Frictional torque analyzing and testing of Gimbaled-mirror seeker under changing environment temperature

Nonlinear friction is the main stabilization error source of missile’s seeker. In this paper, the frictional torque of a gimbaled-mirror seeker under changing environment temperature is analyzed. The torque is consisted of rolling friction due to elastic hysteresis, sliding friction due to pivoting and friction torque due to lubricant viscosity. Based on the theory of thermo-elasticity, axial and radial coupling thermal deformation between precision bearing and its installation structure are both included in the analysis model. Coupling deformation dramatically changes the actual contact angle and axial force of bearing, which consequently change the value of frictional torque. Temperature effect on viscosity of lubricant is also studied and improved Walther Equation is used to fit the viscosity- temperature relationship of lubricant. A measure system based on electrical measure method was established and temperature test chamber was used to simulate the temperature changing. Experiment results have shown that this model is accurate for friction torque calculation of gimbaled seeker under changing environment temperature.