Abstract The recent developments in micro/nano-positioning technologies have highlighted the demand for compact large range three-degrees-of-freedom (3-DOF) XYΘ mechanisms for applications such as sample positioning in nanoimprint lithography, scanning probe microscopy, precision machining, and many more. However, this type of mechanisms suffers from a large footprint, sensing difficulties, and low motion accuracy due to the cross-coupling errors. In this paper, a compact design is proposed to achieve large workspace and high motion accuracy. Prismatic-Prismatic-Revolute (PPR) joints were used to construct this mechanism to yield deterministic large range motions. Laser-based measurement technique based on retroreflectors is proposed to sense large translations and rotation simultaneously with nanometer resolution. A prototype of the proposed mechanism was fabricated to investigate the static and dynamic properties of its structure, and compare these with the computational results. The motion accuracy of the mechanism was improved by using a sliding mode controller based on a nonlinear disturbance observer. The cross-coupling effects and modelling uncertainties were estimated and compensated in this control scheme, which consequently improved the tracking performance. The experimental results showed that the proposed design achieved large workspace, high resolution, improved tracking performance, and required level of compactness as compared with other designs reported in the literature.

中文翻译：

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大范围XYΘ微定位平台的开发与控制

摘要 微/纳米定位技术的最新发展突出了对紧凑型大范围三自由度 (3-DOF) XYθ 机制的需求，例如纳米压印光刻中的样品定位、扫描探针显微镜、精密加工、还有很多。然而，由于交叉耦合误差，这种类型的机构存在占地面积大、传感困难和运动精度低的问题。在本文中，提出了一种紧凑的设计，以实现大工作空间和高运动精度。Prismatic-Prismatic-Revolute (PPR) 关节用于构建这种机制，以产生确定性的大范围运动。提出了基于回射器的基于激光的测量技术，以纳米分辨率同时感测大的平移和旋转。制造了所提出机构的原型，以研究其结构的静态和动态特性，并将其与计算结果进行比较。采用基于非线性扰动观测器的滑模控制器提高了机构的运动精度。该控制方案对交叉耦合效应和建模不确定性进行了估计和补偿，从而提高了跟踪性能。实验结果表明，与文献中报道的其他设计相比，所提出的设计实现了大工作空间、高分辨率、改进的跟踪性能和所需的紧凑程度。采用基于非线性扰动观测器的滑模控制器提高了机构的运动精度。该控制方案对交叉耦合效应和建模不确定性进行了估计和补偿，从而提高了跟踪性能。实验结果表明，与文献中报道的其他设计相比，所提出的设计实现了大工作空间、高分辨率、改进的跟踪性能和所需的紧凑程度。采用基于非线性扰动观测器的滑模控制器提高了机构的运动精度。该控制方案对交叉耦合效应和建模不确定性进行了估计和补偿，从而提高了跟踪性能。实验结果表明，与文献中报道的其他设计相比，所提出的设计实现了大工作空间、高分辨率、改进的跟踪性能和所需的紧凑程度。