Electric-Field Gesture Interface Gets Users’ Hands Off Their Gadgets

Gestures might control portables, car audio, and household electronics

3 min read
Electric-Field Gesture Interface Gets Users’ Hands Off Their Gadgets
Photo: Microchip Technology

Video: Microchip Technology
WAVE YOUR HANDS IN THE AIR: Microchip Technology's sensor  interprets gestures by the way the hand interferes with an electric field it generates.

14 November 2012—Touch screens are de rigueur on yesterday’s high-end mobile devices, but the next revolution in interface technology will get users’ hands off their machines’ displays. And according to Microchip Technology of Chandler, Ariz., this interface is on the way. Today, the company introduced GestIC, a configurable 3-D gesture controller that it says will allow users of smartphones, tablets, and laptops to dial, open apps, manipulate documents, scroll through phone directories and music playlists, and perform a host of other tasks, without touching these gadgets at all.

GestIC identifies gestures by generating an electric field and sensing how a user’s hand movements change it. The chip does this using a set of up to six electrodes. One electrode emits an electric field, which hops around among frequencies in the 70- to 130-kilohertz range in order to minimize interference from things like fluorescent lights and AC chargers. The remaining electrodes act as receivers, measuring the change in the field 200 times a second and allowing the chip to interpret a hand’s position in three dimensions. Microchip says the system works as long as the user’s hand is within 15 centimeters of the electrodes, which can be incorporated below a portable device’s housing or even in its touch screen.

The system features a dedicated chip that does onboard 32-bit digital signal processing (DSP). Using an on-chip library of hand swipes, circular motions, and other gestures, the DSP can do the initial recognition of movements without using any of the phone’s or laptop’s native number-crunching resources.

A video demonstrating GestIC’s capabilities shows that the system packs enough brain power to recognize the series of swiping motions needed to turn the pages in an e-book or PowerPoint presentation, without mistaking the hand’s return motion between swipes as a command.

Fanie Duvenhage, director of Microchip’s human-machine interface division, says that preventing unintended recognition of movements within the electric field—as in the case of pocket dialing—is simple. A phone or tablet can be programmed to start taking commands after a specific gesture—essentially, a gesture password—that is unlikely to be replicated randomly inside a pocket or purse. That’s important, because another basic characteristic the company is trumpeting is that the system’s miserly use of power (it draws as little as 150 microwatts) will allow always-on gesturing, even in small gadgets, where energy is at a premium.

Low power consumption isn’t the only advantage of electric-field gesture recognition. It could also potentially extend the abilities of other gesture interfaces. For example, camera-based gesture controllers, such as Microsoft’s Kinect, work better at longer distances but suffer from blind spots at close range. An e-field sensor could fill in the gap, Duvenhage says. Electric fields also sidestep cameras’ susceptibility to the effects of ambient light and ultrasonic sensors’ sensitivity to noise.

Duvenhage says that the company is already working with several consumer electronics manufacturers, which plan to make a splash at the 2013 International Consumer Electronics Show (CES) in Las Vegas with products showcasing the gesture interface.

Though the firm first focused on the consumer electronics industry because of its quick development cycles, Duvenhage says the technology lends itself to many other markets. Two that the company is pursuing now are light switches that turn on, off, or dim with a wave of the hand, and sensors that let drivers open a car’s sunroof or manipulate the vehicle’s dashboard console without taking their eyes off the road. “It seems obvious that you’d want a ‘switch’ you don’t have to feel around for in the dark, or the ability to control your car with a natural mode of communication,” says Microchip spokesman Eric Lawson.

Duvenhage even imagines GestIC someday being used to detect the movement of a driver’s foot from the accelerator to the brake pedal so that safety functions can be activated, such as seatbelt pretensioning in anticipation of a collision.

Asked whether GestIC can be used as the medium for an air keyboard, Duvenhage said that as sensitive as the system is, it is designed to capture the movement of the hand’s center of mass, not individual finger movements. But he wouldn’t rule out an air keyboard for future iterations.

GestIC may not be alone in the electric-field-based gesture interface race. Last November, Plessey Semiconductors detailed its Electric Potential Integrated Circuit, or EPIC, which the company described as essentially a very sensitive, contactless digital voltmeter capable of measuring millivolt changes in electric fields. The gadget, shown in a video taking electrocardiogram readings through a patient’s sweater, will be used in consumer devices such as hands-free gaming controllers, Plessey says, once some refinements have been made.

Alan Colman, director of the EPIC product line, says the company is working on a gesture interface for small electronics that it wants to show off to manufacturers at CES in January. It is also developing a version of the sensor to be embedded in car seats for monitoring whether the driver is drowsy. However, Coleman would not set a timetable for either of these to be commercialized.

Of course, electric-field sensing isn’t the only way to do gesture interfaces. Microsoft Research recently demonstrated its Digits project, which uses infrared imagers strapped to a user’s wrist to follow fine finger movements.

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