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.

Acoustic levitation is an novel method that could lend itself very useful to fast and precise transportation of small objects. To verify the acoustic field and the modelling assumptions, the acoustic field must be visualised and quantified. Different methods to visualise a pressure gradient are investigated and rated against design requirements. These requirements are: 1. difficulty, as the setup should be buildable within the period of a MSc. thesis. 2. Time per measurement and 3. measurement sensitivity. It is decided that using a double coincidence spherical mirror schlieren setup is most suitable measurement method. To capture the high speed sphenomena of ultrasound acoustic waves in air, the schlieren light source is pulsed and matched to the frequency of the acoustics to ’freeze’ the acoustic wave in the air. Parameters that influence the schlieren image are identified and studied. These parameters are duty cycle, cut-off, ISO, light source phase delay and light source frequency. A horizontal cut-off is determined as the best, while it is determined that the other parameters can be adjusted dependent on the acoustic field. The acoustic field generated by double phased array is observed. Trap locations and types can be identified using the schlieren system. Quantification of the schlieren images has been attempted but without satisfactory results, mainly due to an interesting observation regarding a correlation between the camera focus distance and the pressure gradient. The schlieren system is a useful research tool and successful at visualising the pressure gradient under the assumption that it is constant over the optical axis. Further research is needed to for quantification and to assess the impact of the observation.