A quadrotor unmanned aerial vehicle (QUAV) is an unpiloted aircraft which can achieve hovering with four rotors in a stable manner and can be used in military, or in a growing number of civil applications such as aerial photography, drone delivery services or military search missions. During the past few years, technological advances have reduced the cost, and increased the performance of low-power microprocessors which resulted in an increasing number of quadrotor control technique developments among the research community and also among the general public.
The presented work aims to introduce the design process of a fully functioning test rig which can be used to stabilize one of the basic movements of a quadrotor; its motion of roll. The final project of my Bachelor's Degree documents the specifications, simulation, implementation and the test of a single-axis quadrocopter along with the comparison of the simulation and measurement results.
With the measurements and instrumentations, the project focuses on the design process of the mechanical and electronic system. The implementation of the control algorithm was carried out with the help of a 16-Bit PIC microprocessor on an explorer 16 development board, while accelerometers and gyroscope data were used on a MM7150 motion module. One of the drawbacks of the selected sensor was, however, its closed nature and the accuracy due to its preprogrammed integrated sensor fusion algorithm. In spite of the facts, this minor setback proved to be a factor that made the stabilization and implementation technique more complicated and therefore more challenging.
In order to simulate the presented control algorithm, the complete mathematical and dynamic model of a quadrotor was deduced, thus the simplified equations of the single-axis quadrocopter were determined. Concerning the MATLAB simulation module, the project deals with the investigation of stability and the particularities of the applied PD control algorithm.
The purpose of the simulation was to achieve a better insight and a proper guideline to the control and tuning process. The measurements proved to be very similar to the simulation, however differed slightly due to the approximated physical parameter values and the simplified mathematical model. As a conclusion of the thesis, both the dynamics and the control methods were verified by several measurements carried out on the test bench.
The test rig in its present form is suitable for further investigations concerning different control algorithms and tuning processes. Besides that, it is also relevant in an educational context since the implementation of PID algorithms can be presented on a real-life aerodynamic system.