Generally, manipulators (also called `[[Robot|robots]]' or `[[Mechanism (engineering)|mechanisms]]') are mechanical devices that position and orientate objects. The position of an object in three-dimensional (3D) space can be specified by three numbers ''X, Y, Z'' known as 'coordinates.' In a [[Cartesian coordinate system|Cartesian]] [[Coordinate system#:~:text%3DIn%20geometry geometry%2C%20a%20coordinate%20system a coordinate system%2Cmanifold%20such%20as%20Euclidean%20space such as Euclidean space.|coordinate system]] (named after [[René Descartes]] who introduced [[analytic geometry]], the mathematical basis for controlling manipulators) the coordinates specify distances from three mutually perpendicular reference planes. The orientation of an object in 3D can be specified by three additional numbers corresponding to the orientation [[Euler angles|angles]]. The first [[Remote manipulator| manipulators]] were developed after World War II for the [[Argonne National Laboratory]] to safely handle highly radioactive material [[Teleoperation|remotely]]. The first [[Numerical control|numerically controlled]] manipulators (NC machines) were developed by [[John T. Parsons|Parsons Corp]]. and the [[MIT Servomechanisms Laboratory]], for [[Milling (machining)|milling applications]]. These machines position a cutting tool relative to a Cartesian coordinate system using three mutually perpendicular linear actuators ([[Prismatic joint|prismatic ''P'' joints]]), with ''(PP)P'' [[Kinematic pair#:~:text%3DA%20kinematic%20pair%20is%20a kinematic pair is a%2Celements%20consisting%20of%20simple%20machines consisting of simple machines.|joint topology]]. The first [[industrial robot]],<ref>George C Devol, Programmed article transfer, US patent 2988237, June 13, 1961. </ref> [[Unimation|Unimate]], was invented in the 1950s. Its control axes correspond to a [[spherical coordinate system]], with ''RRP'' joint topology composed of two [[Revolute joint#:~:text%3DA%20revolute%20joint%20 revolute joint (also%20called called%2Crotation%20along%20a%20common%20axis along a common axis.|revolute ''R'' joints]] in series with a prismatic ''P'' joint. Most [[Industrial robot|industrial robots]] today are [[Articulated robot#:~:text%3DAn%20articulated%20robot%20is%20a articulated robot is a%2Cof%20means means%2C%20including%20electric%20motors including electric motors.|articulated robots]] composed of a serial chain of revolute ''R'' joints ''RRRRRR''.
