LeviCursor

Abstract

Figure 1. LeviCursor enables dexterous interactive control of levitated particles. Users can control particle motion using an optical marker attached to a fingernail. Because we use the optimization-based approach to ultrasonic levitation, particle motion is smooth in any direction. We achieve round-trip latencies of 15 ms, sub-millimeter accuracy, and stability in levitation. Please see the accompanying video for demonstration. ABSTRACTWe present LeviCursor, a method for interactively moving a physical, levitating particle in 3D with high agility. The levitating object can move continuously and smoothly in any direction. We optimize the transducer phases for each possible levitation point independently. Using precomputation, our system can determine the optimal transducer phases within a few microseconds and achieves round-trip latencies of 15 ms. Due to our interpolation scheme, the levitated object can be controlled almost instantaneously with sub-millimeter accuracy. We present a particle stabilization mechanism which ensures the levitating particle is always in the main levitation trap. Lastly, we conduct the first Fitts' law-type pointing study with a real 3D cursor, where participants control the movement of the levitated cursor between two physical targets. The results of the user study demonstrate that using LeviCursor, users reach performance comparable to that of a mouse pointer.

Enhancing physical objects with actuated levitating particles

“…Suitably sized objects ( <0.5λ) can be levitated in the low-pressure nodes of the standing wave. Most HCI research into levitation use this method, with two arrays of 40 kHz transducers facing each other (e.g., [1,4,17,18]).…”

“…Users pointed a finger to select an object and the targeted object shook from side to side as feedback. LeviCursor extended the range of interactions possible with levitating objects, using in-air finger movements to directly move an object [1]. Whilst only a limited amount of feedback could be conveyed for these interactions through object movement, it was enough to support successful interaction.…”

“…Levitating particles can be moved in any direction, at high speeds (e.g., up to 80 cm s −1 using standing wave levitation [1]). Multiple particles can be moved independently [18].…”

“…For example, a particle might move to a new position because the user has pressed a button; their expectations of a response from the system add meaning to the particle's movements at that time. Particle movements may also be controlled in real time (e.g., [1]), allowing complex continuous interactions with an immediately visible response. Reacting to a user's actions through particle behaviour is the key mechanism for turning static items into interactive displays.…”

Levitation Simulator: Prototyping Ultrasonic Levitation Interfaces in Virtual Reality

“…Despite the potential of such interfaces and the accumulated body of research [12,17,16,6,19,2], not many applications for levitation interfaces have been developed thus far. Among the few examples are a two-platform jump game [21], and augmented static objects (e.g.…”