2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
British engineers presented a prototype of a gaming machine based on ultrasonic acoustic levitation. It consists of several rings and a small ball floating in the air that follows the position of the player's finger thanks to a hand tracking sensor. The development was presented at the CHI 2020 conference.
Ultrasonic acoustic levitation is based on the interference of sound waves from multiple sources, which creates stable regions with different sound pressures in the air. Including in them small areas with low pressure are formed, surrounded by areas with high pressure. If a sufficiently light and small object is placed in this area, it will remain in it without falling. And regulation of the amplitudes and phases of waves in the array of ultrasonic sources allows you to shift the area with low pressure and the object in it in the desired direction.
Basically, acoustic levitation is considered as the basis for non-contact devices that move small objects that require careful handling. In particular, there are already prototypes of soldering machines and manipulators for moving chips onto microcircuits using this effect. But, as has often happened with other spectacular technologies, engineers are also trying to use it for entertainment purposes. Orestis Georgiou of Ultraleap and his colleagues created a simple game based on acoustic levitation.
The levitation apparatus itself has a design typical for such devices. It consists of two arrays of 9 by 27 emitters operating at a frequency of 40 kilohertz. They are directed at each other and spaced 18 centimeters apart. Between some of the emitters, engineers inserted thin plastic rings or more massive ones, consisting of acoustically transparent fabric (organza or acrylic felt). As a levitating object, the developers chose polystyrene balls with a diameter of one to three millimeters, which are also standard for this task.
The control of the levitating ball makes the installation unusual. To do this, it uses the Leap Motion hand movement sensor, which, using infrared cameras and emitters, creates a three-dimensional model of the hand in real time and transmits commands to arrays of ultrasonic emitters.
The player can control the ball by moving the index finger in the desired direction and thus pass it through the rings. In this case, the control works only with the extended thumb, and if you press it against the hand, the ball stops.
Acoustic levitation is also used to create prototypes for volumetric screens, and these have become much more sophisticated over the years. In 2016, we talked about a display of several irregularly colored balls, working on the principle of electronic ink. And in 2019, engineers first created a screen in which the balls hold a small projection canvas, and then an adjacent group presented a screen that uses only one ball, but it moves at a speed of several meters per second and, together with a high-speed projector, allows you to draw in the air. volumetric colored figures.
