Patent ID: 11938636
Assignee: NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS
Field: Measurement (Instruments)
Classification: CPC B  G  Y | IPC B  G

Claim 0:
1. A feature-guided scanning trajectory optimization method for a three-dimensional (3D) measurement robot, comprising:
(S1) building a 3D digital model of an aircraft surface; obtaining a size of the 3D digital model; extracting features to be measured from the 3D digital model; and classifying the features to be measured;
(S2) calculating a geometric parameter of each type of features to be measured; and generating an initial scanning trajectory of each type of features to be measured;
(S3) building a constraint model of the 3D measurement robot; and optimizing the initial scanning trajectory of each type of features to be measured into a local optimal scanning trajectory; and
(S4) based on the local optimal scanning trajectory, planning a global optimal scanning trajectory of the features to be measured of the aircraft surface by using a modified ant colony optimization algorithm;
wherein the step (S3) comprises:
(S31) based on a flange coordinate system of the 3D measurement robot, converting a posture change of the 3D measurement robot during a scanning process into changes of scanning depth d, yaw angle α, pitch angle β and rotation angle ω; and building the constraint model of the 3D measurement robot;
(S32) based on the constraint model of the 3D measurement robot, traversing initial scanning trajectories of all types of features to be measured; and constructing a trajectory optimization evaluating function E, expressed as:

E=5×10−5×√{square root over ((1.2dmax−d)2)}×√{square root over ((ϕ−0.6ϕmin)2)}+λ+μ√{square root over ((φ−0.3φmin)2)};

wherein ϕ is an out-of-plane angle; φ is an in-plane angle; λ is a penalty factor of the trajectory optimization evaluating function; μ is a penalty factor of the in-plane angle; dmax is a maximum scanning depth; and ϕmin is a minimum out-of-plane angle; and
(S33) repeating the step (S32) successively with the scanning depth, in-plane angle and out-of-plane angle as a single variable to minimize the trajectory optimization evaluating function E, so as to obtain the local optimal scanning trajectory of each type of features to be measured, expressed as:, min
   ⁢
      
   
    E
    ⁡
    (
    
     d
     ,
     α
     ,
     β
     ,
     ω
    
    )
   
  
  =
  
   
    5
    ×
    1
    ⁢
    
     0
     
      -
      5
     
    
    ×
    
     
      
       (
       
        
         1.2
         
          d
          max
         
        
        -
        d
       
       )
      
      2
     
    
    ×
    
     
      
       (
       
        φ
        -
        
         0.6
         
          φ
          min
         
        
       
       )
      
      2
     
    
   
   +
   λ
   +
   
    μ
    ⁢
    
     
      
       (
       
        ϕ
        -
        
         0.3
         
          ϕ
          min
         
        
       
       )
      
      2
     
    
   
  
 

 
  	
  
   s
   .
   t
   .
   
    {
    
     
      
       
        
         
          
           l
           i
          
          ≥
          
           l
           min
          
         
         ,
          
         
          i
          =
          1
         
         ,
         2
        
       
      
      
       
        
         φ
         ∈
         
          [
          
           
            
             -
             4
            
            ⁢
            
             0
             ∘
            
           
           ,
           
            4
            ⁢
            
             0
             ∘
            
           
          
          ]
         
        
       
      
      
       
        
         ϕ
         ∈
         
          [
          
           
            ϕ
            min
           
           ,
            
           
            ϕ
            max
           
          
          ]
         
        
       
      
     
     ;
    
   
  
 

wherein li is an effective scanning width of a 3D measurement scanner; lmin is a width between the initial scanning trajectories; φmin represents a minimum in-plane angle; and φmax represents a maximum in-plane angle.