JP2010009376A - Locating device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning device having standstill stability and its control method. <P>SOLUTION: The positioning device is provided with: a driving part for generating a driving force to move an object; a control part for servo-controlling the driving part to move the object toward a target location; and a fixing part for fixing the object with a fixing force which is larger than the driving force. After the moving object reaches the target location and until the fixing part at least fixes the object, the control part continues servo-control with a servo gain which is smaller than a servo gain in a period when the object is moving. The positioning device is provided with a floating force generation part for floating the object by generating the floating force. After the floating force generation part stops the generation of the floating force and until the fixing part fixes the object, the control part may continue servo-control with the servo gain which is smaller than the servo gain in the period when the object is floated by the floating force generation part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a positioning device and a control method. More specifically, the present invention relates to a positioning apparatus that positions an object at a target position by servo control and a control method thereof.

  There is a positioning device that moves an object toward a target position by using a servo-controlled actuator. Patent Document 1 below describes a control device that cuts off electric power after fixing a shaft of a servo motor. Patent Document 2 below describes that in a positioning device including a piston that is driven by the pressure of a working fluid, the impact when the piston is stopped is reduced.

  Further, Patent Document 3 below describes switching control when the air cylinder is stopped at a target position. Furthermore, Patent Document 4 below describes that the servo gain is stabilized in a servo mechanism using air as a working fluid.

Japanese Patent Application Laid-Open No. 08-071970 Japanese Patent Laid-Open No. 10-131902 JP-A-11-148502 Japanese Patent Laid-Open No. 11-249746

  As described above, the servo-controlled positioning device can move the object toward the target position with high accuracy. On the other hand, depending on the application of the positioning device, the stationary stability of the object that has reached the target position is more important than the position accuracy with respect to the target position. In this application, when a servo control with a high position accuracy is mounted in order to obtain a high stationary stability, the positioning device becomes expensive.

  Therefore, in order to solve the above problem, as a first embodiment of the present invention, a drive unit that generates a driving force for moving an object and a control that servo-controls the drive unit to move the object toward a target position And a fixing unit that fixes the object with a fixing force larger than the driving force, and after the moved object has reached the target position, at least until the fixing unit fixes the object, A positioning device is provided that continues servo control with a servo gain smaller than the servo gain during the period in which the object has moved.

  Further, as a second embodiment of the present invention, a drive unit that moves an object, a control unit that servo-controls the drive unit to move the object toward a target position, and a drive force of the drive unit. The positioning unit includes a fixing unit that fixes with a larger fixing force, and after the moved object has reached the target position, at least until the fixing unit fixes the object, There is provided a control method for continuing servo control with a servo gain smaller than the servo gain during the period in which the object is moving.

  The above summary of the present invention does not enumerate all necessary features of the present invention. Also, a sub-combination of these feature groups can be an invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solution of the invention.

  FIG. 1 is a diagram schematically showing the structure of the positioning device 100. Positioning device 100 includes an operation unit 101 that performs a positioning operation, and a control unit 102 that controls operation unit 101.

  The operation unit 101 includes a main body 111 fixed to a floor or the like on which the positioning device 100 is installed, and a cylinder 150 and a stage 160 that move integrally with the main body 111. A reference mark 170 is held at one end of the stage 160. The reference mark 170 is, for example, an optical pattern indicating a specific point on a transparent glass substrate.

  For example, a manufacturing process of a semiconductor device includes a stage in which fine alignment is required, such as a mask or a reticle and a substrate, a plurality of stacked dies or substrates, and a die and a lead. In such a stage, the alignment target is imaged by a plurality of imaging devices whose relative positions are known. The positioning device 100 can be used for the purpose of detecting the relative positions of a plurality of imaging devices with high accuracy by moving the reference mark 170 back and forth within the field of view of the imaging device.

  The main body 111 includes a base 110, a support 120, a guide 130 and a piston 140. The base 110 is fixed horizontally and becomes a reference for the operation of the positioning device 100 as a whole. The support columns 120 are spaced apart from each other on the base 110 and support both ends of the guide unit 130.

  The guide part 130 extends horizontally, for example, and holds the piston 140 at substantially the center thereof. Further, the guide portion 130 is inserted into the side end surface of the cylinder 150 in the middle portion from the support column 120 to the piston 140 to guide the moving direction of the cylinder 150.

  The piston 140 is located inside the cylinder 150. Inside the cylinder 150, a pair of pressure chambers 152, 154 are formed on both sides of the piston 140. As a result, the cylinder 150 moves horizontally with respect to the piston 140 so that the pressures in the pair of pressure chambers 152 and 154 are balanced.

  Further, the main body 111 includes an encoder 180 and a fixing mechanism 190 disposed on the base 110. The encoder 180 detects the scale of the linear scale 182 mounted on the lower surface of the piston 140 in parallel with the guide portion 130 and generates a pulse signal corresponding to the amount of movement of the cylinder 150 relative to the base 110.

  The fixing mechanism 190 includes a shoe 192 that moves up and down with respect to the base 110. The raised shoe 192 contacts the cylinder 150 and presses the cylinder 150 against the guide portion 130. Thereby, the cylinder 150 is firmly fixed and does not move. On the other hand, since the lowered shoe 192 is separated from the cylinder 150, the movement of the cylinder 150 is not hindered.

  The control unit 102 includes a plurality of control valves 232, 242, 252, and 262, a pair of thrust control units 230 and 240, a levitation force control unit 250, a fixing mechanism control unit 260, a servo control unit 270, and a sequence control unit 280. Further, the control unit 102 discharges the working fluid via the pressure source 210 that supplies pressurized working fluid to each of the control valves 232, 242, 252, 262, and the control valves 232, 242, 252, 262. And an exhaust portion 290. As the working fluid, for example, dry air can be used, but is not limited thereto.

  The pressure source 210 supplies a working fluid with a stable pressure to each of the control valves 232, 242, 252, 262 via the pressure gauge 220. The control valves 232 and 242 are controlled by the thrust control units 230 and 240 to be opened or closed.

  When the control valves 232 and 242 cause the pressure chambers 152 and 154 to communicate with the pressure source 210 according to the control of the thrust control units 230 and 240, the working fluid is supplied to the pressure chambers 152 and 154, respectively. Further, when the control valves 232 and 242 cause the pressure chambers 152 and 154 to communicate with the exhaust unit 290, the inside of the pressure chambers 152 and 154 is exhausted.

  Further, the thrust control units 230 and 240 are controlled by the servo control unit 270. The servo control unit 270 refers to the pulse signal generated by the encoder 180 and monitors the displacement amount of the cylinder 150 with respect to the initial position. Thus, the servo control unit 270 calculates a difference between the current position of the cylinder 150 and the target position, and sends a command to the thrust control units 230 and 240 so that the cylinder 150 moves toward the target position.

  The levitation force control unit 250 supplies the working fluid to the sliding surfaces of the piston 140 and the cylinder 150 via the control valve 252. Thereby, a laminar flow of the working fluid is generated on the sliding surfaces of the piston 140 and the cylinder 150, and the cylinder 150 moves smoothly.

  In the illustrated example, the working fluid is not supplied between the guide portion 130 and the cylinder 150. However, the working fluid flowing out from the pressure chambers 152 and 154 forms a laminar flow between the guide unit 130 and the cylinder 150 to reduce friction between them. As described above, the series of structures including the pressure source 210, the control valve 252 and the levitation force control unit 250 causes the stage 160 and the cylinder 150 holding the reference mark 170 as an object to be levitated by the working fluid.

  Under the control of the fixing mechanism control unit 260, the control valve 262 causes the fixing mechanism 190 to communicate with the pressure source 210 or the exhaust unit 290. When the fixing mechanism 190 communicates with the pressure source 210, the working fluid is supplied and the shoe 192 is raised. Thereby, the cylinder 150 is pressed against the guide portion 130 and fixed. As described above, the fixing mechanism 190 fixes the stage 160 and the cylinder 150 holding the reference mark 170 as an object by pressing the stage 160 toward the guide unit 130.

  On the other hand, when the fixing mechanism 190 communicates with the exhaust part 290, the working fluid is discharged from the fixing mechanism 190. As a result, the shoe 192 is lowered, the cylinder 150 is opened, and can move again.

  The sequence control unit 280 controls the thrust control units 230 and 240, the levitation force control unit 250, and the fixing mechanism control unit 260 in an integrated manner, and executes a control procedure described later. The thrust control units 230 and 240, the levitation force control unit 250, and the fixing mechanism control unit 260 can all be formed as an electric circuit and may be integrated.

  FIG. 2 is a diagram for explaining the operation of the positioning device 100. FIG. 2 shows different states of the positioning device 100 shown in FIG. Accordingly, the same components as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  For example, when the thrust control unit 230 exhausts the pressure chamber 152 through the control valve 232, while the thrust control unit 240 supplies the working fluid to the pressure chamber 154 through the control valve 242, the pressure is applied to the piston 140. The cylinder 150 moves to the left in the figure until the pressure of the working fluid acting from the chambers 152 and 154 is balanced.

  Since the linear scale 182 also moves with the movement of the cylinder 150, the encoder 180 outputs a pulse signal corresponding to the number of scales that have passed with the movement. The servo control unit 270 refers to the pulse signal output from the encoder 180, calculates the difference between the moving amount of the cylinder 150 and the target position, and sends commands to the thrust control units 230 and 240, respectively.

  As described above, the series of structures including the pressure source 210, the control valves 232 and 242 and the thrust control units 230 and 240 move the cylinder 150 and the stage 160 holding the reference mark 170 as an object by the pressure of the working fluid. The drive part to be formed is formed.

  When the cylinder 150 moves to the target position as described above, the fixing mechanism control unit 260 raises the shoe 192 by supplying the working fluid to the fixing mechanism 190 via the control valve 262, and the cylinder 150 It is made to contact with the lower surface of the. Further, when the shoe 192 pushes up the cylinder 150, the cylinder 150 is pressed against the guide portion 130 and is fixed at that position. Thus, the cylinder 150 is fixed at the target position.

  In view of the functions as described above, it is desirable that the braking force when the fixing mechanism 190 fixes the cylinder 150 is larger than the thrust when the cylinder 150 is moved. In other words, the fixing mechanism 190 can adopt any structure as long as it can overcome the thrust of moving the cylinder 150 and brake the movement of the cylinder 150.

  Further, the cylinder 150 that has moved to the target position no longer moves. Therefore, the levitation force control unit 250 may interrupt the supply of the working fluid to the sliding portions of the piston 140 and the cylinder 150 via the control valve 252.

  FIG. 3 is a block diagram schematically showing the structure and operation of the control unit 102 of the positioning apparatus 100 as described above. The control system described below executes control by digital signal processing, but may be controlled by analog signal processing. In the following description, the signal related to the pressure chamber 152 is identified by the symbol “a”, and the signal related to the pressure chamber 154 is identified by the symbol “b”. The reference numerals shown in FIGS. 1 and 2 are also referred to as needed.

  Considering the mass flow rate of the working fluid in the control valves 232 and 242, the mass of the working fluid supplied to each of the pressure chambers 152 and 154 corresponds to the integral value of the flow rates Ga and Gb of the working fluid in the control valves 232 and 242. To do. However, in the cylinder 150, there is leakage of the working fluid to the outside.

  Therefore, the sum of the leakage amount Da from the pressure chamber 152, the leakage amount Db from the pressure chamber 154, the masses m0a and m0b of the existing working fluid in the pressure chambers 152 and 154, and the integrated values of the flow rates Ga and Gb. Is the mass of the working fluid in each of the pressure chambers 152, 154.

  The volumes of the pressure chambers 152 and 154 change according to the position x of the cylinder 150, and are expressed as functions Va (x) and Vb (x) of the position x of the cylinder 150. When the working fluid is a gas such as air, the pressures Pa and Pb of the working fluid in each of the pressure chambers 152 and 154 are determined according to the state equations RT / Va (x) and RT / Vb (x).

  By multiplying the pressure receiving areas Sa and Sb in the pressure chambers 152 and 154 by the pressures Pa and Pb, thrusts Fa and Fb generated in the pressure chambers 152 and 154 are determined. Furthermore, the difference between the thrusts Fa and Fb is the acceleration that generates the thrust F that moves the cylinder 150. When the pressure receiving areas Sa and Sb in the pressure chambers 152 and 154 are equal to each other, the thrust F is equivalent to the differential pressure P between the pressures Pa and Pb.

The thrust F accelerates the movable part with an acceleration characteristic (m / s ² ) inversely proportional to the mass of the movable part. When the acceleration of the movable portion is integrated over time, the velocity v (m / s) of the moving movable portion is obtained. Further, when the velocity v is integrated, the moving amount x (m) of the movable part is obtained. The movement amount x (m) can be observed by a linear encoder formed by the linear scale 182 and the encoder 180.

  The control unit 102 performs the following process on the operation unit 101 having the above characteristics. A position sensor signal indicating a movement amount x indicating the position of the cylinder 150 is input from the encoder 180. The position sensor signal is digitally converted and calculated as a position signal. When the encoder 180 generates the position sensor signal as a pulse signal, the pulse count value can be directly processed as the position signal.

  By subtracting a value indicating the target position from the position signal, a position residual signal Sig_p indicating a difference between the current position and the target position, and an integrated feedback signal Sig_i obtained by integrating the position residual signal Sig_p are generated. Thereby, the integrated value of Sig_p can be fed back to improve the gain with respect to the steady deviation.

  Further, the position signal is differentiated and further subjected to phase compensation calculation by a digital filter, thereby generating a speed signal Sig_v indicating the speed v of the movable part. In the differential calculation in the digital processing, the position signal captured by the position sensor is divided by the sampling period for each sampling period of the controller.

  That is, in the control using the compressed fluid as the working fluid, the integral term becomes the third order, and the second-order differential value of the position signal is fed back to construct a stable feedback system. In the above example, a system equivalent to the feedback of the second-order differential value is formed by the differential calculation and the phase compensation calculation. Thereby, a stable positioning characteristic is obtained.

The position target signal Sig_E is generated by multiplying the position residual signal Sig_p, the integral feedback signal Sig_i, and the speed signal Sig_v by respective gain magnifications (Kv, Kp, Ki). Note that the position target signal Sig_E can be expressed as the following Expression 1.
Sig_E = Kp * Sig_p
+ Ki * Sig_i
+ Kv * Sig_v Formula 1

Based on the position target signal Sig_E generated as described above, drive signals for the control valves 232 and 242 are generated. That is, Sig_A of the command signal to the thrust control unit 230 is generated by, for example, the calculation shown in the following Expression 2.
Sig_A = Sig_E Formula 2

In this case, the command signal Sig_B to the thrust control unit 240 is generated by the calculation shown in the following Expression 3.
Sig_B = −Sig_E Formula 3

  The thrust control units 230 and 240 have servo gains Ksa and Ksb, respectively, and generate command currents to the control valves 232 and 242 according to the input command signals Sig_A and Sig_B. The control valves 232 and 242 supply or discharge the working fluid in the pressure chambers 152 and 154 at a flow rate corresponding to the command current in accordance with each flow rate characteristic g (S).

  FIG. 4 is a flowchart showing in detail a control procedure that the sequence control unit 280 causes the control unit 102 to execute. When the positioning operation is started, the sequence control unit 280 first causes the levitation force control unit 250 to open the control valve 232 and causes the cylinder 150 to float with respect to the piston 140 (step S101). Thereby, the sliding resistance with respect to the piston 140 is lowered, and the cylinder 150 can move smoothly.

  Next, the sequence control unit 280 causes the servo control unit 270 to start servo control, and moves the cylinder 150 toward the target position (step S102). Eventually, it is detected that the cylinder 150 has reached the target position based on the pulse signal output from the encoder 180 (step S103).

  When the cylinder 150 moves to the target position, the sequence control unit 280 first sets the servo control unit with a servo gain smaller than the servo gain during the period in which the cylinder 150 has moved until at least the fixing mechanism 190 fixes the cylinder 150. Servo control is continued at 270 (step S104). The servo gain value set here is stored in the sequence control unit 280, for example. Thereby, the cylinder 150 stops at the target position.

  Note that in step S104, the total gain (sum of servo gains) only needs to be reduced as a result. Therefore, for example, the value of the gain Kv may be decreased independently without changing the gain Kp and the gain Ki.

  In such a case, an effective effect was obtained by reducing the gain Kv by 10%. Thereby, the sensitivity with respect to the disturbance of the positioning apparatus 100 becomes low, and it is possible to suppress the influence generated in the servo system due to an impact or the like generated when a fixing operation described later is started. In other words, by executing the control as in step S104, a high total gain can be set in the positioning device 100 without considering an impact caused by a fixing operation or the like.

  Further, all three servo gains (Kp, Ki, Kv) may be uniformly reduced. In this case, a significant effect appeared by lowering each gain by 5%. Also in this case, the sensitivity of the positioning device 100 to the disturbance is reduced, and the influence of the disturbance on the servo system can be suppressed.

  Next, the sequence control unit 280 causes the levitation force control unit 250 to close the control valve 252 and stops the levitation force (step S105). Further, almost simultaneously with the suspension of the levitation force, the sequence control unit 280 causes the levitation force control unit 250 to move the cylinder 150 until at least the fixing mechanism 190 fixes the cylinder 150 after the levitation force generation unit stops generating the levitation force. Servo control is continued by the servo control unit 270 with a servo gain smaller than the servo gain during the period during which the servo control has floated, that is, a servo gain smaller than that in step S104 (step S106). As a result, the cylinder 150 stops at the target position in a state in which it is difficult to move.

  In step S106, it is effective to reduce the gain Ki of the system that executes the integral calculation to zero. As a result, the error remaining when the cylinder 150 is stopped is accumulated in the integration system, and a sudden driving force is generated for the cylinder 150 when the fixing mechanism 190 described later is released. Is prevented. That is, in step S106, it is preferable to set the servo gain Ki to zero or a value close to zero.

  However, other servo gains (Kp, Kv) need not be changed and are maintained as they are. That is, by reducing the gain Ki, the total gain of the servo system is reduced, but the servo control itself is continued. As a result, the servo control can be continued even after the cylinder 150 reaches the target position.

  Here, the sequence control unit 280 checks whether or not the cylinder 150 is located within a given allowable range from the target position (step S107). Here, the allowable range is, for example, in the case of the above-described imaging apparatus, it is inspected whether or not the reference mark 170 is positioned within the imaging field of the imaging apparatus.

  If the cylinder 150 is located outside or within the allowable range (step S107: NO), the sequence control unit 280 uses the servo gain returned to the servo gain during the period in which the cylinder 150 was moving toward the target in step S102. Then, the servo control unit 270 continues the servo control (step S108). Thereby, even when the position of the cylinder 150 is displaced due to external vibration or the like, the positioning accuracy is ensured.

  In this embodiment, the servo gain is returned to the original value on condition that the cylinder 150 is located within a given allowable range. However, the response when the above condition occurs is not limited to this. For example, the servo gain may be controlled to return stepwise in accordance with the number of occurrences of the retry loop (step S107: NO). That is, the control may be performed so that the retry loop (step S107: NO) is returned to 80% of the servo gain in step S103 until the third time, and the servo gain in step S103 is returned to 90% after the fourth retry. .

  On the other hand, when the cylinder 150 is located within the allowable range (step S107: YES), the sequence control unit 280 causes the fixing mechanism control unit 260 to fix the cylinder 150 (step S109). Thereby, the cylinder 150 is fixed by the fixing mechanism 190 and stops at the target position under high stationary stability. In view of such a function, it is desirable that the fixing force of the fixing mechanism 190 is higher than the driving force of the cylinder 150 by the thrust control units 230 and 240.

  Since the cylinder 150 is fixed by the fixing mechanism 190, the cylinder 150 does not move even if the servo control unit 270 executes servo control. However, by continuing the servo control even while the cylinder 150 is fixed by the fixing mechanism 190, when the positioning operation is started again, the initialization can be omitted and the servo control can be continued.

  Thus, the sequence control unit 280 may cause the servo control unit 270 to continue servo control even after the fixing mechanism 190 fixes the cylinder 150. The servo gain in the servo control in this case may be smaller than the servo gain that has been reduced in step S105.

  In this way, after the cylinder 150 that has moved reaches the target position, the control unit 102 has a servo gain that is smaller than the servo gain during the period in which the cylinder has moved until at least the fixing mechanism 190 fixes the cylinder. The servo control unit 270 is caused to execute servo control. Thereby, the positioning device 100 with high stationary stability is formed without increasing the accuracy of matching the stationary position to the target position.

  That is, since the driving force for the cylinder 150 is reduced by reducing the servo gain, the fixing mechanism 190 can reliably fix the cylinder 150. By installing such a positioning device 100 according to the application, it is possible to reduce the cost of the device or equipment including the positioning device 100 while maintaining the desired stationary stability.

  In the above embodiment, the cylinder 150 is moved using a working fluid such as air. However, the effect of the above control is also effective when the cylinder 150, the fixing mechanism 190, etc. are operated by an electric actuator or the like. become. Further, the floating part may have a structure for obtaining a floating force by magnetism, an electric field or the like.

  FIG. 5 is a diagram schematically showing the structure and function of the calibration device 300 including the positioning device 100. The calibration device 300 calibrates the relative positions of a pair of imaging units 310 arranged along the horizontal direction as shown in FIG. 5A, for example. The calibration of the relative position by the calibration device 300 is also effective when calibrating the relative position of a pair of imaging units 310 arranged to face each other as shown in FIG. 5B.

  That is, when the relative positions of the plurality of imaging units 310 are detected with high accuracy, the positioning device 100 positions the reference mark 170 at a position where both of the imaging units 310 are photographed in common. After the relative position calibration is completed, the reference mark 170 is retracted from the imaging range of the imaging unit 310. In other words, when the relative position is calibrated, the reference mark 170 is positioned in the imaging range of the imaging unit 310 each time.

  Each of the imaging units 310 includes a lens 312 and a camera 314, respectively. The lens 312 enlarges the image. The camera 314 captures an image enlarged by the lens 312. Here, when the magnification ratio of the lens 312 is large, the field of view that the camera 314 can capture becomes small. For this reason, the reference mark 170 is required to be positioned at a predetermined position included in a narrow visual field that can be captured by the camera 314.

  If the viewpoint is changed, the position accuracy of the reference mark 170 that is positioned when the calibration is performed is not required for the set position target as long as the position is within the field of view of the camera 314. Accordingly, if the camera 314 is within the allowable range determined based on the width of the field of view, the positional accuracy exceeding it is not required.

  On the other hand, the relative position of the imaging unit 310 is calculated by imaging the common reference mark 170. However, since the pair of imaging units 310 cannot always capture the reference mark 170 at the same time, the reference mark 170 is high at a certain position until the imaging of the reference mark 170 by both the imaging units 310 is completed. It must be stationary with accuracy.

  The field of view of the imaging unit 310 having a large magnification used in such a case is about several tens of μm. On the other hand, the accuracy required for alignment is sub μm. Accordingly, the range in which the reference mark 170 can be imaged by the imaging unit 310 has a width of about several tens of μm, but there is a high demand for alignment accuracy of the relative position of the imaging unit 310.

  As described above, the positioning target of the positioning apparatus 100 may be the reference mark 170 that is commonly imaged from the plurality of imaging units 310 when calculating the relative positions of the plurality of imaging units 310. Thereby, since the positioning device 100 having the stationary position stability can be equipped without increasing the positioning accuracy to the absolute target position, the cost of the apparatus or equipment including the plurality of imaging units 310 can be reduced.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. In addition, it will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. Furthermore, it is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

It is a figure which shows the structure of the positioning device 100 typically. It is a figure explaining operation | movement of the positioning apparatus. 3 is a block diagram schematically showing the structure and operation of a control unit 102. FIG. It is a flowchart which shows in detail the control procedure which the sequence control part 280 performs. 2 is a diagram schematically showing the structure of a calibration device 300. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Positioning device, 101 Actuating part, 102 Control part, 110 Base, 111 Main part, 120 Post, 130 Guide part, 140 Piston, 150 Cylinder, 152, 154 Pressure chamber, 160 Stage, 170 Reference mark, 180 Encoder, 182 Linear Scale, 190 fixing mechanism, 192 shoe, 210 pressure source, 220 pressure gauge, 230, 240 thrust control unit, 232, 242, 252, 262 control valve, 250 levitation force control unit, 260 fixing mechanism control unit, 270 servo control unit 280 Sequence control unit, 290 exhaust unit, 300 calibration device, 310 imaging unit, 312 lens, 314 camera

Claims (9)

A driving unit that generates a driving force to move the object;
A control unit that servo-controls the drive unit to move the object toward a target position;
A fixing portion for fixing the object with a fixing force larger than the driving force;
After the moved object reaches the target position, at least until the fixing unit fixes the object, the control unit has a servo gain smaller than the servo gain during the period in which the object has moved. A positioning device for continuing the servo control. A levitation force generating unit that generates a levitation force when the object moves to levitate the object, and stops the generation of the levitation force when the object reaches a target position;
After the levitation force generation unit stops generating the levitation force, the control unit performs servo for a period during which the force generation unit levitates the object until at least the fixing unit fixes the object. The positioning device according to claim 1, wherein the servo control is continued with a servo gain smaller than the gain. The drive unit moves the object by the pressure of the working fluid,
The positioning device according to claim 2, wherein the levitation force generating unit levitates the object by a laminar flow of the working fluid.   The control unit is configured to displace the object beyond a given allowable range from the target position during a period from when the object reaches the target position until the object is fixed to the fixing unit. 4. The positioning device according to claim 1, wherein the servo control is continued with a servo gain returned to a servo gain during a period in which the object has moved toward the target position. . A guide unit for guiding a moving direction of the object;
The positioning device according to any one of claims 1 to 4, wherein the fixing unit fixes the object by pressing the object toward the guide unit.   The positioning device according to any one of claims 1 to 5, wherein the object includes a reference mark that is commonly imaged from the plurality of imaging devices when calculating relative positions of the plurality of imaging devices.   When the reference sign is displaced outside the imaging range of the imaging device in a period from when the object reaches the target position until the object is fixed to the fixing unit, The positioning device according to claim 6, wherein the servo gain is increased.   The positioning device according to any one of claims 1 to 7, wherein the control unit continues the servo control even after the object is fixed by the fixing unit. A drive unit for moving an object;
A control unit that servo-controls the drive unit to move the object toward a target position;
A control method of a positioning device including a fixing unit that fixes the object with a fixing force larger than a driving force of the driving unit,
After the moved object reaches the target position, at least until the fixing unit fixes the object, the control unit has a servo gain smaller than the servo gain during the period in which the object has moved. A control method for continuing the servo control.

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