Study On Key Technologies Of New Water-jetpropulsion Type Underwater Robot

Along with the traction of market demand and the promoting of science and technology, underwater robot has become a recognized and important means of development and utilization of ocean. Traditional underwater robot(also called underwater vehicle) is propelled by propeller propulsion and its own attitude is controlled by propeller’s rudder surfaces. Although such propulsion mode has certain convenience and practicability, it is of a number of deficiencies. For example, using such propulsion mode and gestures control mode, it is very difficult to maneuverably drive the underwater robot in low speed and with large angle of attack while attempting to achieve complex movement. Moreover, the noise of the operating propeller, in a certain extent, reduces the concealment of underwater robot. To solve these problems, we, based on the principle of water jet propulsion, studied a new type of water jet propulsion underwater robot. It substitutes propeller with four uniform arranged water jets, and is equipped with 3-DOF(degree of freedom) flexible thrusting limbs. They can easily change the direction of thrust and gestures with stabilizing fins on the limbs. Meanwhile, introducing four vector propulsion system layout solved the problems in traditional underwater robot: simplex motion and poor performance in concealment and maneuverability. In order to further improve the proposed underwater robot’s maneuverability in diving depth control when sailing, we used scalable accordion-case-like compression cylinder structure to control its overall buoyancy and achieved accurate control on diving depth.After having developed three previous generations of water-jet type underwater robot, we here design and develop a new type underwater robot which can sail in omnidirection with given gesture by coordinating propulsion direction and thrust of four vector water jets. The main work and achievements in the thesis are as follows:(1) Designed the structure of four 3-DOF axisymmetric-type propulsion limbs fo such robot and realized their movements, designed the scalable accordion-case-like compression cylinder and fin-shaped structures to ensure the smooth implementation of adjustable diving depth design and production. Besides, waterproof design, gravity, buoyancy computing and the rationality of the structure and reliability were all considered and discussed in the design process;(2) Kinematics and dynamics model of such robot were established, transformation of robot space motion between fixed and mobile coordinate systems was clearly illustrated and a six degrees of freedom motion equation was given.(3) Hardware and software of the control system was designed and a corresponding control scheme of motion was presented;(4) Virtual simulation was carried on such underwater robot.This thesis, centering on the new water-jet-propulsion-type underwater robot research, made some breakthrough in its key technology, successfully resolved its accurate control of diving depth and flexible manipulation of sailing directions. What was discussed in this thesis plays an important role in improving the performance of underwater robot and can provide theoretical reference and technical support to subsequent research.