Research On Calibration Method Of Radial Beam Angle Of Doppler Velocimetry Sonar

Underwater vehicles play an important role in marine resource exploration and national defense,and high-precision navigation is one of the main requirements for underwater vehicles.The Strap-down Inertial Navigation System(SINS)/Doppler Velocity Log(DVL)navigation system has become the mainstream navigation method for underwater vehicles due to its high accuracy,completely independent operation,and concealment.Its accurate DVL calibration results are a prerequisite for high-precision integrated navigation.In order to further improve the accuracy of SINS/DVL integrated navigation,this paper investigates the radial beam angle error during the conversion process between DVL beam radial velocity and 3D velocity,analyzed the causes and effects of radial beam angle error,designed and validated a beam angle calibration method.The beam direction of the piston array DVL originates from the natural directionality of the piston transducer,and its radial beam angle error is related to the assembly accuracy of the transducer.The beam direction of phased array DVL is generated by beamforming technology,and errors in array element spacing and phase shift compensation can affect the accuracy of radial beam angle.Beam angle error affects the accuracy of DVL 3D speed,thereby affecting navigation accuracy.The commonly used DVL calibration methods currently cannot fully correct this error,the large beam angle errors and large carrier sway can increase the residual calibration error.This article proposes two calibration methods for the calibration of DVL radial beam angles:(1)analytical calibration method.Under certain velocity excitation,the conversion formula between radial beam velocity and three-dimensional velocity can be simplified to directly solve for each beam angle.However,this method requires high experimental requirements and is difficult to achieve in practical engineering;(2)The combined calibration method,based on the analytical calibration method,establishes the observation equation of beam angle error and velocity error by analyzing the transitive relation of radial beam angle error in navigation,and designs Kalman filter to realize filtering estimation of beam angle error.The observability calculation and simulation experiments have shown that the combined calibration method is effective.For the combined calibration method,two outfield integrated navigation experiments were conducted using SINS/DVL integrated equipment.On the lake platform,the navigation accuracy of the beam domain calibration method designed in this article is slightly better than that of traditional array calibration methods;On offshore platforms,compared to traditional reference traditional array calibration methods,the navigation error of the beam domain calibration method has been reduced by about 1.5‰.Two experimental results have verified the effectiveness and applicability of the beam domain calibration method.Further analysis of the experimental results shows that in the case of large swing,the speed measurement error caused by beam angle error cannot be fully corrected by the installation deviation angle and scale factor,which is the main reason for the difference in navigation accuracy between the two methods.