A stick-slip positioning stage robust to load variations

In stick-slip positioning, friction between the stick-slip surfaces plays a critical role in positioning accuracy. Positioning performance varies when the load to drive changes. In this paper, by using a form-closed cam, the driving unit is separated from the moving unit to eliminate load influence. The stage is capable of operating in either a stepping mode or a scanning mode. Numerical modeling was conducted to analyze the static and dynamic characteristics of the stage design. In experiments, a number of parameters were tested on the constructed stage, and positioning performance was measured via laser-doppler vibrometry. Experimental results demonstrate that in the stepping mode, the stage has a travel range of 2 mm with incremental step sizes ranging from 30 nm to 2.3 μm. In the scanning mode, the stage has a positioning resolution of 1.15 nm. The measured results also confirm that load variations on the stage have little influence on contact friction force and positioning performance.