Path Plan For Single Beacon Navigation And Positioning Technology

Autonomous Underwater Vehicle(AUV)has been used in many domains.It plays an important role in ocean environment monitoring,submarine mapping,submarine cable laying and other civilian fields,and the use of AUV has been emphasized in military fields such as minefield detection and underwater target strike.Since an accurate position information is the premise of these applications,accurate navigation is one of main technical challenges for AUV.AUV navigation techniques can be divided into three categories including inertial/dead reckoning,geophysical navigation techniques and acoustic navigation techniques.In this thesis,we focus on the research on single beacon navigation belonging to the third category.The two existing navigation methods for single beacon are introduced,which utilize the time of arrival(TOA)and the time difference of arrival(TDOA)respectively.The geometric essences of them are given and their navigation precisions are studied with the method of partial differential matrix.In addition,the robustness against several kinds of errors is discussed,including the beacon coordinate's error,TOA error,sound speed error etc.For the method based on TOA,a path plan is presented to improve its navigation precision.By analyzing the effect of the geometric relations between two navigation points and the beacon on navigation precision,we find that there is an optimal radius for circular trajectory and it deserves the best performance that the angle at beacon is approximately a right angle.Based on these,we propose the path plan including route design and navigation point design.Then,the method of approaching the designed optimal route is presented.The tracking model based on TOA is built to estimate the real-time coordinate of AUV and an approaching trajectory is designed according to the estimated coordinate.Finally,several groups of simulations is implemented to validate the effectiveness of the proposed methods.Under the asynchronous condition,the method based on TDOA generally has a poor performance although it can get rid of this synchronization error.In order to improve the precision for asynchronous navigation,a new navigation method for single beacon based on TDOA and phase difference(PD)is presented.First of all,a scheme to obtain the PD information is proposed via signal alignment,conjugate multiplication,phase unwrapping,and linear fitting(or quadratic fitting),successively,and the equations based on TDOA and PD are established to solve the AUV's coordinate.Then its navigation precision and robustness against several kinds of errors are analyzed.Next the tracking model based on TDOA and PD is constructed to gain a higher navigation precision compared with the proposed navigation method.At last,the effectiveness of the method is validated through several groups of the simulations.