# Optimization-based Feedback Manipulation Through an Array of Ultrasonic Transducers

## TL;DR

This paper introduces a novel ultrasonic transducer array platform for real-time, non-contact manipulation of small objects using optimized acoustic pressure fields, with open-source design details for further development.

## Contribution

The paper presents a new experimental platform utilizing an 8x8 ultrasonic array and numerical optimization for real-time object manipulation, shared openly for community use.

## Key findings

- Successful manipulation of objects on water and solid surfaces
- Real-time phase-shift optimization improves control accuracy
- Platform is adaptable and extendable for larger arrays and more objects

## Abstract

In this paper we document a novel laboratory experimental platform for non-contact planar manipulation (positioning) of millimeter-scale objects using acoustic pressure. The manipulated objects are either floating on a water surface or rolling on a solid surface. The pressure field is shaped in real time through an 8-by-8 array (matrix) of ultrasonic transducers. The transducers are driven with square voltages whose phase-shifts are updated periodically every few milliseconds based on the difference between the desired and true (estimated from video) position. Numerical optimization is used within every period of a discrete-time feedback loop to determine the phase shifts for the voltages. The platform can be used as an affordable testbed for algorithms for non-contact manipulation through arrays of actuators as all the design and implementation details for the presented platform are shared with the public through a dedicated git repository. The platform can certainly be extended towards higher numbers of simultaneously yet independently manipulated objects and larger manipulation areas by the expanding the transducer array.