The Automated Structures Assembly Laboratory (ASAL) has successfully assembled and disassembled a 102-member truss structure, including the placement of 12 hexagonal reflector-type panels on the top surface, using a semi-automated system which requires operator attention only when a problem is encountered which the automated system cannot resolve. The system software data base has also been reconfigured so that the system assembles and disassembles a truss beam. The automated assembly system employs commercially available knowledge-based expert systems to plan the assembly, monitor its operation, and assist the operator during error recovery. It also uses a expert system tools plan the sequence of assembly operations and collision-free paths for the robotic manipulator.
For system reliability, a machine vision guidance system has been implemented to locate and capture the truss nodes that the struts are installed into. The machine vision system uses small "lipstick" CCD cameras and uniquely patterned targets located on each node. The targets are fabricated from retro-reflective material and auxiliary lighting is used to bring them into sharp contrast with the cluttered background which includes glare from the truss structure. An image processing algorithm uses pattern matching techniques to identify each node. Since the nodes may be mounted on non-rigid portions of the truss structure, the vision guidance must be capable of locating two nodes and guiding the manipulator arm to capture first one and then the other, and finally pulling both into position for strut installation. The machine vision guidance system proved to be very reliable and robust for the automated assembly operations
Technology areas:
Telerobotics Program
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Maintained by: Dave Lavery
Last updated: May 10, 1996