Assembly sequence planning for manufacturing by microrobots

The authors present a microassembly system model based on geometric reasoning. Its components, which include an X-Y positioning table with a glass plate fixed on top of it, operating microrobots on the plate, and a CCD-camera, are discussed in detail. Feasibility criteria for the generation of possible assembly sequences and optimisation criteria for selecting the best assembly plan, which reflect the specific features of microassembly, are suggested. For both planning steps, algorithms for an automatic procedure have been developed and implemented. An important advantage of te suggested bottom-up search procedure is that the assembly plan is determined at each step of the algorithm, so that the searching of all feasible sequences and the selection of the best one are integrated into one automated planning procedure. This allows one to replan the assembly process during plan execution, starting from the current process state and without exploring the space of all possible assembly plans. For a multirobot system, a method for decomposition of an assembly plan and its implementation is suggested.