Denavit–Hartenberg parameters
In mechatronics engineering, the Denavit–Hartenberg parameters (also called DH parameters) are the four parameters associated with the DH convention for attaching reference frames to the links of a spatial kinematic chain, or robot manipulator. Jacques Denavit and Richard Hartenberg introduced this convention in 1955 in order to standardize the coordinate frames for spatial linkages.
Source: Wikipedia — Denavit–Hartenberg parameters (CC BY-SA 4.0)