Tying a string round one’s finger is historically carried out to function a visible reminder of one thing vital. However a pair of researchers at Carnegie Mellon College believes that string could be the key to higher and richer haptic experiences in digital and augmented actuality. The staff is working to deal with a significant limitation of current haptic interfaces — they sometimes can solely reproduce one kind of sensation, reminiscent of the sensation of textures. That makes for subpar digital experiences which might be something however totally immersive.
The easiest way to get multi-dimensional haptic results at the moment could be to mix a number of completely different programs and use them concurrently. Nevertheless, in follow, this kind of answer may be very cumbersome, to not point out costly. And for a lot of functions, it’s not possible to do in any respect. As a greater answer, the researchers have launched what they name Reel Really feel. It’s a wearable haptic interface that attaches a person string to every finger. By pulling on, or loosening, every of the strings independently, a variety of sensations could be simulated.
A more in-depth take a look at the electronics (📷: N. DeVrio et al.)
Mounted on the person’s shoulder, the Reel Really feel system makes use of high-torque brushless DC (BLDC) motors to tug strings tethered to the fingers. By adjusting motor torque and velocity programmatically, the system can convincingly render 5 distinct sorts of haptic results: inflexible geometry, haptic animations, impulsive forces, floor compliance, and fine-grained spatial results. This modular strategy permits these sensations to be felt individually or blended collectively to simulate extra advanced tactile experiences.
One of many key design targets was to eradicate the cumbersome, glove-based wearables widespread in prior haptic programs, which could be uncomfortable and fatigue-inducing. As a substitute, Reel Really feel offloads almost the entire system’s weight to the shoulder — a location discovered to be superb for wearable gadgets attributable to its consolation and assist. Every of the 5 strings extends from a motorized spool housed in a compact enclosure weighing 710 grams.
For movement management, the system makes use of GM3506 gimbal motors, that are a sort of BLDC motor in style in drones and digicam stabilizers. These motors supply a powerful torque-to-weight ratio whereas weighing simply 64 grams every. The motors are able to steady operation with clean movement, which is essential for producing sensible haptic results. The fishing line used as string is 2 meters lengthy, guaranteeing a large discipline of movement with out restriction.
Every finger could be managed individually (📷: N. DeVrio et al.)
Every motor is paired with an AS5048A magnetic encoder to observe spool rotation and keep correct power suggestions. In earlier prototypes, the system relied on mechanical restrict switches to detect slack within the strings, however these had been deserted in favor of monitoring the person’s fingertips utilizing cameras on the VR headset. This improved each consolation and efficiency, guaranteeing that the string pressure stays constant with out introducing distracting tactile artifacts.
Driving the {hardware} is a custom-built management board that includes a Teensy 4.1 microcontroller operating at 625 MHz. The microcontroller communicates with a PC over USB 2.0 and handles high-frequency updates from VR functions developed in Unity, operating at 70 frames per second. The microcontroller interfaces with DRV8313 motor drivers, every able to controlling three-phase BLDC motors.
Altogether, the prototype prices roughly $240 in elements, with the vast majority of the expense coming from the motors and encoders. The researchers estimate that, with scaled manufacturing, the price could possibly be decreased to underneath $200 (and presumably even under $100) making the expertise a promising candidate for consumer-grade VR haptics.
