"It’s interesting that they chose capacitive [sensing] back there," said Randy Frank, author of Understanding Smart Sensors and chairman of one of the Sensors in Design tracks at this month's Design West conference. "In the past, vehicles have used infrared or sonic backup sensors to detect if they're getting too close to an obstacle."
Frank surmised that Ford chose capacitive technology because it offered the most logical way to distinguish between the various kinds of objects that could end up behind a car. "For a proximity sensor, it's going to be tougher to filter the cat or the basketball out of the algorithms."
Such a use may be a sign that capacitive sensors are beginning to creep into the vehicle. In-vehicle touch screens already employ the technology, and other areas of the car could follow suit. Audi and Volkswagen offer hands-free liftgate technology similar to Ford's, and we've reported before on Cadillac's plan to employ a capacitive center stack touch screen in its XTS and ATS luxury sedans.
Ford's use of capacitive technology is really just the tip of the automotive sensor iceberg. Today's vehicles are increasingly employing sensors of all kinds to let the control systems know what's going on around them. Resistive pressure sensors have found a home in intake manifolds and air conditioning. Optical sensors are playing a role in forward- and backward-looking systems. MEMS gyroscopes aid in stability control. Encoders monitor wheel speed, and resolvers are increasingly being used for motor positioning in electric cars. And with the advent of new touch screens and hands-free liftgates such as Ford's, capacitive technology is now making its entry into the vehicle.
"This just shows that automakers will explore any viable technology to achieve the results they're looking for," Frank said. "Capacitive just happened to make the most sense for this application."
DESIGN West Conference Information:
DESIGN West comprises seven summits. The conference takes place March 26-29 at the McEnery Convention Center in San Jose, Calif.
DESIGN West main conference page
DESIGN West Keynotes
Embedded Systems Conference
Sensors in Design