It is required to find DOF for a manipulator which in turn decides the number of actuators required. The task is relatively straightforward for open chains –serial manipulators. In most of these, the chain is composed of links connected through revolute or prismatic pairs. The degrees of freedom simply turn out to be the number of moving links in the open chain - and the number of actuators will equal the degrees of freedom. The word “axis” is often used instead of degrees of freedom. Thus a manipulator with six moving links and as many revolute pairs is called a 6-axis manipulator. Note that the actuator used to power the gripper (open and close fingers etc) is not counted as an “axis” – since the function of the actuator on the gripper is solely to open and close the fingers. Also, the actuator for the gripper does not contribute to the positioning and orienting capability of the end-effector. |
