Changes

[[SteamVR Controllers]] - these wireless controllers look like a pair of nunchucks with sensors on top. Each hand holds 1 of the 2 wireless controllers. Each controller has a trigger and a high-res circular haptic trackpad. The sensors allow the controllers to be tracked by the SteamVR Base Stations with the same way as the [[HMD]]. The controllers are tracked with very high precision and low latency.  The sensors on the controllers are [[photodiode]]s.