Research On Waterjet Propulsion And Navigation Control Of Unmanned Vehicles

Small emergency rescue devices have the characteristics of convenient movement and light navigational resistance,etc.The research on rescue devices can promote the development of marine life-saving as well as providing rescue guarantee for offshore workers,which has important theoretical significance and application value.At present,domestic manufacturers still have a big gap in the design of device compared with the developed countries.The aim of this thesis is to design a small rescue unmanned vehicles which can be remotely controlled,stably navigated and applicable in many kinds of water area.The thesis firstly proposes the overall design scheme of the rescue unmanned vehicles including the design of the hull and control function modules.Then through theoretical analysis combined with the numerical model and experimental verification,the thrust of the waterjet propeller is studied.In the following a nonlinear three-degree-of-freedom motion model of the multi-propulsion catamaran under the disturbance of waves is established to analyze the open-loop control of the speed and course of the unmanned vehicles.Finally,the adaptive sliding mode controller is designed to realize stable navigation control under bounded disturbance and parameter perturbation.Detailed information are introduced as follows:1)Based on the working conditions of the rescue unmanned vehicles,determined the design of the hull and selected the functional module.The designed rescue unmanned vehicles adopts the form of multi-waterjet propulsion catamaran the control function modules of which include control center module,navigation and positioning module,communication module,energy management module,etc.2)Through theoretical analysis,numerical modeling and experimental verification,the effect of the speed of both motor and unmanned boat on the thrust of the waterjet propeller is studied.The accuracy of the numerical model is verified by measuring the flow through the mooring test of the propeller.The results show that the energy loss of the waterjet propeller increases lightly with the increase of the speed of the unmanned vehicles.Based on the simulation data set and the regression method of multiple polynomials,the fitting equation of the trust under different working conditions is obtained.3)Based on the force analysis of the unmanned boat,the nonlinear motion model of the multi-propulsion catamaran under the disturbance of wind and waves is established according to the characteristics of multi-propulsion and catamaran.The relationship between thrust and speed,pushing moment and angular velocity is analyzed under different conditions.The analysis results show that the velocity and yaw angular velocity are not stable in the disturbance of wave and the fluctuation percentage decreases with the increase of combined thrust/combined torque.When the turning moment exists,the actual speed tracking design speed will slow down whether there is wave interference or not.4)The speed and course control of under-actuated motion system is analyzed.In the aspect of airspeed control,airspeed controller is designed and compared based on sliding mode method and adaptive sliding mode method,respectively and airspeed tracking performance is analyzed.The results show that both of them can realize speed tracking,but the latter is faster with less consumption when the speed is maintained.In the aspect of course control,the course controller is designed based on backward step method and backward adaptive sliding mode.The analysis shows that both of them can realize the course tracking and the latter has the capability of fast course tracking,small variation of resultant torque and less energy consumption.5)The comprehensive control system of airspeed and course is established.The influence of the nonlinear coupling of airspeed and course on tracking ability and transient response are analyzed from the perspectives of fixed course or varied course while the airspeed is fixed.The results show that the integrated control can track the fixed speed and course well.Through the rapid change of thrust of the propeller,it is still possible to maintain the fixed speed and track the varied course.