論文提要內容： 本文針對兩指抓取剛體的情況，每個抓取點都是摩擦點接觸的狀態。這情況下提出尋找最理想抓取位置的技巧。本文僅針對剛性球體從事分析，分析過程是利用逆向動力學會產生一階的不確定性，因此可選擇一個接觸力當作未定力，其他所有接觸力（抓取力）數值皆由此力決定，接觸點是否發生滑動也是由此力決定。因此藉由此單一的力可定義出最理想的抓取位置，也就是僅需要最小的正向力就可以避免滑動的位置。此外，本文亦藉由此未定力找出剛好無法抓取球體的位置，在這位置之內區域都是可以抓取的區域。 Abstract: A technique to determine the best grasping positions for a two-fingered grasping is suggested in this thesis. We utilize the fact that there is one degree of indeterminacy in an inverse dynamics problem; implying that one contact force may be chosen as the unspecified force, from which values of all other forces may be determined. Hence the condition for slipping can be expressed in terms of this force. We define the best grasping position as the one that requiring the minimum normal force, whose value is also determined by this unspecified force. In this thesis we only treated the case of grasping a spherical object. Results show that the best grasping position is always on the opposite sides of a great circle. The graspable region can also be determined by locating its boundary, which corresponds to the case that the discriminant of a quadratic equation becomes zero.