4.
写出两杆之间的位姿矩阵从坐标系Oi-1-xi-1yi-1zi-1到坐标系Oi-xiyizi的变换矩阵为：
后置坐标系法Aii 1 R ( zi 1 , qi )Trans (0, 0, d i )Trans (ai , 0, 0) R ( xi , a i ) R ( zi 1qi )Trans (ai , 0, d i ) R ( xi , a i ) cos qi sin q i 0 0 cos qi sin q i 0 0 sin qi 0 0 1 0 0 ai 1 0 cos qi 0 0 0 1 0 0 0 cos a i 0 1 0 0 0 1 d i 0 sin a i 0 0 1 0 0 0 1 0 0 cos a i sin qi sin a i sin qi ai cos qi cos a i cos q i sin a i cos qi ai sin q i sin a i cos a i di 0 0 1 0 sin a i cos a i 0 0 0 0 1