Dynamic characteristic of rudder loop with rough revolute joint clearance

The joint clearance of rudder loop has a significant impact in achieving the high-precision attitude control of aircraft. This study proposed a novel revolute joint clearance contact model considering surface topography. Such a model identified that the impact dynamic characteristics were significantly influenced by parameters such as contact speed, roughness, and curvature radius of asperities. The dynamic model of the rudder loop was based on the Lagrange equation and the contact model of revolute joint clearance. The results indicated that rudder angle error, contact force, and impact frequency nonlinearly increased along with the increase of motor speed. The increment of joint clearance caused increased rudder angle error and contact force, but a decreased impact frequency. An increase in contact surface roughness decreased the contact force and exerted insignificant effects on rudder angle and impact frequency. To verify the dynamic model, a dynamic characteristic test rig of rudder loop was established. This study can improve the dynamic analysis accuracy of the rudder loop with clearance and provide a solid theoretical basis for solving the high-precision control of the discontinuous structure.