Research Of Deepwater LBL Positoning And Navigation Technology

With the rapid development of marine technology,the exploitation of deep-sea mineral resource,where the AUV gets used extensively as a convenient exploration tool,is attracting more and more attention.As known,Long Baseline(LBL)positioning technology is one of the requisite methods to ensure the AUV works safely and gets high precision navigation in the deep ocean.Against the background above,influence of different factor was compared and researches which included multiple targets waveform design and detection technology for low-speed movement,holostic adjustment and calibration technology and compensatory technology for movement-error based on Kalman filter was carried out in this paper.For LBL positioning system,robust ranging technology is an essential precondition for high precision positioning,which can be achieved by using frequency-hopping code sequence because of its excellent detection and estimation performance.However,to guarantee the sequence's correlation inhibition performance in sequence construction methods such as the Costas array,contradictions always exist between the sequence quantity and the signal bandwidth and pulse width,which cannot meet the demands that local high precision positioning is offered by quantities of acoustic beacons to cover a wide area in the deep-sea mineral resource exploration.Inspired by the theory of the Costas array in pursuing the perfect pushpin fuzzy function,this paper put forward a sequence expansion method,which gives up the sequence correlation performance under the condition of extensive Doppler frequency shift,to solve the multi-user detection problem and conducted the research in a improved detecting method for the typical detection interference,on the basis of the compression feature of copy-correlation waveform,pulse pair detection and joint detection with copy-relation detection and energy detection.It was proven by the simulation and the experiment that this method ensured high precision ranging and solved the interference problem effectively at the same time.Multi-beacon array not only expands the coverage of LBL,but also brings about problems in calibration precison and efficiency.Calibration method based on the ship survey is affected by the insufficient compensation precison of the deep sea sound velocity and ship's swing,so calibration-precison can hardly be improved,consequently positioning-precison is decreased.In addition,the time spent on calibration is much more than that on exploration,which seriously reduces the operation efficiency.Therefore,a joint calibration method based on holistic adjustment of array net was advanced in this paper,which makes use of high precision ranging data and improves the array configuration relative precison and calibration efficiency.The simulation proved that this approach improved the array configuration relative calibration precison noticeably.It is inevitable that the output data is with invalid or false positioning results and at a low update rate for LBL system when totally depending on acoustic detection,which is not acceptable by the Autonomous Navigation Systems where the real time performances come as the priority.Kalman filter technology has a good effect on data stabilization and output rate boost,but the common model is not easy to converge due to the slow ranging data update rate and serious external interference.In this paper,a divergence restraint method based on the inter-feedback between time delay and position was advanced,which solved the problem that the estimation model and the real motion state do not match.By compensating the ranging sampling time,the positioning error caused by the movement of the target was decreased,a calculation model containing depth information was also analyzed and finally a parameter error detection method based on calculating depth was proposed.It was proven by the experiment that the improved LBL positioning calculating method did promote the stability and reliability of the system.