Active and Passive Detect and Avoid Solutions
Non-co-operative sensors for detect and avoid solutions can be divided into two groups – active and passive. Active sensors, such as radar, ultrasound and LiDAR, emit a signal which is then reflected by an obstacle and detected again by the sensor. Passive sensors detect a signal given off by the object itself, and include visual and infrared cameras. Non-co-operative sensors also provide an advantage in that they do not rely on a data link with another system to acquire information.
Active sensors can use time-of-flight information to provide accurate distance measurements to obstacles, which is extremely useful for rapid collision detection. However, they tend to be larger, heavier and require more power, making them unsuitable for integration into smaller, more SWaP (size, weight and power)-limited drones.
Passive sensors such as EO/IR (electro-optical/infrared) sensors are typically smaller, lighter, consume less power and can offer a very fast scan rate and high resolution. However, due to the lack of reflected signal measurement and time-of-flight data, their estimation of obstacle distances is less accurate. Their performance may also be affected by weather conditions.