The 2013 Cadillac XTS blends input from a number of sensors to enhance driver safety, moving the automaker a step closer to 360-degree sensing and setting the stage for semi-autonomous driving. General Motors researchers are also discussing plans to enhance this sensor fusion by adding GPS input and vehicle-to-vehicle communications.
Cadillac is touting sensor fusion as a key element in what it calls “the most technologically advanced production car the luxury brand has ever offered.” Data from cameras, radar, and ultrasonic sensors is being combined with other data from yaw rate packages and other sensors.
Together, they move GM closer to the goal of providing integrated 360-degree sensing. Most OEMs are moving in similar directions, using a range of tightly integrated sensors to create what GM calls “a safety and convenience bubble” that surrounds the car.
“As you get more and more into urban environments, that safety bubble becomes more important. If you detect something penetrating the safety bubble, you want the driver to react,” said Bakhtiar Litkouhi, GM Research and Development Lab Group Manager for Vehicle Control Systems. “In the absence of a driver reaction, the car can take action.”
Some sensors, such as cameras, have been added to the new XTS to complement existing sensors such as the radar used for adaptive cruise control. That makes it possible for active safety systems to respond more quickly.
For example, radar systems now have around an 18-degree field of view, so they can’t detect a vehicle cutting in front of the driver’s vehicle until there is very little time for the driver to respond. When radar is complemented by cameras, warnings can be provided a bit earlier.
“Adding the larger field of view of a camera provides customers with additional time to respond to an alert,” Litkouhi said.
Going forward, GM plans to do more sensor fusion, augmenting sensors on the vehicle with GPS satellite input.
“Any time you’re dealing with position, GPS can be very important,” Litkouhi said. “Combined with map information, it tells you where you are, whether the road’s curving, and whether the speed limit goes up or down.”
GPS data can also help improve safety by eliminating some of the false positives that can occur with electronic stability control (ESC) systems. Yaw rate sensors in ESC systems can sometimes detect skids when the vehicle is going around a sharp curve.
“If the system understands where the vehicle is on a curved road and knows its position on the road, it can account for curves and changes in grading,” Litkouhi said.
In a press release, Cadillac noted that autonomous test vehicles are already proving the viability of this concept. The company also noted that vehicle-to-vehicle communications will play a role in manual and autonomous driving.