Accurate Watch Hand Alignment based on Robust Control

Watch hand alignment is a preparatory stage of watch manufacturing in industry. Nowadays, this process relies heavily on labor, which contributes a large portion on operation cost, while the alignment precision can just reach about $50 \mu \mathrm {m}$. Meanwhile, there is a need for faster and more efficient way of operation to satisfy the expansion of production capacity. Thus, making the automatic alignment process becomes a promising solution. This paper aims at aligning the watch hand precisely through the micromanipulation technology. First, a micro manipulation system is built for the alignment task. After that, we develop the model of the watch hand for the following controller design, while the factors such as fluid force are considered as the external disturbance. Then, a robust controller based on sensitivity function is built to improve the precision of the alignment. Finally, simulation of the alignment is conducted to prove the performance of the proposed control strategy. The results demonstrate that the method can achieve the alignment of the watch hand with the precision of $1 \mu \mathrm {m}$ within 1 second.