Study On Real-time Control System For Quadrotors

Quadrotors, with many advantages such as simple body structure, superior hovering and low-speed characteristics, convenient and flexible manipulation method, have began to get more and more attentions from researchers and commercial organizations and are becoming the new hotspot areas in unmanned spacecraft domain. This thesis using an own R & D small quadrotor as the research platform, is committed to the real-time control system for quadrotors aimed to hovering and low speed cruising in the indoor environment.First, this thesis analyses the movement pattern and principle for the unique structure of a quadrotor, proposes the function and performance indicators according to the application requirements of the aircraft, designs the body structure and matching the main components properly, completes the real-time control system hardware design.Secondly, applications of the direction cosine matrix method are studied as the attitude solving algorithm for a quadrotor. A high-effective unit orthogonal algorithm for the correction of the direction cosine matrix is implemented. Considering the frequency domain feature of the gyroscope, acceleration sensor and digital compass, the thesis fusion measured attitude data from these sensors by the complementary filter and effectively improves the accuracy of the attitude measurement.Thirdly, based on relevant physics laws and the analysis of a quadrotor in mechanics and dynamics, dynamic equations are established. This thesis simplifies the nonlinear model properly, controls the displacement control loop and attitude control loop by the classic PID algorithm and achieves the intended purpose.Finally, a basic testing platform is built in the laboratory environments in order to carry out physical tests for Attitude Heading Reference System and the flight control algorithms. Experimental results show that the proposed dynamic model and PID control method performance obviously well for attitude control, but the position control method not achieves the desired purpose and still needs to be improved in future research.