Similar to joints in the human body, the joints of an industrial robot makes movement between two links possible. Each joint provides the robot with a parameter that define its configuration. The number of parameters are often used to classify robots.
Connected to each joint are two links, an input link and an output link, which are rigid components. Since stationary robots are fixed to a base, the link nearer to the base is the input link. Movement between the input and output link is controlled at the joint.
These mechanical joints can be classified into one of the following five types:
1. Linear joint
The L–joint: The translational movement between the input and output link is a sliding movement, with its axes parallel. Telescopic cylinders is an example of such joints.
2. Orthogonal joint
The O–joint: This is similar to the L–joint, but its input and output axes are perpendicular.
3. Rotational joint
The R–joint: This joint moves in a rotary motion, its input and output axes perpendicular.
4. Twisting joint
The T–joint: This is also a rotary movement, but the input and output axes are perpendicular.
5. Revolving joint
The V–joint: Similar to the T–joint joint, the output link spins around the input link, but the output axis is parallel to the rotational axis.