Transmitting Beam Control Method of Underwater Acoustic Transducer Array Based on Global Optimization

To improve the performance of the sonar system mounted on the underwater unmanned platform, the beam control method of the compact underwater acoustic transmitting transducer array is studied. For a transmitting array composed of close-packed transducers, many factors can affect the control of the transmitting directivity, such as the position deviation and performance difference of each array element, acoustic scattering, occlusion effect, the mutual coupling among array elements, and so on. To solve this problem, we derive the transmitting steering vector, propose the global optimization method to design the transmitting beam patterns of the compact array, and solve it via second-order cone programming. Then we investigate, by finite-element modeling, the beam control method of a compact linear array. Finally, we manufacture a linear array of eight close-packed ring transducers, use the global optimization method to design the driving-voltage weighting vector, and carry out the experimental verification in an anechoic water tank. The experimental results show that compared with the conventional delay-and-sum (DAS) beamforming method, the proposed method can control the transmitting directivity effectively, suppress the sidelobe significantly, and thus optimize the transmitting beam patterns.