Research On Autonomous Planning And Control Technology Of Submarine In Special Polar Environment

The Arctic is not only rich in natural resources,but also the region with the shortest distance to the three continents of North America,Europe and Asia.Therefore,the strategic significance of the Arctic region is extremely important.However,the unique geodynamic environment,geophysical field environment,meteorology/hydrology and other natural environments in the Arctic have many effects on the track planning and automatic driving of unmanned underwater vehicles in the Arctic.Firstly,the influence of polar environment on the path planning and automatic control of unmanned underwater vehicle and the research on the motion modeling of unmanned underwater vehicle are analyzed.On this basis,the research on the path planning algorithm in polar environment and the research on automatic driving and obstacle avoidance in polar environment are carried out.The main research work includes:(1)In view of the great difference between the path planning and automatic driving of the unmanned underwater vehicle in the polar marine environment and the middle and low latitude marine environment,this paper expounds the influence of the polar environment on the autonomous planning and control of the unmanned underwater vehicle compared with the middle and low latitude marine environment,and puts forward the solution.The influence of polar environment on track planning is mainly reflected in that the distance algorithm in the traditional algorithm is not suitable for the terrain data used in this subject,so the algorithm for calculating distance in polar environment is improved;The unique sea ice in the polar region will also affect the track planning of unmanned underwater vehicles,and the influence of sea ice is added to the decision-making factor of track planning;The influence of polar environment on the autopilot of unmanned underwater vehicle is mainly reflected in that with the increase of latitude,the traditional North pointing inertial navigation system is difficult to be suitable for polar navigation.Therefore,grid inertial navigation algorithm is used instead of North pointing inertial navigation algorithm.(2)In order to improve the authenticity of unmanned underwater vehicle simulation,it is necessary to carry out low error spatial motion modeling for the submarine,introduce the control information of the submarine and the external environment of the submarine simulation,and construct a near real unmanned underwater vehicle motion model,so as to provide a more accurate model for the track planning and motion control of the unmanned underwater vehicle.Through the study of the six degree of freedom motion model of the submarine,the motion model of the submarine is appropriately simplified on the premise that it has little influence on the simulation results and motion characteristics of the unmanned submarine.(3)Aiming at the problem that the existing track search algorithm has poor adaptability to track planning in polar environment,the traditional a*track search algorithm is improved.Based on the idea of artificial potential field,the calculation methods of altitude constraint cost of fixed depth cruise and terrain(sea ice)obstacle avoidance constraint cost of unmanned underwater vehicle are improved.Combining the fixed depth cruise altitude constraint cost,terrain(sea ice)obstacle avoidance constraint cost,shortest distance track constraint cost,terrain following constraint cost and threat avoidance constraint cost with a*track search algorithm,an improved a*track search algorithm is obtained.The simulation results show that by adjusting the weight coefficients of the cost function,the planned track can fit the task.(4)Aiming at the danger caused by ignoring the collision threat in the process of autonomous driving of unmanned underwater vehicle,combined with the track points given by the track planning algorithm,an autonomous driving and obstacle avoidance algorithm based on the improved dynamic window method is designed.When the unmanned underwater vehicle detects that there is no obstacle within the safe distance,it will execute the heading angle control algorithm;When an obstacle is detected within the safe distance,the control algorithm switches to the dynamic improved window method for obstacle avoidance until there is no obstacle within the safe distance of the submersible.The simulation results show that the algorithm has good dynamic switching ability,and can increase the distance between the submarine and obstacles and improve the navigation safety on the premise of track tracking.