Stable Haptic Interaction Using the Excalibur Force Display

Creating a compelling haptic sense of immersion in a virtual environment is a challenging task for the control engineer. A haptic display must render both low impedance free-space motion and high impedance rigid constraints while ensuring stable interaction. This paper outlines a control design approach for the most common haptic display implementation, the impedance display. Two-port absolute stability criteria are used to develop explicit design bounds for virtual coupling networks which guarantee system stability for a broad class of human operators and virtual environments. The technique is applied to the Excalibur three-axis force display. The resulting absolutely stable haptic interface is the centerpiece of a virtual building block simulation which emulates the behavior of LEGO/sup TM/ bricks in a virtual environment.

Authors

• Richard J. Adams
• Daniel Klowden
• Blake Hannaford

Keywords

• Haptic interfaces
• Virtual environment
• Application software
• Impedance
• Humans
• Computer displays
• Rendering (computer graphics)
• Stability criteria
• Force feedback
• Damping
• Haptic Interaction
• Virtually
• Stability Of System
• Stability Criterion
• Human Operator
• Stable Interface
• Rigid Constraints
• Absolute Stability
• Left Side
• Actuator
• Theoretical Results
• Optimal Control
• Software Applications
• Point-of-sale
• Positive Real
• Mechanical Devices
• Control Law Design
• Impedance Levels