This study explores the haptic rendering capabilities of a variable friction tactile interface through psychophysical
experiments. In order to obtain a deeper understanding of the sensory resolution associated with the Tactile Pattern
Display (TPaD), friction discrimination experiments are conducted. During the experiments, subjects are asked to
explore the glass surface of the TPaD using their bare index fingers, to feel the friction on the surface, and to compare
the slipperiness of two stimuli, displayed in sequential order. The fingertip position data is collected by an infrared frame
and normal and translational forces applied by the finger are measured by force sensors attached to the TPaD. The
recorded data is used to calculate the coefficient of friction between the fingertip and the TPaD. The experiments
determine the just noticeable difference (JND) of friction coefficient for humans interacting with the TPaD.
An ecological study of haptic perception and action in tool use has been proposed. The result of such a study would be a theory of tool use to guide haptic interface, telemanipulator, and virtual environment design. As a first step in this study, we conducted an experimental study of haptic information pickup in a single degree-of-freedom positioning task. The task consisted of moving the handle of a one degree-of-freedom manipulandum to a target location using haptic perception. The manipulandum was controlled to exhibit impedances characterizing viscous drag, or damping. Damping in the target region was made to be different from the damping in the surrounding environment (ambient damping). Subjects were instructed to move to, and stop in, the target zone as rapidly as possible. The results of the experiments show that with our apparatus subjects could detect targets designated by differences in target and ambient damping greater than 2.27 N(DOT)s/m. For very large differences in target and ambient damping, subjects performed almost as well using haptic perception alone as they did when they could also see the target.
This paper addresses the performance of force-reflecting interfaces (`haptic displays'). We suggest that an important measure of performance is the dynamic range of achievable impedances, and that an impedance is achievable if it satisfies a robustness property such as passivity. The effects of sampling, inherent interface dynamics, and sensor quantization on dynamic range are discussed. Techniques for achieving very high impedances are presented.
A system for kinesthetic and visual display of virtual environments has been developed which includes a four degree-of-freedom, force-controlled manipulation and a parallel processing architecture for performing real-time environment simulation, manipulation control, and graphics display. The system allows a user to interact with a virtual environment via a virtual hand tool. 'Forces' at the handle of the virtual tool are experienced as real forces at the handle of the manipulandum. The problem of modeling environments composed of rigid bodies with intermittent contact has been addressed. Dynamic equations for environment simulations are generated and solved in real time by an array of interconnected microprocessors. Additional microprocessors safeguard against dangerous motor accelerations and potentially damaging manipulator configurations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.