Patent ID: 11874371
Assignee: ZHEJIANG UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A sparse optimization method based on cross-shaped three-dimensional imaging sonar array, comprising the following steps:
constructing a beam pattern BP(W,u,v,δ,fj) simultaneously applicable to a near field and a far field based on a cross-shaped array, the beam pattern BP(W,u,v,δ,fj) being:, BP
    ⁡
    
      (
      
        W
        ,
        u
        ,
        v
        ,
        δ
        ,
        
          f
          j
        
      
      )
    
  
  =
  
    
      
      
        
          ∑
          
            n
            =
            0
          
          
            N
            -
            1
          
        
        ⁢
        
          
            ω
            n
          
          ·
          
            exp
            ⁡
            
              [
              
                
                  
                    -
                    j
                  
                  ⁢
                  
                    
                      2
                      ⁢
                      π
                      ⁢
                      
                        
                      
                      ⁢
                      
                        f
                        j
                      
                    
                    c
                  
                  ⁢
                  
                    
                      y
                      n
                    
                    ·
                    v
                  
                
                +
                
                  δ
                  ⁢
                  
                    
                      y
                      n
                      2
                    
                    2
                  
                
              
              ]
            
          
        
      
      
    
    ×
    
      
      
        
          ∑
          
            m
            =
            1
          
          M
        
        ⁢
        
          
            ω
            m
          
          ⁢
          
            exp
            ⁡
            
              [
              
                
                  
                    -
                    j
                  
                  ⁢
                  
                    
                      2
                      ⁢
                      π
                      ⁢
                      
                        
                      
                      ⁢
                      
                        f
                        j
                      
                    
                    c
                  
                  ⁢
                  
                    
                      x
                      m
                    
                    ·
                    u
                  
                
                +
                
                  δ
                  ⁢
                  
                    
                      x
                      m
                      2
                    
                    2
                  
                
              
              ]
            
          
        
      
      
    
  

wherein, W is a weight coefficient of the array, including a weight coefficient ωn of a vertical transmitting array and a weight coefficient ωm of a horizontal receiving array;
fj is a transmitting frequency of a vertical beam in j direction;
xm is a position of the m-th element of the horizontal receiving array;
yn is a position of the nth element of the vertical transmitting array;
c is a speed at which sound waves propagate in water;

δ=1/r−1/r0;

r is a target distance;
r0 is a beam focusing distance;

u=sin βa−sin θa;

v=sin βe−sin θe;

βa is a horizontal beam-arrival direction;
θa is a horizontal beam-focusing direction;
βe is a vertical beam-arrival direction;
θe is a vertical beam-focusing direction;
when δ=0, BP is a far field beam pattern; when δ≠0, BP is a near field beam pattern;
constructing an energy function E(W,A) required by sparse optimization according to the beam pattern BP(W,u,v,δ,fj), the energy function E(W,A) being:, E
    ⁡
    
      (
      
        W
        ,
        A
      
      )
    
  
  =
  
    
      
        
          k
          1
        
        ⁡
        
          (
          
            
              ∫
              
                δ
                ⁢
                min
              
              
                δ
                ⁢
                
                  
                
                ⁢
                max
              
            
            ⁢
            
              
                (
                
                  
                    ∑
                    
                      
                        (
                        
                          u
                          ,
                          v
                        
                        )
                      
                      ∈
                      Ω
                    
                  
                  ⁢
                  
                    (
                    
                      
                        
                          B
                          ⁢
                          
                            P
                            ⁡
                            
                              (
                              
                                W
                                ,
                                δ
                                ,
                                u
                                ,
                                v
                                ,
                                
                                  f
                                  j
                                
                              
                              )
                            
                          
                        
                        
                          B
                          ⁢
                          
                            P
                            
                              M
                              ⁢
                              A
                              ⁢
                              X
                            
                          
                        
                      
                      -
                      
                        b
                        d
                      
                    
                    )
                  
                
                )
              
              ⁢
              d
              ⁢
              δ
            
          
          )
        
      
      2
    
    +
    
      
        k
        2
      
      ⁢
      
        A
        2
      
    
    +
    
      
        
          k
          3
        
        ⁡
        
          (
          
            
              R
              o
            
            -
            
              R
              d
            
          
          )
        
      
      2
    
  

wherein, k1, k2 and k3 are the weight coefficients of the corresponding items; bd is the desired beam pattern sidelobe peak; Rd is the ratio of the maximum weight coefficient to the minimum weight coefficient in the weight coefficient matrix W; Ro is the ratio of the desired maximum weight coefficient to the minimum weight coefficient; the value range Ω of u and v corresponds to the part of the sidelobe beam whose intensity is greater than bd; δmin and δmax represent the minimum and maximum values of S, respectively;
introducing an array element position disturbance into a simulated annealing algorithm, and using the simulated annealing algorithm to sparse optimization of the energy function E(W,A); and
after optimization, obtaining a sparse optimization cross-shaped array.