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Collision Avoidance Scheme for Multiple Robotic Systems Environments

IP.com Disclosure Number: IPCOM000043386D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Hecker, EP: AUTHOR [+2]

Abstract

This article describes a collision avoidance scheme for multiple robot environments in which the possibility of collision where the work areas of two or more manipulators intersect is eliminated and the programming complexity is thereby reduced. When using two or more microprocessor robotic manufacturing systems for an application, it may be necessary for the work areas of the manipulators to intersect as shown in the figure. Since more than one manipulator is able to access the common work area (W1FW2), the possibility of collision exists. The motions of the manipulators which have access to this common area must be synchronized to avoid a collision. One existing technique for synchronizing the manipulators is based on a communication path between the two manipulators.

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Collision Avoidance Scheme for Multiple Robotic Systems Environments

This article describes a collision avoidance scheme for multiple robot environments in which the possibility of collision where the work areas of two or more manipulators intersect is eliminated and the programming complexity is thereby reduced. When using two or more microprocessor robotic manufacturing systems for an application, it may be necessary for the work areas of the manipulators to intersect as shown in the figure. Since more than one manipulator is able to access the common work area (W1FW2), the possibility of collision exists. The motions of the manipulators which have access to this common area must be synchronized to avoid a collision. One existing technique for synchronizing the manipulators is based on a communication path between the two manipulators. Each manipulator is capable of sending one signal to the other manipulator and receiving one signal from it. With this system, each manipulator can indicate to the others when it is in the common work area. The other manipulators would then check the status signal of all manipulators that can access the common area before moving into the area. If another manipulator is present, the manipulator wanting to move into the work area waits until all other manipulators have left before moving into the common area. This method has the following disadvantages: 1.When the manipulators are in manual mode, the possibility of a collision still exists since the synchronization signals between the manipulators are not present unless the manipulators are under program control. 2. Before each move into the common work area and after each move out of the common area, the manipulator's program must change the state of its output synchronization signal. This procedure requires time and program space. 3. Since the synchronization signal cannot be changed until after the motion out of the common work area has been completed, there may be a time lag between when the manipulator leaves the common work area and when the other manipulators will be able to detect it. The scheme described herein uses logic similar to the above procedure but instead of synchronization signals between the manipulators, each manipulator has an optical detection system which defines the boundary of the manipulator's work area. The difficulty of implementing the boundary detection system is governed by the number of manipulators involved and the shape of the common work areas. Referring to the drawing, the boundary of manipulator M1 is indicated by boundary line B1, and the boundary of manipulator M2 is indicated by boundary line B2. The area be...