A Guidance Scheme for Automated Tetrahedral Truss Structure Assembly Based on Machine Vision

摘要

The Automated Structures Assembly Laboratory (ASAL) is a unique facility at Langley Research Center used to investigate robotic assembly of truss structures. An industrial robot equipped with a special purpose end-effector has been used to assemble 102 struts into an 8-m-diameter structure, as well as beam structures. Initially, robot motions required to construct the structure were developed with iterative manual procedures. However, this approach is not suitable for in-space applications because of astronaut and time and safety considerations. Thus, an off-line geometric path planner combined with a compact machine vision system has been developed. By providing position information relative to passive targets on the structure, the vision system guides the robot through a critical region, beginning approximately 12 in. from the structure and proceeding to a position where the structure is grasped prior to strut insertion. This approach offsets model uncertainties in the path planner and greatly increases operational reliability. This paper presents details of the machine-vision-based guidance algorithms used during structure assembly. NASA Langley Research Center, Hampton, VA 23681-0001