The Design and Experimental Validation of a Permanent Magnet Long-Stroke Gravity Compensator

Abstract

The ever increasing demand for better and cheaper electronic devices, sensors, optical components, etc. fuels innovation in nanometer precision positioning machines. However, the overall architecture of these machines has not changed much over the past years. A huge improvement in the architecture is currently impossible due to a crucial element of these machines -- namely, the gravity compensator. A gravity compensator is a passive element providing a supporting force that reduces the heat generation of the actuators in the gravity direction. Additionally, the gravity compensator is required to have a low stiffness to limit the disturbance forces due to vibrations present inside the machine. The state of the art gravity compensators are based on permanent magnets, as they are a non-contact solution providing the best performance and excellent vacuum compatibility. However, the current designs are limited to a single operating point. To enable the development of the next generation of nanometer precision positioning machines, a gravity compensator with an operating line is required. Therefore, the goal of this research is: “To design and experimentally validate a magnetic long-stroke gravity compensator for a nanometer precision positioning machine”. In this study the most suitable magnetic design was developed using various modelling techniques. Subsequently, the model and the design were validated by means of measurements taken with an experimental setup. From this study it was concluded that the design requirements can be met using high grade magnets. Thereby, with this Master Thesis, the first step has been taken towards the next generation of nanometer precision positioning machines.