Mathematical Modeling and Dynamic Analysis of a Spherical Contact Vector Thruster

In this paper, a novel spherical contact vector thruster based on gear train, hydraulic cylinder and spherical motor is proposed. In the mechanism, the spherical motor forms a spherical contact with the fairwater. Firstly, according to the classical navigation mechanics theory, the space transformation analysis of the propeller shaft coordinate system is carried out, and the mathematical model of the vector thruster is established. The ranges of roll angle chi and swing angle delta of the propeller shaft are determined. Secondly, the roll and swing motions of the mechanism driven by gear transmission and hydraulic cylinder transmission are analyzed, and the kinematic relationship of the whole vector mechanism is systematically analyzed. The accuracy of the mathematical model is verified by the motion simulation using SolidWorks and MATLAB. Thirdly, the motion trajectory and motion time of the propeller shaft reaching the target position under the three motion modes are compared and analyzed. It is pointed out that the roll swing compound motion is more appropriate. Finally, the dynamic analysis of the vector thruster is carried out, and the change trends of the scaling factors of the vector thrust components with swing angle delta and roll angle chi are studied. Compared with the scaling factors of the vectored water jet propeller proposed in the literature, it is concluded that the spherical contact vector thruster can provide larger lateral force. Therefore, the spherical contact vector thruster has more superior maneuverability.