DuW=了+A,s9-1-AsP=0 Number of constraint s=2 4,=9,'9,=(9) q=gg)'=(9,yp, Degrees of freedom δ=n-S=4 n=6 Parameters of the constraint i,,s=y）,s9=(x9) Φ》= 。agg儿-    T T , , , Q j Q j Q j P i P i P i i j s  x  y  s  x  y  s  2 Degrees of freedom   n  s  4 Number of constraint   T T j j  j q  r Parameters of the constraint        0 P i i i Q j j j r i j Φ r A s r As ( , )   T T i i i q  r     T T T T T T i j i i j  j q  q q  r r  0                                              P i P i i i i i i i Q j Q j j j j j j j r i j y x y x y x y x          sin cos cos sin sin cos cos sin ( , ) n  6 Bj y  x  O j x  j y  Cj j r  Q Q j r Q j s P i s i x  i y  Ci P ir Bi i r P