As the presence of flying robots continues to grow in both commercial and private sectors, it necessitates an understanding of appropriate methods for nonverbal interaction with humans. While visual cues, such as gestures incorporated into trajectories, are more apparent and thoroughly researched, acoustic cues have remained unexplored, despite their potential to enhance human-drone interaction. Given that additional audiovisual and sensory equipment is not always desired or practicable, and flight noise often masks potential acoustic communication in rotary-wing drones, such as through a loudspeaker, the rotors themselves offer potential for nonverbal communication. In this paper, the consequential sound during the flight of a quadrotor is utilized and modified to carry acoustic information while maintaining the visually perceived flight characteristics. A user study (N=192) demonstrates that acoustically augmenting the trajectories of two aerial gestures with the proposed approach makes them more easily distinguishable. This enhancement contributes to human-drone interaction through onboard means, particularly in situations where the human cannot see or look at the drone.

The increasing autonomy and presence of Unmanned Aerial Vehicles (UAVs), especially quadrotors, in everyday applications requires in-depth studies of proxemics in Human-Drone Interaction (HDI) and novel methods of user interaction suitable for different distances. This paper presents a user study (N=32) that evaluates proxemics with a miniature quadrotor (92 mm wheelbase) from four directions (front, back, left, right) in a seated setting investigating preferred approach directions and distances in future home or workplace scenarios. The goal of this study is to determine if humans are willing to allow flying robots of that size and mechanical appearance to approach close enough to enable tactile interaction. Moreover, the participants' inclination to physically interact with the quadrotor is examined. Studies evaluating proxemics in HDI are highly dependent on repeatable results and actually flying robots. In most comparable studies, the quadrotors used did not fly freely or at all, but were moved, manually controlled, or flew barely repeatable trajectories due to unstable onboard navigation. Only few studies have used pose estimation systems that ensure smooth and reproducible trajectories and thus reliable findings of the studies. For this reason, in addition to the presented study and its results, an insight into the used testbed is provided, that also integrates full skeleton pose estimation rather than tracking participants with only a single marker.

Aerial robots such as quadrotors enjoy ever-increasing popularity and emerge in everyday applications that require user interaction. At immediate proximity, physical control of the quadrotor by touch may be desired or even necessary. In this paper we present a tactile 3D touch interaction scenario with a quadrotor by introducing virtual buttons whose operation is detected in the accelerometer data of the built-in Inertial Measurement Unit (IMU) of the quadrotor. By dispensing with additional sensors, we are able to keep the size of the used quadrotor to a minimum and thus address the problem of users being discouraged from interaction with quadrotors at immediate proximity. As an example for the proposed interaction scenario, we introduce MetroDrone, a quadrotor responding to repeated user taps to virtually defined buttons by flying trajectories according to the beat and operated button. This introduces a minimalist interaction technique that requires no intermediary devices and strengthens human-robot connections through shared musical experience.