Motion Control And Attitude Regulation Of Underwater Thermal Glider

Underwater thermal glider, as a new kind of AUV (AutomotiveUnderwater Vehicles), has a great prospect of application in the field ofmarine research, marine resource exploration, seabed terrain detection,marine environmental monitoring, military and economy with theadvantage of small volume, low energy consumption, unpolluted, and so on.Based on Newton-Euler theory and Kirchhoff equation, the underwaterthermal glider six-degree freedom model equipped with ballast and internaladjust mass is derived from defining mass of each module of underwaterthermal glider, body motion equations, ballast and internal adjust massmotion equations. This model both include the general items such asbuoyancy, gravity, hydrodynamic effects, add mass and inertial and theindependent equations of ballast and internal adjust mass. It facilitates tostudy the interaction between glider body and ballast and internal mass,respectively. Using the nonlinear feedback transformation method, theinternal mass motion system was changed into a suspension system, whichconfines the motion range of internal mass into the internal shell space.Through study on the glider dynamics, the relationships among forces,velocities, accelerations of the internal adjust mass, ballast and glider bodywere carried out and the intrinsic nature of underwater thermal glider systemwas revealed.Using small perturbation linearization method, the stabilization andcontrollability of the longitudinal motion were studied and a LinearQuadratic regulator was designed for balanced gliding motion control. Theconsidered finite-time transition was treated as a two-point boundary valueproblem. Based on nonlinear stable-inversion technique, a feed-forward controller was designed. The effectiveness of the designed controller wasverified through numerical simulation.Based on theoretical analysis, the underwater glider prototype wasdesigned, which include the design of pressure shell, mechanism ofattitude regulation system, electric control system and debug system,respectively. In order to use the loading space effectively, the spaceposition and mass distribution of each module were calculated. Based onthin-walled column intensity checking theory, the thickness of the gliderpressure shell was calculated and verified through water pressure integritytest.In this thesis, the experimental system used to determine theperformance of attitude regulation mechanism was designed. Adjustmentperformance of pitch angle and roll angle adjust mechanism were carriedout respectively. Test results show that the designed adjust system fulfillregulation precision requirement.In order to carry out underwater thermal glider adjustmentperformance test, a test system was designed based on ocean thermoclinesimulation pool. Using designed test system, underwater gliderperformance of pitch angle and roll angle regulation were carried outrespectively, which provide test data for further research on underwaterglider control.