Math model of a dual-drive electromechanical steering actuator of a liquid propellant rocket engine

The paper contains development results of math model for dynamics of dual-drive electromechanical steering actuator of the system for controlling the thrust vector of the liquid propellant engine of a crew transportation spacecraft. The steering actuator math model was developed on the basis of a math model of a electromagnetic motor (electric motor with permanent-magnet excitation), as well as math models of electromechanical drives and systems. The paper decomposes the steering actuator into constituent functional elements and develops equations for the moment of inertia of the steering actuator moving parts attached to the shafts of electromagnetic motors, the full moment of resistance to the rotation of shafts in magneto-electric motors, and gear efficiency. It aggregates the non-linear math model of the dual-drive electromechanical steering actuator dynamics. It provides validation results for the developed math model of the dynamics of such steering actuator for both the option where it is operated with one active electromagnetic motor while the other electromagnetic motor stays in cold standby mode and for the option where it is operated with both electromagnetic motors active. Nomograms of transient response and experimental data have a less than 3% discrepancy between them, which validates the developed math model of the dual-drive electromechanical steering actuator.