KR102591945B1 - A processing apparatus for implementing a posture maintaining the rigidity of the robot, and a processing method for implementing the posture maintaining the rigidity of the robot using the same - Google Patents

Abstract

One embodiment of the present invention provides a technology that allows the robot to perform the machining process in the most rigid posture in a machining process using a robot, such as drilling. A processing device that implements a robot rigidity maintenance posture according to an embodiment of the present invention includes a robot having a plurality of links and a plurality of joints and driven by excitation guidance; A processing unit coupled to the end of the robot and equipped with a tool to perform processing on the processing object; a stiffness data unit that generates stiffness data that is a stiffness value for each of the plurality of joints that varies depending on the posture of the robot; And receiving the rigidity data from the rigidity data unit, receiving information about cutting force, which is a force applied to the tool, from the processing unit, and predicting the posture deformation of the robot when the tool works on the processing object. , a control unit that controls the posture of the robot so that the rigidity of the robot is maximized.

Description

A processing apparatus for implementing a posture maintaining the rigidity of the robot, and a processing method for implementing the posture maintaining the rigidity of the robot using the same}

The present invention relates to a processing device that implements a robot rigidity maintenance posture and a processing method using the same to implement a robot rigidity maintenance posture. More specifically, in a machining process using a robot such as drilling, the robot is in the most rigid posture. It is about technology that enables a processing process to be performed.

Recently, manufacturing systems using multiple robots have been increasing, and in the production of products such as automobiles and aircraft, the demand for improved automatic manufacturing efficiency and increased processing precision using robots is continuously increasing.

Robots have very low rigidity compared to machine tools, so structural deformation of the robot may occur due to cutting forces generated during processing of the workpiece. If structural deformation of the robot occurs in this way, machining errors may occur in machining using the robot.

In the prior art, in order to compensate for the robot's processing error, a method was used to reduce the robot's processing error by collecting feedback on the robot's processing using a plurality of sensors and analyzing such information. However, this method was used to reduce the robot's processing error. There is a problem in that the control algorithm developed by can only be applied to some open robot controllers.

Japanese Patent Publication No. 2019-195892 (title of the invention: bending amount estimation device, robot control device, and bending amount estimation method) includes a rocking angle calculation unit that calculates the rocking angle of the four-bar link structure, and a rocking angle calculation unit that calculates the rocking angle of the four-bar link structure. Stiffness showing the correlation between the load calculation unit that calculates the load, the stiffness value that is the value of each component of the stiffness matrix that relates the load received by the four-bar link structure and the amount of deflection of the four-bar link structure, and the rotation angle of the four-bar link structure. Using a value determination function, a stiffness matrix determination unit determines the above-mentioned stiffness value corresponding to the rotation angle of the four-bar link structure detected by the swing angle calculation unit, the load received by the four-bar link structure calculated by the load calculation unit, and the stiffness value are determined. A device including a bending amount calculation unit that calculates the bending amount of a four-bar link structure portion based on the determined stiffness value is disclosed.

Japanese Patent Publication No. 2019-195892

The purpose of the present invention to solve the above problems is to enable the robot to perform the machining process in the most rigid posture in a machining process using a robot, such as drilling.

And, the purpose of the present invention is to enable the above-mentioned control of the robot to be performed while minimizing additional separate devices or complex calculations.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

The configuration of the present invention for achieving the above object includes a robot that is driven by having a plurality of links and a plurality of joints; A processing unit coupled to the end of the robot and equipped with a tool to perform processing on the processing object; a stiffness data unit that generates stiffness data that is a stiffness value for each of the plurality of joints that varies depending on the posture of the robot; And receiving the rigidity data from the rigidity data unit, using information about cutting force, which is a force applied to the tool from the processing unit, to predict posture deformation of the robot when the tool works on the processing object, , a control unit that controls the posture of the robot so that the rigidity of the robot is maximized.

In an embodiment of the present invention, the control unit determines that the rigidity of the robot is maximum when the judgment reference value (Idx), which is a value derived by the following equation, is minimum, Idx is the judgment reference value, and W is the weight. It is a matrix, T is a transpose matrix, and Δx may be a processing error.

Idx = W ^T Δx

In an embodiment of the present invention, the machining error (Δx) is derived by the following equation, where Kx is the stiffness matrix based on the stiffness data, F is the cutting force, and -1 may be the inverse matrix.

Δx = Kx ^-1 F

In an embodiment of the present invention, the stiffness matrix (Kx) is derived by the following equation, where J(θ) is the Jacobian matrix, K _θ is a constant matrix, and θ is the It may be Rz excitation induction, which is the rotational freedom of the end of the tool based on the rotation axis (z-axis) perpendicular to the surface of the processing target.

Kx = J(θ)K _θ ^-1 J(θ) ^T

In an embodiment of the present invention, the Jacobian matrix (J(θ)) may vary according to a change in the Rz excitation induction (θ).

In an embodiment of the present invention, the control unit may derive the minimum value of the judgment reference value (Idx) while varying the Rz excitation induction.

In an embodiment of the present invention, the Rz excitation induction value may be set to any number selected within the range of 0 to 360.

In an embodiment of the present invention, the control unit may store cutting force modeling data, which is data of the cutting force for each of a plurality of machining portions formed on the machining object.

In an embodiment of the present invention, the processing unit may be provided with a force sensor that measures the cutting force.

The configuration of the present invention for achieving the above object includes: a first step in which the stiffness data is transmitted from the stiffness data to the control unit; A second step in which information about cutting force, which is a force applied to the tool, is generated in the control unit; A third step of deriving the minimum value of the judgment reference value (Idx) using the cutting force while varying the Rz excitation induction, which is the rotational freedom of the end of the tool, in the control unit; and a fourth step in which a control signal is transmitted from the control unit to the robot so that the position of the tool is maintained and the posture of the robot is controlled by the Rz excitation induction that minimizes the judgment reference value (Idx).

In an embodiment of the present invention, in the second step, the cutting force may be derived from cutting force modeling data stored in the control unit.

In an embodiment of the present invention, in the second step, a force sensor provided in the processing unit may transmit information measuring the pressure and torque applied to the spindle connected to the tool to the control unit.

The effect of the present invention according to the above configuration is that the robot can perform the machining process in the most rigid posture, thereby improving the machining precision of the robot by minimizing machining errors.

Additionally, the effect of the present invention is that robot rigidity can be controlled while minimizing the use of additional sensors or other devices, thereby significantly improving efficiency in machining processes using robots.

The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic diagram of a processing device according to an embodiment of the present invention.
Figure 2 is a configuration diagram of a processing device according to an embodiment of the present invention.
Figure 3 is an image of an example using a processing device according to an embodiment of the present invention and a comparative example using another device.

Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention may be implemented in various different forms and, therefore, is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, combined)" with another part, this means not only "directly connected" but also "indirectly connected" with another member in between. "Includes cases where it is. Additionally, when a part is said to “include” a certain component, this does not mean that other components are excluded, but that other components can be added, unless specifically stated to the contrary.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

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

In general, the end-effector (tool 221) of the robot 210 has six degrees of freedom (three positional degrees of freedom about three axes, X, Y, and Z, and three rotational degrees of freedom through rotation about each axis). degrees), and therefore, general industrial robots 210 may have six joints.

The present invention relates to an algorithm and a device designed to control the rigidity of the robot 210 as described above. According to this method, the rigidity of the robot 210 can be controlled while minimizing the use of additional sensors or other devices. ) can significantly improve the efficiency of the processing process.

Figure 1 is a schematic diagram of a processing device according to an embodiment of the present invention, and Figure 2 is a configuration diagram of a processing device according to an embodiment of the present invention. As shown in Figures 1 and 2, the processing device of the present invention includes a robot 210 that is driven by having a plurality of links and a plurality of joints; A processing unit 220 coupled to the end of the robot 210 and equipped with a tool 221 to perform processing on the processing object 10; A stiffness data unit 120 that generates stiffness data, which is a stiffness value for each of a plurality of joints that varies depending on the posture of the robot 210; And by receiving the rigidity data from the rigidity data unit 120 and using information about the cutting force, which is the force applied to the tool 221, when the tool 221 works on the processing object 10, the robot 210 It includes a control unit 110 that predicts posture deformation and controls the posture of the robot 210 so that the robot 210 has a posture with maximum rigidity.

The stiffness data of the stiffness data unit 120 collects and stores data on the posture of the robot 210 when performing each processing process, and such stiffness data is acquired through experiment and stored in the stiffness data unit 120. You can. And, using the stiffness data obtained through experiment, the following stiffness matrix can be derived.

The control unit 110 stores in advance the movement path of the tool 221 with respect to the processing object 10, and when the tool 221 moves along the movement path of the tool 221, the tool 221 The posture of the robot 210 at each location on the movement path can be stored in the control unit 110, and using this, the control unit 110 uses the movement path of the tool 221 to control the position of the robot 210. Postural deformation can be predicted.

Here, the posture deformation of the robot 210 may mean that the posture of the robot 210 is changed and determined by reflecting the three-dimensional rotation angle of each of the plurality of joints and the three-dimensional position of each of the plurality of links.

The control unit 110 may store cutting force modeling data, which is data on cutting force for each of a plurality of machining portions formed on the machining object 10. When the user inputs information about the type of processing object 10 into the control unit 110, the control unit 110 searches for information related to the processing object 110 in the cutting force modeling data and uses the matching data. The cutting force for each of a plurality of machining parts of the machining object 10 can be derived and used.

When the cutting force is derived in this way, the robot can be controlled even when offline, improving the stability of machining using the robot.

Alternatively, the processing unit 220 may be provided with a force sensor 222 that measures cutting force. Here, the force sensor 222 may be formed outside or inside the processing unit 220, and the force sensor 222 measures the pressure and torque applied to the spindle connected to the tool 221 within the processing unit 220. can do.

Here, the pressure and torque applied to the spindle can be measured in a three-dimensional direction, and the control unit 110 can derive the cutting force using the pressure and torque values for the spindle, and for this purpose, the control unit 110 A tool dynamometer may be provided to measure cutting force.

The control unit 110 determines that the rigidity of the robot 210 is maximum when the judgment reference value (Idx), which is a value derived by [Equation 1] below, is minimum, Idx is the judgment reference value, and W is the weight matrix. , T is the transpose matrix (hereinafter the same), and Δx may be a processing error.

[Equation 1]

Idx = W ^T Δx

The weight matrix (W) is a matrix that assigns weights to each axis (movement and rotation about the three axes It may be a matrix calculated using a learning program. And, each of the weight matrix (W) and the processing error (Δx) can be formed as a 6x1 matrix.

When the judgment reference value (Idx) is the minimum value, the machining error (Δx) is also minimized, and the machining error in each direction is reduced, so it can be determined that machining is performed in the position where the robot 210 has the greatest rigidity. there is.

The machining error (Δx) is derived by the following [Equation 2], where Kx is the stiffness matrix based on stiffness data, F is the cutting force, and -1 may be the inverse matrix (hereinafter the same).

[Equation 2]

Δx = Kx ^-1 F

As described above, the stiffness matrix is a matrix of stiffnesses according to the Cartesian coordinate system and is obtained from experimentally obtained stiffness data, and the stiffness matrix may be a 6x6 matrix. The cutting force may be a value derived from cutting force modeling data as described above, or may be a cutting force calculated by the control unit 110 using information from the force sensor 222. Additionally, the cutting force F may be a 6x1 matrix.

And, the stiffness matrix (Kx) is derived by the following [Equation 3], where J(θ) is the Jacobian matrix, K _θ is a constant matrix, and θ is the processing target ( 10) It may be the Rz excitation induction, which is the rotational freedom of the end of the tool 221 based on the rotation axis (z-axis) perpendicular to the surface.

[Equation 3]

Kx = J(θ)K _θ ^-1 J(θ) ^T

As the axial stiffness matrix, the constant matrix K _θ may be a 6x6 matrix, and the Jacobian matrix J(θ) may be a 6x6 matrix.

Since the Rz excitation induction is the rotational freedom of the end of the tool 221, it can be expressed as a θ value, which is the rotation angle of the end of the tool 221, and as seen in [Equation 3] above, Jacobian The matrix J(θ) can be varied according to changes in the Rz excitation induction (θ).

And, the control unit 110 can derive the minimum value of the judgment reference value (Idx) while varying the Rz excitation induction. Here, the Rz excitation induction value can be set to any number selected within the range of 0 to 360.

As described above, the Rz excitation induction is the rotational freedom of the end of the tool 221. Specifically, it may be a rotational degree of freedom with the z-axis, which is an axis perpendicular to the machining surface of the processing object 10, as the rotational axis. Accordingly, the Rz excitation value can be selected within the range of 0 to 360, which is formed by dividing the total rotation angle of 360 degrees in units of 1 degree.

And, here, the Rz excitation value can have a value of 0 and a natural number, and by reducing the number of data selected in this way, the time for controlling the robot 210 can be reduced and the efficiency of controlling the robot 210 can be increased. You can. However, it is not limited to this, and it is also possible to select a number including a decimal point within the above range.

The control unit 110 derives the minimum value of the judgment reference value (Idx) while varying the Rz excitation, and controls the posture of the robot 210 by reflecting the Rz excitation value that can minimize the judgment reference value (Idx). You can.

As described above, when the judgment reference value (Idx) becomes minimum, the control unit 110 may determine that the rigidity of the robot 210 is maximized as described above, and in this way, the rigidity of the robot 210 can be determined to be the greatest. The control unit 110 may transmit a control signal to the robot 210 so that it can maintain the largest posture.

Processing device of the present invention; And a processing system including a display device that displays changes in the posture of the robot 210 on a screen can be formed. Specifically, the three-dimensional shape and judgment reference value (Idx) of the robot 210 may be displayed on the display screen, and the user can change the three-dimensional shape and judgment reference value (Idx) of the robot 210 while looking at the display screen. Alternatively, you can visually check whether it is maintained.

Hereinafter, the processing method of the present invention using the processing device of the present invention will be described.

First, in the first step, the stiffness data may be transmitted from the stiffness data to the control unit 110. And, in the second step, information about the cutting force, which is the force applied to the tool 221, may be generated in the control unit 110.

Next, in the third step, the minimum value of the judgment reference value (Idx) can be derived by using cutting force while varying the Rz excitation induction, which is the rotational freedom of the end of the tool 221, in the control unit 110. Then, in the fourth step, control is performed from the control unit 110 to the robot 210 so that the position of the tool 221 is maintained and the posture of the robot 210 is controlled by the Rz excitation guidance where the judgment reference value (Idx) is minimized. Signals can be transmitted.

In the second step, to derive the cutting force, the cutting force may be derived from cutting force modeling data stored in the control unit 110.

Alternatively, in the second step, in order to derive the cutting force, the force sensor 222 provided in the processing unit 220 transmits information measuring the pressure and torque applied to the spindle connected to the tool 221 to the control unit 110. It can be delivered. Here, the force sensor 222 can measure the pressure and torque applied to the spindle connected to the tool 221 in the processing unit 220.

The remaining details regarding the processing method of the present invention are the same as those regarding the processing device of the present invention described above.

Figure 3 is an image of an example using a processing device according to an embodiment of the present invention and a comparative example using another device. Here, (a) in Figure 3 is an image of a machining area where processing was performed using a conventional robot 210, and (b) in Figure 3 is an image with increased rigidity using the robot 210 of the present invention. This is an image of the processing area where processing was performed in this posture. Here, the machining may be drilling.

As shown in Figure 3 (a), when processing is performed using a conventional robot 210, when measuring the diameter at each position on the processing unit 220, areas with different diameters are formed, resulting in processing errors. can confirm. And, as shown in Figure 3 (b), when processing is performed using the robot 210 of the present invention, when measuring the diameter at each position on the processing unit 220, there are no areas with different diameters, so there is no processing error. It can be seen that is minimized.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the patent claims described below, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

10: Processing target
110: control unit
120: Stiffness data unit
210: robot
220: processing unit
221: tools
222: Force sensor

Claims (13)

A robot driven by having a plurality of links and a plurality of joints;
A processing unit coupled to the end of the robot and equipped with a tool to perform processing on the processing object;
a stiffness data unit that generates stiffness data that is a stiffness value for each of the plurality of joints that varies depending on the posture of the robot; and
Receives the rigidity data from the rigidity data unit, uses information about cutting force, which is a force applied to the tool, to predict posture deformation of the robot when the tool works on the processing object, and predicts the rigidity of the robot. It includes a control unit that controls the posture of the robot so that it reaches the maximum posture,
The control unit determines that the rigidity of the robot is maximum when the judgment reference value (Idx), which is a value derived by the following equation, is the minimum, where Idx is the judgment reference value, W is the weight matrix, and T is the transpose matrix. , Δx is a processing error, a processing device that implements a robot rigidity maintenance posture.
Idx = W ^T Δx
delete In claim 1,
The processing error (Δx) is derived by the following equation, where Kx is the rigidity matrix based on the rigidity data, F is the cutting force, and -1 is the inverse matrix. Processing to implement a robot rigidity maintenance posture. Device.
Δx = Kx ^-1 F
In claim 3,
The stiffness matrix (Kx) is derived by the following equation, where J(θ) is the Jacobian matrix, K _θ is a constant matrix, and θ is the rotation axis perpendicular to the surface of the processing target with which the tool contacts. A processing device that implements a robot rigidity maintenance posture, characterized in that Rz excitation induction is the rotational freedom of the end of the tool based on the (z axis).
Kx = J(θ)K _θ ^-1 J(θ) ^T
In claim 4,
The Jacobian matrix (J(θ)) is a processing device that implements a robot rigidity maintenance posture, characterized in that it varies according to the change in the Rz excitation induction (θ).
In claim 5,
The control unit is a processing device that implements a robot rigidity maintenance posture, characterized in that the control unit derives the minimum value of the judgment reference value (Idx) while varying the Rz excitation induction.
In claim 6,
The Rz excitation value is set to any number selected within the range of 0 to 360. A processing device that implements a robot rigidity maintenance posture.
In claim 1,
The control unit is a processing device that implements a robot rigidity maintenance posture, characterized in that it stores cutting force modeling data, which is data of the cutting force for each of a plurality of processing parts formed on the processing object.
In claim 1,
The processing unit is a processing device that implements a robot rigidity maintenance posture, characterized in that it is provided with a force sensor that measures the cutting force.
A processing device that implements a robot rigidity maintenance posture according to any one of claims 1, 3 to 9; and
A processing system comprising a display device that displays changes in the robot's posture on a screen.
In the processing method for implementing the robot rigidity maintenance posture using a processing device that implements the robot rigidity maintenance posture of claim 7,
A first step in which the stiffness data is transmitted from the stiffness data to the control unit;
A second step in which information about cutting force, which is a force applied to the tool, is generated in the control unit;
A third step of deriving the minimum value of the judgment reference value (Idx) using the cutting force while varying the Rz excitation induction, which is the rotational freedom of the end of the tool, in the control unit; and
A fourth step in which a control signal is transmitted from the control unit to the robot so that the position of the tool is maintained and the posture of the robot is controlled by the Rz excitation induction where the judgment reference value (Idx) is minimized. A processing method that implements a robot rigidity maintenance posture.
In claim 11,
In the second step, a processing method for implementing a robot rigidity maintenance posture, characterized in that the cutting force is derived from cutting force modeling data stored in the control unit.
In claim 11,
In the second step, a force sensor provided in the processing unit transmits information measuring the pressure and torque applied to the spindle connected to the tool to the control unit.