw shaft 11.
The coarse / fine movement positioning device 1 includes an axial fine movement mechanism 41 with a rotation mechanism and a coarse movement mechanism 10.

Next, the configuration of the control system of the coarse / fine movement positioning device 1 will be described.
FIG. 4 is a block diagram showing the configuration of the control system of the coarse / fine movement positioning apparatus 1.
As shown in FIG. 4, the control system of the coarse / fine movement positioning device 1 includes a signal adjuster 42 that outputs a plurality of feedback signals having different resolutions based on detection signals of the position sensor 17, and a feedback signal from the signal adjuster 42. The coarse motion control device 45a for controlling the drive motor 14 based on the above, the fine motion control device 45b for controlling the piezoelectric actuator 36 based on the feedback signal from the signal adjuster 42, and the control voltage from the fine motion control device 45b are amplified. And an amplifier 43 that outputs to the piezoelectric actuator 36.

  The signal adjuster 42 has two input terminals and three output terminals, and inputs a detection signal of the position sensor 17 and a command value signal indicating a target position from each input terminal. Further, the detection signal of the position sensor 17 is encoded with the first resolution, and the obtained first encoded signal is output from the first output terminal. Further, the detection signal of the position sensor 17 is encoded with a second resolution higher than the first resolution, and the obtained second encoded signal is output from the second output terminal. Further, a deviation between the second encoding signal and the command value signal is calculated, and a deviation signal indicating the calculated deviation is output from the third output terminal. Both the second encoding signal and the deviation signal are analog signals.

The coarse output control device 45a is connected to the first output terminal, and the first encode signal is input to the coarse motion control device 45a as a feedback signal. A fine movement control device 45b is connected to the third output terminal, and the deviation signal is input to the fine movement control device 45b as a feedback signal.
The coarse motion control device 45a includes a control unit 46a that performs coarse motion positioning processing, a storage unit 47a that stores programs executed by the control unit 46a, various data used for the control unit 46a, processing results of the control unit 46a, and the like. And a motor drive unit 48a for driving the motor 14. Further, the command value signal is output to the signal adjuster 42.

The storage unit 47a stores a coarse motion control program for performing coarse motion control, and a movement destination instruction table that stores a target position at which the moving platform 6 is stopped.
The fine movement control device 45b includes a control unit 46b that executes a fine movement positioning process, a storage unit 47b that stores a program executed by the control unit 46b, various data used for it, processing results of the control unit 46b, and the like, and a piezoelectric actuator 36. And an actuator driving portion 48b for driving the motor.
The storage unit 47b stores a fine movement control program for performing fine movement control.
In the present embodiment, the command value of fine movement control device 45b is always set to “0”.

Next, processing executed by the coarse motion control device 45a will be described.
The control unit 46a activates the coarse motion control program stored in the storage unit 47a, and executes the coarse motion positioning process shown in the flowchart of FIG. 5 in accordance with the coarse motion control program.
FIG. 5 is a flowchart showing the coarse positioning process.
When the coarse movement positioning process is executed by the control unit 46a, as shown in FIG. 5, first, the process proceeds to step S100.

In step S100, the target position is read from the movement destination instruction table, the process proceeds to step S102, and the command value signal indicating the read target position is continuously output until one coarse motion control and fine motion control is completed. The output process is executed, and the process proceeds to step S104.
In step S104, the deviation between the target position and the current position is calculated, the number of rotations of the screw shaft 11 required when the nut 12 moves the length corresponding to the calculated deviation is calculated, and the calculated number of rotations is roughly calculated. A coarse motion control process is output to the motor drive unit 48a as a motion command, and the process proceeds to step S106.

In step S106, a feedback signal is input from the signal conditioner 42, and the process proceeds to step S108, where it is determined whether the drive motor 14 has stopped based on the input feedback signal, and it has been determined that the drive motor 14 has stopped. When (Yes), the process proceeds to step S110, where a coarse movement completion signal indicating that the coarse movement control is completed is output to the fine movement control device 45b, and a series of processes is terminated and the original process is restored.
On the other hand, when it determines with the drive motor 14 not stopping by step S108 (No), it transfers to step S106.

Next, processing executed by the fine movement control device 45b will be described.
The control unit 46b activates the fine movement control program stored in the storage unit 47b, and executes the fine movement positioning process shown in the flowchart of FIG. 6 according to the fine movement control program.
FIG. 6 is a flowchart showing the fine movement positioning process.
When the fine movement positioning process is executed in the control unit 46b, as shown in FIG. 6, first, the process proceeds to step S200.
In step S200, it is determined whether or not a coarse movement completion signal has been input. When it is determined that a coarse movement completion signal has been input (Yes), the process proceeds to step S202, but when it is determined that this is not the case (No). Waits in step S200 until a coarse movement completion signal is input.

In step S202, a feedback signal is input from the signal adjuster 42, the process proceeds to step S204, a fine movement command is generated by PID control so as to eliminate the deviation indicated by the input feedback signal, and the generated fine movement command is transmitted to the actuator drive unit. The fine movement control process output to 48b is executed, and the process proceeds to step S206.
In step S206, it is determined whether or not the deviation indicated by the feedback signal is equal to or smaller than a predetermined value. When it is determined that the deviation is equal to or smaller than the predetermined value (Yes), the series of processes is terminated and the original process is restored. Let
On the other hand, when it is determined in step S206 that the deviation is larger than the predetermined value (No), the process proceeds to step S202.

Next, the operation of the present embodiment will be described.
FIG. 7 is a time chart showing the operation of the coarse / fine movement positioning device 1.
When the coarse / fine movement positioning device 1 starts operation, the control unit 46a activates the coarse movement control program, and the control unit 46b activates the fine movement control program.
When the fine movement control program is activated, the control unit 46b outputs an initial setting command to the actuator driving unit 48b. The actuator drive unit 48b converts the initial setting command into the initial setting voltage Vo, and supplies this to the piezoelectric actuator 36 to hold it. The initial setting voltage Vo is a voltage that gives an extension of about half of the effective stroke of the piezoelectric actuator 36, and the position of the moving base 6 in a state where the initial setting voltage Vo is applied to the piezoelectric actuator 36 is the original position.

Next, the control unit 46a reads the first target position stored in the movement destination instruction table. The command value signal indicating the target position is continuously output to the signal adjuster 42 until one coarse motion control and fine motion control are completed.
The control unit 46a that has read the target position calculates a deviation between the target position and the current position (original position) as shown in FIG. 7, and is necessary when the nut 12 moves a length corresponding to the calculated deviation. The number of rotations of the screw shaft 11 is calculated and output to the motor drive unit 48a as a coarse motion command. The motor drive unit 48 a converts the coarse motion command into a drive signal for the drive motor 14, and supplies this to the drive motor 14.

Since the drive motor 14 is a stepping motor, the drive signal is a pulse signal corresponding to the number of angular steps of the stepping motor necessary for rotating the calculated rotation speed of the screw shaft 11.
When the drive signal is supplied, the drive motor 14 rotates by the number of rotations corresponding to the drive signal, and the screw shaft 11 rotates to move the nut 12 in the axial direction.

  On the other hand, the signal adjuster 42 inputs a pulse-shaped detection signal indicating the unevenness of the scale 18 output by the position sensor 17 as the moving table 6 moves, encodes this with a first resolution, and obtains the obtained first signal. One encoded signal is output as a feedback signal to the control unit 46a. Further, the command value signal is input, the detection signal of the position sensor 17 is encoded with the second resolution, the deviation between the obtained second encoded signal and the command value signal is calculated, and the deviation signal indicating the calculated deviation is fed back. A signal is output to the control unit 46b.

The control unit 46a receives the feedback signal, counts the number of pulses, waits until the moving table 6 stops (stops the rotation of the drive motor 14) while recognizing the position of the moving table 6, and the moving table 6 stops. The position recognized at the time of recognition is recognized as the current position.
As described above, the coarse movement mechanism 10 that rotates the screw shaft 11 and moves the movable table 6 together with the nut 12 relative to the base 5 in the axial direction performs the coarse movement operation of the movable table 6.

In this case, the piezoelectric actuator 36 is only applied with the initial setting voltage Vo and is not subjected to feedback control by the position sensor 17. In addition, the piezoelectric actuator 36 is in a state in which a compressive load due to the preload reaction force of the angular ball bearings 20a and 20b is applied.
When the coarse motion control is completed, the control unit 46a outputs a coarse motion completion signal to the control unit 46b.

When the rough movement completion signal is input, the control unit 46b inputs a feedback signal as shown in FIG. 7, generates a fine movement command by PID control so as to eliminate the deviation indicated by the feedback signal, and uses the generated fine movement instruction as an actuator. It outputs to the drive part 48b. The actuator driving unit 48 b converts the fine movement command into a voltage and applies this control voltage to the piezoelectric actuator 36.
In the axial fine movement mechanism 41 with the rotation mechanism, the relative displacement amount of the outer ring 21a and the inner ring 23a, which is half the displacement of the piezoelectric actuator 36, becomes the fine movement displacement amount of the moving base 6. A voltage obtained by adding a control voltage that gives a displacement twice as much as the deviation and the initial setting voltage Vo is applied.

FIG. 8 is a diagram for explaining the fine movement operation of the axial fine movement mechanism 41 with the rotation mechanism.
For example, when the piezoelectric actuator 36 is extended by 2X, the pressing force generated by the extension presses the outer ring 21b in addition to the preload before fine movement control as shown in FIG. (Left in FIG. 1, hereinafter referred to as the left in the axial direction), the gap 40 is further narrowed by 2 × to absorb the elongation of the piezoelectric actuator 36. The displacement of the gap 40 is in addition to the preload before performing fine movement control on the contact surface between the ball 25b and the outer ring raceway 22b and the inner ring raceway 24b and the contact surface between the ball 25a and the outer ring raceway 22a and the inner ring raceway 24a. They are pressed and elastic deformation occurs between them, and the inner rings 23a and 23b are each displaced by X to the left in the axial direction. It should be noted that the amount of displacement of the inner rings 23a, 23b relative to the amount of displacement of the outer ring 21b can be appropriately set according to the magnitude of the preload, the rigidity of the angular ball bearings 20a, 20b, and other conditions.

On the other hand, when the piezoelectric actuator 36 contracts by 2X, the pressing force decreases, the outer ring 21b is moved in the axial direction (right in FIG. 1, hereinafter referred to as the right in the axial direction), and the gap 40 becomes wider by 2X. The shrinkage of the piezoelectric actuator 36 is absorbed. Due to the displacement of the gap 40, elastic deformation occurs, and the inner rings 23a and 23b are each displaced X to the right in the axial direction.
As described above, since the inner ring 23a, 23b absorbs the displacement 2X of the gap 40 in units of X, the inner rings 23a, 23b are moved to the screw shaft 11 when the force of the angular ball bearings 20a, 20b pressing each other is balanced. At the same time, X moves in the axial direction. In this case, the movement of the screw shaft 11 is absorbed by the extension of the coupling 15, and the movement of the opposite shaft end is absorbed by the play of the support bearing 16.

Thereby, the nut 12 moves X in the axial direction, and the moving base 6 moves X in the axial direction left relative to the base 5. That is, the relative displacement amount of the outer ring 21 a and the inner ring 23 a that is X displacement that is half the 2X displacement (expansion / contraction amount) of the piezoelectric actuator 36 becomes the fine movement displacement amount of the movable platform 6.
Thus, the fine movement operation is performed, and the control unit 46b stops the moving platform 6 at the target position while performing the feedback control so as to eliminate the deviation indicated by the feedback signal.

  In addition, since the gap 40 between the outer rings 21a and 21b is changed by the expansion and contraction of the piezoelectric actuator 36 to perform the fine movement operation, the preload is changed as a result, but the elongation accompanying the fine movement operation of the piezoelectric actuator 36 is the maximum. Since the change in the preload caused by this is about 10 μm, usually about several μm, there is no indentation or the like on the outer ring raceways 22a and 22b, the inner ring raceways 24a and 24b, and the balls 25a and 25b.

  Further, the axial fine movement mechanism 41 with the rotation mechanism does not have a spring having low rigidity, and the angular ball bearings 20a and 20b function as spring members having extremely high rigidity, and are extremely high with respect to a load in the compression direction. By the combination of the rigid piezoelectric actuator 36 and the highly rigid spring member, the axial fine movement mechanism 41 with a rotation mechanism has substantially the same rigidity as a bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically. Since it can be maintained, a responsive and stable fine movement operation can be realized.

Further, the preload reaction force applied to the angular ball bearings 20a and 20b acts on the piezoelectric actuator 36, and the fine movement operation is always performed while applying a compressive load. There is no need to use a spring.
Further, by using only the housing 27 and the screw shaft 11 that are as long as the piezoelectric actuator 36, the bearing unit can be assembled in the same manner as that for assembling the piezoelectric actuator 36 without any special consideration. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.

Furthermore, since the piezoelectric actuator 36 is automatically arranged coaxially when incorporated in the housing 27 with the inner peripheral surface of the housing 27 as a guide, the piezoelectric actuator 36 can be damaged early due to a radial load or moment load. Can be reduced.
Further, since the piezoelectric actuator 36 can be arranged coaxially with the screw shaft 11, the displacement of the piezoelectric actuator 36 can be made a pure axial displacement, and a highly accurate fine movement operation can be performed.

  In this way, in the present embodiment, the first encoded signal obtained by encoding the detection signal of the position sensor 17 with the first resolution is output as a feedback signal to the coarse motion control device 45a, and the detection of the position sensor 17 is performed. A signal adjuster 42 is provided that outputs a deviation signal indicating a deviation between the second encoded signal obtained by encoding the signal with the second resolution and the command value signal as a feedback signal to the fine movement control device 45b.

  As a result, the axial fine movement mechanism 41 with rotation mechanism, the fine movement control device 45b, and the signal adjuster 42 are introduced into an existing positioning device that does not have a fine movement mechanism without introducing a controller dedicated to the coarse / fine movement positioning device. Therefore, it is not necessary to rebuild the system as compared with the conventional case, and the time and labor required for the production can be reduced. Further, since the coarse motion control device 45a is configured to input a feedback signal with low resolution, an inexpensive product can be used as the coarse motion control device 45a, and the coarse motion control device 45a can provide a feedback signal. Since it is not necessary to shorten the reading cycle, the cost can be reduced as compared with the conventional case.

Further, in the present embodiment, the coarse motion control device 45a outputs a coarse motion completion signal indicating that the coarse motion control is completed to the fine motion control device 45b, and the fine motion control device 45b is based on the coarse motion completion signal. Fine movement control is started, and fine movement control is performed when the coarse movement operation is stopped.
As a result, the movements of the coarse motion and the fine motion overlap, and the controls do not interfere with each other so as to correct the motion of the coarse motion with the fine motion. Even if the preload amount of the angular ball bearings 20a and 20b changes due to the displacement of the piezoelectric actuator 36, the angular ball bearings 20a and 20b do not rotate, so that an influence such as an increase in torque accompanying a change in the preload does not occur.

Further, in the present embodiment, the feedback signal to fine movement control device 45b is an analog signal.
As a result, it is not necessary to use an expensive servo control device as the fine movement control device 45b, so that the cost can be further reduced.
Further, in the present embodiment, one outer ring 21a of the angular ball bearings 20a, 20b that are arranged to face each other and are preloaded is restrained in the axial direction on the housing 27, and the distance between the outer rings 21a, 21b is expanded or contracted. It was made to change by.

  As a result, the angular ball bearings 20a and 20b arranged opposite to each other function as a spring member having a very high rigidity, and a combination of the high rigidity in the compression direction of the piezoelectric actuator 36 and the high rigidity spring member allows the axial fine movement with a rotation mechanism. Since the rigidity of the mechanism 41 can be maintained high, it is possible to realize a stable fine movement operation with high responsiveness. In addition, since the reaction force of the preload acts on the piezoelectric actuator 36 and the fine movement operation can be performed while always applying a compressive load, it is possible to prevent the piezoelectric actuator 36 from being damaged due to the tensile load.

Further, in the present embodiment, preload is applied in advance in a state where the piezoelectric actuator 36 is not energized.
Thereby, even if the displacement amount of the piezoelectric actuator 36 becomes zero, the preload is not lost. Further, it is only necessary to energize the piezoelectric actuator 36 only when performing the positioning operation, and the energization time is shortened, so that the durability of the piezoelectric actuator 36 can be improved.

Further, in the present embodiment, the piezoelectric actuator 36 is a laminated type.
Thereby, an inexpensive and low voltage drive piezoelectric actuator 36 can be used.
Furthermore, in the present embodiment, the fine movement control is performed by feeding back the deviation between the current position recognized by the detection signal indicating the relative movement amount between the base 5 and the moving base 6 from the position sensor 17 and the target position.

Thereby, even when there is a lead error of the screw shaft 11, hysteresis of the piezoelectric actuator 36, or the like, highly accurate fine positioning can be performed.
Further, in the present embodiment, the piezoelectric actuator 36 is hollow and fitted to the inner peripheral surface of the housing 27, and the screw shaft 11 is inserted and arranged coaxially with the screw shaft 11.
As a result, it is possible to assemble the bearing unit by the same method as the method of assembling the bearing unit by using only the housing 27 and the screw shaft 11 that are longer by the piezoelectric actuator 36, and the assembly of the axial fine movement mechanism 41 with the rotation mechanism is facilitated. be able to.

  Furthermore, in the present embodiment, the inner peripheral surfaces of the inner rings 23a and 23b are fitted to the outer peripheral surface of the screw shaft 11, and the axial movement of the inner rings 23a and 23b is sandwiched between the inner ring engaging portion 29 and the lock nut 32. In addition to being fixed to the screw shaft 11, the movement of the outer ring 21a in the axial direction is restricted to the housing 27 by the outer ring locking portion 38, and the outer ring 21b is moved in the axial direction by the piezoelectric actuator 36.

As a result, half of the displacement of the piezoelectric actuator 36 can be made the displacement of the screw shaft 11, and the displacement error of the piezoelectric actuator 36 can be halved to realize a highly accurate fine movement operation.
Further, in the present embodiment, the piezoelectric actuator 36 is disposed so as to press the outer ring 21a which is the non-rotating side of the angular ball bearings 20a and 20b.
Thereby, wiring to the piezoelectric actuator 36 can be performed easily.
In the first embodiment, the moving table 6 corresponds to the moving part described in claim 1, 3 or 7, and the signal conditioner 42 corresponds to the signal adjusting means described in claim 1 or 3. .

Next, a second embodiment of the present invention will be described with reference to the drawings. 9 to 11 are views showing a second embodiment of the coarse / fine movement positioning device according to the present invention.
This embodiment is different from the first embodiment in that the second encoded signal is used as a feedback signal to the axial fine movement mechanism 41 with a rotation mechanism instead of the deviation signal. Hereinafter, only the parts different from the first embodiment will be described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.
First, the configuration of the control system of the coarse / fine movement positioning device 1 will be described.

FIG. 9 is a block diagram showing the configuration of the control system of the coarse / fine movement positioning apparatus 1.
As shown in FIG. 9, the control system of the coarse / fine movement positioning device 1 instructs the coarse movement control device 45a and the fine movement control device 45b in addition to the signal adjuster 42, the coarse movement control device 45a, the fine movement control device 45b, and the amplifier 43. It has a sequencer 45c that outputs a value signal.
The coarse output control device 45a is connected to the first output terminal of the signal adjuster 42, and the first encode signal is input to the coarse adjustment control device 45a as a feedback signal. A fine movement control device 45b is connected to the second output terminal, and the second encoded signal is input to the fine movement control device 45b as a feedback signal.

The sequencer 45c includes a control unit 46c that executes a command value signal output process similar to that in step S102, and a storage unit 47c that stores a program executed by the control unit 46c, various data used therefor, processing results of the control unit 46c, and the like. And is configured.
The storage unit 47c stores a control program for executing the command value signal output process and a movement destination instruction table.
In this embodiment, the coarse motion control device 45a does not output a command value signal, and the command values held by the coarse motion control device 45a and the fine motion control device 45b are not used for control and are set to “0”. Has been.

Next, processing executed by the coarse motion control device 45a will be described.
The control unit 46a executes the coarse movement positioning process shown in the flowchart of FIG. 10 instead of the coarse movement positioning process of FIG.
FIG. 10 is a flowchart showing the coarse positioning process.
When the coarse movement positioning process is executed by the control unit 46a, the process first proceeds to step S300 as shown in FIG.
In step S300, a command value signal is input from the sequencer 45c, and the process proceeds to step S302.
In step S302, the deviation between the target position and the current position is calculated based on the input command value signal, and the number of rotations of the screw shaft 11 required when the nut 12 moves the length corresponding to the calculated deviation is calculated. Then, a coarse motion control process for outputting the calculated rotational speed to the motor drive unit 48a as a coarse motion command is executed, and the process proceeds to step S304.

In step S304, a feedback signal is input from the signal conditioner 42, and the process proceeds to step S306, where it is determined whether the drive motor 14 has stopped based on the input feedback signal, and it has been determined that the drive motor 14 has stopped. If yes (Yes), the process proceeds to step S308, where a coarse movement completion signal is output to the fine movement control device 45b, a series of processes are terminated, and the original process is restored.
On the other hand, when it determines with the drive motor 14 not stopping by step S306 (No), it transfers to step S304.

Next, processing executed by the fine movement control device 45b will be described.
The control unit 46b executes the fine movement positioning process shown in the flowchart of FIG. 11 instead of the fine movement positioning process of FIG.
FIG. 11 is a flowchart showing the fine movement positioning process.
When the fine movement positioning process is executed by the control unit 46b, first, the process proceeds to step S400 as shown in FIG.
In step S400, it is determined whether or not a coarse movement completion signal has been input. When it is determined that a coarse movement completion signal has been input (Yes), the process proceeds to step S402, but when it is determined that this is not the case (No). Waits in step S400 until a coarse movement completion signal is input.

In step S402, the command value signal is input from the sequencer 45c, the process proceeds to step S404, the feedback signal is input from the signal adjuster 42, the process proceeds to step S406, and based on the input command value signal and the feedback signal. The deviation between the target position and the current position is calculated, and the process proceeds to step S408.
In step S408, a fine movement command is generated by PID control so as to eliminate the calculated deviation, and a fine movement control process for outputting the generated fine movement instruction to the actuator driving unit 48b is executed, and the process proceeds to step S410.

In step S410, it is determined whether or not the deviation indicated by the feedback signal is equal to or smaller than a predetermined value. When it is determined that the deviation is equal to or smaller than the predetermined value (Yes), the series of processes is terminated and the original process is restored. Let
On the other hand, when it is determined in step S410 that the deviation is larger than the predetermined value (No), the process proceeds to step S404.

Next, the operation of the present embodiment will be described.
When the coarse / fine movement positioning device 1 starts operation, the control unit 46c activates the control program, the control unit 46a activates the coarse movement control program, and the control unit 46b activates the fine movement control program.
When the control program is activated, the control unit 46c reads the first target position stored in the movement destination instruction table. The command value signal indicating the target position is continuously output to the coarse motion control device 45a and the fine motion control device 45b until one coarse motion control and fine motion control are completed.

  When the coarse motion control program is activated, the control unit 46a inputs a command value signal, calculates a deviation between the target position and the current position (original position), and the nut 12 moves a length corresponding to the calculated deviation. The rotational speed of the screw shaft 11 that is sometimes required is calculated, and this is output to the motor drive unit 48a as a coarse motion command. The motor drive unit 48 a converts the coarse motion command into a drive signal for the drive motor 14, and supplies this to the drive motor 14.

When the drive signal is supplied, the drive motor 14 rotates by the number of rotations corresponding to the drive signal, and the screw shaft 11 rotates to move the nut 12 in the axial direction.
On the other hand, the signal adjuster 42 receives the detection signal of the position sensor 17, encodes it with the first resolution, and outputs the obtained first encoded signal as a feedback signal to the control unit 46a. Further, the detection signal of the position sensor 17 is encoded with the second resolution, and the obtained second encoded signal is output as a feedback signal to the control unit 46b.

The control unit 46a receives the feedback signal, counts the number of pulses, waits until the moving table 6 stops (stops the rotation of the drive motor 14) while recognizing the position of the moving table 6, and the moving table 6 stops. The position recognized at the time of recognition is recognized as the current position.
As described above, the coarse movement mechanism 10 that rotates the screw shaft 11 and moves the movable table 6 together with the nut 12 relative to the base 5 in the axial direction performs the coarse movement operation of the movable table 6.

When the coarse motion control is completed, the control unit 46a outputs a coarse motion completion signal to the control unit 46b.
When the coarse movement completion signal is input, the control unit 46b inputs a command value signal and a feedback signal, calculates a deviation between the target position and the current position, and generates a fine movement command by PID control so as to eliminate the calculated deviation. The generated fine movement command is output to the actuator driver 48b. The actuator driving unit 48 b converts the fine movement command into a voltage and applies this control voltage to the piezoelectric actuator 36.

Subsequent operations are the same as those in the first embodiment, and a description thereof will be omitted.
In this manner, in the present embodiment, the encoded signal obtained by encoding the detection signal of the position sensor 17 with the first resolution is output as a feedback signal to the coarse motion control device 45a, and the detection signal of the position sensor 17 is output. A signal adjuster 42 is provided that outputs an encoded signal obtained by encoding at the second resolution as a feedback signal to the fine movement control device 45b.
Thereby, the same effect as that of the first embodiment can be obtained.
In the second embodiment, the signal conditioner 42 corresponds to the signal conditioner described in claim 4.

Next, a third embodiment of the present invention will be described with reference to the drawings. 12 and 13 are diagrams showing a third embodiment of the coarse / fine movement positioning device according to the present invention.
The present embodiment is different from the first embodiment in that the angular ball bearings 20a and 20b are installed in the housing 27 and the nut 61 is rotatably supported. Hereinafter, only the parts different from the first embodiment will be described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

First, the moving mechanism of the coarse / fine movement positioning device 1 will be described.
FIG. 12 is a cross-sectional view of the axial fine movement mechanism 41 with a rotation mechanism.
FIG. 13 is a side view of the coarse / fine movement positioning device 1.
12 and 13, reference numeral 61 denotes a nut of the ball screw device 13, and a nut raceway groove (not shown) facing the shaft raceway groove 11a is formed on the inner peripheral surface as in the first embodiment. The screw shaft 11 is screwed through a plurality of balls (not shown) without play.

The inner peripheral surfaces of the inner rings 23a and 23b of the angular ball bearings 20a and 20b are fitted to the outer peripheral surface of the nut 61 as a front combination, and a threaded portion 62 into which the lock nut 32 is screwed at one end of the nut 61. Is formed.
Reference numeral 63 denotes an inner ring locking portion, which is a large-diameter portion having a diameter substantially equal to the outer diameter of the inner rings 23a and 23b formed at the end of the nut 61 on the opposite side of the threaded portion 62. Lock the sides.

Reference numeral 64 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the inner rings 23a and 23b. Placed in.
Reference numeral 65 denotes an inner ring spacer, which is a cylindrical member having substantially the same outer diameter and inner diameter as the inner rings 23a and 23b. The inner peripheral surface of the inner ring spacer is fitted into the outer peripheral surface of the nut 61, and the inner ring spacer 30 of the inner ring 23b. Located on the opposite side.

Reference numeral 67 denotes a drive motor, which is a hollow motor capable of forward and reverse rotation, such as a stepping motor having a hollow hole into which the screw shaft 11 is inserted, and is coupled to the screw portion 62 side of the nut 61 by a coupling 68. Is driven to rotate.
The angular ball bearings 20a and 20b are opposed to each other through an inner ring spacer 64 in a front combination, and the inner ring 23a, the inner ring spacer 64, the inner ring 23b, and the inner ring spacer 65 are interposed between the inner ring locking portion 63 and the lock nut 32. The axial movement of the inner rings 23 a and 23 b is fixed to the nut 61.

  As in the first embodiment, the outer ring 21a is fitted to the inner peripheral surface of the housing 27, and the outer ring locking portion 38 restricts movement in the axial direction and the outer ring 21b on the non-restricted side is an outer ring spacer. 37 and the non-energized piezoelectric actuator 36, which are pressed by fastening the cover 39, a predetermined preload is applied to the angular ball bearings 20a, 20b, and a gap 40 is formed between the outer rings 21a, 21b.

The screw shaft 11 is fixed to fixed portions 69 arranged on both sides of the base 5, the housing 27 and the drive motor 67 are fixed to the moving base 6, and the coarse movement mechanism 10 moves and rotates in the axial direction. The nut 61 is engaged with the fixed screw shaft 11 and is rotatably supported by the angular ball bearings 20a and 20b.
The axial fine movement mechanism 41 with a rotation mechanism includes angular ball bearings 20a and 20b, a nut 61, an inner ring locking part 63, an inner ring spacer 64, an inner ring spacer 65, a lock nut 32, a housing 27, an outer ring locking part 38, and an outer ring spacer. 37, the piezoelectric actuator 36, the cover 39 and the like are arranged on the same axis of the nut 61 as shown in FIG.

Next, the operation of the present embodiment will be described.
The coarse / fine movement positioning device 1 is equipped with a control system similar to that of the first embodiment. In this case, the motor drive unit 48 a has a function of sending a drive signal for driving the drive motor 67.
When the fine movement control program is activated, the control unit 46b outputs an initial setting command to the actuator driving unit 48b. The actuator drive unit 48b converts the initial setting command into the initial setting voltage Vo, and supplies this to the piezoelectric actuator 36 to hold it. The initial setting voltage Vo is a voltage that gives an extension of about half of the effective stroke of the piezoelectric actuator 36, and the position of the moving base 6 in a state where the initial setting voltage Vo is applied to the piezoelectric actuator 36 is the original position.

Next, the control unit 46a reads the first target position stored in the movement destination instruction table. The command value signal indicating the target position is continuously output to the signal adjuster 42 until one coarse motion control and fine motion control are completed.
The control unit 46a that has read the target position calculates a deviation between the target position and the current position (original position), and calculates the number of rotations of the nut 61 that is necessary when the nut 61 moves a length corresponding to the calculated deviation. This is calculated and output to the motor drive unit 48a as a coarse motion command. The motor drive unit 48 a converts the coarse motion command into a drive signal for the drive motor 67, and supplies this to the drive motor 67.

Since the drive motor 67 is a stepping motor, the drive signal is a pulse signal corresponding to the number of angular steps of the stepping motor necessary for rotating the calculated rotation number of the nut 61.
When the drive signal is supplied, the drive motor 67 rotates by the number of rotations corresponding to the drive signal, and the nut 61 rotates on the screw shaft 11 to move the movable table 6 in the axial direction.

  On the other hand, the signal adjuster 42 receives the detection signal of the position sensor 17, encodes it with the first resolution, and outputs the obtained first encoded signal as a feedback signal to the control unit 46a. Further, the command value signal is input, the detection signal of the position sensor 17 is encoded with the second resolution, the deviation between the obtained second encoded signal and the command value signal is calculated, and the deviation signal indicating the calculated deviation is fed back. A signal is output to the control unit 46b.

The control unit 46a inputs a feedback signal, counts the number of pulses, waits until the moving table 6 stops (stops rotation of the drive motor 67) while recognizing the position of the moving table 6, and the moving table 6 stops. The position recognized at the time of recognition is recognized as the current position.
In this way, the coarse movement mechanism 10 that rotates the nut 61 and moves the movable table 6 together with the nut 61 in the axial direction with respect to the base 5 performs the coarse movement operation of the movable table 6.

In this case, the piezoelectric actuator 36 is only applied with the initial setting voltage Vo and is not subjected to feedback control by the position sensor 17. In addition, the piezoelectric actuator 36 is in a state in which a compressive load due to the preload reaction force of the angular ball bearings 20a and 20b is applied.
When the coarse motion control is completed, the control unit 46a outputs a coarse motion completion signal to the control unit 46b.

When the rough movement completion signal is input, the control unit 46b inputs a feedback signal, generates a fine movement command by PID control so as to eliminate the deviation indicated by the feedback signal, and outputs the generated fine movement command to the actuator driving unit 48b. The actuator driving unit 48 b converts the fine movement command into a voltage and applies this control voltage to the piezoelectric actuator 36.
In the axial fine movement mechanism 41 with a rotation mechanism, as in the first embodiment, the relative displacement amount of the outer ring 21a and the inner ring 23a, which is half the displacement of the piezoelectric actuator 36, is the amount of fine movement displacement of the moving base 6. Become.

  That is, as in the first embodiment, when the piezoelectric actuator 36 is extended by 2X, the pressing force generated by the extension presses the outer ring 21b in addition to the preload before performing fine movement control, and the outer ring 21b is moved to the left in the axial direction, and the gap 40 is further narrowed by 2X to absorb the elongation of the piezoelectric actuator 36. The displacement of the gap 40 causes elastic deformation, and the inner rings 23a and 23b are each displaced by X to the left in the axial direction.

On the other hand, when the piezoelectric actuator 36 contracts by 2X, the pressing force decreases, the outer ring 21b is moved to the right in the axial direction, and the gap 40 becomes wider by 2X to absorb the contraction of the piezoelectric actuator 36. Due to the displacement of the gap 40, elastic deformation occurs, and the inner rings 23a and 23b are each displaced X to the right in the axial direction.
As described above, the inner ring 23a, 23b absorbs the displacement 2X of the gap 40 by dividing the X into X, so that when the force of the angular ball bearings 20a, 20b pressing each other is balanced, the inner rings 23a, 23b together with the nut 61 Move X in the axial direction. The movement of the nut 61 in this case is absorbed by the extension of the coupling 68.

As a result, the nut 61 moves X in the axial direction, and the moving table 6 moves X in the axial direction to the right with respect to the base 5.
Thus, the fine movement operation is performed, and the control unit 46b stops the movable platform 6 at the target position while performing feedback control so as to eliminate the deviation indicated by the feedback signal.
Subsequent operations are the same as those in the first embodiment, and a description thereof will be omitted.

  As in the first embodiment, the axial fine movement mechanism 41 with the rotation mechanism does not have a spring with low rigidity, so that the piezoelectric actuator 36 having very high rigidity against a load in the compression direction. And the highly rigid spring member can maintain the rigidity of the axial fine movement mechanism 41 with the rotation mechanism substantially the same as that of the bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically. Therefore, it is possible to realize a stable fine movement operation with high responsiveness.

Further, since the reaction force of the preload applied to the angular ball bearings 20a and 20b acts on the piezoelectric actuator 36 and always performs a fine movement operation while applying a compressive load, there is no occurrence of breakage due to a tensile load, and this can be avoided. There is no need to use a spring.
Further, by using only the housing 27 and the screw shaft 11 that are as long as the piezoelectric actuator 36, the bearing unit can be assembled in the same manner as that for assembling the piezoelectric actuator 36 without any special consideration. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.

Furthermore, since the piezoelectric actuator 36 is automatically arranged coaxially when incorporated in the housing 27 with the inner peripheral surface of the housing 27 as a guide, the piezoelectric actuator 36 can be damaged early due to a radial load or moment load. Can be reduced.
Furthermore, since the piezoelectric actuator 36 can be arranged coaxially with the nut 61, the displacement of the piezoelectric actuator 36 can be made a pure axial displacement, and a highly accurate fine movement operation can be performed.

In this way, in the present embodiment, the angular ball bearings 20a and 20b are installed in the housing 27 to rotatably support the nut 61, and are arranged so as to face one of the angular ball bearings 20a and 20b. The outer ring 21a is constrained to the housing 27 in the axial direction, and the distance between the outer rings 21a and 21b is changed by expansion and contraction of the piezoelectric actuator 36.
Thereby, an effect equivalent to that of the first embodiment can be obtained.

Furthermore, in the present embodiment, the piezoelectric actuator 36 is hollow and fitted to the inner peripheral surface of the housing 27, and the nut 61 is inserted and arranged coaxially with the nut 61.
As a result, it is possible to assemble the bearing unit by the same method as the method of assembling the bearing unit by using only the housing 27 and the screw shaft 11 that are longer by the piezoelectric actuator 36, and the assembly of the axial fine movement mechanism 41 with the rotation mechanism is facilitated. be able to.

  Furthermore, in the present embodiment, the inner peripheral surfaces of the inner rings 23a and 23b are fitted to the outer peripheral surface of the nut 61, and the axial movement of the inner rings 23a and 23b is sandwiched between the inner ring engaging portion 63 and the lock nut 32. While being fixed to the nut 61, the movement of the outer ring 21a in the axial direction is restricted to the housing 27 by the outer ring locking portion 38, and the outer ring 21b is moved in the axial direction by the piezoelectric actuator 36.

As a result, half of the displacement of the piezoelectric actuator 36 can be made the displacement of the movable table 6, and the displacement error of the piezoelectric actuator 36 can be halved to realize a highly accurate fine movement operation.
Further, in the present embodiment, the piezoelectric actuator 36 is disposed so as to press the outer ring 21a which is the non-rotating side of the angular ball bearings 20a and 20b.

Thereby, wiring to the piezoelectric actuator 36 can be performed easily.
In the third embodiment, the moving table 6 corresponds to the moving unit described in claim 8.
In the first to third embodiments, the feedback signal to the fine movement control device 45b is output as an analog signal. However, the present invention is not limited to this, and the feedback signal is output as a digital signal. You can also.
In the first to third embodiments, the inner ring spacers 30 and 64 are provided between the opposed inner rings 23a and 23b to apply the preload. However, the present invention is not limited to this. The opposite surfaces of 23a and 23b can be extended to a length corresponding to half the width of the inner ring spacers 30 and 64 so that the inner rings 23a and 23b are brought into direct contact with each other.

  In the first to third embodiments, the pre-load is applied to the angular ball bearings 20a and 20b arranged opposite to each other in advance via the non-energized piezoelectric actuator 36. The piezoelectric actuator 36 and the outer rings 21a and 21b or the inner rings 23a and 23b are opposed to each other through a gap so that no preload is generated when the piezoelectric actuator 36 is not energized. May be applied to the piezoelectric actuator 36 to generate a predetermined preload on the angular ball bearings 20a, 20b arranged opposite to each other.

Accordingly, in order to give a predetermined preload to the angular ball bearings 20a and 20b, for example, in the first embodiment, the axial length of the outer ring spacer 37 and the like are precisely adjusted in accordance with the preload amount. So-called preload adjustment is not required, and precise preload adjustment can be easily performed only by applying a predetermined voltage.
Moreover, in the said 1st thru | or 3rd Embodiment, although comprised so that two rolling bearing apparatuses which consist of one angular ball bearing might be opposingly arranged, not only this but a several angular ball bearing is combined in parallel For example, two rolling bearing devices with one set of angular ball bearings on one side and two rolling bearing devices on the other side may be opposed to each other. May be.

In the first to third embodiments, the angular ball bearings 20a and 20b are used as bearings for supporting the screw shaft 11. However, the present invention is not limited to this, and the rotating support portion is rotated at high speed. Needless to say, the present invention can be applied to all the combined motion mechanisms of fine rotation and axial fine movement.
Further, in the first and second embodiments, the feed screw device is configured as the ball screw device 13 for screwing the screw shaft 11 and the nut 12 through the ball. It can also be configured as a sliding screw device in which the nut 11 and the nut 12 are directly screwed together.

In the first to third embodiments, the feedback control is performed during the fine movement control. However, the present invention is not limited to this, and the deviation between the target position and the current position is performed during the coarse movement control. It is also possible to perform feedback control using, so that the coarse motion operation is stopped when the deviation becomes a predetermined value or less.
As a result, the lead accuracy of the screw shaft 11 can be corrected, the correction amount by the fine movement operation of the piezoelectric actuator 36 can be reduced, and it is not necessary to use the piezoelectric actuator 36 having a larger expansion / contraction amount than necessary.

  In the first to third embodiments, the coarse movement mechanism 10 that drives the long stroke range using the ball screw device 13 in which the screw shaft 11 and the nuts 12 and 61 are screwed together, and the nut 12. The piezoelectric actuator 36 is disposed between the movable table 61 and the moving table 6, and an axial fine movement mechanism 41 with a rotation mechanism that changes the position of the base 5 and the moving table 6 by expansion and contraction of the piezoelectric actuator 36 is configured. However, the present invention is not limited to this, and any moving mechanism may be adopted as long as the structure includes a coarse movement mechanism that moves the movable base 6 and a fine movement mechanism that moves the movable base 6 with higher movement accuracy than the coarse movement mechanism. it can. For example, the present invention can be applied to a moving mechanism in which a piezoelectric actuator is disposed between a coarse movement table and a fine movement table and the positions of the base and the fine movement table are changed by expansion and contraction of the piezoelectric actuator.

It is sectional drawing of the axial direction fine movement mechanism 41 with a rotation mechanism. 2 is a plan view of the coarse / fine movement positioning device 1. FIG. It is a side view of the coarse / fine movement positioning device. 3 is a block diagram showing a configuration of a control system of the coarse / fine movement positioning apparatus 1. FIG. It is a flowchart which shows rough movement positioning processing. It is a flowchart which shows a fine movement positioning process. 3 is a time chart showing the operation of the coarse / fine movement positioning apparatus 1; It is a figure for demonstrating the fine movement operation | movement of the axial direction fine movement mechanism 41 with a rotation mechanism. 3 is a block diagram showing a configuration of a control system of the coarse / fine movement positioning apparatus 1. FIG. It is a flowchart which shows rough movement positioning processing. It is a flowchart which shows a fine movement positioning process. It is sectional drawing of the axial direction fine movement mechanism 41 with a rotation mechanism. It is a side view of the coarse / fine movement positioning device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coarse / fine motion positioning device 2 Linear guide mechanism 3 Rail 4 Slider 4a Moving base mounting surface 5 Base 6 Moving base 10 Coarse moving mechanism 11 Screw shaft 11a Shaft raceway 12, 61 Nut 13 Ball screw device 14, 67 Drive motor 16 Support Bearing 17 Position sensor 18 Scale 20a, 20b Angular contact ball bearing 21a, 21b Outer ring 22a, 22b Outer ring raceway 23a, 23b Inner ring 24a, 24b Inner ring raceway 25a, 25b Ball 26 Fitting shaft 27 Housing 27a Screw hole 29, 63 Inner ring locking part 30, 64 Inner ring spacer 31, 65 Inner ring spacer 32 Lock nut 33, 62 Screw part 34 Coupling attachment part 36 Piezoelectric actuator 36a Hollow part 37 Outer ring spacer 38 Outer ring locking part 39 Cover 40 Clearance 41 Axial fine movement mechanism with rotating mechanism 42 signal conditioner 45a coarse motion controller 45b Turning control apparatus 45c sequencer 46a~46c controller 47a~47c storage unit 48a the motor driving unit 48b actuator driving unit

Claims (8)

The coarse motion based on a feedback signal relating to the movement of the moving unit, a coarse moving mechanism for moving the moving unit, a fine moving mechanism for moving the moving unit with higher movement accuracy than the coarse moving mechanism, and a moving result of the moving unit. A coarse / fine motion positioning device comprising: a coarse motion control device that controls a mechanism; and a fine motion control device that controls the fine motion mechanism based on the feedback signal;
Based on a position sensor that detects the position of the moving unit, and a detection signal of the position sensor, the feedback signal of the first resolution is output to the coarse motion control device, and the second resolution higher than the first resolution A coarse / fine movement positioning apparatus, comprising: a signal adjusting means for outputting the feedback signal to the fine movement control apparatus. In claim 1,
The coarse motion control device outputs a coarse motion completion signal indicating that the coarse motion control is completed to the fine motion control device,
The coarse / fine movement positioning apparatus starts fine movement control based on the coarse movement completion signal. In any one of Claim 1 and 2,
The coarse motion control device outputs a command value signal indicating a target position of the moving unit to the signal adjusting means,
The signal adjustment means outputs an encoded signal obtained by encoding the detection signal of the position sensor with the first resolution to the coarse motion control device as the feedback signal, and outputs the detection signal of the position sensor to the second motion signal. A coarse / fine movement positioning apparatus, wherein a deviation signal indicating a deviation between an encoded signal obtained by encoding with a resolution and the command value signal is output as the feedback signal to the fine movement control apparatus. In any one of Claim 1 and 2,
The signal adjustment means outputs an encoded signal obtained by encoding the detection signal of the position sensor with the first resolution to the coarse motion control device as the feedback signal, and outputs the detection signal of the position sensor to the second motion signal. A coarse / fine movement positioning apparatus characterized in that an encode signal obtained by encoding at a resolution is output as the feedback signal to the fine movement control apparatus. In any one of Claims 1 thru | or 4,
The coarse / fine movement positioning device, wherein the feedback signal to the fine movement control device is an analog signal. In any one of Claims 1 thru | or 5,
The coarse / fine movement positioning device, wherein the feedback signal to the fine movement control device is a digital signal. In any one of Claims 1 thru | or 6,
The coarse movement mechanism is driven based on a screw shaft rotatably supported by a base, a nut screwed to the screw shaft and fixed to the moving portion, and a drive signal from the coarse movement control device. And a motor for rotating the screw shaft,
The fine movement mechanism includes two rolling bearing devices that are arranged opposite to each other and applied with a preload, a housing that is fixed to the base and into which each outer ring of the rolling bearing device is fitted, and a control voltage from the fine movement control device. A piezoelectric actuator that expands and contracts in accordance with the inner ring, the inner ring of the rolling bearing device is fitted to the screw shaft, the inner ring is fixed to the screw shaft in the axial direction, and one of the outer rings is fixed in the axial direction. The coarse / fine motion positioning device is characterized in that the axial distance between the outer rings is changed by expansion and contraction of the piezoelectric actuator. In any one of Claims 1 thru | or 6,
The coarse motion mechanism is driven based on a screw shaft fixed to a base, a nut screwed to the screw shaft and rotatably supported by the moving unit, and a drive signal from the coarse motion control device. And a motor for rotating the nut,
The fine movement mechanism includes two rolling bearing devices that are arranged opposite to each other and applied with a preload, a housing that is fixed to the moving part and into which each outer ring of the rolling bearing device is fitted, and a control voltage from the fine movement control device. And a piezoelectric actuator that expands and contracts in response to the inner ring. The inner ring of the rolling bearing device is fitted into the nut, the inner ring is fixed to the nut in the axial direction, and one of the outer rings is constrained in the axial direction. The coarse / fine movement positioning device is characterized in that the axial distance between the outer rings is changed by expansion and contraction of the piezoelectric actuator.

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