Depending on the type of drone and its function, there can be a few essential sensors or an extensive number of sensors on board. Whether the drones are civilian or military craft, the sensors fall roughly into three categories: Make Them Fly, Make Them Work and Diagnose & Prevent Problems.
Make Them Fly
An inertial measurement unit (IMU) (with accelerometers, gyroscope and magnetic sensing), pressure sensors, GPS, airflow, LiDAR and others provide critical flight direction, altitude, distance and control input. However, sensors are also part of the gas engine or motor(s) providing the lift and thrust. For the engine, many of the same types of sensors found in automobiles are required to control fuel delivery, ignition and emissions. With either power source, position sensors could be used for controlling and monitoring flight control elements.
Make Them Work
An essential sensor for the simplest monitoring is a camera. However, some drones are used to monitor the environment and could have several different types of chemical sensors to detect unhealthy levels of pollutants and even dangerous or toxic chemicals. The application, from helping first responders to monitoring crops or livestock, dictates the type(s) of sensors required. For example, thermal sensors can locate people, cattle or other living heat sources. Numerous other types of sensors such as color sensors and more could be used in different aerial applications.
Diagnose & Prevent Problems
Deeply embedded sensing in power management and other integrated circuits protects motor controls and power supplies. In these devices, temperature sensors monitor the standard operating temperatures and when they start to exceed predetermined limits, a warning is sent to prevent a catastrophic failure. Similarly, overvoltage and undervoltage sensing prevents abnormal voltage fluctuations from causing problems. Temperature sensors could be located at several critical points in a drone to provide advanced detection for motors or simply for monitoring the ambient to ensure that all internal components operate within safe limits.
With the increasing interest in and number of drones, sensor innovators should have drones on their radar.