The Hardware Development sub-system’s main responsibilities are the development of flight measurement systems, the collection, and processing of flight data, the implementation of a telemetry system in cooperation with the Communications sub-system, as well as the UAVs’ electric equipment, such as servomotors, batteries and ESCs (Electronic Speed Controllers).
Flight data collection is an inseparable part of the design optimisation, as it allows us to examine our UAVs’ performance under different conditions. Some of the most important flight parameters include position, altitude, velocity, pressure and acceleration. The sub-system is responsible for creating sensor boards, which include sensors, a microcontroller and various peripherals. The sensors we pick according to the hardware specifications (e.g. required voltage) and mission requirements measure various physical quantities and convert them to electric signals that can be read and processed by a microcontroller. The data is stored for later retrieval. The sub-system’s members program the microcontroller, often using existing code libraries, or developing their own for more efficient utilization of flight data.
The first measurement system that has been developed was soldered on prototyping boards. The sub-system is currently developing SensorBoard v2.0, which will be printed on a Printed Circuit Board (PCB). It will include sensor chips, as well as an ATMega microcontroller. The next version to be designed (SensorBoard v3.0) will be similar, but will have an ARM microcontroller and will be programmed using STM32 libraries.
The Aeronautics project plans to implement a telemetry system for future UAVs. That is, the data measured on board will not only be saved, but also transmitted live from the UAV to a ground station. This way we will have better knowledge of the UAV’s situation at any given moment during the flight.
The telemetry system will include a transmitter and an antenna on the UAV’s boards. A Ground Control Station (GCS) will also be constructed which will have a receiver and an antenna.
Research is being done in cooperation with the Communications sub-system in order to find the best implementation parameters, in order to achieve fast and reliable communication.
Servomotors, batteries, ESCs
In order to control the attitude of a UAV, control surfaces are used. These are surfaces on the UAV’s wings and tail that can be moved by a servomotor, thus generating differences in pressure which result in aerodynamic forces that rotate the aircraft around its axes of freedom. The Aeronautics project usually uses two ailerons, an elevator and a rudder. The servomotors that move these are chosen by the Hardware Development sub-system, after conducting research based on the amount of torque required, using both online as well as ASAT-developed tools.
The sub-system is also responsible for the selection of the battery that powers the aircraft’s motor. Several parameters are taken into consideration, such as nominal voltage, capacity, discharge current and battery mass and type.
Finally, in order to control the speed of the motor, Electronic Speed Controllers (ESCs) are used. It is the Hardware Development sub-system’s responsibility to connect these to the motor and the battery of the UAV.