Event camera for acoustic levitation

Abstract

systems. Miniaturization creates challenges in handling delicate, small components, rendering traditional methods inadequate, necessitating an alternative. Acoustic levitation, which uses ultrasound waves to suspend objects without physical contact, offers a promising solution for containerless transportation. This technology can accommodate various materials regardless of their electromagnetic or optical properties and eliminates particle generation due to friction. Applications span across chemistry, biology, and high-tech industries, enabling manipulation and assembly of small components. However, acoustic levitation is highly sensitive to environmental factors such as temperature and air currents, which can compromise stability. Most studies have primarily focused on understanding the dynamics of acoustic levitation and developing models to describe the underlying physical phenomena. This study shifts towards actively controlling them by adding artificial damping. To achieve this, this thesis introduces the use of event cameras, which capture high-speed movements without redundant frame data, making them highly efficient. The goal is to create a control feedback loop to correct for disturbances and improve the step response of acoustically levitated objects. The methodology involved integrating an event camera into the acoustic levitation setup and implementing a tracking algorithm to track the position of a levitated object. System identification was performed, revealing higher-order harmonics and allowing the development of a second-order model of the levitated object. This model was used to design a feedback controller integrated with the event camera. Experimental results demonstrated a substantial improvement in system performance. The bandwidth of the system improved to 40.8 Hz, the settling time decreased from 10 seconds to 0.8 seconds, an improvement by a factor of 12.5. Additionally, the steady-state error was significantly reduced, and the introduction of artificial damping successfully eliminated the first resonance peak, though a second higher-order resonance peak remains. This work highlights the potential of using event cameras in control loops for acoustic levitation, representing a significant step towards more precise control of levitated objects.