Spanning large workspaces using small haptic devices

Exploring large virtual environments using a small haptic device with limited-workspace capabilities is a challenging task because the user very quickly reaches the borders of the physical workspace of the device. In the case of a computer mouse, this problem is solved by lifting the device off the table and repositioning it at a different location. With most ground-based haptic devices such indexing procedure is not possible and requires the use of an additional switch to decouple the device from the cursor and allow the user to relocate the end-effector at the center of the physical workspace. Below certain physical workspace dimensions such indexing methods become cumbersome to the operator and therefore different control paradigms are required. This paper presents a new approach referred to as workspace drift control which progressively relocates the physical workspace of the device mapped inside the virtual environment towards the area of interest of the operator without disturbing his or her perception of the environment. This technique uses the fact that people are greatly influenced by what they perceive visually and often do not notice small deviations of their hand unless that small deviation has a corresponding visual component.