The flight computer is the central processing unit of the rocket. Here all necessary calculations are performed, which are needed to start, control and measure the rocket. The flight computer is divided into control engineering and sensor technology.
The control technology is the heart of the flight computer where all sensors and data unite. In the beginning, the module deals with the simulation of a complete control loop. The aim is to control the activation of the airbrakes, to determine the influence on real parameters, and thus to predict the behaviour of the rocket from the viewpoint of the flight computer from take-off to landing. Besides, the required altitude must be reached as accurately as possible. Furthermore, the sensors used are modelled to implement the control software seamlessly on the microcontroller.
Sensors and Data Acquisition
This part of the flight computer deals with the acquisition of sensor data. This includes the development of the central flight computer board. This board contains the flight computer as well as various sensors whose data are needed for the control of the rocket. On the software side, the module deals with the development and maintenance of drivers for the sensors and data storage as well as the operating system of the flight computer. The required sensors include barometers and thermometers for altitude determination, various accelerometers for position determination, and a GPS receiver to locate the rocket after landing. The data of the sensors are not only stored in the internal data memory of the rocket but also transferred to the telemetry via a serial interface.
The telemetry system consists of two parts, one of which is located in the rocket and the other on the ground, which is therefore called the ground station. Both parts use the same circuit board, which only differ in assembly and the antennas used. The connection between the two parts is made by two transceivers, both on 70cm and 433 Mhz. One of them uses the LoRa standard, while the other one uses APRS coding. The reason for using two connections is reliability and their different application areas.
The radio system in the rocket receives the data from the flight computer, formats and encodes them accordingly, and sends them to the ground station. Due to the limited size and shape of the rocket, the optimization of an appropriate antenna holds a great challenge.
The ground station receives data from the rocket, which contains both position and various environmental data, and makes this data available to a PC via a serial connection for display. Therefore, a receiver for the ground station must exist. It is also planned to send data to the rocket to be able to communicate with it before the rocket is launched.
The ground station allows interaction with the rocket. It consists of a briefcase containing the hardware for the requirements. This includes the visualization of the received sensor data of the rocket. Furthermore, the launch of the rocket and the communication with it in advance shall be enabled.