Calibration equipment for rocket nozzle motion testing and its error analysis

The 3D motion parameter measurement of a rocket motor nozzle is a premiss for accurately controlling the nozzle, and the calibration equipment is the key to ensure motion testing at a high precision. To test accurately 3D motion parameters, this paper proposes a new calibration equipment to directly simulate the actual motion of the rocket motor nozzle and to supply the standard position and motion parameters for static and dynamic calibrations. After analyzing the motion of the rocket motor nozzle, a new mechanism consisting of a base, a lifting table, a swing table and a standard nozzle model is proposed, which concludes three degrees of freedom, rotation on X and Y coordinate axes, lifting on Z coordinate axis. The terminal error expression is derived by the theory of multi-system kinematic error in consideration of the geometric errors effect on pointing errors and nozzle center position errors, then the origin of geometric errors is analyzed. By the simulated results, the distribution states of pointing errors and center position errors in rotation ranges are obtained. On the basis of the obtained results, it suggests that the orthogonality errors mostly influncing pointing errors should be controlled below 15″, and the axis intersection errors mostly influncing center position errors should be controlled below 80μm.