Of All the Backhanded Things…

Virtual reality (VR) has been around for decades, but recent advancements in technology have made it more immersive than it ever was before. One area where VR has seen significant growth is in the use of haptic devices, which allow users to feel and interact with virtual objects, which greatly enhances the illusion of reality. Suffice it to say that if a VR user reaches out for a virtual object and feels absolutely nothing, it does not make for a highly engaging experience.

Haptic devices are typically gloves or controllers that are worn or held by the user. They use various mechanisms, such as vibrations, pressure sensors, and even temperature changes, to simulate the feeling of touching objects in the virtual world. And some of these systems can actually be fairly convincing.

However, there is one major issue with present devices — the bulkiness, discomfort, and limited range of motion that is commonly seen with them. For example, haptic gloves can be uncomfortable and restrict hand movements, which can make it difficult to perform certain actions in the virtual world. Similarly, some haptic controllers are heavy and awkward to use, which can detract from the overall experience.

The human-computer interaction gurus in Pedro Lopes’ lab at The University of Chicago have just described another innovative device that they have built, this time to solve the problems with current haptic glove implementations. Their device provides full-hand electro-tactile stimulation to simulate the sense of touch, and does it all from the back of the hand, leaving the palmar side completely free of instrumentation.

A wrist-worn device was developed, containing a Seeeduino XIAO development board and a Bluetooth module. Power was provided by rechargeable LiPo batteries. After receiving requests via Bluetooth, the microcontroller sends the appropriate signal to a DAC, which controls the amount of electrical stimulation that is sent to a series of electrodes precisely positioned on the back of the hand.

By leveraging the phenomenon called referred sensation, in which a sensation is perceived in a part of the body other than where the stimulation occurred, they showed that they were able to stimulate the palmar side of the hand almost exclusively. This was possible because the palmar side of the hand is far more sensitive than the back. Because of this fact, the team was able to adjust the electro-stimulation intensity until it was at just the right level where the less sensitive back of the hand could no longer detect it, but the palmar side could.

Through careful positioning of the electrodes, it was possible to create specific sensations in precise positions on the hand. A total of eleven separately controllable regions of the hand, across all five fingers and the palm, was achieved using these methods.

The system may not be quite perfect — user studies showed that participants felt over 90 percent of the sensations on the palmar side, but there was generally some perception of stimulation on the back of the hand as well. Furthermore, electro-tactile stimulation systems require a calibration process for each new user before the first use, so it is not something that will work right out of the box. As is the case with all electro-tactile systems, simulating continuous pressure is still not possible — the sensations produced feel more like momentary taps.

While not yet perfect, this work is a significant leap forward for tactile glove technology, eliminating the obstructions that interfere with normal interactions. The researchers are working to improve the current shortcomings of the system, and also add some new features. They have been working to send continuous electrical waveforms, instead of just brief pulses, to simulate the feeling of textures, for example.