Attitude control algorithm for a 2-DOF parallel vector propulsion mechanism on AUV

To overcome the disadvantages of some vector propulsion methods, such as external acurators and redundant degrees of freedom, a 2 degree-of-freedom(2-DOF) vector propulsion mechanism scheme is introduced, which is based on limited-DOF parallel mechanism and the actuator can be arranged internally. The fixed platform of the RS+2PRS mechanism can be used as the rear bulkhead of AUV, and the movable platform of the mechanism as the mounting base for the propeller. The proposed mechanism has a compact structure, high stiffness, and is well sealed. The movement decoupling analysis shows that the two independent movable parameters of the mechanism are the precession angle and the nutation angle. The nonlinear mapping model can be built between the Euler attitude angles and the driving parameters of the mechanism. The joint simulation analysis was carried out using MATLAB and ADAMS, and the experiment equipment was built. By changing the relative positions of driving components in two prismatic pairs, the 2 DOF attitude adjustment of the AUV rear propeller can be achieved, and the AUV heading and pitch angles can be adjusted rapidly. Research shows that the physical design of the propulsion mechanism is reasonable, and the attitude control algorithm is correct. This propulsion mechanism can improve the maneuverability and capability of the AUV, and this research lays a theoretical foundation for the further 2 DOF vectored thrust engineering application. © 2019, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.