📖 The Quick Answer
Radar measures distance and speed using radio waves and works in any weather, but has poor resolution. Cameras see color and detail like a human eye, but struggle in low light and bad weather. LiDAR sends laser pulses to build a precise 3D map, very accurate but expensive and limited in heavy rain or fog. Modern systems fuse two or more for safety.
⚙ How It Works (Sensors and Algorithm)
Radar (24 or 77 GHz) emits radio waves and measures the time of return and Doppler shift, giving range and relative speed of objects. Camera (CMOS sensor) captures images at 30 to 60 fps; a neural network classifies objects. LiDAR (Light Detection and Ranging) emits laser pulses and measures return time, building a dense 3D point cloud with centimeter-level accuracy at ranges up to 200 meters. Modern ADAS computers fuse these streams to compensate for each sensors weaknesses.
🛡 What It Protects Against
Different sensors protect against different failure modes. Camera-only systems can be fooled by glare or rain. Radar-only systems do not see lane markings or read signs. LiDAR struggles with heavy precipitation. Fusion of all three is the gold standard for AV development.
⚠ Limitations and When It Fails
Radar: low resolution, can be fooled by overhead signs or guardrails, blocked by mud or snow caked over the bumper. Camera: needs visible light, blinded by sun glare, hidden by dirty windshield, struggles in heavy rain or snow. LiDAR: expensive ($1,000 to $10,000 per sensor), reduced range in heavy rain or fog, large form factor on some systems.
🚗 Which Vehicles Have It
Camera + radar fusion: Toyota TSS, Honda Sensing (most), Ford Co-Pilot360, Hyundai SmartSense, Nissan ProPilot, Mercedes Distronic, BMW Driving Assistant, GM Super Cruise. Camera only: Subaru EyeSight (stereo), Tesla Autopilot (post 2021). Camera + radar + LiDAR: Mercedes Drive Pilot, Lucid Air, Volvo EX90, Polestar 3, Lotus Eletre, several Chinese EVs.
🔧 Related TSBs and Recalls
Most sensor-fusion TSBs come from collision-repair shops missing a calibration step. Any windshield replacement (camera) or front-bumper repair (radar) requires recalibration. LiDAR units are typically packaged in the roof line and require special calibration too.