Implementation of a 6-DOF Parallel Continuum Manipulator for Delivering Fingertip Tactile Cues

• Published in: IEEE transactions on haptics Vol. 12; no. 3; pp. 295 - 306
• Main Authors: Young, Eric M., Kuchenbecker, Katherine J.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.07.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cues; DC motors; device design; End effectors; fingertip; Force; Haptic display; Haptic interfaces; Jacobians; Legged locomotion; Lookup tables; Manipulators; Nickel titanides; Parallel degrees of freedom; Phase change materials; Proportional derivative; Shape memory alloys; Shear forces; Tactile; wearable; Wires
• ISSN: 1939-1412; 2329-4051; 2329-4051
• DOI: 10.1109/TOH.2019.2920928

Existing fingertip haptic devices can deliver different subsets of tactile cues in a compact package, but we have not yet seen a wearable six-degree-of-freedom (6-DOF) display. This paper presents the Fuppeteer (short for Fingertip Puppeteer), a device that is capable of controlling the position and orientation of a flat platform, such that any combination of normal and shear force can be delivered at any location on any human fingertip. We build on our previous work of designing a parallel continuum manipulator for fingertip haptics by presenting a motorized version in which six flexible Nitinol wires are actuated via independent roller mechanisms and proportional-derivative controllers. We evaluate the settling time and end-effector vibrations observed during system responses to step inputs. After creating a six-dimensional lookup table and adjusting simulated inputs using measured Jacobians, we show that the device can make contact with all parts of the fingertip with a mean error of 1.42 mm. Finally, we present results from a human-subject study. A total of 24 users discerned 9 evenly distributed contact locations with an average accuracy of 80.5%. Translational and rotational shear cues were identified reasonably well near the center of the fingertip and more poorly around the edges.