Research On Motion Control Of Tilting Quadrotor Based On The Combination Of Backstepping And QP

Due to the increasing maturity of micro-electromechanical technology,unmanned aerial vehicles are used in daily life in a plurality of fields,and the demand for interactive operations between aircraft and the environment has been more and more prominent.In order to overcome the shortcomings of the underdrive of the traditional quad-rotor and realize the independent control of the aircraft position and attitude,this paper takes the quadrotor with tilting propellers as the research subject,and research on its system modeling,motion control,control distribution,prototype trial production and debugging.The main research contents of the thesis are as follows:(1)System modeling:In this paper,four servos are added to the traditional quad-rotor,so that the propeller of the aircraft can tilt around its arm,and generate force in both the horizontal and vertical directions.Because it is different from the traditional multi-rotor layout structure,the kinematic model is constructed by the rotation matrix through coordinate transformation,and the six-degree-of-freedom motion control model in space is described by Newton’s Euler method,under the aircraft body coordinate system.(2)Research on motion control:Considering that the eight-input six-output model of the tilting quadrotor aircraft is more complicated and expensive linearization cost,the nonlinear backstepping method is employed for control.In order to avoid the difficulty of deriving the virtual control law in the calculation process of the backstepping method,a filter was used to replace the derivation operation with an integral operation,and an integral term for the system error was proposed to build up the stability of the system,and the integral command filter backstepping controller is designed;And,the unknown external disturbance is identified by a nonsingular terminal sliding mode disturbance observer.The simulation depicts that the proposed controller can complete the tracking of the three-dimensional trajectory in less time,and the tracking effect is more accurate.(3)Research on control distribution:Aiming at the characteristics of the tilting quadrotor as an overdrive system,the control distribution scheme is studied,and two control schemes are proposed.First of all,under ideal conditions without considering the actual physical constraints of the actuator,linearize the nonlinear control allocation problem into a linear unconstrained optimization problem,and use the generalized inverse method to solve it;And then,considering the physical constraints of propeller lift and motor tilt angle in actual flight.The target function is chosen as the consumption of the tilting quadrotor,and the distribution problem can be transformed into a nonlinear quadratic programming problem.Simulation comparison experiments depict that the two allocation methods are effective,and the quadratic programming method can achieve better allocation effects than the generalized inverse method,and avoid control overshoot when the trajectory changes in control.(4)Prototype trial production:Based on the classic four-rotor F450,this paper designs and builds a test prototype of a tilt-rotor aircraft.With the help of Matlab/Simulink platform,Pixhawk Support Package(PSP)toolbox and RflySim platform,the feasibility of independent position and attitude control of the tilt-rotor was debugged and verified.