Cameras and Radar Sensors Help Drivers See More

Perhaps the most sophisticated sensors in today’s vehicles are the ones that enhance the driver’s vision. Cameras and radar sensors usually are found on high-end vehicles, but several suppliers are working to extend these sensors to a broader range of vehicles. Delphi, TRW and Continental have different approaches.

In its parking guidance system (PGS), Delphi uses a rear-view camera instead of ultrasonic sensors. The company claims it is a lower cost solution to the parking problem. Advanced algorithms take the information provided by the camera, determine if there is sufficient room to park the vehicle and calculate the backing path. The driver receives spoken step-by-step instructions required to park the car and a visual indication on the vehicle's display. Scalability allows the system to provide a variety of parking assistance possibilities depending on the requirements of the vehicle manufacturer. 

TRW Automotive Holdings Corp. expects its AC100 24 GHz radar technology, priced at about half that of a 77 GHz radar sensor, to make its Collision Mitigation Braking (CMB) system attractive to a wide vehicle market. Designed to solve problems associated with city traffic and traffic jams, TRW’s CMB technology is applied at close distance (6-7 meters or 20-23 feet). Within this distance, a 20 kph (12.4 mph) speed reduction can be achieved by braking, with limited deceleration, before a crash occurs.

With a range of up to 150 m (492 feet), the 24 GHz radar can also enable driver assistance functions such as Adaptive Cruise Control. This allows the technology to address high-speed highway driving up to 160 kph (99.4 mph). The combination of city and high-speed driving satisfies many of the needs of today’s mass market vehicles.

The benefits of combining radar and camera-based vision sensors have been exploited in several vehicles. However, Continental engineers are looking to take the combination even further to prevent accidents. In those instances with insufficient braking room, the ability of the driver to steer around an obstacle to prevent a collision can provide another collision avoidance alternative. Continental’s Emergency Steer Assist (ESA) concept employs long range information from radar and expects to add video images from camera systems similar to those already used for Intelligent Headlamp Control. The combination gives the driver a far ranging threat assessment on a high-speed highway.

Using the EPS in conjunction with ESC, the driver can steer to the right or left and avoid a collision, especially in an unexpected stopped traffic situation. The ESC’s roll is to keep the vehicle on the road during the rapid steering maneuver and to stabilize it by the selective and early application of initial braking pressure to individual wheels. Since the necessary components for ESA are already present in many vehicles, Continental engineers feel confident that vehicle manufacturers can implement this feature relatively inexpensively (see Fig. 4).

No Camera. No Radar. No Problem.

For systems without radar and cameras, Nexteer Automotive, formerly Delphi Steering, has another possible solution. Nexteer engineers expect EPS to improve vehicle safety and stability by simply adding another control feature to ESC. By taking inputs from the stability control system, EPS can provide wheel torque and assist the driver to regain control quicker than with the brakes or engine alone. These systems will continue to rely on Hall Effect sensors in EPS systems to increase safety.