Multiple-robot control and interference prevention method

• US 5,561,742 A
• Filed: 09/24/1993
• Issued: 10/01/1996
• Est. Priority Date: 01/28/1992
• Status: Expired due to Term

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Watanabe, Atsushi, Terada, Tomoyuki
• Primary Examiner(s): Davis, George B.
• Application Number:
  US08/122,428
• Time in Patent Office: 1,103 Days
• Field of Search: 395/90, 395/83, 395/84, 395/93, 364/461
• US Class Current: 700/255
• CPC Class Codes: B25J 9/1669 characterised by special application, e.g. multi-arm co-operation, assembly, grasping
• CPC Class Codes: G05B 2219/49143 Obstacle, collision avoiding control, move so that no collision occurs
• CPC Class Codes: G05B 2219/49153 Avoid collision, interference between tools moving along same axis

Abstract

A multiple robot control method in which a spatial region is defined for each of a plurality of robots. The spatial region is defined according to a region which a robot occupies and the spatial region depends on a position and orientation of each robot. The robots are mounted close to each other and may be commanded so as to be operated at the same time. The spatial region for a robot is defined at every unit operation command, and is defined by one or two planes which are parallel to each other in the X-Z plane, and move horizontally in a specified direction (Y-axis direction) for all robots. It is then determined whether a defined spatial region for a first robot crosses a defined spatial region for a second robot. If it is found that the defined spatial regions do not cross each other, the first robot is operated according to an operation command since it is ensured that no interference between robots occurs. If it is found that the spatial regions do cross each other, operation of the first robot is stopped, and the first robot is kept in a waiting state until the spatial region of the first robot moves depending on the operation of the second robot such that the spatial regions no longer cross each other.

Claims

1. A multiple-robot control method for a plurality of robots which are mounted close to each other and are commanded to operate by unit operation commands, comprising the steps of:

defining a spatial region necessary for a three-dimensional operation of a robot for each of said plurality of robots at every unit operation command, wherein said defining a spatial region necessary for a three-dimensional operation of a robot comprises defining at least one plane for each robot, and wherein respective said at least one plane is parallel to another and moves horizontally in a specified direction according to movement of an associated robot;

determining whether a spatial region defined for a first robot crosses a spatial region defined for a second robot; and

judging whether interference between robots occurs based upon the result of the determining step.

2. A multiple-robot control method according to claim 1, further comprising the steps:

determining that the spatial region defined for the first robot crosses the spatial region defined for the second robot; and

controlling said robots so that said first robot is stopped operating, and is kept in a waiting state until the spatial region defined for at least one of the first and second robots shifts and the spatial regions defined for the first and second robots do not cross each other.

3. A multiple-robot control method according to claim 1, wherein said defining a spatial region necessary for a three-dimensional operation of a robot comprises setting said at least one plane defining a spatial region for a respective robot to a position such that said at least one plane is tangential to at least one of an assumed sphere coveting a wrist and hand of the robot, an assumed sphere covering an elbow joint of the robot, and a cylinder representing a base of the robot, and the at least one sphere and cylinder is contained in a region defined by the at least one plane.

4. A multiple-robot control method according to claim 1, wherein said defining a spatial region necessary for a three-dimensional operation of a robot comprises setting said at least one plane defining a spatial region for a respective robot to a position such that said at least one plane is tangential to at least one of an assumed sphere covering a wrist and hand of the robot, an assumed sphere covering an elbow joint of the robot, and a cylinder representing a base of the robot which is detected at a position which is furthest from the robot base in a direction of movement of said at least one plane.

5. A multiple-robot control method according to claim 4, wherein said defining a spatial region necessary for a three-dimensional operation of a robot comprises setting said a central position of said assumed sphere covering the wrist and the hand of the robot to a position where a predetermined offset value is added to the wrist center position, and determining the radius of the sphere on the basis of a structure of the wrist and hand.

6. A multiple-robot control method according to claim 1, wherein said unit operation command at which the spatial region of each respective robot is defined is equivalent to one block of an operating program which is taught to the respective robot.

7. A multiple-robot control method according to claim 1, wherein said unit operation command at which the spatial region of each respective robot is defined is equivalent to one unit during which an operating command taught to the robot is interpolated.

8. A multiple-robot control method according to claim 1, wherein said defining a spatial region at a unit operation command comprises maintaining the defined spatial region until a next unit operation is started, and transmitting data defining a maintained spatial region to an adjacent robot;

and

said determining comprises determining whether the spatial region of the robot receiving the maintained spatial region data crosses said spatial region of the robot transmitting the maintained spatial region data, thus determining whether the robots interfere with each other.

9. A multiple-robot control method according to claim 8, further comprising:

determining that the spatial region of the receiving robot crosses the spatial region of the transmitting robot;

stopping the operation of the receiving robot; and

keeping the receiving robot in a waiting state until the spatial region of the receiving robot is moved, depending on the operation of the transmitting robot, such that the spatial regions of the robots do not cross each other.

10. A multiple-robot control method according to claim 1, wherein at least one of said plurality of robots is a vertical multi-joint type robot.