Robot control system and machining system

Abstract

This robot control device is capable of easily giving instructions on an operating procedure for causing a robot to feed a workpiece to a fixation mechanism, and performs control on the robot that feeds and extracts a workpiece to and from the fixation mechanism of a machine tool. The robot control device comprises: a communication unit which transmits and receives a signal for ordering or checking the operating condition of said fixation mechanism; a memory unit which stores therein the specification of the signal transmitted or received by the communication unit; and an instruction unit which sets the signal transmitted or received by the communication unit.

Description

Technical Field

[0001] The present invention relates to a robot control device and a processing system.

Background Art

[0002] Conventionally, a robot has been used to supply a workpiece to industrial equipment such as a machine tool. In this case, the robot grips the workpiece and supplies the gripped workpiece to the fixing mechanism of the spindle of the machine tool. As the fixing mechanism for fixing the workpiece, for example, a chuck having about two to four claws or a mechanism for sucking the workpiece by air is used (see, for example, Patent Document 1). In such a system, it is necessary to set a teaching program for sequentially specifying the operation procedures of the robot and the fixing mechanism, that is, the posture and operation speed of the robot, the operation of the hand for gripping the workpiece, the operation of the fixing mechanism, and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to obtain sufficient machining accuracy on a machine tool, it is necessary to supply the workpiece such that the center position formed by the center position of the workpiece and each claw coincides, and the direction of the workpiece is parallel to the direction of the claw. In order to realize such an operation by a robot, a teaching operation for aligning the center position and posture of the workpiece with the fixing mechanism is required. In order to teach accurately, even a skilled person requires a lot of time and labor, and it is a very difficult operation for an operator who is not familiar with the robot.

[0005] For this reason, a technique that can easily teach the operation procedure of supplying the workpiece to the fixing mechanism by the robot is desired.

Means for Solving the Problems

[0006] A robot control device according to one aspect of the present disclosure is a robot control device for controlling a robot that supplies and removes workpieces to and from a fixing mechanism of a machine tool, comprising: a communication unit that transmits and receives signals to instruct or confirm the operating state of the fixing mechanism; a storage unit that stores the specifications of the signals transmitted and received by the communication unit; and a teaching unit that sets the signals transmitted and received by the communication unit. [Effects of the Invention]

[0007] According to the present invention, it is possible to easily teach the robot the procedure for supplying a workpiece to a fixing mechanism. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of a processing system according to one embodiment of the present disclosure. [Figure 2] Figure 2 illustrates the setting screen for the operation procedure in the machining system shown in Figure 2. [Figure 3] Figure 2 illustrates the setting screen for the workpiece supply operation procedure in the machining system shown in Figure 2. [Figure 4A] This diagram shows the operation when fixing the workpiece to the fixing mechanism according to this embodiment. [Figure 4B] This diagram shows the operation when fixing the workpiece to the fixing mechanism according to this embodiment. [Figure 5A] This diagram shows the process of correcting the orientation error of the workpiece. [Figure 5B] This diagram shows the process of correcting the orientation error of the workpiece. [Figure 5C] This diagram shows the process of correcting the orientation error of the workpiece. [Figure 6A] This diagram shows the process of correcting the positional error of the workpiece. [Figure 6B] This diagram shows the process of correcting the positional error of the workpiece. [Modes for carrying out the invention]

[0009] Embodiments of the present disclosure will be described below with reference to the drawings. Figure 1 is a block diagram showing the configuration of a machining system 1 according to one embodiment of the present disclosure. The machining system 1 of this embodiment comprises a machine tool 10, a numerical control device 20, a robot 30, and a robot control device 40. The machining system 1 uses the robot 30 to supply and remove workpieces W from the machine tool 10.

[0010] The machine tool 10 has a fixing mechanism 11 for holding the workpiece W. The fixing mechanism 11 in this embodiment is a chuck having a base member 111 that rotates with the spindle and three gripping claws 112 arranged at equal intervals in the circumferential direction on the end face of the base member 111, which grip the workpiece W by moving (opening and closing) in the radial direction. The fixing mechanism is not limited to the illustrated configuration, and may have, for example, four or more gripping claws, or may be configured to hold the workpiece W by attraction using vacuum force or magnetic force.

[0011] The numerical control device 20 is a well-known control device for controlling the machine tool 10. The numerical control device 20 outputs a signal to the robot control device 40 indicating the state of the fixing mechanism 11, and operates the fixing mechanism 11 in response to a signal received from the robot control device 40 instructing the opening and closing of the fixing mechanism 11.

[0012] The robot 30 is controlled by a robot control device 40 to supply and retrieve the workpiece W. Typically, a vertical articulated robot can be used as the robot 30, but other types of robots may also be used. The robot 30 in this embodiment has an arm 31 having multiple joints, a gripping mechanism 32 provided at the tip of the arm 31 for gripping the workpiece W, and a force sensor 33 that detects force values ​​that reflect the force acting on the gripping mechanism 32 due to interaction with the workpiece W.

[0013] The gripping mechanism 32 has a plurality of gripping fingers 321 for gripping the workpiece W. The force sensor 33 can be a sensor that detects force, bending moment, strain, etc. acting on the gripping fingers 321 or the body of the gripping mechanism 32, and may be configured to detect the current value, torque, etc. of the motor on the drive shaft of the arm 31. In other words, the force sensor 33 may be part of the arm 31. Furthermore, a 3-axis or 6-axis force sensor such as a strain gauge type, capacitive type, magnetic type, or optical type may be used as the force sensor 33.

[0014] The robot control device 40 is itself an embodiment of the robot control device according to this disclosure. The robot control device 40 of this embodiment includes a communication unit 41, a storage unit 42, a teaching unit 43, an execution control unit 44, a force sensor value acquisition unit 45, an error correction unit 46, and a simulation unit 47. The robot control device 40 can be realized by one or more computer devices that have, for example, memory, a processor, an input / output interface, etc., and execute an appropriate control program. Each component of the robot control device 40 is a classification of the functions of the robot control device 40 and does not necessarily have to be clearly distinguishable in terms of physical configuration and program configuration. In addition, a display device 51, such as a display panel, and an input device 52, such as a keyboard or mouse, are connected to the robot control device 40 to realize a user interface. The display device 51 and the input device 52 may be provided integrally with the robot control device 40, or the display device 51 and the input device 52 may be provided integrally with, for example, a touch panel.

[0015] The communication unit 41 transmits and receives signals for instructing or confirming the operating state of the fixing mechanism 11. Specifically, the communication unit 41 receives from the numerical control device 20 a signal that becomes ON in one of the states where the gripping claws 112 of the fixing mechanism 11 are closed and where the gripping claws 112 are open, and becomes OFF in the other state. Further, the communication unit 41 transmits to the numerical control device 20 a signal for requesting to close or open the gripping claws 112 of the fixing mechanism 11. The specifications of these signals, that is, the mode of the signals and the addresses of the input / output interfaces used for the transmission and reception of the signals, may vary depending on the type of the fixing mechanism 11. As an example, depending on the type of the fixing mechanism 11, there are those that output ON when the gripping claws 112 are closed and those that output OFF. Also, the signals transmitted and received by the communication unit 41 are not limited to ON / OFF signals, and may be analog signals or signals that transmit information based on the change over time of ON / OFF.

[0016] The storage unit 42 stores the signal specifications transmitted and received for each type of the fixing mechanism 11. The type of the fixing mechanism 11 can be specified by its model, but may also be specified by a code or the like used by the user to identify the fixing mechanism 11, or may be specified based on a group set based on the signal specifications. That is, a plurality of fixing mechanisms 11 may be treated as different types for each individual, or a group including a plurality of models of the fixing mechanism 11 may be treated as one type.

[0017] As an example, as shown in FIG. 2, the teaching unit 43 arranges icons representing the operation procedures of unit operations, such as the supply operation of the workpiece W and the take-out operation of the workpiece W, in the space (execution line) set in the display device 51 in the order of execution, so that various parameters for specifying the operation procedure of the robot 30 that realizes the unit operation represented by each icon can be automatically set. That is, it can be configured to provide a user interface that can easily teach the operation of the robot 30. Examples of the parameters for specifying the operation procedure include the coordinates of the reference point of the robot 30, the positions of each drive axis, the speed (especially the speed approaching the fixing mechanism 11), the state of the gripping finger 321, and the like. Further, the teaching unit 43 can be configured to switch the screen displayed on the display device 51 to a setting screen that allows the user to input the minimum information necessary for setting the operation procedure of the unit operation when arranging the icon representing the unit operation or when selecting the icon representing the unit operation, as needed.

[0018] When setting the operation procedure for the supply or take-out of the workpiece W, the teaching unit 43 refers to the storage unit 42 and sets the signals transmitted and received by the communication unit 41 according to the type of the fixing mechanism 11. Further, the teaching unit 43 receives the input of the user and sets the operation procedure for the supply or take-out of the workpiece W by the fixing mechanism 11 and the robot 30 based on the received input. For this purpose, when an icon representing the supply or take-out of the workpiece W is arranged on the execution line, the teaching unit 43 displays a setting screen that prompts the user for the minimum necessary input. FIG. 3 illustrates a setting screen 1000 for setting the supply operation of the workpiece W displayed by the teaching unit 43 on the display device 51. The teaching unit 43 is configured to be able to set the operation procedure of the supply operation of the workpiece W in a single setting screen 1000.

[0019] The workpiece W supply operation includes the steps of: causing the numerical control device 20 to open the gripping claws 112 of the fixing mechanism 11; positioning the tip of the robot 30 at a supply start position set to place the workpiece on the rotation axis of the spindle of the machine tool 10; moving the workpiece W in the axial direction of the fixing mechanism 11 by the robot 30 to a minimum insertion length or more and inserting it into the fixing mechanism 11; and causing the numerical control device 20 to close the gripping claws 112 of the fixing mechanism 11.

[0020] The teaching unit 43 automatically sets the type of signals to be transmitted and received by the communication unit 41 and the address of the input / output interface in the steps of opening the gripping claws 112 and closing the gripping claws 112, according to the type of fixing mechanism 11. The teaching unit 43 may be configured to obtain the type of fixing mechanism 11 from the numerical control device 20, but it is preferable to configure it to identify the type of fixing mechanism 11 based on user input so that an existing numerical control device 20 can also be used. For this reason, the setting screen 1000 in Figure 3 displays a pull-down menu 1001 that allows the user to input the fixing mechanism.

[0021] The teaching unit 43 displays a pull-down menu 1002 on the setting screen 1000 in Figure 3, which allows the user to select the supply start position from a number of preset values, specifically a number of a preset coordinate, in order to teach the robot 30 to the supply start position, that is, to set the operation parameters required by the execution control unit 44. The setting screen 1000 displayed by the teaching unit 43 also includes a button 1003 that pops up a window for modifying the preset value (coordinate) of the supply start position. The window that pops up when the button 1003 is operated may include multiple text boxes that display editable numerical values ​​for (X, Y, Z, W, P, R) that specify the position and orientation of the robot's tip reference point.

[0022] The teaching unit 43 displays a text box 1004 on the setting screen 1000 that prompts the user to input the minimum insertion length in the process of inserting the workpiece W into the fixing mechanism 11.

[0023] Furthermore, the teaching unit 43 displays on the settings screen 1000 a test execution button 1005 that starts the process of executing the operation procedure by the execution control unit 44 and optimizing the operation procedure based on force feedback values ​​by the error correction unit 46, and a button 1006 that pops up a window for adjusting parameters such as speed and judgment threshold when optimizing the operation procedure based on force feedback values, as shown in Figure 3.

[0024] The execution control unit 44 causes the stationary mechanism 11 and the robot 30 to execute the operation procedure according to the procedure taught by the teaching unit 43. Preferably, the execution control unit 44 is configured to immediately reflect the operation procedure corrected by the error correction unit 46 and operate the stationary mechanism 11 and the robot 30 accordingly.

[0025] The force sensor acquisition unit 45 acquires force values ​​from the force sensor detector 33 during the execution of an operation procedure, which reflect the force generated by the interaction between the workpiece W and the robot 30. In other words, the force sensor acquisition unit 45 acquires the magnitude and direction of the force that the workpiece W exerts to push back against the robot 30's gripping mechanism 32 when the workpiece W comes into contact with the fixing mechanism 11.

[0026] The error correction unit 46 corrects errors in the robot's position and posture during the operation procedure based on the force values ​​acquired by the force value acquisition unit, thereby optimizing the operation procedure. The details of the error correction performed by the error correction unit 46 are described below.

[0027] Figures 4A and 4B illustrate the operation of supplying and fixing the workpiece W to the fixing mechanism 11 according to this embodiment. When supplying the workpiece W to the fixing mechanism 11, the robot 30 operates along the direction L in which the workpiece W is supplied to the fixing mechanism 11. The robot 30 then supplies the cylindrical workpiece W to near the center position of the gripping claws 112, and when the machine tool 10 closes the gripping claws 112, the workpiece W is fixed to the center position of the base member 111.

[0028] If the workpiece W can be supplied to the base member 111 of the fixing mechanism 11 in the correct position and orientation, the central axis of the base member 111 and the workpiece W will coincide when the gripping claws 112 are closed, as shown in Figure 4A. In this case, the machine tool 10 can achieve good machining accuracy.

[0029] However, when supplying the workpiece W, if there is a large error in the position and orientation of the workpiece W relative to the base member 111, when the gripping claws 112 are closed, the workpiece W may be fixed in a state where its central axis is misaligned with the base member 111, as shown in Figure 4B. In this case, the machine tool 10 cannot obtain good machining accuracy.

[0030] Therefore, the error correction unit 46 performs a process (force sensor value control) to correct the positional and orientation errors between the workpiece W and the fixing mechanism 11, as described below.

[0031] Figures 5A, 5B, and 5C illustrate the operation to correct the posture error of the workpiece W. As shown in Figure 5A, the robot control device 40 controls the robot 30 to position the workpiece W on the base member 111. In the example shown in Figure 5A, the workpiece W has a posture error relative to the base member 111. Subsequently, the error correction unit 46 of the robot control device 40 performs force value control to correct the parameters of the operation procedure based on the force values.

[0032] Specifically, while force sensing value control is being performed, the error correction unit 46 controls the robot 30 to press the workpiece W against one of the gripping claws 112. That is, while force sensing value control is being performed, the error correction unit 46 uses the robot 30 to press the workpiece W against the fixing mechanism 11 in a direction substantially perpendicular to the direction in which the workpiece W is supplied to the fixing mechanism 11.

[0033] Figure 5B shows the operation to correct the posture of the workpiece W when the workpiece W is pressed against the gripping claws 112. As shown in Figure 5B, when the robot 30 presses the workpiece W against the gripping claws 112, a moment M1 is generated around the center of the contact surface between the workpiece W and the gripping claws 112 (center of rotation C). Here, if we let F be the reaction force to the force pressing the workpiece W against the gripping claws 112, and let r2 be the distance from the center of rotation C of the workpiece W to the position where force F acts, then the moment M1 can be expressed as [M1 = r2 × F].

[0034] When the force sensor 33 detects a moment M1, the error correction unit 46 performs force sensor control so that the moment pressing the workpiece W against the fixing mechanism 11 becomes 0. In other words, when the force sensor 33 detects a moment M1, the error correction unit 46 uses the robot 30 to rotate the workpiece W around the rotation center C, thereby correcting the posture of the workpiece W. As a result, as shown in Figure 5C, the workpiece W rotates in a direction that reduces the moment M1, and the error in the posture of the workpiece W is corrected.

[0035] Figures 6A and 6B show the operation for correcting the positional error of the workpiece W. As shown in Figure 6A, the robot control device 40 controls the robot 30 to position the workpiece W on the end face of the base member 111. In the example shown in Figure 6A, the workpiece W has a positional error relative to the base member 111. Subsequently, the error correction unit 46 performs force sensing value control.

[0036] Specifically, the error correction unit 46, while performing force sensing value control, transmits a control signal to the numerical control device 20 using the communication unit 41, causing the machine tool 10 to perform the action of closing the gripping claws 112 of the fixing mechanism 11. In other words, the numerical control device 20 operates the fixing mechanism 11 in conjunction with the force sensing value control by the robot 30 and the robot control device 40.

[0037] When the gripping claws 112 are closed, as shown in Figure 6B, the workpiece W receives a force F1 from the gripping claws 112 in a direction substantially perpendicular to the direction in which the workpiece W is supplied to the fixing mechanism 11. When the force sensor 33 detects the force F1, the error correction unit 46 corrects the position of the workpiece W by moving it in a direction that reduces the force F1 through the action of force sensor control.

[0038] When the gripping claws 112 are closed during force sensing control, if a positional error occurs in the workpiece W, the workpiece W moves in a direction that eliminates the positional error due to the action of force sensing control. The force sensing control described above may include, but is not limited to, impedance control or damping control.

[0039] Furthermore, the machine tool 10 may repeat the operation of the fixing mechanism 11 a predetermined number of times. The error correction unit 46 causes the fixing mechanism 11 to repeatedly open and close the gripping claws 112 a predetermined number of times while force value control is being performed. As a result, the error in the position and orientation of the workpiece W is corrected each time the gripping claws 112 are opened or closed. If the fixing mechanism 11 is a suction mechanism, the machine tool 10 causes the workpiece W to be picked up and released a predetermined number of times while force value control is being performed. As a result, the error in the position and orientation of the workpiece W is corrected each time it is picked up and released.

[0040] Furthermore, the robot 30 or machine tool 10 is equipped with a movement detector that detects the amount of movement of the workpiece W, and the error correction unit 46 may repeatedly perform force sensing value control when the fixing mechanism 11 is activated until the amount of movement of the workpiece W is less than or equal to a predetermined distance or angle.

[0041] Furthermore, if an excessive force or moment occurs while the fixing mechanism 11 is operating, the machine tool 10 may release the workpiece W using the fixing mechanism 11, then operate the fixing mechanism 11 again to fix the workpiece W with the fixing mechanism 11. In other words, if the value detected by the force sensor 33 is greater than or equal to a predetermined value indicating an excessive force or moment when the fixing mechanism 11 is operating, the machine tool 10 may interrupt the operation of the fixing mechanism 11, release the workpiece W using the fixing mechanism 11, then operate the fixing mechanism 11 again to fix the workpiece W with the fixing mechanism 11.

[0042] Furthermore, although a method has been described in which the workpiece W is pressed against the fixing mechanism 11 and then the fixing mechanism 11 is closed, the workpiece W may also be pressed against the fixing mechanism 11 after it has been closed.

[0043] The simulation unit 47 executes a simulation of the operation procedure and displays the simulation results. Preferably, the simulation unit 47 displays the calculated force values ​​along with the simulation results. For example, in addition to force values, parameters such as velocity and contact threshold during the simulation may also be displayed along with the simulation results. Preferably, the display of the simulation results by the simulation unit 47 is performed as part of the setting screen 1000. In other words, it is preferable to ensure that space is available for displaying the simulation results by the teaching unit 43. If a problem occurs during the simulation, the simulation unit 47 may be configured to identify abnormal values ​​among the displayed parameters, for example, by highlighting them. This allows the user to easily identify parameters that may be causing problems.

[0044] Although embodiments of the present disclosure have been described above, the present invention is not limited to the embodiments described above. Furthermore, the effects described in the embodiments described above are merely a list of preferred effects arising from the present invention, and the effects of the present invention are not limited to those described in the embodiments described above.

[0045] For example, the robot control device according to the present invention can be configured to similarly allow setting of the operation procedure related to workpiece removal. [Explanation of Symbols]

[0046] 1. Processing System 10 Machine tools 11 Fixing mechanism 111 Base member 112 Gripping claw 20 Numerical control devices 30 robots 31 Arm 32 Gripping mechanism 321 Grasping fingers 33 Force Sensor 40 Robot control devices 41 Communications Department 42 Storage section 43. Instruction Department 44 Execution Control Unit 45 Force value acquisition section 46 Error correction section 47 Simulation Department Double job

Claims

1. A robot control device for controlling a robot that supplies and removes workpieces to and from a fixed mechanism, A communication unit that transmits and receives signals to indicate or confirm the operating status of the fixed mechanism, A storage unit that stores the specifications of the signals transmitted and received by the communication unit, A teaching unit that sets the signals transmitted and received by the communication unit, Equipped with, The teaching unit is a robot control device that receives user input, identifies the type of fixing mechanism based on the received input, and sets the operation procedure for supplying or removing a workpiece by the fixing mechanism and the robot.

2. A robot control device for controlling a robot that supplies and removes workpieces to and from a fixing mechanism, A communication unit that transmits and receives signals to indicate or confirm the operating status of the fixed mechanism, A storage unit that stores the specifications of the signals transmitted and received by the communication unit, A teaching unit that sets the signals transmitted and received by the communication unit, The system includes a simulation unit that performs a simulation of the operation procedure for supplying or removing a workpiece by a fixing mechanism and a robot, and displays the results of the simulation, The teaching unit receives user input and sets the operation procedure based on the received input. Robot control device.

3. An execution control unit that causes a fixing mechanism and a robot to execute the aforementioned operation procedure, During the execution of the aforementioned operation procedure, a force sensing value acquisition unit acquires force sensing values ​​that reflect the force generated by the interaction between the workpiece and the robot, Based on the force values ​​acquired by the force value acquisition unit, an error correction unit corrects errors in the robot's position and posture during the operation procedure. A robot control device according to claim 1 or 2, comprising:

4. The robot control device according to claim 3, wherein the execution control unit sets parameters based on the type of the fixing mechanism.

5. The robot control device according to claim 1 or 2, wherein the teaching unit is configured to allow the operation procedure to be set on a single setting screen.

6. The robot control device according to claim 5, wherein the teaching unit is configured to set the robot's operating parameters to preset values, and the setting screen includes a button to pop up a window for modifying the preset values.

7. The robot control device according to claim 1, wherein the storage unit stores the specifications for each type of fixing mechanism.

8. A machining system comprising: a robot control device according to claim 1 or 2; a machine tool having a fixing mechanism; and a robot controlled by the robot control device for supplying and removing workpieces to and from the fixing mechanism.

9. A computer device for teaching the operation of a robot that supplies and removes workpieces to and from a fixed mechanism, Equipped with at least one processor, The aforementioned at least one processor is At the very least, display a user interface on the display device for teaching the robot's movements. The aforementioned user interface is Settings to identify the type of fixing mechanism, At a minimum, one of the following settings is required: the coordinates of the robot's reference point, the robot's position, the speed at which the robot approaches the fixing mechanism, and the state of the robot's hand holding the workpiece. The setting of signals for sending and receiving signals with respect to the fixed mechanism, according to the type of fixed mechanism, A computer device configured to allow user input.

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