FANUC R2000ib 165F R30ia FANUC Lr Mate 200id FANUC M710ic 50 R30ia FANUC M-2000ia FANUC Arcmate 100ic R30ia

Robotic Degrees of Freedom

One of the key characteristics of an industrial robot is the number of axes it has. It is often one of the first items listed when viewing a robot’s specifications. However, many may not understand the importance of the axes and how they control a robot’s range of motion. Each axis of a robot represents a degree of freedom or in simpler terms an independent motion. Each axis allows a robot to gain a degree of freedom, meaning it has increased functionality. The more axes a robot has, the more degrees of freedom it has which allows it access to greater amounts of space.

The most common robots have between four to six axes, but they can have a little as one axis or as many as ten or more. Six-axis robots such as the FANUC M-10ia or the FANUC R-2000ib are heavily utilized in industrial settings because they provide more functionality with six degrees of freedom. The six-axis robot is designed to mimic the human arm, since human arms have six degrees of freedom. Having six degrees of freedom also allows every angle of a unit of space to be reached. Below is a breakdown of the degree of freedom provided by each axis of a robot:

  • Axis 1 - Axis 1 allows the robot to rotate from its base.
  • Axis 2 - Axis 2 provides the robot with forward extension and back extension of its lower arm.
  • Axis 3 - Axis 3 provides the robot the ability to raise and lower its upper arm.
  • Axis 4 - This axis can rotate the robot’s upper arm in a rolling motion.
  • Axis 5 - Axis 5 raises and lowers the wrist of the robot’s arm.
  • Axis 6 - This axis can rotate the wrist of the robot arm.

Six-axis robots, like the Motoman HP20, have an enhanced range of motion and are not only able to move on the x, y, and z planes, but can also perform roll, pitch, and side movements with their numerous degrees of freedom. A three-axis robot can only operate on the x, y, and z planes because it lacks the other three axes for additional movements. While four or five axis robots can operate on all three planes as well as perform additional motions such as rotation or lifting of the robot’s wrist. 4 axis robots are commonly used in palletizing applications due to the limited amount of movement needed to take something off a conveyor and placed on a pallet. The 4 axis FANUC M-410ib/160 can complete almost any palletizing operation without the need for the 2 additional axis. As depicted in the list above, a robot’s range of motion increases with each axis it has. Robots with numerous axes provide users with an enhanced work envelope, allowing for greater flexibility since they are more adaptable with a variety of movements available. Robots with auxiliary axis can operated robotic tracks and robotic positioners. With the integration of an aux axis board, the FANUC Arcmate 100ic can control a positioners in a weld cell.

As mentioned above, six-axis robots are designed to mimic human arm movements and provide the same degrees of freedom as human arms. This makes them ideal solutions from taking on repetitive, tedious, and even dangerous manufacturing jobs once only held by humans. They can perform all the same motions as their human counterparts without tiring or risking their safety. Their extended reach enhances their range of motion and when combined with their numerous degrees of freedom allows for greater access to even hard to reach objects.

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