Optimal connection of loops in laminated object manufacturing

There are manufacturing applications where a tool needs to move along a prescribed path performing machining operations. An excellent application of this problem is found in the increasingly popular layered manufacturing (LM) methods, where the laser traces the profile of a layer by moving along the path while the laser turns on. The path is typically described by a sequence of curves. For the entire process, the tool must move along each curve exactly once. For typical paths, significant time may be wasted in the movement between the end point of one curve to the start point of the next one along which the laser is turned off. Normally, this non-cutting motion is a straight-line motion so to minimise the distance. A good process plan would minimize the time wasted on such motion. A maximum linear intersection (MLI) algorithm is proposed to solve this problem. Next, we present a variation of the GA based method to solve it. We compare the performance of these two techniques, both in terms of jumping distance and the computing time requirement, with a view to their application to real-time path planning in LM applications. (C) 2003 Elsevier Science Ltd. All rights reserved.