In this paper, three-dimensional (3D) elliptical vibration cutting (EVC) method is presented to fabricate optical parts of difficult-to-cut materials, which vibrates the diamond tool at a 3D ellipse trajectory driven by the nonresonant principle. The surface quality of the workpiece is determined by the elliptical motion parameters of the cutting tool. So this paper adopts genetic algorithm (GA) to optimize ellipse parameters to get better surface quality. An optimization model is established to minimize the surface roughness of the workpiece. And the validity of the proposed approach is verified by a numerical example. This research can direct designers to choose the optimum ellipse parameters to machine optical parts in the cutting experiments.
A method of non-singular Terminal sliding mode control was proposed for landing asteroids with uncertainty and strong nonlinearity based on RBF neural network. The dynamics of the detector in the landing environment was analyzed, and the nominal trajectory guidance method based on optimal polynomial was designed, by which the consumption of fuel was suboptimal. Controller was designed using non-singular Terminal sliding mode. The influences caused by unknown disturbance and uncertainty during landing phase was compensated by RBF neural network real-time compensation, which could effectively suppress the influence of external disturbance and weaken the system chattering. Simulation results show that the proposed method was effective.
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