Altitude cascade control of an avian-like flapping robot considering articulated wings and quasi-steady

This paper intends to stabilize the flight of an avian-scale flapping robot with articulated. Modeling has been performed using Multibody dynamics, considering a tail.  The equations of motion have been derived from Lagrange equations. Kampf mechanism, inspired by the birds, is used to drive the inner and outer wings with a phase shift. The aerodynamic model has been obtained from applying the blade element theory to the wings divided into twelve elements, considering the inner and outer wing distinction. The aerodynamic forces emerging from the movement of wing elements, in terms of flapping frequency and flight speed, are determined separately. Regarding the flight path angle and effective angle of attack, aerodynamic forces of the entire wings have been achieved in horizontal and vertical axes. The coupling of aerodynamic and dynamic completes the nonlinear time-periodic equations. Due to the impact of the fuselage pitch angle on the flight altitude, the cascade control was used to control fuselage and tail pitch angles in inner loops and altitude in the outer one. Proportional-derivative-integral control has been used to control the performance of the loops, the coefficients of which have been optimally designed