Collaborative Research: Towards a Fundamental Understanding of a Simple, Effective and Robust Approach for Mitigating Friction in Nanopositioning Stages

纳米定位平台是一种机械装置，用于在从光谱到微添加剂制造等广泛的纳米技术过程中进行精确定位。因此，它们的精度、速度和成本对精密工程在汽车、航空航天和国防工业中的应用至关重要，因此直接影响到经济福利和国家安全。对于越来越多的大位移纳米定位应用，使用机械(即滑动或滚动)轴承的工作台目前是唯一在商业上可行的选择。然而，由于摩擦的不利影响，机械轴承工作台的精度较低，定位速度较低。该奖项支持对一种简单但有效的方法进行科学研究，以减轻运动前摩擦对机械轴承工作台的影响，方法是使用顺应性接头将轴承连接到工作台。通过这项研究获得的知识将在不显著增加成本的情况下提高机械轴承工作台的定位速度和精度，从而有助于纳米技术工艺的商业可行性。其更广泛的影响计划包括：(I)与美国纳米定位工作台制造商Aerotech，Inc.合作，促进知识和技术转让；(Ii)在两所大学开发教育课程，并通过美国精密工程学会提供的教程培训专业工程师；以及(Iii)面向代表不足的少数族裔中学生，旨在激励和装备下一代高技能制造工程师。本研究的目的是对通过摩擦隔振器作用于伺服控制质量的非线性运动前摩擦的动力学和补偿有一个基本的了解。经验研究表明，当伺服控制质量(例如，纳米定位平台)通过摩擦隔离器(即，柔顺关节)与非线性运动前摩擦相互作用时，定位精度和速度显著提高。然而，人们对摩擦隔离器的动力学知之甚少。这项研究的前提是，在某些情况下，当运动前的摩擦通过摩擦隔振器作用于伺服控制质量时，可能会发生有害的动力学现象(如极限环)。这一前提将得到科学的检验，以发现产生它们的有害现象和环境，从而得出如何避免它们的见解。为了实现这一目标，将使用各种工具，如非线性动力学分析中的多尺度方法，对摩擦、摩擦隔振器和伺服参数(例如，质量、刚度和阻尼)之间的相互作用进行数学表征。此外，还将在机械轴承纳米定位阶段进行严格的数值和物理实验，以指导、验证或改进数学特征。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nanopositioning stages are mechanical devices used for precise positioning in a wide range of nanotech processes, ranging from spectroscopy to micro additive manufacturing. Hence, their precision, speed and cost are critical to precision engineering applications in the automotive, aerospace and defense industries, and therefore directly impact economic welfare and national security. Stages that use mechanical (i.e., sliding or rolling) bearings are currently the only commercially viable option for a growing number of large-displacement nanopositioning applications. However, mechanical bearing stages suffer from poor precision and low positioning speeds due to the adverse effects of friction. This award supports a scientific investigation into a simple but effective approach for mitigating the effects of pre-motion friction on mechanical bearing stages by connecting the bearing to the stage using a compliant joint. Knowledge created through this investigation will increase the positioning speed and precision of mechanical bearing stages without significantly increasing their cost, hence contributing to the commercial viability of nanotech processes. Its broader impact plan includes: (i) collaborations with Aerotech, Inc., a U.S.-based nanopositioning stage manufacturer, to facilitate knowledge and technology transfer; (ii) educational curriculum development at two universities and training of professional engineers through tutorials offered by the American Society for Precision Engineering; and (iii) outreach to underrepresented minority middle school students, aimed at inspiring and equipping the next generation of highly-skilled manufacturing engineers. The objective of this research is to gain a fundamental understanding of the dynamics and compensation of nonlinear pre-motion friction acting on a servo-controlled mass through a friction isolator. Empirical studies have demonstrated significant improvements in positioning precision and speed when a servo-controlled mass (e.g., a nanopositioning stage) interacts with nonlinear pre-motion friction through a friction isolator (i.e., a compliant joint). However, very little is known about the dynamics of the friction isolator. The premise of this research is that, under certain circumstances, harmful dynamic phenomena (e.g., limit cycles) could occur when pre-motion friction acts on a servo-controlled mass through a friction isolator. This premise will be tested scientifically, to discover the harmful phenomena and circumstances that give rise to them, leading to insights on how to avoid them. To achieve this goal, mathematical characterizations of interactions between friction, friction isolator and servo parameters (e.g., mass, stiffness and damping) will be made using various tools, like the method of multiple scales, from nonlinear dynamic analysis. This will be complemented by rigorous numerical and physical experimentation on mechanical bearing nanopositioning stages, to guide, validate or refine the mathematical characterizations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.