JP2004074368A - Cable display device in robot off-line teaching system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly detect a twisting state or a winding state of a cable installed on a robot, so that for the state of the cable is easily grasped on a screen. <P>SOLUTION: The twisting state of the cable 8 installed on the robot provided with an upper arm 5, a hand 6, etc., and the winding state of the cable around the upper arm 5 are detected. The detected state of the cable is drawn as a collection 10 of points on the screen for off-line teaching. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a robot offline teaching system that displays a robot having an arm and a hand attached to the tip of the arm on a screen and operates the robot on the screen to teach the robot to perform a required operation. The present invention relates to a cable display device in a robot offline teaching system for displaying a twisted state or a wrapped state of a cable attached to a robot.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a hand of an industrial robot (hereinafter, simply referred to as a “robot”) holds a tool such as welding or painting, and moves the tool along a predetermined work line to perform required work. A known robot system is known. In this type of robot system, as a teaching method of teaching required operation data to the robot, the operation is simulated (simulated execution) on a screen of a CRT or the like, and the operation is executed without stopping the production line. There is a so-called off-line teaching method for creating a program for the program. That is, in this teaching method, a real robot in a real space is created as a virtual robot model in a virtual space of a computer, displayed on a screen such as a CRT, and the operation of the real robot is imitated by the virtual robot model on this screen. Thus, the operation of the actual robot is confirmed and the operation program is created.
[0003]
By the way, usually, a tool to be gripped by the robot hand is attached with a distal end portion of a cable such as a welding wire, a hose or the like (hereinafter, simply referred to as “cable”) extending from the robot body side. Therefore, when checking the operation of the robot and creating an operation program using the offline teaching system as described above, if the winding and torsion of the cable are not taken into consideration, the feed resistance of the cable when operating on the actual machine will be reduced. There is a possibility that the cable may become extremely large or may damage the cable in some cases.
[0004]
As a prior art in which checking for such a winding of a cable is disclosed in Japanese Patent Application Laid-Open No. 10-275007. In the robot simulation method described in this publication, an angle formed between each projection point of the arm-side fixed point and the hand-side fixed point of the cable with respect to a plane orthogonal to the rotation axis of the robot's wrist and the rotation center in the plane is described. By determining whether or not the angle is within a preset range, the winding of the cable around the arm is detected.
[0005]
[Problems to be solved by the invention]
However, in the conventional simulation method described in the above publication, each projection point of the arm-side fixed point and the hand-side fixed point of the cable is obtained, and the rotation angle of the cable is calculated based on these projection points. Therefore, this method is effective for a type of robot in which the hand performs only a twisting (twisting) operation on the arm, but performs a bending (bend) operation in addition to the twisting (twisting) operation. For a robot of the type, there is a problem that the projection point of the fixed point on the hand side changes due to this bending operation, and it is not possible to calculate an accurate cable rotation angle.
[0006]
Further, in the above-described conventional method, since it is configured to notify the operator (user) of the determination result of the cable wrapping check or the like, in other words, only the presence or absence of the wrapping, the operator can check the actual cable However, there is a problem that it is not possible to grasp the arrangement state of the operation program, and it is not possible to easily perform the correction processing of the operation program based on the arrangement state.
[0007]
The present invention has been made in order to solve such a problem, and it is possible to accurately detect a torsion state or a winding state of a cable attached to a robot, and easily detect the cable state on a screen. It is an object of the present invention to provide a cable display device in a robot offline teaching system that can be grasped.
[0008]
[Means for Solving the Problems and Functions / Effects]
In order to achieve the above object, a cable display device in a robot offline teaching system according to the present invention includes:
In a robot off-line teaching system that displays a robot having an arm and a hand attached to the tip of the arm on a screen, and operates the robot on the screen to teach a required operation to the robot,
Cable state detecting means for detecting a torsion state of a cable attached to the robot or a winding state of the cable around the arm; and drawing means for drawing a cable state detected by the cable state detection means on the screen. It is characterized by having.
[0009]
In the present invention, when a robot displayed on the screen is operated on the screen to teach a required operation to the robot offline, when a cable is routed through the internal space of the arm, the torsion state of the cable, Alternatively, the winding state of the cable when the cable is routed through the outer periphery of the arm is detected by the cable state detecting means, and the detected cable state is drawn on the screen by the drawing means. Therefore, the operator performing the offline teaching can visually recognize a state close to the actual cable wiring state through the screen only by looking at the screen at the time of the teaching operation. It can be done easily.
[0010]
In the present invention, the cable state detecting means may be configured to detect a position of the cable based on a total rotation angle around the axis of the arm and / or the hand and an attachment angle at each of the fixed portions on the base end side and the distal end side of the cable. It is preferable to detect a twisted state or a winding state. By doing so, even when the hand performs a bending operation in addition to the torsional operation with respect to the arm, the torsional angle of the cable is calculated by extracting only the rotation angle around the axis of the arm and / or the hand. Therefore, the torsion angle of the tool attached to the hand can be accurately obtained, and thereby the torsion state or the winding state of the cable can be accurately grasped.
[0011]
In each of the above inventions, it is preferable that the drawing means draws the cable state by a set of points or a strip of points that are continuous in an arc or ring around the arm. In this way, even if the position of the arm moves, the twisted or wrapped state of the cable can always be displayed around the arm, and the convenience for the user is further improved.
[0012]
In this case, the cable state detecting means includes a judging means for judging that the twisted state or the winding state of the cable has exceeded the normal range, and when the judging means judges that the normal state has been exceeded. It is preferable that the drawing unit issues a warning by changing the color of the group of points or the band. By doing so, the operator can determine at a glance whether the cable is abnormally twisted or wound, based on the change in the color of the group of points or the band displayed around the arm, which further enhances the convenience for the user. improves.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, specific embodiments of the cable display device in the robot offline teaching system according to the present invention will be described with reference to the drawings.
[0014]
FIG. 1A is a perspective view of an articulated welding robot according to an embodiment of the present invention, and FIG. 1B is an explanatory diagram of each axis operation of the welding robot. .
[0015]
The welding robot 1 of the present embodiment is a six-axis articulated robot, and has a swivel head 3 mounted on a fixed base 2 so as to be swivelable in the direction of arrow J1 around a vertical axis, and a right and left upper part of the swivel head 3. A lower arm 4 attached to the lower arm 4 so as to be swingable in the direction of arrow J2 around the axis, and to be swingable in the direction of arrow J3 around the left and right axis and twisted in the direction of arrow J4 around its own axis; (Twist) An upper arm 5 operably attached, and a bendable (bend) operation in the direction of arrow J5 at the end of the upper arm 5 and a twist (twist) operation around its own axis in the direction of arrow J6. And a hand 6 that is attached to the camera.
[0016]
A welding gun 7 as a welding tool is mounted on the hand 6, and the tip of a cable 8 is connected to the welding gun 7. The proximal end of the cable 8 is fixed to the upper surface of the proximal end of the upper arm 5.
[0017]
By the way, as shown in FIG. 2B, the welding robot 1 is simulated on a screen 9 such as a CRT and the like, and an operation program for the welding robot 1 is created. In the teaching system, usually, the cable 8 attached to the welding gun 7 is not displayed on the screen 9, and the movement of the cable 8 is ignored. For this reason, as shown in FIG. 2A, in the actual machine, even when the cable 8 is wound around the arm (upper arm 5), the state may be taught. If such teaching is performed, the cable 8 will be damaged when the actual machine is actually operated.
[0018]
In order to avoid such inconvenience, in the present embodiment, at the time of the off-line teaching, the winding state of the cable 8 around the arm (the upper arm 5 in the present embodiment) is detected, and the cable state is displayed on the screen 9. Is displayed. Hereinafter, the specific processing content of the determination and display of the winding state will be described with reference to the flowchart shown in FIG. These processes are performed by an arithmetic processing unit (not shown) built in the present offline teaching system. In the following description, the symbol S indicates a step.
[0019]
In the present embodiment, since the distal end of the cable 8 is fixed to the welding gun 7 and the base end of the cable 8 is fixed to the upper surface of the base end of the upper arm 5, the system shown in FIG. Only the J3 to J6 axes shown in FIG. When these J3-J6 axes are converted into an X, Y, Z-axis coordinate system, X3-Y3-Z3 axes, X4-Y4-Z4 axes, X5-Y5-Z5 axes, X6 as shown in FIG. -Y6-Z6 axis, and in this case, the rotation axes are four axes of Y3 axis, X4 axis, Y5 axis, and X6 axis.
[0020]
S1: In the XYZ axis coordinate system, the attachment angle C6 (see FIG. 4B) of the cable 8 at the tool portion (welding gun 7) is input, and the attachment angle of the cable 8 at the fixed portion (upper arm 5). C3 (see FIG. 4C) is input. Here, in the present embodiment, these angles C6 and C3 are set as rotation angles from the Z axis.
[0021]
S2 to S3: The robot axis angles θ1 to θ6 in the XYZ axis coordinate system of all six axes of the robot are captured, and the welding robot 1 is drawn on the screen 9 based on the captured values.
S4: At the time of off-line teaching of the welding robot 1, the rotation angle θ4 around the X4 axis and the rotation angle θ6 around the X6 axis related to the winding of the cable 8 around the upper arm 5, in other words, the twist angles of the two axes performing the twist operation. The addition value θ4 + θ6 is calculated, and from this addition value, the winding angle α of the cable 8 is calculated by adding the mounting angle C6 of the distal end portion and the base end portion of the cable 8 and subtracting C3, that is, by the following equation.
α = θ4 + θ6-C3 + C6
[0022]
S5: Whether or not the calculated absolute value | α | of the winding angle α is less than 180 °, in other words, the twist angle of the cable 8 from the reference position is within 180 ° to the left and right (total 360 °). It is determined whether or not there is. The processing performed in steps S4 and S5 is performed by the cable state detecting means and the determining means in the arithmetic processing unit.
S6 to S7: When | α | <180 ° is satisfied, the color of the cable 8 on the screen is designated as a standard color (for example, green). On the other hand, when | α | ≧ 180 °, the color of the cable 8 is designated as a warning color (for example, yellow).
[0023]
S8: Based on the calculated winding angle α, a cable is drawn around the upper arm 5 by the drawing means in the arithmetic processing unit, and the process returns to step S1. Here, the drawing of the cable on the screen is performed as shown in FIG. 5B with respect to the cable state (the arrow P indicates the rotating state) in the actual machine shown in FIG. It is formed by an aggregate 10 of points (spheres) that are continuous in an arc so as to surround the periphery of the upper arm 5 ′. Among these points, the larger diameter point indicates the fixed position (start point) of the cable 8, and a plurality of small diameter points connected to this start point are the rotation angle of the cable 8, in other words, the upper part of the cable 8. This shows a state of being wound around the arm 5. The aggregate 10 at this point naturally follows the movement of the upper arm 5 even when the upper arm 5 moves, and is always displayed around the upper arm 5 '.
[0024]
Thus, the operator executing the offline teaching of the welding robot 1 merely looks at the group 10 of points displayed around the upper arm 5 ′ on the screen 9, and the winding state of the cable 8 around the upper arm 5 in the actual machine. Can be easily grasped. In this case, when the color of the point aggregate 10 is green, there is no danger of breakage of the cable, and when the color of the aggregate 10 changes to yellow, there is a risk of breakage. , The offline teaching operation can be performed more easily.
[0025]
In the present embodiment, the color specification of the point aggregate 10 is set to two levels of green and yellow, but this color specification may be set to three levels of green, yellow, and red depending on the winding angle. good. Further, in the present embodiment, a description has been given of a case where a set of points is used to draw a cable state. However, this drawing may be performed in various other embodiments such as using a band or an arrow display. . Alternatively, the winding angle may be simply displayed as a numerical value without performing drawing.
[0026]
In the present embodiment, the case where the cable 8 is disposed along the outer peripheral surface of the upper arm 5 has been described. However, the present invention relates to a case where the cable 8 is disposed so as to pass through the internal space of the upper arm 5. Can also be applied. However, in this case, not the winding state of the cable but the torsion state of the cable becomes a problem.
[0027]
In the present embodiment, the system in which the base end of the cable 8 is fixed to the upper surface of the base end of the upper arm 5 has been described. However, in the present invention, the base end of the cable 8 is connected to the base end of the lower arm 4. The present invention can also be applied to a fixed member or a member fixed to the fixed base 2.
[0028]
In the present embodiment, the welding robot has been described as an example. However, it goes without saying that the present invention can be applied to other robots other than the welding robot.
[Brief description of the drawings]
FIG. 1A is a perspective view of an articulated welding robot according to an embodiment of the present invention, and FIG. 1B is an explanatory diagram of each axis operation of the welding robot.
FIGS. 2A and 2B are diagrams showing a comparison between an actual machine and an offline teaching system.
FIG. 3 is a flowchart of a process of determining and displaying a winding state of a cable.
FIGS. 4A and 4B are explanatory views (b) and (c) of a rotation axis (a) and a cable attachment angle in an XYZ axis coordinate system.
FIG. 5 is a diagram illustrating a cable state (a) of an actual device and a drawing state (b) on a screen.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welding robot 2 Fixed base 3 Revolving head 4 Lower arm 5 Upper arm 6 Hand 7 Welding gun 8 Cable 9 Assembly of 10 screens

Claims (4)

In a robot off-line teaching system that displays a robot having an arm and a hand attached to the tip of the arm on a screen, and operates the robot on the screen to teach a required operation to the robot,
Cable state detecting means for detecting a torsion state of a cable attached to the robot or a winding state of the cable around the arm; and drawing means for drawing a cable state detected by the cable state detection means on the screen. A cable display device in a robot offline teaching system, comprising: The cable state detecting means is configured to twist or wind the cable in a twisted state based on a total rotation angle of the arm and / or the hand around the axis, and an attachment angle at each of the fixed portions on the proximal and distal ends of the cable. The cable display device in the robot offline teaching system according to claim 1, wherein the cable display device detects a state. The cable display in the robot off-line teaching system according to claim 1, wherein the drawing unit draws the cable state by a set or a band of points continuous in an arc or an annular shape around the arm. apparatus. The cable state detecting means includes a judging means for judging that the torsion state or the winding state of the cable has exceeded a normal range, and when the judging means judges that the cable has exceeded the normal range, the drawing The cable display device in the robot offline teaching system according to claim 3, wherein the means issues a warning by changing a color of the group of points or the band.

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