How it works

What is the resolution of Ultrahaptics? 

906 views 27/07/2018 Nicci 7

We are often asked about the resolution of the Ultrahaptics technology. Our development kits comprise an array, with up to 256 ultrasound transducers, and a Leap Motion® camera module.

These components have different factors that contribute to the overall resolution of the system: 

Hand tracking position accuracy 

The Leap Motion® camera module uses visible and infrared light to track hand position and orientation and has a very high resolution, typically sub-millimeter with a range of up to 80cm for the Orion® driver.

The Leap Motion camera module’s frame rate can be between 20 and 200 frames per second, depending on the user settings and available computing power. The higher the frame rate, the better the tracking of any haptics. 

Tip: Read more on how the Leap Motion® camera module works

Control point size 

The ultrasound array creates the controls points felt on your hand in mid-air. The dimensions of these are determined by the wavelength of the ultrasound.

Our technology uses transducers with a fixed frequency of 40kHz; the speed of sound is approximately 340m/s at room temperature. This gives a wavelength of about 8.5mm. Each control point will, therefore, be about 8.5mm in diameter. With higher frequency ultrasound the wavelength, and hence control point diameter, is smaller.

Control point position 

When it comes to control point position, the Ultrahaptics array is capable of steering with sub-millimeter accuracy within the interaction zone. This allows for control points to be accurately placed anywhere on the hand and for accurate tracking of sensation to the hand.

This means control point positions can be changed faster than hand movement can be detected, allowing for the creation of complex shapes and sensations in mid-air! 

Haptic update rate 

Ultrahaptics SDK provides two modes of operation: Amplitude Modulation and Time-Point Streaming.

Amplitude Modulation uses fixed-frequency control points, whose position and intensity can only be updated at a rate based on the modulation frequency. For example, with a modulation frequency of 200Hz, haptic control point position can be updated at a maximum every 5ms, or 400 times a second.

With Time Point Streaming, a much faster update rate is available. The STRATOS Platform has an update rate of 40000 times per second or 40kHz! 

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