Vehicles are equipped for radar for numerous ADAS applications. Corner radar is one such system wherein radar sensors are placed on the four corners of a vehicle to see beyond the curve. This is well suited for applications such as turn assist, Automated emergency braking (AEB), Vulnerable road user (VRU) detection beyond the purview of the driver. With range of more than 70m, wide FoV and working at 77Ghz this is best suited for AEB applications as dictated by regulatory bodies. This blog explains in brief corner radar and its applications.
Radar technology for passenger and commercial vehicles has come a long way from its initial usage in terms of technology advancements, a general acceptance of use cases, improved accuracy & precision, and even classification. But its adaptation is seeing a measured response for cases other than long-range radar applications. Considering the future requirements both from a regulatory point of view (NCAP) and customer expectations (L3 and above), it is evident that Corner radar is not only playing a major role but also might be a mandatory requirement. This article outlines such future requirements and describes how a corner radar can meet them.
Understanding corner Radar
Corner Radar is similar to other radar sensors across the car, with modifications to mounting resulting in a specific field of view to address various challenges in applications such as lane change assist, blind-spot detection, tune assist, etc. The following image explains in few mounting options as well field of view.
Figure 1: Corner Radar Positions
ENCAP take on Corner Radar
The 2025 roadmap for Europe NCAP marks a clear expansion for previous use cases like AEB and also new testing scenarios in the primary safety section. Compared to the 2020 roadmap, where Automatic Emergency Braking (AEB) for vulnerable Road users was a major new addition, the 2025 roadmap aims at bringing in more scenarios with respect to collision avoidance. The 2025 roadmap to AEB looks forward to three priority areas where the ratings will be updated.
To apply brakes or assist in applying brakes during the crossing and turning scenarios comes under the purview of AEB junction. Turning crashes are mostly due to misjudgment or driver inattention. One such scenario is depicted in the figure below where the collision can be with a car, pedestrian, cyclists, or powered two-wheelers.
Figure 2: AEB Junction scenario
The usual forward-looking camera or radar cannot cover the entire scope for both left and right turns. This mandates the requirement of corner radar on both right and left front side. The requirements of these corner radar can be defined as having a wide field of view of about 120 deg to 150 degrees along with short-range coverage (40-80m).
AEB Reverse crashes:
ENCAP 2025 roadmap also has planned to include pedestrian use cases in reverse scenarios as improvements for Back over or reversing crashes test cases. This could include pedestrian or VRUs directly straight behind the ego vehicle or the VRUs can walk in perpendicularly to the ego vehicle.
Figure 3: AEB reverse scenario
As depicted in the figure, the coverage of rear center sensors might be limited, and is difficult to cover this entire area. With reverse corner radars on both sides, it is easier to detect low reflecting pedestrians and provide AEB functionality. This would include a VRU protection rating scheme in the ENCAP.
For both these scenarios, a corner radar system mounted at all four corners of the car with same or similar detection capabilities can act as the sensor system to meet the 5-star rating
With 77Ghz radar being adopted across radar applications in the automotive sector, radar is set to replace sensors like ultrasonic with limited capabilities. Radars are being used in SRR, MRR, and LRR applications such as adaptive cruise control, blind-spot detection, and park assist. With rules put forth by regulators, cars are required to be equipped with a pedestrian and vehicle detection system and have an AEB (autonomous emergency braking) system, wherein cars can take of collision avoidance when a user fails to do so. Radar is all set to do be the sensor of choice for AEB with its ability to see beyond the curve as compared to the camera while being cost-effective than a Lidar sensor.