Hybrid Microassembly Combining Robotics and Water Droplet Self-Alignment

This paper reports an in-depth study of a hybrid microassembly technique that combines a robotic micromanipulator and a water droplet self-alignment, which greatly improves the performance of robotic microassembly. The method is experimentally studied on a custom-made microrobotic test platform adapted for the experiments. Four important measures of the microassembly technique are investigated--yield, capability, accuracy, and speed. Yield is studied by a large number of tests with random process parameters and statistical-modeling methods. Accuracy is measured by studying the final assembly results under a scanning electron microscope (SEM). Capability is assessed by testing parts of various sizes and shapes. Using a high-speed camera, the duration and trajectories of droplet self-alignment of the hybrid assembly process are studied. The experimental results indicate that such a hybrid assembly technique has very low requirements on the precision, which is comparable with the dimensions of the micropart, of the handling robot while being able to achieve micrometer precision. Moreover, successful assembly can be easily achieved with part sizes that range from 50 to 300 m. The experiments also show that parts of different sizes can be reliably assembled together using the proposed method.