Version1:Hardware

From Albatross

To allow the software to stabilize, control and monitor the aircraft under a wide variety of conditions, quite a lot of electronics are required - see the block diagram below.

[edit]

Computing Hardware

To run the filtering and control algorithms, computational hardware is required - we chose to use a Bluewater Systems Snapper [1], which integrates a 400 MHz Intel XScale ARM-based CPU with memory, peripherals and a reasonably large FPGA onto a 70x40 mm PCB module. While we don't really need the FPGA, using it makes the hardware design easier and more flexible, and the software implementation much more straightforward. By using Snapper, we saved months designing uninteresting computer hardware. Furthermore, it gives us much more processing power than most commercially available UAV designs, and it lets us adapt our design to changing requirements in a very agile fashion.

[edit]

Sensors

To fly the aircraft, we need a suitable collection of sensors to measure relevant flight parameters such as position, speed, attitude (angles with respect to the horizon), altitude, heading and so on - the most important of these are altitude, airspeed, and attitude. Altitude and airspeed are measured with Pressure Sensors attached to a Pitot-Static assembly. Attitude can not be easily measured directly (or at least not in a way that is independent of weather conditions), so Inertial Sensors (accelerometers and rate-gyroscopes) are used in combination with a data fusion algorithm known as a Kalman Filter. Separately, neither accelerometers or rate-gyroscopes provide enough information to estimate attitude, but when combined, a reliable estimate can be generated. We chose to use Analog Devices silicon micro-machined inertial sensors for their good performance, small size, and low power consumption.

To measure absolute position, altitude, and ground-speed, a GPS receiver is used. We chose the U-Blox TIM-LA, for its excellent performance (in particular its 4 Hz update rate), and small size (25x25 mm).

[edit]

Other

To communicate with the Groundstation, enabling real-time monitoring and command, Aerocomm AC4486 long-range two way data radios were chosen. The are quite compact (42x48x5 mm), and have a range of over 20 km (line of sight).

Finally, a plethora of support systems are needed, including the Power Supply, the Supervisor microcontroller, and Debug and Expansion interfaces.

[edit]