Maximum virtual stiffness is a critical performance measure for haptic devices. Stable haptic interaction is necessary for realistic feeling of virtual environment. The virtual environment is determined by the application and device. To ensure the stable haptic interaction, the virtual environment must be suitable for the device. Therefore, the virtual stiffness should not be greater than the minimum value of maximum virtual stiffness that a haptic device can stably render in the workspace. This paper proposes a method, utilizing the eigenvalue and eigenvector of stiffness matrix in joint space, to analyze and measure the maximum virtual stiffness distribution in the work space of a haptic device. Therefore, for a given haptic device, the maximum virtual stiffness at each position and orientation can be forecasted by this method. A new sufficient condition for haptic stability is also presented in the view of driven motor in this paper. A series experiments validate the effectiveness of this method.
Tactile Exploration Strategies With Natural Compliant Objects Elicit Virtual Stiffness Cues
