Understand Sensors – Automotive LIDAR

According to reports, the competition between LIDAR and other sensor technologies (camera, radar, and ultrasonic) has increased the demand for sensor fusion, and also requires careful selection of photodetectors, light sources, and MEMS micromirrors.

LIDAR and other sensor technologies

With the advancement of sensor technology, imaging technology, radar, LIDAR, electronic equipment and artificial intelligence technology, dozens of advanced driver assistance system (ADAS) functions have been realized, including collision avoidance, blind spot monitoring, lane departure warning and parking assistance. Synchronize the operation of such systems through sensor fusion to allow fully autonomous vehicles or unmanned vehicles to detect the surrounding environment and warn the driver of potential road hazards, and even take evasive actions independent of the driver to avoid collisions.

Self-driving cars must also be able to distinguish and recognize objects ahead at high speeds. Using distance judgment technology, these self-driving cars must quickly build a 3D map of a road about 100 meters away, and can create high-resolution images at a distance of 250 meters. If the driver is not present, the car’s artificial intelligence must make the optimal decision.

One of the several basic methods for this task is to measure the round-trip time of flight (ToF) from the energy pulse from the self-driving car to the target and back to the vehicle. When the speed of the pulse through the air is known, the distance of the reflection point can be calculated. This pulse can be ultrasound (sonar), radio waves (radar) or light (LIDAR).

For these three ToF technologies, if you want to have a higher angular resolution image, LIDAR is the best choice. This is because the diffraction (beam divergence) of LIDAR images is smaller and the ability to recognize nearby objects is better than radar (see figure) 1). For high-speed situations that require sufficient time to deal with potential hazards such as head-on collisions, higher angular resolution is particularly important.