In my degree thesis I have participated in the design and realisation of a four rotor helicopter, also known as quadrocopter. In this document I show my work as a part of this project. My task was to solve the determination of the position and orientation of the machine. For this an IMU modul, an infrared distance sensor and an optical flow modul were available. I have verified that these sensors are suitable for this purpose, and I have fit them to the microcontroller that is used as the main control unit. I have deduced the orientation from the signals of the gyroscope and the accelerometer. For the fusion of these two solution I used a simplified complementary filter. After this I have analyzed how the position can be calculated from the accelerations and the signals from the optical flow modul. I have also examined how a complementary filter can be used here as a sensor fusion algorithm. Realising these in the software I have got a capable orientation measurement, with which the quadrocopter is able to keep its direction. I have implemented a low computation demand algorithm that generates roughly the same results. A position determining code has also been written, but there was no opportunity to test it. During the developement other tasks came up, from which I show the most important ones. I have implemented the timing of the program that run on the machine, and I have made made it simple to move the code. Using this, now the program is running properly on two different hardware. I have also realised a code that receives and process the signal of a seven channel remote controller. I have written an algorithm that manages a buzzer, and found a solution for the problems coming from the varying voltage of the battery. At the end of my degree thesis I analyze the possibilities of further developement.