The CyberCarpet is a small implementation of a ball bearing platform.
The ball-bearing CyberCarpet was the first prototype of a rotary treadmill developed as part of the CyberWalk research project. It is based on a ball array design and combines the various components provided by the CyberWalk project: markerless position tracking, optimal control and omnidirectional capabilities. However, scaling to the desired size for real walking (at least 4x4 m) proved difficult.
Principle of Operation
The CyberCarpet device consisted of a conveyor belt mounted on a rotary table. This turntable was actuated by a servo motor via a toothed belt. Thus the platform had two degrees of freedom, one linear and one rotating. Rotations and linear movements were transmitted to the user via a series of balls. These balls were mounted inside the top and are passively driven by the conveyor belt. The system had been tested with a model car representing a person running on the platform. GPS data from real walking was used to define movement patterns. The position of the vehicle was estimated by markerless tracking and compared to triangulation by strings.
The platform was able to reach speeds of up to 2 m/s on the belt system and 2 rad/s on the rotaryOF. The running surface, a hexagonal shape with a diameter of approx. 0.8 m, consisted of 4332 balls (8 mm diameter) driven by the underlying belt.
Until October 2007, the CyberCarpet was the fastest and largest implementation of its kind.