Collision-free motion planning and scheduling

The positioning, motion coordination and test ordering procedures of new testing equipment for printed circuit boards is presented. The equipment structure consists of four mobile probes whose movements must be coordinated to avoid collisions both with obstacles and with each other. This paper explains the algorithm used to obtain the optimum path between two points in a space with obstacles based on traditional methods but including new ideas to reduce the computation times. A new method for motion coordination that obtains the optimum sequence of consecutive or simultaneous probe movements is also introduced and is based on the decomposition of the sequence of movements into stages in which only movements without interferences are permitted. Finally, the ordering of the tests can be viewed as a traveling salesman problem, and the paper presents the results of various methods when applied to the specific characteristics of the equipment involved. (c) 2010 Elsevier Ltd. All rights reserved.