Research And Implementation On Multi-Beacon Aided Acoustic AUV Integrated Navigation Algorithm

As the underwater exploration and development keep going deeper into ocean,autonomous underwater vehicles(AUV)nowadays play a significant role in civilian/military underwater application,such as resource exploration and mine exclusion.Accurate acoustic positioning aided integrated navigation system is applied to ensure application effectiveness and recovery safety for vehicles.The multi-beacon navigation system has higher accuracy and coverage than the single-beacon navigation system,but the existing integrated navigation system based on long baseline positioning(LBL)is still defective while applied to the navigation for moving vehicles.In this paper,the principle of LBL is reviewed firstly.Then we pointed out that low update rate of positioning result and poor real-time performance of long baseline positioning system reduce its effectiveness and accuracy while locates/navigates for the vehicle.We proposed an integrated navigation algorithm based on extended Kalman filter,which employs distance and velocity as measurement information.It owns the ability to update location results with any number of beacons in real time.To improve the stability of the navigation system influenced by measured outliers,a least squares extrapolation method with limited confidence is proposed for the preprocessing of the velocity information,and Kalman filtering state and covariance estimation are used to ranging pre-processing.Finally,observable theory of nonlinear system based on Lie derivative is used to analyze the observability of the system.Furthermore,to verify the effectiveness and stability of the proposed algorithm,the tracking performance of the navigation system under different beacon numbers,different and trajectories is simulated.Single beacon navigation system can inhibit error increment with dead reckoning system effectively,but is not able to amend east/west orientation error advisably and timely at the same time.Double beacon navigation system has splendid error convergence speed and positioning accuracy,but is has non-modified area in linear array center.With three beacons auxiliary,system has splendid tracking performance(1.0 ?0.2m)no matter within the beacon array,at the array edge or outside of the array.After that,the influence of beacon calibration error and ranging error on the tracking performance is also analyzed.Finally,based on the algorithm,the lake trial data is processed,whose result shows that,the tracking performance of system is impacted by error of motion model and measurement data jointly.In experiment,the ranging accuracy has a decisive effect on positioning precision of system.Precise distance and effective judgment of leak and mistakenly identified can improve the precision and stability of the system.Under the effective distance information aided,the positioning error of single beacon system can be kept within 5m.And the positioning accuracy of multi-beacon systems can achieve 1.5 ?0.9m,indicates navigation system with data pre-processing can stably provide high precision for the target real-time.