Patent ID: 11883160
Assignee: CHINA NATIONAL INSTITUTE OF STANDARDIZATION
Field: Medical technology (Instruments)
Classification: CPC A  G | IPC A

Claim 7:
8. The positioning method of the FRCS based on the rigid upper arm model according to claim 7, wherein, step 4 comprises:
step 41: projecting the three marking points M1, M2 and M3 on the skin surface of the human upper arm to the reference axis vector, for a time ta in the process, there being relational formulas, {
     
      
       
        
         
          
           
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wherein {right arrow over (Rta1)}represents a vector starting from a perpendicular foot from the marking point M1 to a vector {right arrow over (Atarm )} and pointing to the marking point M1 at the time ta, {right arrow over (Rta2)}presents a vector starting from a perpendicular foot from the marking point M2 to the vector {right arrow over (Atarm )} and pointing to the marking point M2 at the time ta, {right arrow over (Rta3)} presents a vector starting from a perpendicular foot from the marking point M3 to the vector {right arrow over (Atarm )} and pointing to the marking point M3 at the time ta; ntafir, ntasec and ntathd respectively represent ratios of vectors starting from MD and pointing to perpendicular feet from the marking points M1, M2 and M3 to the vector {right arrow over (Atarm )} at the time ta; Mta1 represents position coordinates of the marking point M1 at the time ta, Mta2 represents position coordinates of the marking point M2 at the time ta, Mta3 represents position coordinates of the marking point M3 at the time ta, MtaD represents position coordinates of the midpoint MD at the time ta, and MtaU represents position coordinates of the acromion point at the time ta;
step 42: marking nfir=[nt0fir nt0+Δtfir nt0+2Δtfir . . . ntSfir],, n
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in combining formulas {circle around (6)} with formula {circle around (7)}, and obtaining that at the time ta:, n
    
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step 43: selecting a proportion coefficient ntjal at time tj when arms are vertically downward in a human standing posture as a standard coefficient, adding a correction amount {right arrow over (Atacps )} to the {right arrow over (Atarm )} at the a time ta to make:, n
   
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wherein nal′ and {right arrow over (Atarm′)} after corrected meet requirements of formulas {circle around (4)} and {circle around (5)};
step 44: according to the correction amount {right arrow over (Atacps )} without changing modulus |{right arrow over (Atarm)}| of the central axis vector, obtaining |{right arrow over (Atarm′)}| as follows:

|{right arrow over (Atarm′)}|=|{right arrow over (Atarm)}+{right arrow over (Atacps)}|=|{right arrow over (Atarm)}|  ({circle around (8)});

step 45: in a conical generatrix set satisfying a first column of formula {circle around (6)}, a first column of formula {circle around (7)}, and formula {circle around (8)}, a conical generatrix set satisfying a second column of formula {circle around (6)}, a second column of formula {circle around (7)}, and formula {circle around (8)}, and a conical generatrix set satisfying a third column of formula {circle around (6)}, a third column of formula {circle around (7)}, and formula {circle around (8)}, respectively selecting solutions and combining the solutions to obtain {right arrow over (Atarm′)}, and then obtaining a final correction {right arrow over (Atacps)}, according to the final correction {right arrow over (Atacps)}, rewriting formula {circle around (1)} as:

RCSF=MU+{right arrow over (Acps)}+{right arrow over (Dpm)}  {circle around (13)}

wherein {right arrow over (Dpm )} is resolved according to an axis vector {right arrow over (Arm′)} in a correction direction.