Research On Multi-beam Precise Footprints Reduction Model Considering The Attitude Change During The Transmission Period

Footprints reduction is an important process of post-processing multi-beam bathymetric data,which directly affects the accuracy of the final topography data.In the footprints reduction process,attitude correction is one of the key links to control the quality of multi-beam sounding data.Correctly analyzing the effect of multi-beam transducer attitude is particularly important for improving the accuracy of multi-beam sounding data.Because the multi-beam transducer is divided into an independent transmitting array and receiving array and there is a time difference in the beam propagation process,therefore,in addition to the attitude at the moment of beam transmission or reception,there must be a change in the attitude of the transducer during the beam propagation process.Most of the existing research regard the multi-beam transmitting and receiving transducers as a whole,and believe that the transducer has the same attitude at the time of beam transmitting and receiving,and does not take into account the impact of the attitude changes in the process.In this regard,this paper focuses on the research of the attitude of the transducer,and first studies the impact of transducer attitude changes on sounding results at the time of beam transmission and reception,and then proposes a footprints reduction model based on the hyperbola intersection taking into account the attitude change.The main research work is as follows:(1)Summarizes the parameters involved in the footprints reduction process and two common footprints reduction models.Through in-depth study of the process of multi-beam footprints reduction,the parameters involved in the process are summarized in detail,and the calculation process of the sounding point coordinates of the conventional footprints reduction model and virtual concentric array model is further collated.(2)Based on the principle of multi-beam measurement,the conventional footprints reduction model and the VCCA model,studied the effect of the attitude change of the multi-beam transducer on the sounding results.Firstly,based on the principle of multibeam measurement,analyzed the influence of the attitude angles of the transducer on the sounding results;Then,set the simulation data,used the conventional footprints reduction model and VCCA model to calculate the beam footprint coordinates,and compared the results of the two algorithms to analyze the effects of a single roll(pitch,bow)change and comprehensive attitude change on the sounding results,and further analyze the applicability of the conventional footprints reduction model.(3)A multi-beam sounding footprints reduction algorithm based on hyperbola intersection is proposed.The algorithm is based on the VCCA model and abstracts the energy of the transmitted and received beams into two regular conical surfaces with the same vertex,then the beam footprint as the intersection point of the two hyperbola formed by the plane projection of the transmission cone and the reception cone.The hyperbolic parameter definition and solution method are derived,and the beam footprint coordinates are calculated by solving the intersecting hyperbolic equation.The experimental analysis selects the measured shallow and medium-deep water data,uses the conventional beam homing algorithm,the algorithm in this paper and the VCCA algorithm to process the data,and analyzes and compares the data results to verify the effectiveness of the algorithm.