JP3065579B2 - Robot interference check method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines, on a computer, whether or not a tool mounted on an arm or a tip of a robot interferes with a workpiece or peripheral equipment when the robot operates according to a predetermined program. The present invention relates to a robot interference check method.

[0002]

2. Description of the Related Art Conventionally, as a method of creating operation data of a robot, 1) At a work site where a robot is installed, an operator moves a robot arm to directly teach a position / posture and a route necessary for the operation. The method can be broadly divided into a method and 2) an offline teaching method in which a robot operation program is created in advance by a computer.

[0003] Recently, the use of the latter offline teaching method has been increasing in response to the trend of high-mix low-volume production.
In this case, since an operation program is created in a place different from the work site, it is necessary to verify the validity of the operation data, particularly, the presence or absence of robot interference.

As an interference check of the robot arm,
It is possible to calculate, on a computer, the relationship between the relative positions and postures of the individual surfaces constituting the object surface for two objects such as a robot arm and a workpiece, and determine whether or not they intersect. Many. However, an actual object usually has a complicated shape, and if the combination of surfaces between two objects is checked comprehensively, the amount of calculation becomes enormous.

As a countermeasure against this, a paper (“Manipulator Avoidance of Obstacles” by Hiroaki Ozaki, Journal of the Robotics Society of Japan, Vo
l.2 No.6 (December 1984)) assumes that the two objects are rectangular parallelepiped as shown in FIG. 13, and furthermore, omits the consideration of the posture of the objects and can simplify the intersection determination condition. An interference check method for examining the presence or absence of intersection after approximation is proposed. If there is a possibility of interference, the rectangular parallelepiped is sequentially divided and checked, thereby increasing the accuracy of approximation and speeding up the entire processing.

[0006]

However, in the conventional rectangular parallelepiped sequential division method, two objects are limited to a rectangular parallelepiped only. Therefore, when this method is actually applied, it is necessary to roughly approximate the object to be subjected to the interference check with a single rectangular parallelepiped, or to represent a combination of a plurality of rectangular parallelepipeds. There is.

On the other hand, another prior art (JP-A-62-437)
No. 06, JP-A-1-173205), as shown in FIG. 14, in order to increase the efficiency of the interference check processing, each arm of the robot is approximated by a sphere and a rough interference check is performed. It has been proposed that the number of combinations of objects to be checked for interference be reduced first.

However, when each arm of the robot is approximated by a sphere, for example, a large number of works are arranged in a wide area, and in a wide range of work in which the robot moves while moving, the calculation amount of the interference check becomes enormous and the processing efficiency increases. The improvement is not enough.

SUMMARY OF THE INVENTION An object of the present invention is to provide a robot interference check method capable of expanding the applicable range of an object to be subjected to interference check and performing a highly accurate and efficient interference check.

[0010]

SUMMARY OF THE INVENTION According to the present invention, an approximation step of approximating one of two objects to be subjected to an interference check to a general shape column and approximating the other to a rectangular parallelepiped; In the bottom view projected on the plane parallel to the bottom of the general shape column and the side view projected on the side perpendicular to the bottom of the general shape column, the interference requirement where the two projected figures have a common point is described. A necessary condition determination step to determine, and a sufficient condition determination step to determine a sufficient interference condition in which the center of the circumscribed sphere is included in the general shape column, and when the interference necessary condition is satisfied but the interference sufficient condition is not satisfied, Dividing the object approximated to a rectangular parallelepiped into a plurality of smaller rectangular parallelepiped, using the rectangular parallelepiped divided in the dividing step and the object approximated to the general shape column, the necessary condition determination step and sufficient conditions An interference checking method for a robot, characterized by returning to the constant process.

[0011]

[0012]

According to the present invention, as shown in FIG. 1, a general shape column (including a plate material), such as a polygonal column or a cylinder, in which a bottom shape composed of a combination of a line segment and an arc is elongated in a vertical direction.
Also, the interference check can be applied. Therefore, in addition to the conventional combination of a rectangular parallelepiped and a rectangular parallelepiped, the applicable range of the target object can be expanded, the shape can be approximated with high accuracy, and the creation of an interference check shape model can be made more efficient.
This method can be applied not only to interference check between a robot and a work or peripheral equipment, but also to interference check between two robots. In addition, by examining the presence or absence of interference by dividing into a bottom projection view and a side projection view of a general shape column, 2
Since dimensional numerical calculations are sufficient, a high-speed interference check can be performed.

[0014]

[0015]

[0016]

FIG. 2 is an explanatory diagram showing interference requirements according to the present invention. The necessary interference condition between the general-shaped column 1 and the rectangular parallelepiped 2 will be described. Ball 2 circumscribing cuboid 2
is calculated, and if the circumscribed sphere 2a does not intersect with the general shape column, it can be determined that there is no possibility of interference even in the original rectangular parallelepiped 2. On the other hand, if the circumscribed sphere 2a intersects with the general-shaped column 1, there is a possibility of interference, so the process shifts to a more detailed interference check.

In the determination of the interference necessary condition, a bottom projection projected on an XY plane parallel to the bottom of the general-shaped column 1 and a side projection projected on a side parallel to the Z-axis perpendicular to the bottom of the general-shaped column 1 It is determined whether or not both have a common point. That is, as shown in FIG. 2A, the circumscribed sphere 2a and the general-shaped column 1 of the rectangular parallelepiped 2 are projected on an XY plane,
Interference on the XY plane can be determined based on whether or not both projected figures have a common point. Further, as shown in FIG. 2 (2), the circumscribed sphere 2a of the rectangular parallelepiped 2 and the general shape column 1 are projected on, for example, an XZ plane, and the height level of the bottom surface of the general shape column 1 and the height level of the upper surface are determined. Interference at the height level can be determined based on whether or not even a part of the projected figure (circle) of the circumscribed sphere 2a is positioned therebetween.

If the interference requirement is satisfied, then a sufficient interference condition is determined. Similarly, even under the condition of sufficient interference, the projection can be divided into a bottom projection view and a side projection view. When the center of the circumscribed sphere 2a is included in the interior of the general shape column 1, the interference is ensured.

If the necessary interference condition is satisfied and the sufficient interference condition is not satisfied, the presence or absence of interference cannot be determined. Therefore, the rectangular parallelepiped 2 is divided into several small rectangular parallelepipeds, and each rectangular parallelepiped interferes with the general shape column 1. The necessary conditions and sufficient interference conditions are determined.

By repeating the determination of the necessary interference condition, the determination of the sufficient interference condition, and the division of the rectangular parallelepiped,
The presence or absence of interference can be determined with necessary accuracy.

FIG. 3 is an explanatory diagram showing a method for examining interference between a polygonal prism and a rectangular parallelepiped. The polygonal column E1 has a vertex P
0 to Pn-1, top vertices Q0 to Qn-1, height h, and point P
0 is located at the origin of the coordinate axis, and the coordinates of each point are Pi (Xi, Yi, 0), Q
It is represented by i (Xi, Yi, h). Here, the vertices P0 to Pn-1 are P
When going toward 0 → P1 →... → Pn−1, the left side should be oriented inside the polygonal prism. The rectangular parallelepiped E2 has three sides of lengths w, k, and d, and a center of gravity G (Xd, Yd, Zd).

At this time, the radius r of the circumscribed sphere E2a of the rectangular parallelepiped E2 is r = (w ² + k ² + d ² ) ^1/2 / 2 (1), and the center of the circumscribed sphere E2a coincides with the center of gravity G.

The necessary condition for interference between the polygonal column E1 and the rectangular parallelepiped E2 is that the polygonal column E1 intersects with the circumscribed sphere E2a or that the circumscribed sphere E2a is included in the interior of the polygonal column E1. On the other hand, the sufficient interference condition is that the center of the circumscribed sphere E2a is included inside the polygonal column E1.

The interference requirements are considered separately for the XY plane and the Z-axis direction. In the XY plane, a) a circle having a radius r centered on the center of gravity G is a line segment PiPi + 1 (i = 0,..., N-1;
Pn = P0) and b) the center of gravity G is polygon P0
It suffices to satisfy any one of the following conditions: P1 ... Pn-1.

Regarding the condition a), as shown in FIG. 4, when the projection of the polygonal prism E1 and the circumscribed sphere E2a onto the XY plane is considered, the equation of the straight line PiPi + 1 is represented by (Yi + 1-Yi) (X− Xi) − (Xi + 1−Xi) (Y−Yi) = 0 (2)

Whether this line segment PiPi + 1 intersects a straight line GH perpendicular to the line segment PiPi + 1, that is, both end points Pi and Pi + 1
Is located on both sides of the straight line GH, ((Xi + 1-Xi) (Xi + 1-Xd) + (Yi + 1-Yi) (Yi + 1-Yd)) * {(Xi + 1 -Xi) (Xi-Xd) + (Yi + 1-Yi) (Yi-Yd)} <0 (3)

When the equation (3) is satisfied and the distance d between the line segment PiPi + 1 and the center of gravity G (Xd, Yd, Zd) is smaller than the radius r as shown in the following equation (4) (d <r ) The requirements are met.

[0028]

(Equation 1)

If the equation (3) does not hold, the necessary condition is satisfied when the distance between the end point Pi and the center of gravity G is smaller than the radius r as in the following equation (5).

R> ｛(Yi-Yd) ² + (Xi-Xd) ² ｝ ^1/2 (5) Next, regarding the condition b), as shown in FIG. 5 and the following equation (6), the center of gravity G From the center angles of the polygons P0P1... Pn-1 with respect to each side, and if the sum is 2π, the center of gravity G
Are contained inside the polygons P0P1... Pn-1.

[0031]

(Equation 2)

Therefore, when the expressions (3) and (4), or the expressions (5) or (6) are satisfied, the interference requirement on the XY plane is satisfied.

Next, in the Z-axis direction, the necessary interference condition between the circumscribed sphere E2a and the polygonal column E1 is expressed by the following equation (7).

| Zd−h / 2 | <h / 2 + r (7) Therefore, Equation (3) and Equation (4) or Equation (5)
Alternatively, when Expression (6) is satisfied and Expression (7) is satisfied, the interference requirement between the polygonal prism E1 and the rectangular parallelepiped E2 is satisfied.

Next, regarding sufficient interference conditions between the polygonal column E1 and the rectangular parallelepiped E2, since the center of the circumscribed sphere E2a is included in the polygonal column E1, the radius r = That is, the condition of 0 is satisfied.

FIG. 6 is an explanatory diagram showing a method of examining the interference condition between a cylinder and a rectangular parallelepiped. The cylinder E3 is arranged along the Z axis with the coordinate origin at the center, the center of the bottom surface (0,0, -h / 2), the center of the top surface (0,0, h / 2), the radius R, and the height h. Having. The rectangular parallelepiped E2 has three sides of lengths w, k, and d, and a center of gravity G (Xd, Yd, Zd). At this time, the radius r of the circumscribed sphere E2a of the rectangular parallelepiped E2
Is: r = (w ² + k ² + d ² ) ^1/2 / 2 (1) The distance L between the center of gravity G and the Z axis is L = (Xd ²
+ Yd ² ) ^1/2 .

First, regarding the interference requirement, a) that the distance L is equal to or less than the sum of the radius R and the radius r in the XY plane, that is, L ≦ R + r (10) is satisfied, and b) in the Z-axis direction. , | Zd | ≦ h / 2 + r (11) must be satisfied.

Next, regarding sufficient interference conditions, the circumscribed sphere E2a
Is included in the inside of the cylinder E3, so that both the conditions of the radius r = 0 in the equations (10) and (11) are satisfied.

FIG. 7 is an explanatory diagram showing a method of performing a general interference check between a robot and a work object. When a detailed interference check is started for a robot working over a wide area, a huge amount of calculation is required to find an interference position. Therefore, prior to the detailed interference check,
It is preferable to perform a general interference check.

Conventionally, as shown in FIG. 14, each arm of the robot is approximated by an individual sphere. However, when working over a wide range, the amount of calculation of the general check is considerably large. In the present invention, the sphere 5a including the entire operation range of the robot 5 and the sphere 6a including the target work 6 are calculated and approximated by the two spheres 5a and 6a, thereby greatly reducing the calculation amount of the rough check. doing.

First, regarding the interference requirements, two spheres 5
Assuming that radii r1 and r2 of a and 6a and distance d between the centers of the respective spheres, when d> r1 + r2 (12), the spheres 5a and 6a do not intersect with each other, and the robot 5 interferes with the target work 6. Does not meet the requirements. If it is found that there is no interference in such a schematic check, it is not necessary to perform a detailed interference check thereafter.

FIG. 8 is a flowchart showing an embodiment of the present invention. In this example, an interference object between one robot and a group of environmental objects is targeted. In the detailed check for sequentially dividing a rectangular parallelepiped, an environmental object is modeled by a general shape column, and a robot arm is modeled by a combination of a plurality of rectangular solids. As will be described, such a method can also be applied to an interference check between robots.

First, in step a1, one object to be checked is selected from the environment, and in step a2, the general interference check described with reference to FIG. 7 is performed. In step a3, if the interference requirement for the general check is not satisfied, it is determined that there is no interference with the object, and the process shifts to interference check for the next environmental object. In step a4, if there are any remaining environmental objects to be checked, step a1
, But if not, the interference check ends.

When the interference necessary condition for the outline check is satisfied, the process proceeds to step a5, where one target object is selected from the robot arm, and the robot object selected in step a6 and the environmental object are compared with each other. The interference requirement described in FIGS.

FIG. 9 is a flowchart showing the operation of step a6. In step b1, a circumscribed sphere of a rectangular parallelepiped approximating the robot object is generated, and as described with reference to FIG. 3 in step b2, it is determined whether or not the general shape column and the circumscribed sphere intersect. Then, it is determined that the interference requirement is satisfied, and the process ends. On the other hand, if they do not intersect, the process proceeds to step b4, where it is determined that the interference requirement is not satisfied, and the process ends.

Next, returning to step a7 in FIG. 8, if the interference requirement of the detailed check is not satisfied, it is determined that there is no interference between the robot object and the environmental object, and the interference with the next robot object is determined. Move to check. If there is any robot object to be checked in step a8, the process is restarted from step a5.
Then, the process proceeds to 4 to determine whether there is any remaining environmental object. On the other hand, if the interference requirement for the detailed check is satisfied in step a7, the interference sufficient condition described in FIGS. 2 to 6 is determined in the next step a9.

FIG. 10 is a flowchart showing the operation of step a9. In step c1, it is determined whether or not the general-shaped column includes the center of the circumscribed sphere. If the column includes the center of the sphere, the process proceeds to step c2 to determine that the sufficient interference condition is satisfied, and ends. On the other hand, if it does not include the center of the sphere, the process proceeds to step c3, where it is determined that the sufficient interference condition is not satisfied, and the process ends.

Next, returning to step a10 in FIG. 8, if the interference sufficient condition for the detailed check is satisfied, it is determined that there is interference between the robot object and the environmental object, and the processing is terminated.
On the other hand, if the sufficient conditions for interference of the detailed check are not satisfied,
The process proceeds to step all to determine whether or not the margin of the distance between the robot object and the environmental object is smaller than a predetermined interference check accuracy. If there is no allowance for the distance between the objects, it is determined that there is interference, and the process ends. If there is a margin in the distance between the objects, the process proceeds to step a12, in which the rectangular parallelepiped approximating the robot object is divided into a plurality of smaller rectangular parallelepipeds and approximated. Then, the process returns to step a6, and the detailed check on the divided rectangular parallelepiped is repeated. carry out.

In this manner, a rough interference check and a detailed interference check between the robot object and the environment object are performed, and further, in a place where the presence or absence of interference is delicate, the interference check is repeated while being divided into a plurality of rectangular parallelepiped models. As a result, a quick and reliable interference check can be performed.

FIG. 11 is an explanatory view showing an example of a robot system to which the interference check method according to the present invention can be applied, and FIG. 12 is a perspective view showing an example of a work. The robot system 20 is used as a welding robot or a bridge painting robot in a small shipbuilding assembly process. A 6-axis vertical articulated robot 21 is mounted on a turning table 22 and mounted on an X-axis rail 23 and a Y-axis rail 24. It is composed. On the conveyor roller 30, the work 40 of FIG.
Is mounted. The work 40 is formed by vertically setting plate-shaped members 42 and 43 on a flat main plate 41 having a notch 41a and welding them together.

The posture of the robot 21 and the traveling position on the rail are controlled by a robot controller (not shown). The operation program mounted on the robot controller can be created on another computer, and such an interference check is also executed on the computer after the program is created.

The allowance for interference check between the workpiece 40 and the robot 21 is, for example, 1 m during welding work.
m, and at other times, 20 mm.

During the welding operation, the robot arm and the welding tool mounted on the tip of the arm need to be brought very close to the work 40. The shape of the work 40 is also rarely a simple shape such as a rectangular parallelepiped, and generally has many complicated shapes as shown in FIG. In the conventional interference check method, the target work is approximated by a rectangular parallelepiped. Therefore, if the shape is complicated, accurate results cannot be obtained unless approximated by a combination model of many rectangular parallelepipeds. Moreover, if there are many types of target works, it takes a lot of time to create this combination model.

Therefore, a model having a shape closer to the target work requires a smaller number of divided objects. For example, by adopting a general-shaped column including a plate-like member or a columnar member as an approximate model, the number of divided objects can be reduced. The interference check can be performed with high accuracy and without any trouble in model creation without increasing the number of interferences.

[0055]

As described in detail above, according to the present invention, the applicable range of the target object can be extended to a general shape column other than the combination of the conventional rectangular parallelepiped and the rectangular parallelepiped, and it takes time and effort to create a model with high accuracy. Interference check can be performed without using In addition, by examining the presence or absence of interference by dividing the projection into a bottom projection view and a side projection view of a general-shaped column, two-dimensional numerical calculation is sufficient, so that a high-speed interference check can be performed.

[0056]

[0057]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an object shape to which an interference check method according to the present invention is applied.

FIG. 2 is an explanatory diagram showing interference requirements according to the present invention.

FIG. 3 is an explanatory diagram showing a method for examining an interference condition between a polygonal prism and a rectangular parallelepiped.

FIG. 4 is a projection view of the polygonal column E1 and the circumscribed sphere E2a on the XY plane.

FIG. 5 is a projection view of the polygonal column E1 on the XY plane.

FIG. 6 is an explanatory diagram showing a method of examining an interference condition between a cylinder and a rectangular parallelepiped.

FIG. 7 is an explanatory diagram showing a method of checking for a general interference between a robot and a workpiece.

FIG. 8 is a flowchart showing an embodiment of the present invention.

FIG. 9 is a flowchart showing the operation of step a6.

FIG. 10 is a flowchart showing the operation of step a9.

FIG. 11 is an explanatory diagram showing an example of a robot system to which the interference check method according to the present invention can be applied.

FIG. 12 is a perspective view showing an example of a work.

FIG. 13 is an explanatory diagram of a conventional rectangular parallelepiped sequential division method.

FIG. 14 is an explanatory diagram showing another example of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 General shape column 2 Rectangular parallelepiped 2a Bounding sphere

Continued on the front page (72) Fumihiro Honda 1-1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Inside the Akashi Plant (72) Inventor Masaaki Hirayama 1-1-1, Kawasaki-cho, Akashi-shi, Hyogo (56) References JP-A-64-48107 (JP, A) JP-A-1-180602 (JP, A) JP-A 8-108383 (JP, A) Hiroaki Ozaki, Obstacle of manipulator Evacuation, Journal of the Robotics Society of Japan, December 1984, Vo. 2 No. 6, page 76 to page 80 (58) Fields investigated (Int. Cl. ⁷ , DB name) B25J 19/06 G05B 19/4093

Claims (1)

(57) [Claims] 1. An approximation step of approximating one of two objects to be subjected to interference check to a general shape column and approximating the other to a rectangular parallelepiped. A necessary condition determining step of determining an interference requirement where two projected figures have a common point in a bottom projection projected on a plane parallel to the bottom and a side projection projected on a side perpendicular to the bottom of the general shape column; and A sufficient condition determination step for determining a sufficient interference condition in which the center of the circumscribed sphere is included in the general shape column; and, when the interference necessary condition is satisfied but the interference sufficient condition is not satisfied, the object approximated to a rectangular parallelepiped is reduced to a smaller size. Dividing into a plurality of rectangular parallelepiped, and using the rectangular parallelepiped divided in the dividing step and the object approximated to the general shape column, returning to the necessary condition determining step and the sufficient condition determining step. Robot interference check method.