AcoustoBots: A swarm of robots for acoustophoretic multimodal interactions

Abstract: Acoustophoresis has enabled novel interaction capabilities, such as levitation, volumetric displays, mid-air haptic feedback, and directional sound generation, to open new forms of multimodal interactions. However, its traditional implementation as a singular static unit limits its dynamic range and application versatility. This paper introduces AcoustoBots - a novel convergence of acoustophoresis with a movable and reconfigurable phased array of transducers for enhanced application versatility. We mount a phased array of transducers on a swarm of robots to harness the benefits of multiple mobile acoustophoretic units. This offers a more flexible and interactive platform that enables a swarm of acoustophoretic multimodal interactions. Our novel AcoustoBots design includes a hinge actuation system that controls the orientation of the mounted phased array of transducers to achieve high flexibility in a swarm of acoustophoretic multimodal interactions. In addition, we designed a BeadDispenserBot that can deliver particles to trapping locations, which automates the acoustic levitation interaction. These attributes allow AcoustoBots to independently work for a common cause and interchange between modalities, allowing for novel augmentations (e.g., a swarm of haptics, audio, and levitation) and bilateral interactions with users in an expanded interaction area. We detail our design considerations, challenges, and methodological approach to extend acoustophoretic central control in distributed settings. This work demonstrates a scalable acoustic control framework with two mobile robots, laying the groundwork for future deployment in larger robotic swarms. Finally, we characterize the performance of our AcoustoBots and explore the potential interactive scenarios they can enable.

Insights into AcoustoBots: A Paradigm in Acoustophoretic Swarm Robotics

The introduction of AcoustoBots marks a significant advancement in acoustophoretic systems, combining swarm robotics with acoustophoresis to overcome the inherent limitations of static, singular units. AcoustoBots leverage a mobile and modular platform to enable dynamic multimodal interactions through the strategic deployment of phased array transducers mounted on mobile robots. This paper thoroughly investigates the design, implementation, and potential applications of this novel system, highlighting its capacity for independent and cooperative interactions in expansive environments.

The concept of AcoustoBots centers on enhancing application versatility in acoustophoretic systems. Traditional acoustic levitation and interaction setups rely on fixed, stationary devices, limiting their scalability and flexibility. AcoustoBots address these constraints by integrating mobility and adjustable orientation through a hinge actuation system, allowing for a richer variety of interactions within broader spatial contexts.

Design and Implementation

The AcoustoBots platform combines several technical elements:

• Mini-PAT Boards: Each robot is equipped with an 8x8 phased array transducer, controlled by an FPGA board, which enables the precise emission of ultrasonic waves necessary for acoustophoretic manipulation.
• Mobility and Modularity: The robots utilize self-propelled Mona platforms, affording them the ability to traverse various surfaces and adjust the deployment of the phased arrays.
• Hinge Actuation System: A dynamic system facilitating the reorientation of the mounted transducers, allowing them to alternate between horizontal, inclined, and vertical positions.

AcoustoBots also innovate with the BeadDispenserBot, which automates the particle supply for acoustic levitation, enhancing the platform's usability in particle manipulation scenarios.

Performance Evaluation

The research details rigorous experimental evaluations of the AcoustoBots system. Tests on hinge actuation precision and the accuracy of the bead dispensing process underscore the system’s capability to maintain precise spatial alignment crucial for effective multimodal interaction. Additionally, the focal point measurements in acoustophoretic applications yield promising results, suggesting effective integration of haptic feedback, audio projection, and particle levitation.

Implications and Future Directions

AcoustoBots open new avenues for practical and theoretical exploration in swarm robotics and multimodal interfaces. Practically, their ability to generate scalable, interactive experiences has applications across mixed-reality environments, industrial automation, and public installations, facilitating diverse and immersive user engagements. Theoretically, the system sets a precedent for future research into distributed acoustophoretic control algorithms and enhanced sensory experiences.

The potential scalability of this swarm-based approach is underscored, with future work aimed at overcoming communication constraints and enhancing decentralized control systems to efficiently manage larger swarms. Future enhancements may involve integrating additional sensory modalities such as taste and smell, broadening the scope of multisensory interaction scenarios.

Conclusion

The AcoustoBots paper presents a comprehensive exploration of a novel acoustophoretic framework that valiantly tackles previous limitations in static systems. By merging swarm robotics with acoustophoretic capabilities, AcoustoBots not only extend the spatial and functional boundaries of multimodal interactions but also lay the groundwork for the next generation of interactive, dynamic environments. The implications for both current practical applications and future theoretical advancements are substantial, promising to inspire further research and development in this innovative intersection of robotics and acoustophoretic technology.