An Automated Pick-and-Place Method for Irregular-Shaped Microspheres Inspired by Chopstick Operation

This paper proposes an automated irregular-shaped microbead assembly method inspired by the manipulation way of chopsticks that includes a lifting pickup strategy inspired by Tangyuan ingestion and an adhesion-vibration release strategy emulating the dumpling plating. Drawing inspiration from the Tangyuan moving process with chopsticks, the lifting strategy picks up the microbeads at a relatively lower position, thus minimizing damage to assembled micro-objects and enhancing the success rate of picking up irregularly shaped microbeads. The adhesion-vibration strategy utilizes the adhesion force between the substrate and the microspheres as well as the inertia of the microbeads to mitigate the rolling phenomenon and achieve precise release for irregular microbeads. Subsequently, a modular direct-description-method-based feed-forward model is developed to control the opening and closing of the tips accurately. Finally, the above-mentioned elements are integrated with visual recognition and position control techniques to establish an automated microbead assembly method. The developed method exhibits a high pickup success rate and high accuracy release of irregular microbeads validated through pick-and-place experiments and eventually applies to both 2D and 3D assemblies. The results indicate that the proposed method achieves a final pickup success rate of 95% for irregular microbeads, with a maximum release error of $9.34~\mu $ m and an average error of $7.62~\mu $ m at release. These release errors are equivalent to 4.67% and 3.81% of the average diameter of the assembled microbeads, respectively.