Unmanned Systems Technology 014 | Quantum Tron | Radio links and telemetry | Unmanned Aerial Vehicles | Protonex fuel cell | Ancillary systems | AUVSI 2017 Show report

Agile Sensor Technologies has developed a motor control system for providing information about motor performance in multicopter UAVs more efficiently. It provides feedback on temperature, current draw, speed and other operating parameters pertinent to maintenance, flight and safety-critical decision making (writes Rory Jackson from the AUVSI show). Agile’s vice-president of engineering Howard Rideout explained, “We’ve centralised the system by taking the distributed form factor’s separate speed controllers – one for each motor – and mounted them on a single hub. “In addition, we made the hub the data aggregation point of the system and integrated an SD card for all the motor sensor data, and we are streaming it back to the operator from there.” The company has also abandoned the Hall effect sensors previously used to detect rotor position in favour of sensorless detection with sinusoidal control. “It’s field-oriented control with sensorless detection, which promotes a much more convenient arrangement in terms of connections to the motor, and provides additional efficiency compared with the back-EMF based commutation systems that run in other such systems.” Rideout added. “And the next version will be scaled down further, to 100 x 100 mm, for a four-motor system.” To minimise form factor, the microcontroller was switched to a smaller unit and moved to the main board. CAN bus connectivity was added to support pulse width modulation inputs for throttle control, and serial CAN bus links were included to integrate control and data on a shared interface to reduce space and weight consumption. A reprogrammable FPGA in the central hub reduced the impact of code rewrites and allowed it to interface to different autopilot systems such as Pixhawk. Necessary code rewrites were enabled thanks to the reprogrammable FPGA central hub. “It already handled multiple motors, but in terms of the modified data requirements, we updated the firmware and developed new microcontroller code,” Rideout said. “A lot of the work centred on comms protocols for the feedback data, using a specific UART protocol to adapt to a standard MAVLink output for Pixhawk.” Better UAV motor feedback Airborne vehicles