Why your next car might track passengers with radar

Plenty of cars (and not just autonomous ones) use radar to spot outside dangers on the road, like that pick-up truck in your blindspot.

But in the near future, radar imaging could be used to monitor what’s going on inside of your car.

It could detect a baby left in the backseat, for example, or alert a distracted driver. It could even measure a passenger’s heart rate through their chest movement. 

Carmakers are looking into radar technology since they’ll need seat sensors and alerts in new U.S. vehicles by 2025 to prevent child fatalities. In 2019 there were 52 hot car deaths in the United States, according to the National Highway Traffic Safety Administration. More than half of them involved children left in a car, most of them kids under 2 years old. 

That’s why the FCC waived restrictions to allow Tesla and other companies — including Brose, IEE Sensing, and more — to incorporate radar technology inside of vehicles. 

Other carmakers such as General Motors, Ford, Volkswagen, Toyota, Hyundai, Subaru, Volvo, Honda, and others have all supported legislation to put seat reminders in cars. These trigger an audible warning to drivers if they open the rear door at the start of a trip, but don’t open it when it’s over. 

An imaging radar chip can replace a car’s cameras, infrared cameras, weight sensors in the seat, and touch sensors in the steering wheel.

Ian Podkamien, head of automotive at Israel-based Vayyar, an imaging chip company, said its single-chip radar system can provide a view of the entire car, including the trunk, without the need to record any faces or identifying information.

Podkamien says it can differentiate between inanimate objects and passengers. So if a briefcase is left behind, the system doesn’t freak out car owners by indicating their kid might be in the backseat. 

Vayyar also claims it can track the driver’s body and head position to make sure they’re not nodding off behind the wheel. And it keeps count of how many passengers enter and leave the car to make sure nobody is left behind. It’s so effective, claims Podkamien, that it can “see” through a blanket to notice a baby in its car seat.

Is it safe? 

“We are talking about a device that is transmitting about 1,000 times weaker signal than your WiFi in your smartphone,” which many keep next to the bed at night, he said. All FCC waivers were for radar systems operating within the 60 GHz spectrum band, a standard for WiFi used to connect, say, a tablet to a TV.

Jeff Jury, however, says that monitoring passengers without a camera can make it hard to accurately know what’s going on in the car. 

He is the general manager for connected cars at Xperi, which recently released a camera-based cabin monitoring system. A system without cameras is “weaker” and more prone to false positives, Jury claims. Xperi’s cameras don’t use any radar sensors. 

Vayyar’s Podkamien argues that only using radar can make the car experience safer for passengers and cheaper for carmakers. “[It’s] increasing safety while reducing cost,” while maintaining the same high resolution and wide field of view cameras offer, he said. He, too, believes radar can “help minimize false alarms.”

Jury counters that radar is “inferring” about scenarios based on movement or audio cues rather than knowing from immediate visual analysis. But the systems all have the same goal. “We’re all about creating a safer environment in the car,” he said. Jury said that none of the information collected by the system is stored externally. 

Like Vayyar, South Korean startup released a radar chip that can detect people underneath blankets and monitor the breathing and heart rates of passengers. 

Why is that useful? Before a crash, the car could adjust the seat belt or air bag positioning based on the size of the passenger. After a crash, it could share vital statistics with emergency responders.

Here’s the chip in action:

Bitsensing and Vayyar’s chips can also sense about 6.5 feet around the car. That enables features like , which detects activity around a parked car to warn away would-be intruders who get too close.

Swedish mobility firm Veoneer and emotional AI startup Affectiva want to incorporate radar sensing to check on passengers in autonomous vehicles and make sure the robocars don’t start driving before passengers are done climbing into the car or buckling their seat belt.

Radar might be used for “immersive” entertainment, too, Xperi’s Jury said. Future cars might play calming music to bring a driver’s heart rate down or something more upbeat if they’re dozing off.

But in the near future, drivers will have to settle for knowing they haven’t left anyone in the back seat.