Design of Gearless Electromechanical Actuation System for Rudder Control Applications on the Landing Craft Air Cushion Hovercraft

This paper proposes the design method of a gearless electromechanical actuation system (GLEMA) for the application in the steering rudder control on the landing craft air cushion hovercraft. The GLEMA is designed based on the stiffness optimization which has a significant effect on its control accuracy, immunity and dynamic response performance since the actuator is directly connected to the rudder surface without buffer. A detail design of the GLEMA considering the resonance relationship between mechanical stiffness and servo stiffness is presented. The stiffness model was simulated to study the influence of structural parameters on mechanical stiffness and the influence of control parameters on servo stiffness. On the basis of meeting the electrical requirements, detail analysis and stiffness optimization of the GLEMA are discussed. Besides, an adaptive PI position control based on the load observer and feedforward angle controller is used to improve the disturbance immunity and tracking accuracy of the GLEMA. Furthermore, a prototype is manufactured base on the analysis model and the experiment platform is designed. The proposed position control strategy is tested and compared with traditional three-closed-loop control. Finally, the experimental results validated the capability of the GLEMA to obtain the step response accuracy and frequency response accuracy.