Considering the flectional and rotatable characteristics of the flexible axis of spherical gears and gimbals

a method of making dimensionally vectorial force from the thruster is proposed

by using the flexible axis driving the screw propeller.And then the kinematic model is built with several solution rules

which is simulated in MATLAB

so as to analyze the relationship between the parameters of linear motors and the orientation of the screw propeller.The results reveals that two linear motors could drive the flexible axis to a one and only state

so is the orientation of the vectorial fore caused by the screw propeller.The solution and anlysis of the model will make contribution to the design of the thruster’s control system.