Closed Cycle Haptics
Closed cycle haptic devices take input from users and provide output within the same device. These devices vary in complexity, force feedback on steering wheels and joysticks being simple examples, research grade devices used to interact with virtual objects by touch with six degrees of freedom being a complex example.
Complex closed-cycle haptic devices are rarely used in games, largely due to the expense. A notable exception is Haptic Battle Pong, a tennis game developed by computer science researchers at Stanford [Morris and Joshi, 2004]. Haptic Battle Pong uses a Phantom, a haptic device by SensAble Technologies to receive players' raquet swings. The Phantom also provides tactile feedback as the player hits the ball, fires weapons at another player, or is struck by weapons, all with six degrees of freedom.
Morris, D. and Joshi, N. (2004). Haptic Battle Pong. Stanford University.