速度分量： =bc0s00 y=-asin 00 C B .0= c (a +b)sin 0 0 M(x,y) bc cos0 be X 京= cot g0, a (a+b)sin0( a+b) ac sin 0 ac (a+b)sin 0 (a+b) 17y B c  b r M(x,y ) a x y  速度分量:       sin cos y a x b = − =   (a b)sin c +  =  cot , ( )sin ( ) cos    g a b bc a b bc x + = +  = ( )sin ( ) sin a b ac a b ac y + = − + = −    17