Acoustic Peg-In-Hole Assembly with Phased Transducer Array and Microscope

Abstract

Microassembly is becoming increasingly critical in modern smart manufacturing, placing higher demands on system performance—particularly for in situ and in vivo applications in biomedicine, photonics, sensors, and microrobotics. Non-contact mechanical microassembly has emerged as a promising solution, addressing challenges such as part contamination, limited environmental compatibility, and undesired microscopic forces. This paper presents an ultrasonic-driven non-contact microassembly system capable of performing a representative peg-in-hole assembly. The system primarily consists of an ultrasonic phased transducer array, which serves as a holographic acoustic end-effector, and a microscope that provides visual feedback. Elliptical and semi-elliptical holographic acoustic end-effectors are designed and generated by generative adversarial networks. A homogeneous transformation strategy is employed to generate pre-planned phase-only hologram (POH) sequence, while a closed-loop control strategy dynamically adjusts the end-effector’s pose by integrating real-time visual feedback. Experimental results demonstrate that, with disturbances compensated by the closed-loop strategy, the system can stably adjust the peg’s position and orientation to achieve acceptable alignment accuracy. It successfully manipulates high-aspect-ratio objects to complete the peg-in-hole assembly in fluidic and strong magnetic environments. Moreover, the system requires no preset object position or orientation and does not alter the object’s form or structure during operation, demonstrating strong potential for broader in situ applications.