JP2024005713A - Measurement system, control unit, and measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the new problem in which: an increase in a measurement range according to an object to be measured may reduce measurement accuracy.

SOLUTION: A measurement system includes: a pair of displacement sensors that are arranged opposite to each other in a thickness direction of an object to be measured; a moving mechanism that changes the relative position of the pair of displacement sensors to the object to be measured in the thickness direction of the object to be measured; a thickness calculation unit that calculates the thickness of the object to be measured based on displacement output from each of the pair of displacement sensors; and a control unit that calculates an instruction for adjusting the relative position of the pair of displacement sensors to the object to be measured according to a change in the shape in the thickness direction of the object to be measured.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a measurement system, a control device, and a measurement method.

For example, the thickness of a workpiece is measured for use in manufacturing control and traceability. There are various methods for measuring the thickness of a workpiece, and one example is a method using a pair of sensors.

For example, Japanese Patent Laid-Open No. 2003-106834 (Patent Document 1) discloses a thickness meter that measures truly accurate thickness by correcting errors caused by edge tracking operations and changes in ambient temperature using a simple method. do.

JP-A-04-369409 (Patent Document 2) discloses an optical thickness measuring device that uses an optical displacement sensor to non-contactly measure the thickness (plate thickness, etc.) of an object to be measured.

Japanese Unexamined Patent Publication No. 01-101410 (Patent Document 3) discloses a thickness measuring device including a set of ultrasonic ranging sensors facing each other at a constant distance.

Japanese Patent Application Publication No. 2003-106834 Japanese Patent Application Publication No. 04-369409 Japanese Patent Application Publication No. 01-101410

In the method using a pair of sensors as described above, if the displacement that occurs in the measurement target changes significantly, it is necessary to use a displacement sensor that has a measurement range that corresponds to the magnitude of the displacement that can occur in the measurement target.

One object of the present invention is to solve a new problem in which measurement accuracy may decrease due to the measurement range becoming larger depending on the measurement target.

A measurement system according to an embodiment of the present invention includes a pair of displacement sensors arranged opposite to each other in the thickness direction of a measurement target, and a movement mechanism that changes the relative position of the pair of displacement sensors with respect to the measurement target in the thickness direction of the measurement target. , a thickness calculation unit that calculates the thickness of the measurement target based on the displacement output by the pair of displacement sensors, and adjusts the relative position of the pair of displacement sensors to the measurement target according to the change in the shape of the measurement target in the thickness direction. and a control unit that calculates a command to do so.

According to this configuration, the relative positions of the pair of displacement sensors with respect to the measurement target are adjusted according to changes in the shape of the measurement target in the thickness direction, so the size of the measurement range required for the pair of displacement sensors can be suppressed. Measurement accuracy can be improved by

The thickness calculation unit may calculate the thickness of the measurement target by adding displacements output by the pair of displacement sensors. According to this configuration, the thickness of the measurement target can be calculated by adding the displacements output by the pair of displacement sensors, which simplifies the process and also allows the relative position of the pair of displacement sensors to the measurement target to change. However, the calculation is not affected by the thickness.

Each of the pair of displacement sensors may be calibrated to output zero as the displacement when a reference workpiece of known thickness is placed between the pair of displacement sensors. According to this configuration, the thickness of the measurement target can be calculated using the reference work as a reference.

The control unit may calculate the command so that the displacement output by one of the pair of displacement sensors becomes a predetermined target value. According to this configuration, the command is calculated based on the displacement output by one of the displacement sensors, so the processing can be simplified.

The control unit may calculate the command so that the displacements respectively output by the pair of displacement sensors match. According to this configuration, the required measurement range can be minimized by equally sharing the displacement measured by the pair of displacement sensors.

The measurement system may further include an additional displacement sensor disposed at the front stage that supplies the measurement target between the pair of displacement sensors. The control unit may calculate the command so that the displacement output by the additional displacement sensor becomes a predetermined target value. According to this configuration, the command is calculated based on the displacement output by the additional displacement sensor arranged at the front stage, so that response performance can be improved.

The pair of displacement sensors may be white coaxial confocal type displacement sensors. According to this configuration, measurement accuracy can be improved compared to other methods.

According to another embodiment of the present invention, a pair of displacement sensors are arranged to face each other in the thickness direction of the measurement target, and a moving mechanism that changes the relative position of the pair of displacement sensors with respect to the measurement target in the thickness direction of the measurement target. A control device is provided that configures a measurement system comprising: The control device includes a thickness calculation unit that calculates the thickness of the measurement target based on the displacement outputted by the pair of displacement sensors, and a thickness calculation unit that calculates the thickness of the measurement target based on the displacement outputted by the pair of displacement sensors, and a thickness calculation unit that calculates the thickness of the measurement target based on the displacement of the pair of displacement sensors. and a control unit that calculates a command for adjusting the position.

A measurement method according to yet another embodiment of the present invention includes the steps of calculating the thickness of the measurement target based on the displacements respectively output by a pair of displacement sensors arranged opposite to each other in the thickness direction of the measurement target; A step of calculating a command for adjusting the relative position of the pair of displacement sensors with respect to the measurement target according to the shape change in the thickness direction, and a step of calculating the command to adjust the relative position of the pair of displacement sensors with respect to the measurement target of the measurement target. and a step of outputting to a moving mechanism that changes the thickness in the thickness direction.

According to the present invention, even if the possible displacement of the workpiece is relatively large, it is possible to prevent the measurement range required for the displacement sensor from increasing and improve measurement accuracy.

FIG. 2 is a diagram for explaining an example of a problem to be solved by the measurement system according to the present embodiment. 1 is a schematic diagram showing a configuration example of a measurement system according to the present embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of the controller of the measurement system according to the present embodiment. It is a figure for explaining the processing example of thickness measurement in the measurement system according to this embodiment. FIG. 3 is a diagram for explaining a processing example of follow-up control in the measurement system according to the present embodiment. It is a figure which shows the example of the effect of follow-up control in the measurement system according to this Embodiment. FIG. 2 is a schematic diagram showing an example of a functional configuration of a controller according to the present embodiment. FIG. 3 is a diagram for explaining a first implementation example of follow-up control in the measurement system according to the present embodiment. FIG. 7 is a diagram for explaining a second implementation example of follow-up control in the measurement system according to the present embodiment. It is a schematic diagram which shows the modification of the measurement system according to this Embodiment. 3 is a flowchart illustrating an example of a processing procedure executed by a controller according to the present embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the figures are designated by the same reference numerals, and the description thereof will not be repeated.

<A. Application example＞
First, an example of a scene to which the present invention is applied will be described.

FIG. 1 is a diagram for explaining an example of a problem to be solved by a measurement system according to this embodiment. Referring to FIG. 1, a measurement system 1 includes a pair of displacement sensors 10-1 and 10-2 (hereinafter referred to as "displacement sensors 10) is used to measure the thickness of the workpiece 20. More specifically, with the relative position between displacement sensor 10-1 and displacement sensor 10-2 fixed, the displacement measured by displacement sensor 10-1 and the displacement measured by displacement sensor 10-2 are The thickness of the workpiece 20 is measured using the .

The displacement sensor 10 may be a non-contact type displacement sensor or a contact type displacement sensor. As a non-contact type displacement sensor, a displacement sensor of an optical type (laser type, LED type, TOF type), ultrasonic type, eddy current type, etc. can be used.

As the optical displacement sensor, a white coaxial confocal displacement sensor (see, for example, Japanese Patent No. 5790178) or a triangular distance measuring displacement sensor may be used. In the following description, a configuration example using a white coaxial confocal type displacement sensor will be shown as an example.

In FIG. 1, a workpiece 20 is transported in the transport direction. For example, the measurement position of the workpiece 20 in the transport direction and the thickness measured at each measurement position are recorded in association with each other.

The measurement range of the displacement sensor 10-1 is determined to cover the position where the top surface of the work 20 may exist, and the measurement range of the displacement sensor 10-2 is determined to cover the position where the bottom surface of the work 20 may exist. determined.

As shown in FIG. 1(A), when the surface of the workpiece 20 is approximately parallel to the conveyance direction, the measurement range of the displacement sensor 10-1 is determined to cover changes that may occur on the upper surface of the workpiece 20. do it. Furthermore, the measurement range of the displacement sensor 10-2 may be determined so as to cover changes that may occur on the lower surface of the workpiece 20.

On the other hand, as shown in FIG. 1(B), when the workpiece 20 is warped or bent, it is necessary to determine the measurement range of the displacement sensor 10 so as to cover the displacement caused by the warp or bend. be. That is, if the workpiece 20 is warped or bent, it is necessary to use the displacement sensor 10 with a wider measurement range. As the measurement range becomes wider, the resolution becomes relatively lower and the measurement accuracy may also become lower.

The measurement system 1 according to the present embodiment can suppress the size of the measurement range required for the displacement sensors 10-1, 10-2 by making the displacement sensors 10-1, 10-2 follow the shape of the workpiece 20. , this can improve measurement accuracy.

FIG. 2 is a schematic diagram showing a configuration example of the measurement system 1 according to the present embodiment. Referring to FIG. 2, measurement system 1 includes a pair of displacement sensors 10-1 and 10-2 arranged on frame 50 so as to sandwich workpiece 20 therebetween. The frame 50 includes a main part 52 and an upper arm 54 and a lower arm 56 fixed to both sides of the main part 52. The main portion 52, the upper arm 54, and the lower arm 56 are integrated to form the frame 50.

The displacement sensor 10-1 arranged on the upper arm 54 has a measurement range in the direction from the upper arm 54 toward the work 20 (the thickness direction of the work 20), and the displacement sensor 10-2 arranged on the lower arm 56 has a measurement range in the direction from the upper arm 54 toward the work 20 (the thickness direction of the work 20). , has a measurement range in the direction from the lower arm 56 toward the workpiece 20 (in the thickness direction of the workpiece 20). That is, the displacement sensors 10-1 and 10-2 have a measurement range in a direction perpendicular to the transport direction (transport surface) of the workpiece 20.

The measurement system 1 further includes a controller 100, sensor controllers 200-1 and 200-2, a motor driver 210, and an encoder 70. Sensor controllers 200-1 and 200-2 and motor driver 210 are connected to controller 100 via field network 4. Examples of the field network 4 include EtherCAT (registered trademark), EtherNet/IP (registered trademark), PROFINET (registered trademark), PROFIBUS (registered trademark), DeviceNet (registered trademark), FL-net, CompoNet (registered trademark), etc. may also be used.

The controller 100 is an example of a control device, and is realized using a computer such as a PLC (programmable logic controller), for example.

Sensor controller 200-1 is connected to displacement sensor 10-1, and sensor controller 200-2 is connected to displacement sensor 10-2. The sensor controllers 200-1, 200-2 generate the light irradiated from the displacement sensors 10-1, 10-2, and determine the displacement based on the reflected light incident on the displacement sensors 10-1, 10-2. measure. The sensor controllers 200-1 and 200-2 switch start/stop of measurement according to instructions from the controller 100, and provide measurement results to the controller 100.

Motor driver 210 rotates motor 60 according to instructions from controller 100.

The encoder 70 is arranged in correspondence with the conveyance direction of the workpiece 20. The encoder 70 provides the controller 100 with a pulse signal (encoder information) indicating the conveyance amount or the conveyance position of the workpiece 20 .

The frame 50 is configured to be movable in the thickness direction of the workpiece 20. That is, the frame 50 is configured to be movable in a direction perpendicular to the transport surface of the workpiece 20. As an example, the frame 50 is mechanically connected to a motor 60 and is moved by rotation of the motor 60.

In this way, the motor 60 and the motor driver 210 correspond to a moving mechanism that changes the relative position of the pair of displacement sensors 10 (displacement sensors 10-1, 10-2) with respect to the workpiece 20 in the thickness direction of the workpiece 20.

In this specification, "the relative position of a pair of displacement sensors with respect to a measurement object" means the positional relationship when the pair of displacement sensors are moved relative to the measurement object in an integrated state. In other words, it refers to the positional relationship when a pair of displacement sensors (two displacement sensors) is moved relative to the measurement target while maintaining the relative position between the two displacement sensors forming the pair of displacement sensors. In other words, the moving mechanism moves the pair of displacement sensors 10 (displacement sensors 10-1, 10-2) relative to the workpiece 20 are changed in the thickness direction of the workpiece 20.

The controller 100 adjusts the workpiece of the frame 50 (displacement sensors 10-1, 10-2) according to the shape of the workpiece 20 so that the measurement range required for the displacement sensors 10-1, 10-2 is as small as possible. Adjust the relative position to 20. Details of the processing by the controller 100 will be described later.

Note that, as described later, the measurement system 1 may further include a sensor for measuring the position of the workpiece 20 in the thickness direction.

<B. Hardware configuration example of controller 100>
Next, an example of the hardware configuration of the controller 100 according to this embodiment will be described.

FIG. 3 is a block diagram showing an example of the hardware configuration of the controller 100 of the measurement system 1 according to the present embodiment. Referring to FIG. 3, the controller 100 includes a processor 102 such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit), a memory 104, a storage 106, an upper network interface 108, and a USB (Universal Serial Bus). ) interface 110, memory card interface 112, and field network interface 114.

The processor 102 reads various programs stored in the storage 106, expands them to the memory 104, and executes them, thereby realizing necessary processing in the controller 100.

Storage 106 typically stores a system program 120 and a control program 122 that includes computer readable code necessary for control operations.

Execution of the program stored in the storage 106 causes the controller 100, which is a computer, to execute processes as described below, and also causes the controller 100, which is a computer, to realize a functional configuration as described below.

The upper network interface 108 controls data communication with other devices via the upper network. USB interface 110 controls data communication to and from supporting devices via a USB connection.

The memory card interface 112 is configured to allow a memory card 116 to be attached or removed, and is capable of writing data to the memory card 116 and reading various data (user programs, trace data, etc.) from the memory card 116. There is.

Field network interface 114 controls data communication via field network 4.

FIG. 3 shows an example of a configuration in which necessary functions are provided by a processor executing a program. Some or all of these provided functions can be implemented using a dedicated hardware circuit (for example, an ASIC ( It may be implemented using an FPGA (Field-Programmable Gate Array) or an FPGA (Field-Programmable Gate Array).

In this specification, a "processor" is not limited to a processor in a narrow sense that executes processing using a stored program method, but may include hard-wired circuits such as ASIC and FPGA. Therefore, the term "processor" can also be read as processing circuitry whose processing is predefined by computer readable code and/or hardwired circuitry.

<C. Thickness measurement>
Next, a processing example of thickness measurement in the measurement system 1 according to the present embodiment will be described.

In the measurement system 1 according to this embodiment, the displacement measured by the displacement sensor 10 may be an absolute value or a relative value. An example of processing when using the displacement sensor 10 that outputs displacement in relative values will be described.

FIG. 4 is a diagram for explaining an example of thickness measurement processing in the measurement system 1 according to the present embodiment. When using the displacement sensor 10 that outputs relative displacement, it is necessary to calibrate it in advance and value the measurement range.

Referring to FIG. 4(A), during calibration, a reference work 30 (reference thickness Dst) having a known thickness is placed between displacement sensors 10-1 and 10-2. With the reference workpiece 30 placed, the measurement results (displacements) output by the displacement sensors 10-1 and 10-2 are set to a reference value (zero). That is, with the reference workpiece 30 placed, the displacement sensors 10-1 and 10-2 both output zero as measured values. At the same time, measurement ranges 12-1 and 12-2 of displacement sensors 10-1 and 10-2 are also set.

The displacement sensors 10-1 and 10-2 measure the change from the state in which the reference work 30 is placed and output it as displacements d1 and d2. Immediately after the calibration shown in FIG. 4A is performed, the displacement d1=0 and the displacement d2=0.

In this way, each of the displacement sensors 10-1 and 10-2 outputs zero as a displacement when the reference workpiece 30 of known thickness is placed between the displacement sensors 10-1 and 10-2. It is calibrated as follows.

For convenience of explanation, it is assumed that when a workpiece to be measured approaches each of the displacement sensors 10-1 and 10-2, a positive (+) displacement is output. That is, each of the displacement sensors 10-1 and 10-2 is configured to output a larger value as a displacement as the surface of the workpiece 20 approaches the displacement sensors 10-1 and 10-2.

Using the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2, the thickness D of the workpiece to be measured is calculated according to the following formula.

D=Dst+(d1+d2)
Note that, contrary to the measurement range pricing shown in FIG. 4(A), when the workpiece to be measured approaches each of the displacement sensors 10-1 and 10-2, a negative (-) displacement is output. You can do it like this. That is, each of the displacement sensors 10-1 and 10-2 may be configured to output a larger value as a displacement as the surface of the workpiece 20 becomes farther from the displacement sensors 10-1 and 10-2.

In this case, the thickness D of the workpiece to be measured is calculated according to the following formula using the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2.

D=Dst-(d1+d2)
As shown in FIG. 4(B), it is assumed that, during measurement after calibration, the reference work 30 is displaced by a displacement Δd toward the displacement sensor 10-2, for example. At this time, the displacement d1 output from the displacement sensor 10-1 becomes 0-Δd=-Δd, and the displacement d1 output from the displacement sensor 10-2 becomes 0-Δd=-Δd. The thickness D measured in this state becomes the reference thickness Dst, as shown by the following formula.

D=Dst-Δd+Δd=Dst
As described above, the measurement system 1 according to the present embodiment uses a pair of displacement sensors 10-1 and 10-2 that are arranged opposite to each other in the thickness direction of the measurement object (workpiece), so that the measurement object is positioned in the thickness direction. Even if it deviates, the thickness of the object to be measured can be accurately measured. That is, even if a positional shift occurs in the thickness direction, the displacement d1 and the displacement d2 cancel each other out, so that the measurement results are not affected.

<D. Follow-up control>
Next, a processing example of thickness measurement in the measurement system 1 according to the present embodiment will be described.

As described above, even if the measurement target (work) is displaced in the thickness direction, the measurement results are not affected. However, if the workpiece is warped or bent, it is necessary to ensure that the measurement range of the displacement sensor 10 is sufficiently wide.

In the measurement system 1 according to the present embodiment, the measurement range required for the displacement sensor 10 is adjusted by adjusting the position (relative position) of the displacement sensors 10-1 and 10-2 in the thickness direction with respect to the measurement target (work). Reduce size. In the following, the control for adjusting the positions of the displacement sensors 10-1 and 10-2 will also be referred to as "follow-up control" for convenience of explanation. By employing follow-up control, the decrease in measurement accuracy is suppressed and the measurement accuracy is improved.

FIG. 5 is a diagram for explaining a processing example of follow-up control in the measurement system 1 according to the present embodiment. FIG. 5 shows an example of measuring the thickness of a workpiece 20 that is warped or bent.

As shown in FIG. 5A, when measuring the thickness of a portion of the workpiece 20 that is close to a flat state, the surface of the workpiece 20 to be measured is the measurement range 12-1 of the displacement sensor 10-1 and In any of the measurement ranges 12-2 of the displacement sensor 10-1, the position is relatively close to the reference value (zero).

On the other hand, as shown in FIG. 5(B), when measuring the thickness of a portion of the workpiece 20 that is largely curved, the measurement target surface of the workpiece 20 is the measurement range 12-1 of the displacement sensor 10-1. In any of the measurement ranges 12-2 of the displacement sensor 10-1, the position is located relatively far from the reference value (zero).

More specifically, the displacement d1 output by the displacement sensor 10-1 in FIG. 5(B) is larger than the displacement d1 output by the displacement sensor 10-1 in FIG. 5(A). Furthermore, while the displacement d2 output by the displacement sensor 10-2 in FIG. 5(A) is approximately zero, the displacement d2 output by the displacement sensor 10-2 in FIG. 5(B) is a negative value.

FIG. 5(C) shows a state in which the displacement sensors 10-1 and 10-2 are moved by a height ΔH in the thickness direction of the workpiece 20 compared to FIG. 5(B). As a result, the position where the surface of the workpiece 20 to be measured exists in the measurement ranges 12-1 and 12-2 moves by the height ΔH.

Therefore, the displacement d1 output by the displacement sensor 10-1 in FIG. 5(C) is smaller by the height ΔH than the displacement d1 output by the displacement sensor 10-1 in FIG. 5(B). Further, the displacement d2 outputted by the displacement sensor 10-2 in FIG. 5(C) is larger by the height ΔH than the displacement d2 (minus value) outputted by the displacement sensor 10-2 in FIG. 5(B). That is, the absolute values of the displacements d1 and d2 output by the displacement sensors 10-1 and 10-2, respectively, become smaller, which means that the required measurement ranges 12-1 and 12-2 become narrower.

In this way, by executing follow-up control when measuring the thickness of the workpiece 20, it is possible to suppress expansion of the measurement range required for the displacement sensors 10-1 and 10-2.

FIG. 6 is a diagram showing an example of the effect of follow-up control in the measurement system 1 according to the present embodiment. FIG. 6(A) shows an example of measurement ranges 12-1 and 12-2 when follow-up control is not applied, and FIG. 6(B) shows an example of measurement ranges 12-1 and 12-2 when follow-up control is applied. An example of 12-2 is shown below.

As shown in FIG. 6, by providing follow-up control, the measurement range required for the displacement sensors 10-1 and 10-2 can be reduced.

Note that FIG. 6 conceptually shows an example of the effect, and does not quantitatively show the effect of the follow-up control of the measurement system 1 according to the present embodiment.

<E. Functional configuration example>
Next, an example of the functional configuration of the measurement system 1 according to the present embodiment will be described.

FIG. 7 is a schematic diagram showing an example of the functional configuration of the controller 100 according to the present embodiment. Each module shown in FIG. 7 may be realized by the processor 102 of the controller 100 executing the system program 120 and/or the control program 122 (FIG. 3).

Referring to FIG. 7, controller 100 includes a follow-up control module 150, a thickness calculation module 160, a measurement position calculation module 170, and a profile information output module 180 as functional configurations.

The tracking control module 150 measures the displacement d1 output by the displacement sensor 10-1, the displacement d2 output by the displacement sensor 10-2, and an additional displacement sensor 80 and sensor controller 200-3 (see FIG. 10), which will be described later. Based on at least one of the calculated displacements d3, a position command for controlling the positions of the displacement sensors 10-1 and 10-2 (frame 50) is calculated. That is, the follow-up control module 150 calculates a command for adjusting the relative positions of the pair of displacement sensors 10 with respect to the workpiece 20 in accordance with changes in the shape of the workpiece 20 in the thickness direction. Details of the process of calculating the position command will be described later. The calculated position command is output from the controller 100 to the motor driver 210.

The thickness calculation module 160 calculates the thickness of the workpiece 20 (workpiece thickness) based on the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2. At this time, the reference thickness Dst used in the calibration is referred to, and the arithmetic expression "thickness D=reference thickness Dst+displacement d1+displacement d2" is sequentially executed. That is, the thickness calculation module 160 calculates the thickness of the workpiece 20 by adding the displacements d1 and d2 output by the displacement sensors 10-1 and 10-2, respectively.

The measurement position calculation module 170 calculates the position (measurement position) in the transport direction of the workpiece 20 whose thickness has been measured, based on encoder information from the encoder 70 .

The profile information output module 180 associates the thickness of the workpiece 20 (workpiece thickness) with the position (measurement position) of the workpiece 20 in the transport direction at which the thickness was measured, and outputs the result as profile information. The profile information may be stored in the storage 106 of the controller 100, or may be stored in a server (not shown) via an upper network.

<F. Implementation example of follow-up control>
Next, an implementation example of follow-up control in the measurement system 1 according to the present embodiment will be described.

(f1: Implementation example using displacement from one displacement sensor 10)
As one implementation example, tracking control may be realized using displacement from one displacement sensor 10. Although either the displacement sensor 10-1 or the displacement sensor 10-2 may be used, for example, the displacement sensor 10-1 that measures the displacement up to the top surface of the workpiece 20 can be used. As an example, the relative positions of the displacement sensors 10-1 and 10-2 with respect to the workpiece 20 are controlled so that the displacement d1 output by the displacement sensor 10-1 becomes a predetermined target value.

FIG. 8 is a diagram for explaining a first implementation example of follow-up control in the measurement system 1 according to the present embodiment. Referring to FIG. 8, follow-up control module 150 of controller 100 includes a differentiator 151 and a PID controller 152.

The differentiator 151 calculates the difference (deviation) between the displacement d1 output by the displacement sensor 10-1 and a predetermined target value.

The PID controller 152 performs a PID calculation based on the deviation output from the differentiator 151 to calculate a position command.

By employing the follow-up control module 150 as shown in FIG. 8, the displacement sensors 10-1, 10-2 can The relative position with respect to the workpiece 20 can be adjusted.

In this way, the follow-up control module 150 calculates the position command so that the displacement output by one of the pair of displacement sensors 10 becomes a predetermined target value.

(f2: Implementation example using displacement from a pair of displacement sensors 10)
As another implementation example, tracking control may be realized using displacements from a pair of displacement sensors 10. In the measurement system 1 according to this embodiment, the thickness of the workpiece is calculated by adding the displacements from the pair of displacement sensors 10.

By equally sharing the displacement measured by the pair of displacement sensors 10, the required measurement range can be minimized. Equally sharing the displacement to be measured means that the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2 exhibit the same value.

Therefore, the relative positions of the displacement sensors 10-1 and 10-2 with respect to the workpiece 20 are controlled so that the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2 match.

FIG. 9 is a diagram for explaining a second implementation example of follow-up control in the measurement system 1 according to the present embodiment. Referring to FIG. 9, follow-up control module 150 of controller 100 includes a differentiator 153 and a PID controller 154.

The difference calculator 153 calculates the difference (deviation) between the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2.

The PID controller 154 performs a PID calculation based on the deviation output from the difference device 153 to calculate a position command.

By employing a follow-up control module 150 as shown in FIG. 9, the shape of the workpiece 20 to be measured is adjusted based on the displacement d1 outputted by the displacement sensor 10-1 and the displacement d2 outputted by the displacement sensor 10-2. Thus, the relative positions of the displacement sensors 10-1 and 10-2 with respect to the workpiece 20 can be adjusted.

In this way, the follow-up control module 150 calculates the position command so that the displacements d1 and d2 output by the displacement sensors 10-1 and 10-2, respectively, match.

(f3: Implementation example using displacement from an additional displacement sensor)
In yet another implementation, displacements from additional displacement sensors may be used to implement tracking control.

FIG. 10 is a schematic diagram showing a modification of the measurement system 1 according to the present embodiment. Referring to FIG. 10, measurement system 1 differs from the configuration example shown in FIG. 2 in that a displacement sensor 80 and a sensor controller 200-3 are added upstream of frame 50 in the transport direction. There is. That is, the measurement system 1 shown in FIG. 10 further includes an additional displacement sensor 80 disposed at the front stage that supplies the workpiece 20 between the displacement sensors 10-1 and 10-2.

The displacement sensor 80 measures the distance (displacement) to the workpiece moving in the transport direction. The displacement sensor 80 may be the same type of displacement sensor as the displacement sensor 10, or may be a different type of displacement sensor. Since the displacement output by the displacement sensor 80 is used for follow-up control, it is preferable to use a displacement sensor with high responsiveness (short measurement delay time).

The sensor controller 200-3 executes the necessary processing to calculate the displacement measured by the displacement sensor 80, and provides the calculated displacement to the controller 100.

The control logic for realizing follow-up control in the measurement system 1 shown in FIG. 10 is the same as that shown in FIG. 8. That is, the follow-up control module 150 calculates the position command so that the displacement output by the additional displacement sensor 80 becomes a predetermined target value.

By adopting the configuration shown in FIG. 10, the shape of the workpiece 20 can be acquired before the workpiece 20 reaches the measurement position of the frame 50 (displacement sensors 10-1, 10-2). Responsiveness (control performance) can be improved. By increasing the responsiveness of the follow-up control, the measurement range required for the displacement sensors 10-1 and 10-2 can be further narrowed.

(f4: modified example)
Although FIGS. 8 and 9 show an example in which a position command is calculated by performing PID calculation, the present invention is not limited to this, and any control system can be adopted. For example, in addition to the PID calculation, a feedforward element may be added, or modern control such as fuzzy control may be employed. Furthermore, the position command may be calculated using any AI.

<G. Processing procedure example>
Next, an example of a processing procedure of relay unit 250 in measurement system 1 according to the present embodiment will be described.

FIG. 11 is a flowchart showing an example of a processing procedure executed by controller 100 according to the present embodiment. Each step shown in FIG. 11 may be realized by the processor 102 of the controller 100 executing the system program 120 and/or the control program 122 (FIG. 3).

Referring to FIG. 11, the controller 100 selects a displacement d1 output from the displacement sensor 10-1, a displacement d2 output from the displacement sensor 10-2, and a displacement d3 measured by an additional displacement sensor 80, which will be described later. A position command for controlling the position of the frame 50 is calculated based on at least one (step S2). That is, the controller 100 calculates a command for adjusting the relative positions of the pair of displacement sensors 10-1 and 10-2 with respect to the workpiece 20 in accordance with changes in the shape of the workpiece 20 in the thickness direction.

Then, the controller 100 outputs the calculated position command to the motor driver 210 (step S4). That is, the controller 100 outputs the calculated command to a moving mechanism (motor 60 and motor driver 210) that changes the relative positions of the pair of displacement sensors 10-1 and 10-2 with respect to the workpiece 20 in the thickness direction of the workpiece 20. .

Next, the controller 100 calculates the thickness D of the workpiece 20 using the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2 (step S6). That is, the controller 100 calculates the thickness of the workpiece 20 based on the displacement d1 output by the displacement sensor 10-1 and the displacement d2 output by the displacement sensor 10-2.

The controller 100 calculates the position (measurement position) in the transport direction of the workpiece 20 at which the thickness D has been measured, based on the encoder information from the encoder 70 (step S8). Then, the controller 100 associates the thickness D of the workpiece 20 with the measurement position and outputs it as profile information (step S10).

Note that the processing in steps S2 and S4 (follow-up control) and the processing in steps S6 to S10 (thickness measurement) may be performed in the opposite order, or may be performed independently. When each is executed independently, the execution cycles may be different.

<H. Estimating and presenting the required measurement range>
By adopting the follow-up control according to the present embodiment, the measurement range required for the displacement sensor 10 ideally covers the difference between the maximum or minimum thickness of the workpiece 20 to be measured and the reference workpiece 30. All you have to do is set it up so that it can be done.

However, in follow-up control, a response delay (for example, delay time or dead time) may occur, so the relative position of the frame 50 (displacement sensors 10-1, 10-2) with respect to the workpiece 20 must be adjusted completely according to the shape of the workpiece 20. There may be cases where it is not possible to make adjustments to match. Therefore, it is necessary to determine the size of the measurement range required for the displacement sensor 10 in consideration of the positional error that may occur in the follow-up control.

Parameters for follow-up control (for example, motor response speed, control system gain, etc.) can be obtained in advance, so based on these parameters, position errors that may occur in follow-up control can be calculated, and the measurement range that is theoretically required can be calculated. The required measurement range size of the displacement sensor 10 may be estimated by adding the calculated positional error to (the displacement of the workpiece 20 to be measured from the reference workpiece 30). Furthermore, an appropriate type among a plurality of types of displacement sensors may be presented to the user, etc., depending on the estimated size of the measurement range.

In this way, by estimating and presenting the size of the measurement range required for the displacement sensor 10, the user can select an appropriate displacement sensor 10 at the design stage.

<I. Modified example>
For convenience of explanation, the above description focused on the pair of displacement sensors 10; A plurality of pairs may be arranged. By arranging a plurality of pairs of displacement sensors 10, the thickness can be measured at a plurality of positions within the plane of the workpiece 20, respectively.

There are no restrictions on the shape or material of the measurement target (work 20).

In the above description, a configuration example in which the controller 100 executes both thickness measurement and follow-up control of the workpiece 20 has been shown, but the thickness measurement and follow-up control may use different processing resources. For example, the sensor controller 200 may measure the thickness and transmit the measured thickness of the workpiece 20 to the controller 100.

Furthermore, thickness measurement may be shared and executed by a plurality of processing resources, and follow-up control may be shared and executed by a plurality of processing resources.

In this way, in the measurement system 1 according to the present embodiment, the processing resources for executing necessary processing may be designed in any manner.

In the above description, the frame 50 on which the pair of displacement sensors 10 is arranged is moved in the thickness direction of the work 20. Any structure may be adopted as the mechanism for changing the direction.

<J. Additional notes＞
This embodiment as described above includes the following technical idea.

[Configuration 1]
a pair of displacement sensors (10-1, 10-2) arranged oppositely in the thickness direction of the measurement target (20);
a moving mechanism (60, 210) that changes the relative position of the pair of displacement sensors with respect to the measurement object in a thickness direction of the measurement object;
a thickness calculation unit (160; 102) that calculates the thickness of the measurement target based on the displacements respectively output by the pair of displacement sensors;
A measurement system comprising: a control unit (150; 102) that calculates a command for adjusting relative positions of the pair of displacement sensors with respect to the measurement object according to a change in shape of the measurement object in the thickness direction.

[Configuration 2]
The measurement system according to configuration 1, wherein the thickness calculation unit calculates the thickness of the measurement target by adding displacements respectively output by the pair of displacement sensors.

[Configuration 3]
According to configuration 2, each of the pair of displacement sensors is calibrated to output zero as a displacement when a reference workpiece (30) having a known thickness is placed between the pair of displacement sensors. measurement system.

[Configuration 4]
According to any one of configurations 1 to 3, the control unit calculates the command so that the displacement output by one of the pair of displacement sensors becomes a predetermined target value. measurement system.

[Configuration 5]
4. The measurement system according to any one of configurations 1 to 3, wherein the control unit calculates the command so that the displacements respectively output by the pair of displacement sensors match.

[Configuration 6]
further comprising an additional displacement sensor (80) disposed at a preceding stage for supplying the measurement target between the pair of displacement sensors,
The measurement system according to any one of configurations 1 to 3, wherein the control unit calculates the command so that the displacement output by the additional displacement sensor becomes a predetermined target value.

[Configuration 7]
7. The measurement system according to any one of configurations 1 to 6, wherein the pair of displacement sensors are white coaxial confocal type displacement sensors.

[Configuration 8]
A pair of displacement sensors (10-1, 10-2) arranged opposite to each other in the thickness direction of the measurement object (20), and changing the relative positions of the pair of displacement sensors with respect to the measurement object in the thickness direction of the measurement object. A control device (100) constituting a measurement system (1) comprising a movement mechanism (60, 210),
a thickness calculation unit (160; 102) that calculates the thickness of the measurement target based on the displacements respectively output by the pair of displacement sensors;
A control device comprising: a control unit (150; 102) that calculates a command for adjusting relative positions of the pair of displacement sensors with respect to the measurement object according to a change in shape of the measurement object in the thickness direction.

[Configuration 9]
a step (S6) of calculating the thickness of the measurement target (20) based on the displacements respectively output by a pair of displacement sensors (10-1, 10-2) disposed opposite to each other in the thickness direction of the measurement target (20);
a step (S2) of calculating a command for adjusting the relative position of the pair of displacement sensors with respect to the measurement object according to a change in the shape of the measurement object in the thickness direction;
A measuring method comprising the step (S4) of outputting the calculated command to a moving mechanism (60, 210) that changes the relative position of the pair of displacement sensors with respect to the measurement object in the thickness direction of the measurement object.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 measurement system, 4 field network, 10, 80 displacement sensor, 12 measurement range, 20 work, 30 reference work, 50 frame, 52 main part, 54 upper arm, 56 lower arm, 60 motor, 70 encoder, 100 controller, 102 processor, 104 memory, 106 storage, 108 upper network interface, 110 interface, 112 memory card interface, 114 field network interface, 116 memory card, 120 system program, 122 control program, 150 follow-up control module, 151, 153 differentiator, 152 , 154 PID controller, 160 thickness calculation module, 170 measurement position calculation module, 180 profile information output module, 200 sensor controller, 210 motor driver, 250 relay unit.

Claims (9)

a pair of displacement sensors arranged opposite to each other in the thickness direction of the measurement target;
a moving mechanism that changes relative positions of the pair of displacement sensors with respect to the measurement object in a thickness direction of the measurement object;
a thickness calculation unit that calculates the thickness of the measurement target based on the displacements respectively output by the pair of displacement sensors;
A measurement system comprising: a control unit that calculates a command for adjusting relative positions of the pair of displacement sensors with respect to the measurement object according to a change in shape of the measurement object in a thickness direction. The measurement system according to claim 1, wherein the thickness calculation unit calculates the thickness of the measurement target by adding displacements respectively output by the pair of displacement sensors. The measurement according to claim 2, wherein each of the pair of displacement sensors is calibrated so as to output zero as the displacement when a reference workpiece of known thickness is placed between the pair of displacement sensors. system. The control unit calculates the command so that the displacement output by one of the pair of displacement sensors becomes a predetermined target value. measurement system. 4. The measurement system according to claim 1, wherein the control unit calculates the command so that the displacements respectively output by the pair of displacement sensors match. further comprising an additional displacement sensor disposed at a preceding stage that supplies the measurement target between the pair of displacement sensors,
The measurement system according to any one of claims 1 to 3, wherein the control unit calculates the command so that the displacement output by the additional displacement sensor becomes a predetermined target value. 4. The measurement system according to claim 1, wherein the pair of displacement sensors are white coaxial confocal type displacement sensors. A control device constituting a measurement system including a pair of displacement sensors arranged opposite to each other in the thickness direction of a measurement target, and a movement mechanism that changes the relative position of the pair of displacement sensors with respect to the measurement target in the thickness direction of the measurement target. And,
a thickness calculation unit that calculates the thickness of the measurement target based on the displacements respectively output by the pair of displacement sensors;
A control device comprising: a control unit that calculates a command for adjusting relative positions of the pair of displacement sensors with respect to the measurement object according to a change in shape of the measurement object in a thickness direction. Calculating the thickness of the measurement target based on the displacements respectively output by a pair of displacement sensors arranged opposite to each other in the thickness direction of the measurement target;
calculating a command for adjusting the relative position of the pair of displacement sensors with respect to the measurement object according to a change in the shape of the measurement object in the thickness direction;
A measuring method comprising: outputting the calculated command to a moving mechanism that changes relative positions of the pair of displacement sensors with respect to the measurement object in a thickness direction of the measurement object.

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