A parallel genetic algorithm for performance-driven VLSI routing

This paper presents a novel approach to solve the VLSI (very large scale integration) channel and switchbox routing problems. The approach is based on a parallel genetic algorithm (PGA) that runs on a distributed network of workstations. The algorithm optimizes both physical constraints (length of nets, number of vias) and crosstalk (delay due to coupled capacitance). The parallel approach is shown to consistently perform better than a sequential genetic algorithm when applied to these routing problems. An extensive investigation of the parameters of the algorithm yields routing results that are qualitatively better or as good as the best published results. In addition, the algorithm is able to significantly reduce the occurrence of crosstalk     

Novel moving-magnet electrodynamic feed units for small machine tools

Small feed motions in the mm and cm range today are mostly realised with miniaturised leadscrew motor systems, piezo stages and moving-coil actuators. A short survey on typical properties of those existing feed units for small machine tools is given first. A simple yet powerful complement or alternative to the above-mentioned small drives are single-phase linear direct drives with moving magnets. Especially motor designs with slotted stator winding offer high force densities and good dynamics. Combination of those short-stroke motors with ball or flexure guides and with embedded position or force control resp. leads to particular compact feed units. Such modules are currently being developed at Technische Universität Dresden for applications in future small machine tools and in automation. Two different prototypes of those feed modules are presented in this paper. With travel ranges of 11 and 14 mm, resp., peak forces of 39 and 112 N resp., linear force characteristics and speeds up to 1.6 m/s they feature attractive properties. A first module with ball-guided slide already contains an integrated low-cost position sensor and embedded state space position control. A second module with flexure-guided mover is currently being extended with latter embedded control components. Due to their high compactness, force density, dynamics and modularity, the developed feed units can widely be used in future small machine tools and in automation.