“…As we mentioned previously, the grasping tasks is a task-priority based behavior. The task-space DOFs [13] are used to describe the required DOFs to accomplish the grasping task; so we define n1, n2, and n3 to represent the task-space DOFs of the endeffector position, the end-effector attitude, and the base attitude constraints, respectively, (herein, for spatial case, n1=n2=n3=3; for planar case, n1=2 and n2=n3=1) [14]. Furthermore, the relationship between the grasping tasks and the minimum task-space DOFs is concluded in Table 1.…”