Holograms get touchy

Holograms are set to get another dimension as researchers at the University of Tokyo develop tactile response for mid-air displays. The system consists of three components; a holographic display, a hand tracker and a tactile display. The tactile display produces force on the user’s hand without any contact by using radiation pressure of airborne ultrasound. Researchers pinpoint possible applications in digital signage.

The team; Takayuki Hoshi, Daisu Abe and Hiroyuki Shinoda, point out that mid-air displays are becoming increasingly common and developments allowing a user to manipulate the image are also growing in prevalence. However, they note that most systems that produce tactile feedback in free space involve attaching a device to fingers and/or palms. The researchers discount these methods pointing out that skin and device are always in contact, leading to undesired touch feelings.

Other systems involve controlling the position of tactile devices so that they contact with the skin only when tactile feedback is required. However, the research paper pinpoints problems with this system that is based around bulky robot arms.

Instead the researchers propose a method for producing tactile sensation with airborne ultrasound. They write: “The method renders desired pressure pattern in free space by using wave field synthesis with high spatial and temporal resolution. Users can feel the pressure with their bare hands”.

The team developed a prototype consisting of 91 ultrasound transducers, which could move a focal point along a Z-axis. The force generated at the focal point was 0.8 gf. The paper demonstrates how the interaction system tracks a user’s hand and provides tactile feedback when collision occurs between the hand and a virtual object.

Hoshi, Abe and Shinoda also show how the output force can be increased to represent the feeling of impact.