Current sensing for battery of UAVs is critical for determining battery capacity in order to calculate the remaining flight time, and detecting fault. Magnetoresistive sensors are highly suitable for current sensing on UAVs due to their higher accuracy, lower energy consumption, and smaller size than Hall-effect and flux-gate sensor, and as well as its non-invasive measurement in contrast to the shunt resistors. This finding provides insight into selection strategy of current sensors for UAVs. Anyway, shunt resistors are widely used in UAV, such as Microhm MMS series and custom shunts.
The global interest for unmanned aerial vehicles (UAVs) is growing rapidly in both military and civilian operations. UAVs have found applications such in condition monitoring, geographical mapping, and performing certain dangerous tasks. It is important to monitor the operation status of the battery of UAVs in order to determine the remaining flight time, avoid the over-discharge which can lead to the permanent battery damage, and detect faults. Current sensing can provide data on the current being driven from the battery over time, and these data can be used to calculate how much battery capacity has been consumed during flight.
Sensing accuracy is essential to avoid measurement error which would accumulate over time and result in a large deviation. Apart from measurement accuracy, the other parameters of current sensors such as cost, size, linear range, operating temperature, supply voltage, energy consumption, measurement mode (invasive or non-invasive)are also important for current measurement on UAVs .
Therefore, it is worthwhile to study and compare these parameters when selecting current sensors for UAVs. Four physical principles are typically applied to measure the current of a conductor, namely, Ohm’s law (shunt resistors), Faraday’s law of induction (search coils), Faraday effect (fiber-optic current sensors), and magnetic-field sensing (Hall-effect sensor, magnetoresistive (MR) sensors, flux-gate sensors, etc.).Since search coils only work with AC current and fiber-optic current sensors are of high cost and large size, they are not suitable for UAVs. Shunt resistors are common in UAVs, while the magnetic sensors are gaining in popularity because of their non-invasive nature. Microhm provide full size (from 0805 to 8420) and various shapes shunt resistors for UAV engineers' options.
