Unconstrained omni-directional walking in virtual worlds

CyberWalk project

Experimental validation on the CyberCarpet small-scale ball-array platform 

Last update: December 20, 2011

This page reports on the first experimental results obtained (in October 2006) from the integration of the activities of three CyberWalk partners: TUM, ETH, and ourselves (UOR). We tested our control laws on the small-scale ball array platform developed by TUM. A car-like robot carrying a picture of human head and shoulders represents the walking user. The position and orientation of the car are extracted from the images acquired by a fixed overlooking camera. The design and implementation of the visual tracking algorithm have been performed by ETH.

A sketch of the mechanics of the CyberCarpet.
The platform is made of a linear treadmill mounted on a actuated turntable. The available commands are therefore two: a linear motor (red one) and an angular motor (green one).

A picture of the small-scale prototype.
Notice the small balls fitted into an array board which keeps them in contact with the underneath carpet. The motion of these balls, freely rotating in place, reflects the carpet movements on the above standing user.

An example of the tracking system.
The red circle identifies the position of the head, while the outer ellipse matches the position of the shoulders. The orientation of the user is represented by a small white segment (the semi-axis of the ellipse).

Experimental results

The overall architecture (platform actuation + visual tracking + control laws) was tested on several relevant scenarios.
The video clips can be found in the latest project NEWS here. The performed experiments are composed by three subwindows, as shown in the picture on the right:

  • The upper left window shows the images grabbed by the overlooking camera which are used for the user's pose extraction

  • On the upper right window, a front view of the scene make it possible to follow the motion of both the car and the platform

  • Finally, the lower window shows a side view of the scene, in order to better appreciate the movements of the platform

Martin (TUM) Michael (ETH) Paolo (UOR)


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