The Touch Thimble: Providing Fingertip Contact Feedback During Point-Force Haptic Interaction

Abstract

Touching a real object with your fingertip provides simultaneous tactile and force feedback, yet most haptic interfaces for virtual environments can convey only one of these two essential modalities. To address this opportunity, we designed, prototyped, and evaluated the Touch Thimble, a new fingertip device that provides the user with the cutaneous sensation of making and breaking contact with virtual surfaces. Designed to attach to the endpoint of an impedance-type haptic interface like a SensAble Phantom, the Touch Thimble includes a slightly oversize cup that is suspended around the fingertip by passive springs. When the haptic interface applies contact forces from the virtual environment, the springs deflect to allow contact between the user's fingertip and the inner surface of the cup. We evaluated a prototype Touch Thimble against a standard thimble in a formal user study and found that it did not improve nor degrade subjects' ability to recognize smoothly curving surfaces. Although four of the eight subjects preferred it to the standard interface, overall the Touch Thimble made subjects slightly slower at recognizing the presented shapes. Detailed subject comments point out strengths and weaknesses of the current design and suggest avenues for future development of the device. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Pennsylvania's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs-permissions@ieee.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it. ABSTRACTTouching a real object with your fingertip provides simultaneous tactile and force feedback, yet most haptic interfaces for virtual environments can convey only one of these two essential modalities. To address this opportunity, we designed, prototyped, and evaluated the Touch Thimble, a new fingertip device that provides the user with the cutaneous sensation of making and breaking contact with virtual surfaces. Designed to attach to the endpoint of an impedance-type haptic interface like a SensAble Phantom, the Touch Thimble includes a slightly oversize cup that is suspended around the fingertip by passive springs. When the haptic interface applies contact forces from the virtual environment, the springs deflect to allow contact between the user's fingertip and the inner surface of the cup. We evaluated a prototype Touch Thimble against a standard thimble in a formal user study and found that it did not improve nor degrade subjects' ability to recognize smoothly curving surfaces. Although four of the eight subjects preferred it to the standard interface, overall the Touch Thimble made subjects slightly slower at recognizing the presented shap...

Design of a wearable skin stretch cutaneous device for the upper limb

“…Moreover, cutaneous feedback provides an effective and elegant way to simplify the design of this type of haptic interfaces: cutaneous receptors' very low activation thresholds [2] enable researchers to design small, lightweight and inexpensive cutaneous haptic interfaces [3], [4], [5]. Finally, cutaneous feedback has been also proven to play a key role in enhancing the performance and effectiveness of teleoperation and immersive systems [6], [7], [8], [9], [10].…”

Two Finger Grasping Simulation with Cutaneous and Kinesthetic Force Feedback

“…4), it uses three servo motors and can render higher forces at the fingertip. The idea of providing realistic cutaneous sensations while using haptic interfaces has been also discussed in [16]. However, the thimble there presented was only able to provide the cutaneous sensation of making and breaking contact with virtual surfaces.…”

HapTip: Displaying Haptic Shear Forces at the Fingertips for Multi-Finger Interaction in Virtual Environments

“…When a contact occurs in the simulation, the finger cap enters in contact with the fingertip. Similar systems were proposed later on by Kuchenbecker et al (2004Kuchenbecker et al ( , 2008 and Gonzalez et al (2015). These devices can generate contact feedback anywhere on the fingertip.…”