Modeling Of A Unmanned Aerial Vehicle During Take-off/Landing And Flight Dynamics Simulation

The UAV plays an important role in military and civil fields, and has extensive developing prospect. But the technique of take-off and landing is still a weak point which constrains usage of the UAV with fixed wings. Now the mode of automatic take-off and landing with wheels points out a developing trend. In order to realize automatic control during take-off and landing, it is necessary to establish its model, and then study control laws based on the model. In this thesis, the mathematical models during take-off and landing is established.The course of take-off and landing are both divided into three phases:The phase from flying at safe height to contacting the ground. The model of this phase is same with the general model of flight with the only difference of aerodynamic derivatives which allow for ground effect.The phase with nose-wheel off the ground. The phase with three wheels on the ground. When the UAV is taking off, supporting forces, rotational friction and side forces acting on three wheels from the ground is determined. When the UAV is landing, the supporting force and friction are also computed in accordance with braking effect. Then the forces and moments experienced by the UAV are summed up, eventually a full nonlinear model is derived from Newton Second Law.In order to research on flight function and flight control, guide, navigation system, a complete flight real-time simulation system is needed. The flight dynamics system realized in this thesis is a key component of it and comprises three functional modules: the module of aerodynamics deals with aerodynamic derivatives, forces and moments; the module of six-degree model calculates the flight parameters; the module of undercarriage simulates forces and moments acting on the UAV from the ground when it slides on the ground. What is more, the output interface of this system, which means the result can be output to file or Socket port, is also realized. This flight dynamics system can be run independently or integrated with the flight real-time simulation system using an interface which is also carried out.