High Degree of Freedom Robots
Robotic degrees of freedom control the movements that an industrial robot is capable of. Each degree of freedom is represented by a robotic axis. The more axes an articulated robot has, the more degrees of freedom or motions it will be capable of. For most manufacturing processes six degrees of freedom are sufficient. This is why six-axis robots are the most common out of all axis configurations. The six axes of the FANUC R-2000ib/165F provide it with the range of motion to be able to automate various manufacturing applications. While six-axis robots are considered the gold standard for manufacturing automation, there are some cases when more robotic axes are needed which is where high-DOF robots come in.
A high degree of freedom robot is one that has seven or more robotic axes. The typical industrial robot has between four to six axes, but some robots can have as many as fifteen. High-DOF robots feature an enhanced range of motion since they have a higher number of axes or degrees of freedom. There are typically three types of high-DOF robots; robot transfer units (RTUs), seven-axis articulated robots, and dual arm robots.
The first type of high-DOF robot, an RTU, is actually a six-axis robot that is integrated to a track system. The track system is considered the seventh axis. RTUs are needed when an application involves a large work envelope or for automating a large volume production. Integrating the Yaskawa MH165 with a track system allows it to quickly transfer parts from one side of a warehouse to another. RTUs allow robots to efficiently work with large workpieces, preventing stoppages for repositioning. In large volume operations, RTUs help robots increase their speed and quickly automate a sequence of production applications.
Seven-axis articulated robots feature a similar structure as a six-axis robot, but with an extra axis in its arm. This extra axis allows for better EOAT placement for greater access to parts. The seventh axis can also be useful for avoiding surrounding objects to prevent collision while the robot is operating. For instance, the seventh axis of the Motoman VA1400 allows it to move its elbow to avoid contact with peripherals without compromising the positioning of its EOAT.
If a robot has more than seven axes it is most likely a dual arm robot. As the name implies, dual arm robots feature two robotic manipulator arms on either side of the robot body. The two arms can operate separate from one another on different tasks or they can operate together. One arm of a dual arm robot may be used to retrieve parts while the other assembles or both arms may work to assemble the same workpiece. Yaskawa Motoman was one of the first to introduce dual arm robots. Since then other manufacturers have developed their own dual arm versions including ABB.
High-DOF robots are mainly used for automating material handling applications. RTUs are ideal for tasks such as automated part transfer, palletizing, and machine tending. Dual arm robots can automate assembly and packaging among many other material handling processes. Seven-axis robots can be used for welding automation in addition to material handling.