Development in industry is asking for improved resolution and higher accuracy in dimensional metrology. In this paper,we proposed a control displacement method based on a polarization ellipsometirc interferometer and phase-locked loop technique. The proposed principle was set up. The experimental results of step and step displacements with a step value of 5 nm were presented. We also analyzed the resolution,the potential minimal displacement of the established system. The results show that the position error induced by the ellipticty deviation of the light beam becomes negligible thanks to our signal processing circuit with high-order filter. This method could be useful for many applications in nano dimensional metrology and semiconductor industry.
太阳能光伏电源是一种非常有潜力的再生能源,但应用成本高、投资回报率低是当前制约独立光伏水泵系统在光照充足的农村地区大面积推广的瓶颈之一。该文研究工作的核心是优化光伏水泵系统、提升效率,在不增加硬件投入的前提下,一是利用一种最大功率点跟踪(maximum power point tracking,MPPT)算法优化光伏转换效率,二是在异步电动机的损耗方面优化进而提升效率,利用一种最小损耗点跟踪(minimum loss point tracking,MLPT)算法提高水泵用异步电动机效率,并且将MPPT与MLPT耦合。通过样机试验验证了优化策略的实际运行情况,其节能效果具有一定的实际意义,从而可有效提高投资回报率。
Pneumatic muscle (PM) of flexible actuators used in bionic robot is an active area of recent research. A novel PM with shape memory alloy (SMA) braided sleeve is proposed in this paper, and SMA is used to improve PM working characteristics. Based on the principle of virtual work, output force model of PM and relationship with braided wire inner-stress are established, and analysis of PM deformation has shown that braided wire length is the key factor of output force characteristic. Based on the crystal structure transitions, the relationship of temperature with wire shrinkage is derived. Then, the synthetic dynamics of novel PM is established. A physical prototype of PM with SMA braided sleeve is developed, and test platform that is built for the experiment. Experiment and simulation test of static isometric-length, static isobaric-pressure, and dynamic characteristics are done. The experimental results are compared with the simulation of theoretical model. Moreover, based on experiment, model of output force was improved by adding a correction factor to deal with the elastic force of rubber tube. The results analysis demonstrates that the established models are correct, and SMA wires can reinforce PM and make PM working characteristics adjustable. PM proposed in this paper has greater output force and is beneficial to achieve more accurate control that is useful for manipulating fragile things.
