JP2019212123A - Control system, control method for control system, and program for control system - Google Patents

Abstract

To eliminate misalignment of position information of each device and perform high-precision position control at the time of controlling devices that have respective clocks and update position information at different respective periods by a controller.SOLUTION: A control system 1 includes a controller 100 and a processing unit 510 and the like. The processing unit 510 and the like include a clock unit 511 or the like, a position information update unit that updates position information at a predetermined cycle, and a transmission unit that transmits the updated position information and time information on a time of the update to the controller 100. The controller 100 includes a reception unit 106 that receives the position information and the time information, a coordinate conversion unit 104 that converts the position information into world coordinate system position information using a coordinate conversion formula, an estimation unit 105 that estimates position information between world coordinate system position information based on the world coordinate system position information and the time information; and a world coordinate system management unit 104 that manages the world coordinate system position information and the estimated position information on a time axis.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control system for controlling a plurality of control applications including a robot using a control device, a control method for the control system, and a program for the control system.

  When the robot conveys the workpiece to the workpiece fixing position of the machine tool, it is necessary to teach the robot the workpiece fixing position. The position at this time is expressed in the robot coordinate system. Furthermore, when the machine tool processes a workpiece, it is necessary to designate a machining position expressed in the coordinate system of the machine tool. Therefore, when programming, it is necessary to be conscious of a plurality of coordinate systems, which is a very complicated operation.

  Conventionally, in order to solve such a problem, as in Patent Document 1, for example, the position of a set point on the robot coordinate system is obtained using the robot coordinate system as the world coordinate system, and further on the machine tool coordinate system. It is disclosed that the relative relationship between the robot coordinate system and the machine tool coordinate system is derived by measuring the position of the set point.

JP 2011-48467 A

  However, the image processing apparatus, the robot, and the machine tool update the position information at each cycle. For example, the position of the image processing apparatus in the camera coordinate system is updated every several hundred ms, while the position of the robot coordinate system is updated every several ms. Therefore, when the position of the workpiece flowing on the conveyor is measured by the camera, when the robot controller receives the position information, the workpiece has advanced to a position different from that at the time of measurement.

  In addition, each of the image processing apparatus, the robot, the machine tool, and the controller has a clock, and these clocks always shift. As described above, each cycle is different, and a clock that generates the cycle also shifts. Therefore, it is difficult to eliminate the positional information shift as described above.

  Therefore, an object of the present invention is to eliminate positional deviation and to perform highly accurate position control when a controller is used to control a device that has each timepiece and updates position information at different periods. It is to provide a control system, a control method for the control system, and a program for the control system.

In order to solve the above problem, the control system of this disclosure is:
A control system comprising a controller and a processing device connected to the controller and performing a predetermined process related to a workpiece,
The processor is
A timekeeping section that keeps time,
A position information update unit that updates the position information output from the processing device at a predetermined period in a coordinate system in the processing device;
A transmission unit that transmits the position information updated by the position information update unit and time information when the update is performed to the controller;
The controller is
A receiving unit that receives the position information and the time information from the processing device;
The position information is converted into a world coordinate system position of the world coordinate system by using a predetermined coordinate transformation expression that represents a relative relationship between the coordinate system and the world coordinate system in the processing apparatus from which the position information is output. A coordinate conversion unit for converting information,
An estimation unit that estimates position information between the world coordinate system position information based on the world coordinate system position information and the time information;
A world coordinate system management unit that manages the world coordinate system position information and the position information estimated by the estimation unit on a time axis;

  In the control system described above, the processing device updates the position information of the workpiece or the like at a predetermined cycle by the position information update unit, and transmits the updated position information and the updated time information to the controller by the transmission unit. To do. The updated time information is based on the time measured by the time measuring unit. The controller receives position information and time information from the processing device by the receiving unit, and converts the position information to world coordinate system position information of the world coordinate system by the coordinate conversion unit. The conversion by the coordinate conversion unit is performed using a coordinate conversion formula given in advance representing the relative relationship between the coordinate system in the processing apparatus that outputs the position information and the world coordinate system. Further, the estimation unit estimates position information between the world coordinate system position information based on the world coordinate system position information and the time information. The world coordinate system management unit manages the world coordinate system position information and the position information estimated by the estimation unit on the time axis.

  According to the control system described above, even when the coordinate systems in the processing device are different and the position information is updated at different periods, the position information output from the processing device is the time information when the position information is updated. And sent to the controller. Therefore, by converting the position information in the coordinate system of the processing device into the world coordinate system position information in the controller, the position information of each processing device can be managed on the time axis in the unified world coordinate system. Moreover, even when the update period of the position information in the processing device is long or when there is no punctuality in the update, the position information between the world coordinate system position information is estimated based on the time information. Therefore, the position information of the processing devices and the estimated position information can be managed on the time axis in the unified world coordinate system, and the positional information in each processing device is eliminated, and highly accurate position control is performed. It can be carried out.

  In the control system of one embodiment, it is preferable that the time measuring unit has a time correction function.

  In the control system of this embodiment, the timekeeping unit in each processing device has a time correction function, so that a delay due to communication is corrected, and a common time axis between the controller and each processing device. The position information with the time information above is exchanged. As a result, even when the coordinate systems in the processing apparatuses are different and the position information is updated at different periods, the positional information in each processing apparatus can be eliminated and highly accurate position control can be performed. .

  The control system of one embodiment may include a display unit that displays the world coordinate system position information.

  In the control system of this embodiment, the position information of the processing device in the coordinate system is converted into the world coordinate system position information and displayed on the display unit. Therefore, the user can easily set the relative relationship between the controller and the processing device.

In order to solve the above problem, a control method of the control system of this disclosure is:
A control method in a control system comprising a controller and a processing device connected to the controller and performing a predetermined process related to a workpiece,
In the processing apparatus,
A step of measuring time;
Updating the position information output from the processing device with a predetermined period in a coordinate system in the processing device;
Transmitting the updated location information and updated time information to the controller, and
In the controller,
Receiving the position information and the time information from the processing device;
The position information is converted into a world coordinate system position of the world coordinate system by using a predetermined coordinate transformation expression that represents a relative relationship between the coordinate system and the world coordinate system in the processing apparatus from which the position information is output. Converting to information;
Estimating position information between the world coordinate system position information based on the world coordinate system position information and the time information,
Managing the world coordinate system position information and the estimated position information on a time axis.

  According to the control method of the control system of this disclosure, the position information output from the processing device is the position information even when the coordinate systems in the processing device are different and the position information is updated at different periods. It is transmitted to the controller together with the updated time information. Therefore, by converting the position information in the coordinate system of the processing device into the world coordinate system position information in the controller, the position information of each processing device can be managed on the time axis in the unified world coordinate system. Moreover, even when the update period of the position information in the processing device is long or when there is no punctuality in the update, the position information between the world coordinate system position information is estimated based on the time information. Therefore, the position information of the processing devices and the estimated position information can be managed on the time axis in the unified world coordinate system, and the positional information in each processing device is eliminated, and highly accurate position control is performed. It can be carried out.

  In order to solve the above-described problem, the program of the control system of the present disclosure is a program for causing a computer to execute the control method of the control system.

  The control method of the control system can be implemented by causing a computer to execute the program of this disclosure.

  As is clear from the above, according to the control system, the control system control method, and the control system program of the present disclosure, when the controller controls each device having each clock and updating position information at different periods. In addition, it is possible to eliminate position information misalignment and perform highly accurate position control.

It is a figure which shows schematic structure of the control system in 1st Embodiment. It is a functional block diagram of a control system. It is a figure which shows an example of the timing of communication with a 1st control application and a 2nd control application, and a controller. It is a flowchart which shows the procedure of the process of a control system. It is a figure which shows an example of GUI in an integrated development environment. It is a figure for demonstrating the relationship between a reference | standard coordinate system and an object coordinate system. It is a figure for demonstrating the relationship between a reference | standard coordinate system and an object coordinate system. It is a figure which shows an example of the sheet | seat for calibration in which the target pattern was drawn. It is a conceptual diagram which shows a function block schematically. It is a conceptual diagram which shows a function block schematically. It is a figure which shows the example of a program in a ladder diagram. It is a figure which shows the functional block of the control system in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of a control system 1 according to the first embodiment. As shown in FIG. 1, the control system 1 includes a controller 100, an integrated development environment 200, an image processing device 510, a robot 520, a machine tool 530, a first conveyor 546, and a second conveyor 544. ing.

  The controller 100 is connected to the host computer 300 and the touch panel 400 via the host network 3. The controller 100 is connected to the image processing apparatus 510, the robot controller 522, the machine tool 530, and the servo amplifier 540 via the industrial network 2. Further, the controller 100 is connected to the integrated development environment 200. For the industrial network 2, for example, EtherCAT (registered trademark) is used.

  The controller 100 is, for example, a PLC (Programmable Logic Controller), a robot control program for controlling the operation of the arm type robot 520, and a sequence for controlling the operation of the end effector attached to the robot 520 and the operation of the machine tool 530. A control program is executed and a control signal is output.

  The integrated development environment 200 is a computer such as a personal computer, for example, and is connected to the controller 100 so as to be communicable. The integrated development environment 200 has a function of downloading a robot control program and a sequence control program executed by the controller 100 to the controller 100, a function of debugging these programs, a function of simulating these programs, and the like. Yes.

  For example, the robot 520 is a six-axis vertical articulated robot, and is connected to the robot controller 522 so as to be communicable. The robot 520 includes a power source such as a servomotor, and drives the servomotor via the robot controller 522 and operates each joint axis by a control signal output from the controller 100 based on the robot control program.

  An end effector is attached to the tip of the robot 520, and the end effector drives a servo motor in the end effector via the robot controller 522 by a control signal output from the controller 10 based on a sequence control program. To do. The end effector is attached to the tip of the robot 520, and includes, for example, a mechanism for gripping a component.

  The machine tool 530 processes a workpiece W on a mounting portion such as a table or a tool post with a tool. The processed workpiece W is gripped by an end effector attached to the robot 520 and placed on the first conveyor 546.

  The second conveyor 544 includes a servo motor 542, and the servo motor 542 is connected to the servo amplifier 540. The servo amplifier 540 includes a counter and an encoder, and the counter and the encoder are electrically connected. The encoder is electrically connected to a servo motor 542 for driving the second conveyor 544.

  The counter measures the amount of movement of the second conveyor 544 based on the pulse wave generated from the encoder. More specifically, the encoder generates a pulse signal according to the amount of movement of the second conveyor 544. The counter receives the pulse signal from the encoder and counts the number of pulses included in the pulse signal, thereby measuring the movement amount of the second conveyor 544. The counter transmits the count value of the pulse wave to the controller 100 via the servo amplifier 540 at regular communication cycles.

  A camera 512 is connected to the image processing apparatus 510. The camera 512 images the workpiece W moving on the second conveyor 544. The image processing apparatus 510 transmits the captured image to the controller 100 at regular communication cycles.

  The workpiece W is a product or a semi-finished product, and may be an electronic component such as a connector, for example.

  FIG. 2 is a functional block diagram of the control system 1 in the present embodiment. As shown in FIG. 2, the controller 100 includes an upper network interface 101, a logic processing unit 102, a world coordinate system management unit 104, a position data estimation processing unit 105, a field network interface 106, and a clock 108. ing. The logic processing unit 102 includes a motion processing unit 103.

  The controller 100 is connected to the host computer 300, the touch panel 400, and the integrated development environment 200 via the host network interface 101.

  Further, the controller 100 is connected to the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 as processing devices via the field network interface 106.

  The first control application engine 700 and the second control application engine 710 are connected to a control application 600 such as a robot 520 and a machine tool 530.

  The first control application engine 700 controls the end effector attached to the robot 520 and the machine tool 530. Only one first control application engine 700 is also shown in FIG. 2 for the sake of simplicity. The second control application engine 710 controls the robot 520. The robot controller 522 shown in FIG. 1 has functions of a first control application engine 700 and a second control application engine 710.

  The controller 100, the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 are provided with clocks 108, 701, 711, 511, and 541 as timekeeping units, respectively. In addition, an actuator 600 is connected to the first control application engine 700 and the second control application engine 710 via an I / O interface. Furthermore, a camera 512 is connected to the image processing apparatus 510 via an I / O interface.

(Overall processing)
Next, the whole process in the control system 1 of this embodiment is demonstrated. The world coordinate system management unit 104 of the controller 100 manages the world coordinate system. The image processing apparatus 510, the first control application engine 700, the second control application engine 710, the machine tool 530, and the servo amplifier 540 manage their local coordinate systems.

  The first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 have a function as a position information update unit, and the position in each local coordinate system in each cycle. Update. Here, in the first control application engine 700, the position means the position of the end effector and the position of the workpiece W on the mounting portion of the machine tool 530 or the tool on the machine tool 530. In the second control application engine 710, the coordinate values represented by the six axes of the robot 520 are used. Furthermore, in the image processing apparatus 510, it means an image taken by the camera 512. The servo amplifier 540 refers to the encoder value.

  FIG. 3 is a diagram illustrating an example of the timing of communication between the first control application engine 700 and the second control application engine 710 and the controller 100. As shown in FIG. 3, the first control application engine 700 and the second control application engine 710 transmit and receive data at a period different from the control period of the controller 100.

  When the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 update the position information, each time the position information is updated is added to the position information.

  The first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 transmit position information and time information to the controller 100 via the industrial network 2. That is, the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 have a function as a transmission unit that transmits the updated position information and time information to the controller 100. Yes.

  The world coordinate system management unit 104 of the controller 100 receives position information and time information via the field network interface 106. Therefore, the world coordinate system management unit 104 and the field network interface 106 have a function as a reception unit.

  The world coordinate system management unit 104 as a coordinate conversion unit of the controller 100 converts the world coordinate system into a world coordinate system by using a coordinate conversion formula representing a relative relationship between the world coordinate system and each coordinate system given in advance. The position data estimation processing unit 105 as an estimation unit of the controller 100 performs position data estimation processing until new data is obtained from the first control application engine 700 or the like.

  The world coordinate system management unit 104 of the controller 100 manages position data obtained from the first control application engine 700 or the like or estimated position data as position data at a predetermined time in the world coordinate system.

  The user program operating on the controller 100 can perform position control for each control application using the position of the world coordinate system expression, and can manage the command position of the world coordinate system expression.

  The integrated development environment 200 can display position information in the world coordinate system managed by the controller 100. The user can input position information in the world coordinate system from the integrated development environment 200. Therefore, the integrated development environment 200 has a function as a display unit of the controller 100.

  Next, a processing procedure in the control system 1 will be described with reference to the flowchart shown in FIG. FIG. 4 is a flowchart showing a processing procedure of the control system 1.

  First, the user executes CAE software such as three-dimensional CAD / CAM in the host computer 300, and sets the positional relationship between the world coordinate system, the control application, and the camera (S10). Next, the user captures the CAE data from the host computer 300 into the integrated development environment 200 (S20). As a method for capturing CAE data in the integrated development environment 200, for example, there is a method of converting CAE data into a DFX file and capturing the converted data.

  On the setting screen of the integrated development environment 200, the user performs setting between the coordinate system between the world coordinate system and each local coordinate system in each control application 600 (S30).

  FIG. 5 is a diagram illustrating an example of a GUI (Graphical User Interface) 210 in the integrated development environment 200. As shown in FIG. 5, the user inputs the relative relationship between the world coordinate system and each local coordinate system of each control application in this GUI 210. A measurement tool is provided on the GUI 210, and data of the measurement tool is displayed on the GUI 210 as a reference value.

  After setting the coordinate system as described above, the user creates a user program in the integrated development environment 200 (S40). After creating the user program, the user downloads the user program from the integrated development environment 200 to the controller 100.

  The controller 100 starts control of the operation of the control application 600, the image processing in the image processing apparatus 510, and the operation of the servo amplifier 540 according to the user program (S60).

  According to the controller 100 and the user program, the clocks 701, 711, 511, and 541 of the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 are corrected (S70).

  The first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 transmit position data at a predetermined time to the controller 100 at their respective update cycles (S80).

  The world coordinate system management unit 104 of the controller 100 converts the position data updated at the same time into position representation of the world coordinate system as position data at the same time (S90).

  When the new position data cannot be obtained from the image processing apparatus 510, the position data estimation processing unit 105 of the controller 100 estimates the position data based on the encoder value obtained from the servo amplifier 540 (S100).

  The world coordinate system management unit 104 of the controller 100 passes the position of the world coordinate system expression to the user program or the integrated development environment 200 (S110).

  The user program passes the command position of the world coordinate system expression to the controller 100 (S120).

  The controller 100 converts the command position of the world coordinate system expression back to the local coordinate system of each control application 600 and passes it to the first control application engine 700 and the second control application engine 710 (S130).

  Hereinafter, although illustration is omitted in FIG. 4, the processing of steps S70 to S130 is repeated until the end of the control.

(Coordinate conversion formula between world coordinate system and each local coordinate system)
Next, a coordinate conversion formula between the world coordinate system and each local coordinate system will be described with reference to FIGS. 6 and 7 are diagrams for explaining the relationship between the reference coordinate system and the object coordinate system.

  To represent the position and orientation of the robot 520 itself, tool, workpiece W, etc., it is displayed by the origin position of the Cartesian coordinate system fixed to the object and the direction of each coordinate axis when viewed from a certain Cartesian coordinate system. I do. The former is called a reference coordinate system, and the latter is called an object coordinate system.

As shown in FIG. 6, the reference coordinate system is Σ _A , the origin is O _A , and the three orthogonal axes are X _A , Y _A , and Z _A. Further, the object coordinate system is Σ _B , the origin is O _B , and the three orthogonal axes are X _B , Y _B , and Z _B. Moreover, what the origin _O origin from _{A O B} toward vectors _{(O B} position vector) viewed in the reference coordinate system sigma _A written as ^A P _B, 3 axes _{X B,} Y B, unit vector pointing in the direction of _{Z B} those expressed in reference coordinate system sigma _{a ^{a, a X B, a Y B}} , and be written as a _{Z B.}

At this time, the position of the object when viewed in the reference coordinate system sigma _A can be represented by ^A P _B, the posture can be expressed by ^{_{(A X B, A Y B}} , A Z B). Incidentally, the upper left subscripts A indicates that the vector is represented by a reference coordinate system sigma _A.

The posture of the object can be represented by three vectors ( ^A X _B , ^A Y _B , ^A Z _B ), and these are represented by a rotation matrix ^A R _{B.
^{A R B = [A X B}} , A Y B, A Z B]

As shown in FIG. 7, a reference coordinate system Σ _A and an object coordinate system Σ _B are given, the position of the object coordinate system Σ _B with respect to the reference coordinate system Σ _A is ^A p _B ], and the posture rotation matrix is ^A Assume that R _B is given. At this time, the point marked in the ^{B r} with respect to the object coordinate system sigma _B, when viewed in the reference coordinate system sigma _A,
^A r = ^A R _B ^B r + ^A p _B
It becomes.

This relationship is expressed using a 4 × 4 matrix ^A T _B
^A r = ^A T _B ^B r
It can be expressed as.

This equation is called a homogeneous transformation equation, and ^A T _B is called a homogeneous transformation matrix. By using the homogeneous conversion equation, it is possible to represent both parallel movement and rotational movement.

  In the present embodiment, the world coordinate system management unit 104 of the controller 100 uses such a homogeneous conversion formula to convert each local coordinate system to the world coordinate system, and from the world coordinate system to each local coordinate system. Inverse conversion to

In the present embodiment, the position expression using the local coordinate system A is as follows.
(X _A , Y _A , Z _A , φ _A , θ _A , ψ _A , t _A )

In addition, the position expression (X _W , Y _W , Z _W , φ _W , θ _W , φ _W , t _W ) using the world coordinate system is as follows.

Here, (φ _n , θ _n , ψ _n ) is a roll, pitch, and yaw angle, and represents a rotation angle. T _n represents time information.

(Calibration method)
Next, a calibration method for identifying the positional relationship between the robot coordinate system and the camera coordinate system will be described. As the calibration method, a conventional calibration method can be used. For example, the calibration method disclosed in JP 2012-187651 A can be used.

  In the calibration according to the present embodiment, the calibration sheet S on which the target pattern shown in FIG. 8 is drawn is used. FIG. 8 is a diagram illustrating an example of the calibration sheet S on which the target pattern is drawn according to the present embodiment. The target pattern shown on the calibration sheet S includes five circles (marks) whose inside is divided by about 90 °. As will be described later, the calibration is basically performed using four marks. However, in the additionally arranged one mark, the arrangement direction of the calibration sheet S is unified in a predetermined direction. Used to do.

[First stage]
In the first stage, the user places the calibration sheet S on which the target pattern is drawn in the field of view of the camera 512. Then, the user gives an imaging instruction from the controller 100 to the image processing apparatus 510. Then, the image processing apparatus 510 transmits an image (an image including a target pattern as a subject) obtained by imaging to the controller 100.

  The controller 100 performs measurement processing on the received image, and determines the coordinate values of the center points for the four marks arranged at the four corners included in the target pattern. As a result, the coordinate values [pixel] of the image coordinate system for the four marks included in the target pattern are acquired. The four coordinate values acquired are (xi1, yi1), (xi2, yi2), (xi3, yi3), and (xi4, yi4).

[Second stage]
As the second stage, the user moves the second conveyor 544 to place the calibration sheet S on which the target pattern is drawn within the tracking range (operating range) of the robot 520, and operates the robot 520, The positional relationship between the four marks included in the target pattern and the robot 520 is associated.

  More specifically, first, the user moves the conveyor 544 to place the calibration sheet S within the tracking range (operating range) of the robot 520. It is assumed that the count value of the encoder before the movement of the second conveyor 544 (at the start of calibration) is acquired in advance. This count value is set to E1.

  Subsequently, the user positions the hand tip of the robot 520 so as to correspond to one mark on the calibration sheet S by operating a teaching pendant attached to the robot controller 522 or the like. When the user gives an instruction in this positioned state, the position information of the robot 520 (coordinate value in the robot coordinate system indicating the position of the hand tip of the robot 520) grasped by the robot controller 522 is obtained from the image processing apparatus. 510 to the controller 100. The process of positioning the tip of the hand of the robot 520 and transmitting the position information of the robot 520 in the positioned state to the controller 100 is repeatedly executed for all four marks included in the target pattern.

  By such a procedure, position information of the robot 520 corresponding to the four marks included in the target pattern is acquired. The position information of the robot 520 corresponding to the four marks acquired is, for example, (X1, Y1), (X2, Y2), (X3, Y3), (X4, Y4).

  When the calibration sheet S is disposed within the tracking range (operating range) of the robot 520, the position information of the robot 520 corresponding to all four marks is transmitted from the image processing apparatus 510 to the controller 100. Until maintained.

  The controller 100 also stores the count value when the second conveyor 544 is moved to the robot operating range (upstream). This count value is set to E2.

[Stage 3]
In the third stage, the user further moves the second conveyor 544 to place the calibration sheet S at the most downstream position in the tracking range (operating range) of the robot 520 and operates the robot 520 to operate the target. The positional relationship between one mark included in the pattern and the robot 520 is associated.

  More specifically, the user first moves the second conveyor 544 to place the calibration sheet S at the downstream end of the tracking range (operating range) of the robot 520.

  Subsequently, the user operates the teaching pendant or the like to associate the tip of the hand of the robot 520 with the first mark on the calibration sheet S (the mark having acquired the coordinate values (X1, Y1) in the second stage). Position to do. When the user gives an instruction in this positioned state, the position information (the coordinate value in the robot coordinate system indicating the position of the hand tip of the robot 520) grasped by the robot controller 522 is sent to the controller 100. Sent.

  By such a procedure, the position information of the robot 520 corresponding to the first mark included in the target pattern is acquired. The position information of the robot 520 corresponding to the acquired first mark is (X5, Y5).

  The controller 100 also stores the count value in the state where the second conveyor 544 is moved to the operating range (downstream) of the robot 520. This count value is set to E3.

[Parameter calculation processing]
Using the parameters acquired by the first to third stage processes as described above, first, the movement amounts dX and dY of the workpiece W per count from the encoder are calculated. More specifically, it is calculated according to the following formula.

dX = (X5-X1) / (E3-E2)
dY = (Y5-Y1) / (E3-E2)
These formulas indicate that the robot 520 is between the state where the second conveyor 544 is moved to the operating range (upstream) of the robot 520 and the state where the second conveyor 544 is moved to the operating range (downstream) of the robot 520. This means that the amount of change in the position information of the robot 520 relative to the amount of change in the count value that occurs when the tip of the hand is positioned at the same mark in the calibration sheet S is calculated. The movement amounts dX and dY of the workpiece W per count are determined by these arithmetic expressions. That is, the calibration between the robot and the conveyor is realized.

  Further, the coordinate values (xi1, yi1), (xi2, yi2), (xi3, yi3), (xi4, yi4) of the camera coordinate system acquired in a state where the calibration sheet S is arranged in the field of view of the camera 512. The coordinate values (X1, Y1), (X2, Y2), (X3, Y3), (X4) of the robot coordinate system acquired with the second conveyor 544 moved to the operating range (upstream) of the robot 520. , Y4), six parameters A to F of the conversion formula relating to the conversion of the coordinate system are determined. That is, parameters A to F that satisfy the following expression (or that minimize the error) are determined using a known method.

X = A · xi + B · yi + C
Y = D ・ xi + E ・ yi + F
Thereby, calibration for identifying the positional relationship between the robot coordinate system and the camera coordinate system is realized.

(Method of estimating position)
Next, a method for estimating the position of the workpiece W in the present embodiment will be described. The measurement of the image processing apparatus 510 is longer than the communication cycle of the controller 100, and the measurement time is not punctual. Therefore, the controller 100 estimates the position of the workpiece W in a cycle in which position data cannot be obtained from the image processing apparatus 510.

  The image processing apparatus 510 transmits two images captured at time N-1 and time N and time data when the two images are captured to the controller 100 via the industrial network 2.

  The position data estimation processing unit 105 of the controller 100 measures the difference between the number of moving pixels of feature points such as edges in the workpiece W in two images and the time. As a result, the position data estimation processing unit 105 of the controller 100 determines the moving speed and moving direction of the workpiece W. Then, the position data estimation processing unit 105 of the controller 100 estimates the position of the workpiece in the control cycle of the controller 100 based on this vector information.

(Clock correction method)
Next, a clock correction method will be described. As the clock correction method, a conventional method can be used, and for example, the method disclosed in Japanese Patent No. 5794449 can be used.

  The controller 100 has a function of transmitting a time synchronization frame for time adjustment to the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540. Hereinafter, in order to simplify the description, the first control application engine 700, the second control application engine 710, the image processing apparatus 510, and the servo amplifier 540 are referred to as slave units.

  When each slave unit receives the time synchronization frame from the controller 100, the slave unit immediately transmits the time synchronization frame to the next slave unit without adding data to the frame. As a result, the time required from the reception of the time synchronization frame by one slave unit to the transmission to the next slave unit is substantially constant. In addition, the time for the time synchronization frame to move on the line inside the slave unit and the system bus between the slave units is uniquely defined from the line length and is constant. Therefore, it can be said that the time required to transfer the time synchronization frame to the next slave unit is almost equal for the slave unit.

  Therefore, the time required from when a time synchronization frame is transmitted from a slave unit to when the time synchronization frame is received by the next slave unit and output from the next slave unit is the same for each slave unit. Can be considered constant. When such a fixed time is referred to as a reference time and is set to t0, that is, the propagation delay time required from when the time synchronization frame is transmitted from the controller 100 to when the time synchronization frame is output from the first slave unit is , T0.

  Similarly, the propagation delay time required from when the time synchronization frame is transmitted from the first slave unit until the time synchronization frame is received by the second slave unit and output to the next slave unit. Becomes t0. Accordingly, the propagation delay time required from when the time synchronization frame is transmitted from the controller 100 to when the time synchronization frame is transmitted from the second slave unit is 2 × t0. Similarly, the propagation delay time required from when the time synchronization frame is transmitted from the controller 100 to when the time synchronization frame is transmitted from the transmission control unit of the Nth slave unit is N × t0. In addition, the internal processing of each slave unit, that is, the time for transmission on the system bus between slave units is much longer than the time required to receive the time synchronization frame and output it to the next slave unit. It can be ignored for a short time. Therefore, t0 may be a time required for internal processing of the slave unit.

  Thus, since the propagation delay time is almost fixed at the connection position of each slave unit, in the Nth slave unit, “N × t0” is stored in the memory or register as the correction time based on the propagation delay time. Store. In the example of the present embodiment, “t0” is stored in the register of the first image processing apparatus 510, and “2 × t0” is stored in the register of the second first control application engine 700. The register of the second second control application engine 710 stores “3 × t0”.

  As described above, the correction time stored in the register of each slave unit is a time obtained by adding t0 in order from the slave unit close to the controller 100 (the Nth slave unit is “N × t0”). Therefore, when the user manually stores the correction time in the register, the user confirms the slave unit to be set from the controller 100 and confirms the corresponding correction time using the setting tool device. It can be set individually, or each slave unit can be provided with a switch for setting a correction time, etc., and the user can set it for each unit by operating the switch. This switch is, for example, a switch that identifies the Nth switch. Then, each slave unit multiplies the correction reference time t0 stored and held in advance by N specified by the switch to obtain the correction time and stores it in the register.

  Further, the controller 100 as a master may automatically set the correction time for the register of each slave unit. That is, as an initial process at power-on or system startup, the controller 100 acquires connection position information of each slave unit, calculates the correction time of each slave unit for which correction time is set, and calculates the calculated time. Notify each slave unit of the correction time. Then, the slave unit that has received the notification stores the sent correction time in the register. That is, the controller 100 transmits a profile request message to each slave unit prior to communication. Each slave unit sends its own profile (model information, etc.). Thereby, the controller 100 recognizes the configuration information indicating what slave unit is set in each node from the received profile information of the slave units configuring each node. Therefore, the controller 100 can obtain the correction time by multiplying the reference time t0 while obtaining what number each slave unit is connected to based on the collected configuration information.

  Next, time adjustment at the time of actual control execution will be described. The controller 100 broadcasts time information of the clock 108. That is, when the time alignment condition is satisfied, the controller 100 starts preparation for transmission of transmission data (time information) for the time synchronization frame. In this embodiment, the transmission condition is a time-up of the transmission timer. Therefore, the time synchronization frame transmission processing is performed at regular intervals at a time interval set by the transmission timer. This time synchronization frame is transmitted with the highest priority.

  The controller 100 latches the time information of the clock 108 serving as the master time, and stores it in the data portion of the time synchronization frame. The controller 100 encodes the time synchronization frame generated in this way and transmits it to the first slave unit. If the time information is latched, the controller 100 transmits the time synchronization frame with the highest priority without delay.

  Then, the time synchronization frame (serial) is received by the first slave unit (in this embodiment, the image processing apparatus 510). The first slave unit can acquire the master time stored in the time synchronization frame.

  The first slave unit latches the master time sent in the received time synchronization frame, and obtains the current time by adding the correction time stored in the register to the master time. The own clock (in this embodiment, the clock 511 of the image processing apparatus 510) is corrected based on the determined time.

  The correction of the clock based on the obtained current time can be realized, for example, by performing a process of updating the time of the clock by overwriting it with the obtained current time. In addition, when updating is performed by overwriting in this way, the value indicated by the clock is scattered discretely before and after correction. In order to prevent this, the first slave unit uses a predetermined correction algorithm or the like, and corrects the time to gradually and gradually adjust to the master time by increasing or decreasing the clock speed. You may do it.

  The first slave unit transmits a time synchronization frame to the second slave unit.

  The time synchronization frame transmitted in the digital chain manner in this manner is received by the slave unit (here, the second first control application engine 700) adjacent to the next stage. Similarly to the above, the second slave unit obtains the master time stored in the received time synchronization frame, and adds the correction time (2 × t0) to the current time. In the present embodiment, the clock 701) of the first control application engine 700 is corrected. Then, the first control application engine 700 transmits the received time synchronization frame to the third slave unit.

  In this way, each slave unit sequentially transfers the time synchronization frame sent from the controller 100 to the adjacent slave units by the digi chain method. Further, the time of the Nth slave unit is corrected by adding the station delay ((N−1) × t0) of N−1 slave units existing between the controller 100 and the master time. Do

  Note that the clock correction method described above is merely an example, and other methods may be used in addition to the method disclosed in Japanese Patent No. 5141972, for example.

(Faction block)
The position information expressed in the world coordinate system may be output as output information of the function block of IEC61131-3. FIG. 9 is a conceptual diagram schematically showing the function block 180. FIG. 10 is a conceptual diagram schematically showing the function block 190.

  The function block 180 is stored in, for example, a main memory or a storage device of the controller 100. As shown in FIG. 9, the function block 180 includes a receiving unit 181 that receives a structure array variable World in which the position and time of the world coordinate system are possible, an enable unit 182 that receives TRUE or FALSE, and a local of the Nth control application. A receiving unit 183 that receives a structure variable Apply [N] in which the position and time of the coordinate system are stored.

  The function block 180 also outputs an output unit 184 that outputs a structure array variable World in which the position and time of the world coordinate system are possible, and an output that outputs an output variable Status indicating whether the function block 180 is operating normally. Unit 185, an output unit 186 that outputs an output variable Error when an abnormality occurs, and an output unit 187 that outputs an output variable ErrorID in which an error code is stored.

  The function block 190 is stored in, for example, a main memory or a storage device of the controller 100. As shown in FIG. 10, the function block 190 includes a receiving unit 191 that receives a structural array variable World in which the position and time of the world coordinate system are possible.

  The function block 190 also outputs an output unit 193 that outputs a structure array variable World in which the position and time of the world coordinate system are possible, and a structure variable Apply that stores the position and time of the local coordinate system of the Nth control application. An output unit 194 that outputs [N], an output unit 195 that outputs an output variable Status indicating whether the function block 190 is operating normally, and an output unit 196 that outputs an output variable Error when an abnormality occurs. And an output unit 197 for outputting an output variable ErrorID in which an error code is stored.

  FIG. 11 is a diagram showing a program example in a ladder diagram defined by IEC61131-3. As shown in FIG. 11, when SW1 is TRUE, the structure array variable Appli [1] storing the position and time of the coordinate system of the first control application is converted, and the position and time of the converted coordinate system are , Stored in the structure array variable World of the world coordinate system, and output from the output unit 184.

  When the function block 180 is operating normally, the output variable Status output from the output unit 185 is TRUE. When abnormal, the output variable Error output from the output unit 186 becomes TRUE, the error code is stored in the output variable ErrorID, and is output from the output unit 187.

  Also, as shown in FIG. 11, when SW2 is TRUE, when the receiving unit 191 receives a structure array variable World in which the position and time of the world coordinate system are possible, the position of the local coordinate system of the first control application The time is converted, stored in the structure array variable Apply [1], and output from the output unit 194.

  When the function block 190 is operating normally, the output variable Status output from the output unit 195 is TRUE. If an abnormality occurs, the output variable Error output from the output unit 196 becomes TRUE, and an error code is stored in the output variable ErrorID and output from the output unit 197.

  The position information expressed in the world coordinate system may be displayed on the GUI of the integrated development environment 200 shown in FIG. 5 in addition to the mode of outputting the function block output information as described above.

  As described above, according to the present embodiment, the clocks 108, 701, 711, 511, 541 of the controller 100, the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540 are used. , The controller 100 updates the position of each local coordinate system updated in each cycle from the first control application engine 700, the second control application engine 710, the image processing device 510, and the servo amplifier 540. Receive updated time information. Accordingly, it is possible to manage each piece of position information represented in different coordinate systems and updated at different periods as position information of a unified world coordinate system at a common time.

  As a result, the user program operating on the controller 100 can issue a command or monitor the position using the position expressed in the world coordinate system.

  Further, even when position data is output from a control application engine or the image processing apparatus 510 that has a long update period or has no punctuality, the position can be estimated by the control period in the controller 100. As a result, the command position can be output to the control application engine in the control cycle of the controller 100.

  Furthermore, according to the present embodiment, not only the position of the world coordinate system can be managed, but also the speed and acceleration data can be calculated. 400, and the integrated development environment 200. Further, in the integrated development environment 200, the output position, velocity, and acceleration data of the world coordinate system can be displayed on the GUI.

  In the present embodiment, information such as speed, acceleration, torque, and current value may be transmitted from the first control application engine 700 and the second control application engine 710 to the controller 100. Note that the first control application engine 700 and the second control application engine 710 are merely examples, and the number of control application engines can be appropriately increased or decreased as necessary.

(Second Embodiment)
Next, a second embodiment of the present disclosure will be described with reference to the accompanying drawings. In the first embodiment, the aspect in which the first control application engine 700 and the second control application engine 710 are provided outside the controller 100 has been described. However, the present embodiment is different from the first embodiment in that the first control application engine 700 and the second control application engine 710 are provided inside the controller 100.

  FIG. 12 is a diagram illustrating functional blocks of the control system 1 in the present embodiment. As shown in FIG. 12, in the present embodiment, a first control application engine 700 and a second control application engine 710 are provided inside the controller 100.

  The first control application engine 700 and the second control application engine 710 are not provided with a clock, and the control application 600 such as the robot 520 or the machine tool 530 is provided with a clock 601.

  Further, although not shown, the control application 600 also includes a position information update unit that updates the position information, and a transmission unit that transmits the time and position information at which the position information was updated to the controller 100.

  Even in such a configuration, the controller 100 corrects the clocks 601, 511, and 541 in the control application 600, the image processing device 510, and the servo amplifier 540, and the controller 100 performs the control application 600, the image processing device 510, and The position of each local coordinate system updated in each cycle and the updated time information are received from the servo amplifier 540. Accordingly, it is possible to manage each piece of position information represented in different coordinate systems and updated at different periods as position information of a unified world coordinate system at a common time.

(Modification)
In the above-described embodiment, the aspect in which the position of the workpiece W is estimated based on the image transmitted from the image processing apparatus 510 has been described. However, the present invention is not limited to such an embodiment. For example, the counter value provided in the servo amplifier 540 may be transmitted from the servo amplifier 540 to the controller 100, and the position of the workpiece W may be estimated based on this counter value.

  In the above-described embodiment, the mode in which the position of the workpiece W is estimated by transmitting an image from the image processing apparatus 510 and analyzing the image in the controller 100 has been described. However, the present invention is not limited to such an embodiment. For example, the image processing apparatus 510 measures the difference between the number of moving pixels of feature points such as edges in the workpiece W in the two images taken at time N-1 and the time N and the time, and the moving speed of the workpiece W The moving direction may be determined. Then, information on the moving speed and moving direction of the workpiece W may be transmitted from the image processing apparatus 510 to the controller 100 so that the controller 100 estimates the position of the workpiece W.

  The above embodiments are merely examples, and various modifications can be made without departing from the scope of the present invention. The plurality of embodiments described above can be established independently, but combinations of the embodiments are also possible. In addition, various features in different embodiments can be established independently, but the features in different embodiments can be combined.

DESCRIPTION OF SYMBOLS 1 Control system 100 Controller 101 Clock 510 Image processing apparatus 511 Clock 600 Control application 700 1st control application engine 701 Clock 710 2nd control application engine 711 Clock

Claims (5)

A control system comprising a controller and a processing device connected to the controller and performing a predetermined process related to a workpiece,
The processor is
A timekeeping section that keeps time,
A position information update unit that updates the position information output from the processing device at a predetermined period in a coordinate system in the processing device;
A transmission unit that transmits the position information updated by the position information update unit and time information when the update is performed to the controller;
The controller is
A receiving unit that receives the position information and the time information from the processing device;
The position information is converted into a world coordinate system position of the world coordinate system by using a predetermined coordinate transformation expression that represents a relative relationship between the coordinate system and the world coordinate system in the processing apparatus from which the position information is output. A coordinate conversion unit for converting information,
An estimation unit that estimates position information between the world coordinate system position information based on the world coordinate system position information and the time information;
A world coordinate system management unit that manages the world coordinate system position information and the position information estimated by the estimation unit on a time axis;
Control system. The timekeeping unit has a time correction function,
The control system according to claim 1. A display unit for displaying the world coordinate system position information;
The control system according to claim 1 or 2. A control method in a control system comprising a controller and a processing device connected to the controller and performing a predetermined process related to a workpiece,
In the processing apparatus,
A step of measuring time;
Updating the position information output from the processing device with a predetermined period in a coordinate system in the processing device;
Transmitting the updated location information and updated time information to the controller, and
In the controller,
Receiving the position information and the time information from the processing device;
The position information is converted into a world coordinate system position of the world coordinate system by using a predetermined coordinate transformation expression that represents a relative relationship between the coordinate system and the world coordinate system in the processing apparatus from which the position information is output. Converting to information;
Estimating position information between the world coordinate system position information based on the world coordinate system position information and the time information,
Managing the world coordinate system position information and the estimated position information on a time axis,
Control system control method. A program in a control system that includes a controller and a processing device that is connected to the controller and performs a predetermined process related to a workpiece.
In the processing apparatus,
A step of measuring time;
Updating the position information output from the processing device with a predetermined period in a coordinate system in the processing device;
Transmitting the updated location information and updated time information to the controller, and
In the controller,
Receiving the position information and the time information from the processing device;
The position information is converted into a world coordinate system position of the world coordinate system by using a predetermined coordinate transformation expression that represents a relative relationship between the coordinate system and the world coordinate system in the processing apparatus from which the position information is output. Converting to information;
Estimating position information between the world coordinate system position information based on the world coordinate system position information and the time information,
Managing the world coordinate system position information and the estimated position information on a time axis,
Control system program.

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