Haptic texture device

Design and manufacturing of a pin actuator enabling high quality texture reproduction based on finger mounted haptic pin array

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Tactile Internet (TI) is the next step in the evolution of our digital communication. It will extend the conventional audiovisual interaction by enabling the users to convey the sense of touch over vast distances in real time. The potential to transfer haptic (touch) information will have a significant impact on many industries as well as on everyday life. However, there is still a long way to go in achieving a fully immersive user experience. One of the most significant shortcomings of today’s haptic devices is their lack of ability to reproduce texture. The conventional way of high-quality texture reproduction is to control the vertical displacement of pins in a two-dimensional finger-mounted pin array. In such a Haptic Texture Device (HTD) the final quality of the texture will solely depend on the actuation method of a single pin. A Haptic Texture Device Actuator (HTDA) needs to match the fingertip’s force sensitivity and spatial resolution and the reaction time of a human for fingertip stimuli. It must also be small enough to be integrated into handheld or wearable haptic devices. We have based our work on an existing HTD design that is fast enough to match the human reaction time and has a small enough pitch between adjacent pins to match the fingertip’s spatial resolution. However, in other aspects of haptic perception, the design fell short of the expectations. We have improved the HTDA of this base design to match every requirement of haptic perception. To match the force sensitivity of the fingertip, we have added a Hall-effect sensor to the actuator design for position measurement and implemented a closed-loop actuator control based on the measured pin position. Using the same actuator concept in a new configuration allowed us to decrease the actuator length by 12.5% while increasing the force output by 50%. Besides not fully matching the requirements of human haptic perception, the base design had a serious flaw. Due to minimal design, the HTDA’s of the base design tend to interfere, causing unwanted pin actuation. We were able to mitigate this issue by adding a backiron to our design. A backiron is essentially a layer of ferromagnetic material around the actuator, which besides magnetic shielding, also contributed to the 50% increase in force output. Our improved HTDA design enables the development of a HTD, capable of high quality texture reproduction.