The joints and links of a robot, hence a description of the articulation of a robot gives a description of its configuration.
In robotics, the description of the structure of a robot in terms of the type of each joint (i.e. translational or rotational) and the directions of the joint axes. There are five standard robot configurations: articulated (revolute), Cartesian-coordinate, cylindrical-coordinate, SCARA, and spherical-coordinate.
spherical-coordinate robot (polar-coordinate robot, spherical-configuration robot, spherical-polar robot)
A robot having a rotational joint, joint angle θ1, with a vertical axis above the base frame (i.e. a waist joint), a rotational joint, joint angle θ2, with a horizontal axis at the end of the first link (i.e. a shoulder joint) and a translational joint, joint offset d3, with axis normal to the axis of the shoulder joint. The workspace is thus a hollow sphere centred on the base frame. The diagram shows an idealized spherical coordinate robot.