Cobot stands for collaborative robot. Edward Colgate, Witaya Wannasuphoprasit and Michael Peshkin first proposed this term in 1996: they defined a cobot as "a robotic device, which manipulates objects in collaboration with a human operator". Cobots were first designed in order to constrain human operator movements, in particular man-machine environments, but maintaining the human-object mechanical interaction: human movements are constrained by the definition of what is called virtual surfaces.