Design And Research On Flight Control System For Small Scale Unmanned Quad-rotor

Small scale unmanned quad-rotor has been widely used in engineering practice community and has significant research value.It possesses lots of advantages such as simple mechanical structure,convenient operation,the functions of vertical takeoff and landing(VTOL),hovering and fast flight attitude transformation.For the flight attitude control of unmanned quad-rotor,there are still some issues on accurate measurement,calculation and output.To acquire a stable flight attitude control,an X-type unmanned quad-rotor is designed based on STM32 microprocessor.Dual processors,dual gyroscopes and dual accelerometers are integrated into the hardware architecture.Flight attitude information in real time is collected.Quaternion complementary filter algorithm and cascade PID control algorithms are adopted in attitude calculation and output.The experiments show that the designed X-type unmanned quad-rotor obtains good measurement precision and high flying performance.The purpose of getting stable flight attitude control is attained.The main works in this dissertation are as follows:(1)The six degrees of freedom(6 DOF)nonlinear mathematical model of small scale unmanned quad-rotor is established.Earth coordinate system and body coordinate system are defined for quad-rotor.Then,dynamics equation is established by Newton-Euler method,and kinematics equation is established by geometry method.Finally,the nonlinear mathematical model is simplified by adding some restrictions.(2)A hardware experiment platform of X-type unmanned quad-rotor is designed based on STM32 microprocessor.Modular design has been used in the hardware experiment platform which contains main processor,sensor modular,driver modular,remote control modular,wireless communication modular and power modular.For the platform,dual processors,dual gyroscopes and dual accelerometers are the core parts.(3)The flight control system of small scale unmanned quad-rotor is designed.Attitude calculation and control algorithm are the core parts of flight control system.Quaternion complementary filter algorithm,which fuses the measurement data from gyroscope,accelerometer and magnetometer,has been adopted for attitude calculation to export Euler angles.In order to solve the problem of coupling relationship between attitude control and position control,cascade PID algorithm is used in attitude control,and classic PID algorithm is adopted in position control.(4)Feasibility and effectiveness of flight control system for small scale unmanned quad-rotor are verified by experiments.The contrast experiment of gyroscopes and accelerometers shows that dual sensors can improve measurement precision of attitude.The filter contrast experiment of attitude angle output demonstrates that the quaternion complementary filter algorithm can improve output precision of attitude angle.The experiments of parameter settings for cascade PID and practical flying indicates that the designed X-type unmanned quad-rotor is reasonable and effective with smaller output error.The purpose of getting stable flight attitude control is achieved.