Robots generally need to move or re-arrange objects in their workspace, aka manipulation. Manipulation is accomplished through an end-effector. An end effector can be a tool but more general-purpose end -effectors try to duplicate the flexibility of the human hand. Research in manipulation tends to be either in motion control and planning (getting the end-effort to the right place and position), mobile manipulation (manipulating or pre-grasping while walking or rolling but also not falling over because the arm is stretched out too far), or dexterous grasping