| Quadrotors have been widely applied in the field of detection,inspection,security,and aerial photography because of the simple structures and control algorithm,efficient modularization and modest cost.However,the dynamic performance and anti-disturbance ability are affected by its under-actuated characteristic.Consequently,the article designs the quadrotor actuated by bidirectional motors,as well as the corresponding flight control algorithm and components to improve the dynamic performance of attitudes and trajectories tracking with disturbance rejection,which is verified and tested in both simulation and experiment.The results and innovations are illustrated below:Firstly,the kinetic and dynamic modeling based on quaternion is conducted in the common coordinate systems to avoid singularity phenomenon when wide-range maneuver occurs,and the attitude transformation matrix based on quaternion is derived.Secondly,the functional logics and with-load transfer function model of bidirectional motor are analyzed.The attitude-position cascade control system is designed after the implementation of PID and ADRC controllers and parameter tuning.The torque of roll,pitch and yaw of bidirectional motors is analyzed with the proof of stability.The corresponding control allocation matrix of bidirectional motors is designed,that is,the mapping from motor speed to thrust and torque.Thirdly,the differential flatness of quadrotor is used to build plane model,which conducts path planning of point-to-point,point-to-vertical and flip by means of hp-adaptive pseudospectral optimal control method.The maneuverability of quadrotor actuated by bidirectional motors is proved to be possible.Lastly,the quadrotor simulation system is built,including motors,electronic speed controllers,physical frames,controller and other components,to perform tracking of attitudes and trajectories.To improve mobility and to apply flight control algorithm,the architecture of quadrotor is designed with light-weight frame,bidirectional rotors,programmable flight control board and electronic speed controller,in which the experiments to test thrust and torque and tracking attitudes are conducted.The simulation results state that bidirectional motors can use reverse current to drive motors to decelerate and reverse-rotate rapidly,the quadrotor driven by bidirectional motors can improve the rapidity of tracking the attitude angle and spiral trajectory,and the ADRC controller can effectively enhance anti-disturbance ability.The motor test verifies that the collocation of blade and motor can generate considerable thrust and torque with direction-changing rapidity.The quadrotor driven by bidirectional motors can track both step-single-axis attitude angles and sinusoidal-double-axis attitude angles,and improves dynamic performance compared to quadrotor driven by unidirectional motors. |
