Research On Equilibrium And Control Strategy Of A Over-actuated Quadrotor

Quadrotor is a kind of the simple structure,small size,vertical take-off and landing Unmanned Aerial Vehicle,has shown a great application value in the military and civilian areas,and becomes a hot research field in unmanned aerial vehicles.The conventional quadrotor is an inherent underactuated system with six degrees of freedom in space and has only four independent control inputs.Therefore,it has a limited maneuverability;that is,it cannot track an arbitrary trajectory over time.In this thesis,a new over-actuated unmanned aerial vehicle is studied,which provides the independent control of single degree of freedom with more control inputs than the degrees of freedom.Obviously,compared with the classic quadrotor,the over-actuated quadrotor has the advantages of strong environmental interaction ability and wide application range,but its motion characteristics and control methods are more complex.The purpose of this thesis is to study and explore the flight mechanical characteristics of the overactuated quadrotor with tilt mechanism.In this thesis,flight mechanics model of the over-actuated quadrotor is established and simplified firstly.Then the equilibrium equations of six degrees of freedom are derived.According to the underdetermined equilibrium equations,the characteristics of equilibrium in different hover mode are analyzed including the energy consumption characteristics using parameterization method and optimization method.Secondly,For controllability analyzing,8 new equivalent controls are defined and the control derivatives of the over-actuated quadrotor in different equilibrium mode are derived and analyzed.Finally,the control allocation strategies for translational velocity control with constant attitude and attitude control with constant velocity are propose.The control strategies are verified through flight simulations.