Helicopter Model Research Paper

Robust Control for Helicopter Model D.Supriya1, P.S.Manoharan2, Asst.professor, P.T.R. College of Engineering and Technology, Madurai Associate professor, Thiagarajar College of Engineering, Madurai. [e-mail], [e-mail] Abstract— A paper discusses the problem of designing the robust control for a helicopter model, which is a nonlinear system with two degrees of freedom and cross couplings. The objective of this work is to stabilize the helicopter model, to attain a particular position and to make it to track a reference trajectory using robust µ-synthesis. The control scheme is implemented for the uncertainty and disturbances present in the system. The mathematical model of linearized helicopter

pitch angles of all the blades of the main rotor are changed by an identical amount at every point on azimuth, but at the constant rotor speed. However, in case of helicopter model, pitch angles of all blades are fixed and speed control of the main rotor is employed to achieve vertical control. Similarly, yaw control in a helicopter model is varied by varying the voltage of the power supplies to the DC motors. A change in the voltage value results in a change in the rotation speed of the propeller. This further result in a change of the corresponding position of the beam. Thus the control inputs to the system are the voltages of the power supplies to the DC motors. There are four state variables that are measured, which are known as vertical angle, horizontal angle, vertical angular velocity and horizontal angular velocity. The vertical and horizontal angles are physically measured using incremental encoders placed at the

As shown in Fig., the pitch is defined when the nose of the helicopter goes up and the yaw is defined positive for a clockwise rotation. Also in Fig., there is a thrust force F_Pacting on the pitch axis that is normal to the plane of the front propeller and a thrust force acting F_yon the yaw axis that is normal to the real propeller. Therefore a pitch torque is being applied at a distance r_Pfrom the pitch axis and a yaw axis is applied at a distance r_yfrom the yaw axis. The gravitational forceF_g, generates a torque at the helicopter centre of mass that pulls down on the helicopter nose. As shown in Fig., the centre of mass is a distance of l_cmfrom the pitch axis along the helicopter body length.

The Euler Lagrange method is used to derive the nonlinear equations describing the motions of the helicopter. From its nonlinear equations of motions, the linear state-space model of the helicopter is found in 4. The potential energy due to gravity is

V=m_heli 〖gl〗_cm sin⁡θ (3.1)

The total kinetic energy is

T=T_(r,p)+ T_(r,y)+T_t