Dynamically Adjustable LiDAR with SPAD Array and Scanner 2021-01-0091
An important function of an Automated Driving (AD) system is to detect objects including vehicles and pedestrians on the road. Typical devices for detecting those objects include cameras, millimeter-wave RADAR, and light detection and ranging (LiDAR). LiDAR uses the flight time of a short-wavelength electromagnetic wave. Because of that LiDAR is expected to find even small objects such as tire fragments on a road in high resolution. The detection performance required for LiDAR depends on the operational design domain (ODD). For example, while a vehicle is travelling at high speeds, LiDAR needs to detect apparently small objects at long distances, and while it is travelling at low speeds, LiDAR has to detect objects over a wide angular range. Conventional LiDAR is developed to satisfy all requirements, providing performance including detection distance, resolution, and angle of view tends to expose issues such as cost and size when it is mounted onboard.
To solve these problems, we have built LiDAR with a new structure consisting of an originally developed light receiving unit and scanning unit, which are the main components. The light receiving units uses an array of high-sensitivity single-photon avalanche diodes (SPADs). Its vertical resolution can be selected by changing the number of SPADs per pixel. The scanning unit has introduced a reciprocal motion system, which enables dynamically choosing the range and speed of scanning, with the range of scanning 100 ° or wider. With these mechanisms, it is possible to select a high-resolution and narrow-angle mode when detecting small objects at long distances, and low-resolution and wide-angle mode for detecting many objects at short distances. Therefore, the LiDAR can adjust its performance dynamically according to driving scenes. We have confirmed that our LiDAR is effective for detecting objects under various conditions.