What are Robotic Axes?
Industrial robots are often defined by the number of axes they have. It is common to see terms such as six-axis, five-axis, etc., in robotics. However, those new to robotics may not understand the importance of robot axes or even what they do.
A robotic axis represents a degree of freedom or independent motion. Industrial robots consist of multiple links that are connected to one another. Each link connection is a robotic axis. Robotic axes can also be referred to as robot joints. Within each axis is a motor that powers the relative motion of the joint. Each axis of a robot is responsible for a specific motion. The more axes a robot has the more movements it will be capable of. This is why the FANUC Arcmate 120ic along with other six-axis robots are so common. Their axis configuration provides them with a full range of motion which is ideal for most robotic applications.
Axis Types
There are five main types of robotic axes that are used for industrial robots. Two types are responsible for linear motions. They are called linear and orthogonal joints. While rotational, twisting, and revolving joints provide rotary motions. Industrial robots may be designed with a single axis type or a combination of axis types. Articulated robots are usually comprised of multiple rotary joints.Axis Configurations
The axis configurations of industrial robots can vary greatly. The most common ones are those with four, five, and six axes, with six axes being the most common. Most industrial robots feature three major axes which are located in the robot body and arm. Robots may also contain one to three minor axes which are located in the robotic wrist. Six-axis robots are capable of accessing a single unit of space from any angle. The Yaskawa Motoman MH6 can rotate, reach up, down, forwards, and backwards. It can also complete pitch, roll, and yaw movements for a full 360 degrees of rotation in its wrist. Six-axis robots can automate a wide variety of applications given their full range of motion.Four and five axis robots are not quite as flexible as six-axis robots but are still fairly common. These axis configurations are popular for palletizing automation as their less flexible motion provides greater stability for heavy lifting. The FANUC M-410ib/300 is a four-axis palletizing robot.
Less common axis configurations include three-axis and seven-axis robots. Three-axis robots are designed with only the three major axes. They lack the ability to rotate workpieces with their wrist. Three-axis robots are best for simple part handling processes. Many gantry and SCARA robots contain three axes. However, there are also some four-axis versions of these robot types which allow for part rotations.
Seven-axis robots are relatively new to robotics. These robots feature an additional axis in their arm for greater end-effector mobility. Seven-axis robots are able to maneuver around objects for better tooling positioning.
There are even robots with more than seven axes. Most industrial robots with greater than seven axes are dual arm robots. Instead of a single robotic arm they have two for axis configurations of up to fourteen.