Inverse dynamic modeling and analysis of a coaxial helicopter's swashplate mechanism

In this paper, the application of the principle of virtual work to the inverse dynamic modelling of a coaxial helicopter's swashplate mechanism is discussed. The swashplate mechanism is always designed as a configuration of multi closed-loop kinematic chains which dynamics is difficult to be analyzed, especially for coaxial layout. Firstly, the whole mechanism is decomposed into two submodules, the lower one and the middle-upper one, with driving torques of actuators and aerodynamic hinge moments as the input to each submodule respectively. After derivation of Jacobian matrices for the main components, the equations of equilibrium about the two submodules are constructed based on the principle of virtual work and then combined to achieve the complete inverse dynamic model. Furthermore, an integrated actuating system model for coaxial helicopter is established by combining the inverse dynamic model with mechanism kinematics, rotor dynamics, actuator dynamics and command allocation. Based on that model, an efficient approach to load analysis for actuators of helicopter in flight is created. Finally, a series of simulation for load analysis of actuators is performed.