Performance study on commercial magnetic sensors for measuring current of unmanned aerial vehicles

The industrial investment in unmanned aerial vehicles (UAVs) is soaring due to their multiple autonomous applications, such as aerial photography, rescue operations, surveillance, and scientific data collection. Current sensing is critical for determining battery capacity in charging and discharging process and alerting for system fault during the flight. Shunt resistors and Hall-effect sensors are traditionally used in UAVs. Recently, magnetoresistive (MR) sensors are gaining enormous attention from researchers. MR sensors tend to consume less power, and they are smaller in size than the Hall-effect sensors. In this paper, a number of off-the-shelf MR sensors were investigated to evaluate the possibility of applying them for UAVs. Another type of magnetic sensor (fluxgate) and shunt resistor was also studied and compared as a reference. The relative scoring method is adopted to evaluate the sensor performance under different metrics, and the results disclose that the MR sensors are highly suitable for current sensing of UAVs due to their higher accuracy, lower energy consumption, wider temperature endurance, smaller size, and less weight than other magnetic current sensors. They are also very competitive with traditional shunt resistors through the overall comparison. The remanence, thermal stability, and cross-field sensitivity of MR sensors are further discussed. This finding provides insight into the selection strategy of current sensors for UAVs and can enhance the industrial development of UAV potentially.