Patent ID: 11886162
Assignee: GUANGDONG OCEAN UNIVERSITY
Field: Control (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for identifying pitch error and yaw error of a numerically-controlled (NC) machine tool, comprising:
(S1) acquiring a Cartesian coordinate system of a target machine tool;
(S2) setting each axis of the Cartesian coordinate system as movement axis; wherein each of the movement axis has three measurement trajectories; and the three measurement trajectories are mutually parallel to a corresponding axis, and are not on the same plane;
(S3) selecting one of the axis of the Cartesian coordinate system as the movement axis; and obtaining positioning error data between an actual operation measurement point and an ideal operation measurement point of the target machine tool, when the target machine tool moves along the three measurement trajectories corresponding to the movement axis; and
(S4) according to a spatial angle geometric relationship and the positioning error data, obtaining a pitch error angle and a yaw error angle of the target machine tool;
wherein the spatial angle geometric relationship is obtained through steps of:
selecting the actual operation measurement point from each of the three measurement trajectories in step (S3) to form a plurality of actual operation measurement points;
connecting the plurality of actual operation measurement points to form an error plane;
projecting a normal vector of the error plane respectively onto two coordinate planes of the Cartesian coordinate system where the movement axis in step (S3) is located to obtain a first projection vector and a second projection vector; and
taking an included angle formed by a unit vector of the movement axis and the first projection vector as the pitch error angle, and an included angle formed by the unit vector of the movement axis and the second projection vector as the yaw error angle;
for the ideal operation measurement point Pvik (luvik, lvvik, lwvik) and the actual operation measurement point Pvik′ (luvik′, lvvik′, lwvik′), the pitch error angle and the yaw error angle are expressed as follows:, θ
    
     wv
     1
    
   
   =
   
    arc
    ⁢
      
    cos
    ⁢
    
     
      
       
        (
        
         
          l
          
           wv
           i
          
          
           k
           2
           ′
          
         
         -
         
          l
          
           wv
           i
          
          
           k
           1
           ′
          
         
        
        )
       
       ⁢
       
        (
        
         
          l
          
           uv
           i
          
          
           k
           3
           ′
          
         
         -
         
          l
          
           uv
           i
          
          
           k
           1
           ′
          
         
        
        )
       
      
      -
      
       
        (
        
         
          l
          
           wv
           i
          
          
           k
           3
           ′
          
         
         -
         
          l
          
           wv
           i
          
          
           k
           1
           ′
          
         
        
        )
       
       ⁢
       
        (
        
         
          l
          
           uv
           i
          
          
           k
           2
           ′
          
         
         -
         
          l
          
           uv
           i
          
          
           k
           1
           ′
          
         
        
        )
       
      
     
     
      
       
        
         [
         
          
           
            (
            
             
              l
              
               vv
               i
              
              
               k
               2
               ′
              
             
             -
             
              l
              
               vv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
           ⁢
           
            (
            
             
              l
              
               wv
               i
              
              
               k
               3
               ′
              
             
             -
             
              l
              
               wv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
          
          -
          
           
            (
            
             
              l
              
               vv
               i
              
              
               k
               3
               ′
              
             
             -
             
              l
              
               vv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
           ⁢
           
            (
            
             
              l
              
               wv
               i
              
              
               k
               2
               ′
              
             
             -
             
              l
              
               wv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
          
         
         ]
        
        2
       
       +
        
       
        
         [
         
          
           
            (
            
             
              l
              
               wv
               i
              
              
               k
               2
               ′
              
             
             -
             
              l
              
               wv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
           ⁢
           
            (
            
             
              l
              
               uv
               i
              
              
               k
               3
               ′
              
             
             -
             
              l
              
               uv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
          
          -
          
           
            (
            
             
              l
              
               wv
               i
              
              
               k
               3
               ′
              
             
             -
             
              l
              
               wv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
           ⁢
           
            (
            
             
              l
              
               uv
               i
              
              
               k
               2
               ′
              
             
             -
             
              l
              
               uv
               i
              
              
               k
               1
               ′
              
             
            
            )
           
          
         
         ]
        
        2
       
      
     
    
   
  
  ;
 

wherein luvik represents an ideal operation distance, and luvik′ represents an actual operation distance;
a superscript k represents a measurement trajectory of the three measurement trajectories;
u, v and w in a subscript respectively represent an error direction, and each are selected from x, y and z axes;
vi in the subscript represents a movement direction, wherein i represents an i-th measurement point on a measurement trajectory k of the three measurement trajectories;
v is selected from the x, y and z axes; and
i is 1, 2, . . . .