Wearable Haptics CPSC 599.86 / 601.86 Sonny Chan University of Calgary
“Grounded” Kinaesthetic Haptic Displays
Virtual Reality A new driving force for haptics technology…
The future of haptics?
HaptX VR Glove
How do we render haptics to a device that looks like this?
Spectrum of “wearability” [From C. Pacchierotti et al. , IEEE Transactions on Haptics 10(6), 2017.]
Wearability • Wearability can be increased by moving the grounding of the system closer to the point of application of the stimulus • Tradeoff is that we gradually lose the kinaesthetic component of haptic feedback • Therefore, we must investigate effective cutaneous rendering
somatosensory system cutaneous receptors kinaesthetic receptors Touch Perception
Cutaneous Perception • Inputs from different types of mechanoreceptors embedded in the skin vibration and texture perception - pressure and skin stretch (grasped object) -
Receptor Feature Sensitivity Primary Functions Terminal • very low frequency vibration detection Sustained pressure, very low Merkel • coarse texture and pattern perception frequencies (<5 Hz) Temporal changes in skin Meissner • low frequency vibration detection deformation (5-40 Hz) • high frequency vibration detection Temporal changes in skin Pacinian • fine texture perception deformation (40-400 Hz) • direction of object motion due to skin stretch Sustained downward pressure, Ru ffi ni • finger position lateral skin stretch [Adapted from S. J. Lederman & R. L. Klatzky, Attention, Perception, & Psychophysics 71(7), 2009.]
Cutaneous Haptic Rendering • Four “primitives” of cutaneous sensation: - Normal indentation - Lateral skin stretch - Relative tangential motion - Vibration [diagram from R. S. Johansson & A. B. Vallbo, Trends in Neurosciences 6, 1983.]
Wearable Haptic Interfaces for the finger and for the hand
Normal Indentation • Displays sensations of: - Contact and pressure - Curvature - Softness/hardness [From F. Chinello et al. , IEEE Transactions on Haptics 11(1), 2018.]
Lateral Skin Stretch & Relative Tangential Motion • Shear force applied to the skin • Displays sensations of - Friction / slip - Indentation (e.g. Braille) - Caress [From D. Leonardis et al. , IEEE Transactions on Haptics 10(3), 2017.]
Vibration textures, materials, caress [Haptuator Planar, Tactile Labs, Montréal, QC]
Kinaesthetic Stimuli can be fully or partially actuated… [Maestro Hand Exoskeleton, ReNeu Robotics Lab, UT Austin]
Kinaesthetic Stimuli … or completely passive [From I. Choi et al. , Proc. IEEE/RSJ IROS , 2016.]
Haptic Gloves with vibrotactile actuation [From Y. Kim et al. , Proc. IEEE MultiMedia , 2009.]
HaptX VR Glove
Haptic Rendering for wearable displays
✓ Normal indentation Consider the Primitives… ✓ Lateral skin stretch ✓ Vibration
What about your avatar? 3-DOF 6-DOF
How many degrees of freedom?
A Constraint-based God-object Method For Haptic Display C. B. J. K. Salisbury Zilles Department of Mechanical Engineering Artificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge, MA Abstract Haptic display is the process of applying forces to a human “observer” giving the sensation of touching and interacting with real physical objects. Touch is unique among the senses because it allows simultaneous ex- ploration and manipulation of an environment. A haptic display system has three main components. Does “God-Object” still work? The first is the haptic interface, or display device - generally some type of electro-mechanical system able to exert controllable forces on the user with one or more degrees of freedom. The second is the object model - a mathematical representation of the object containing its shape and other properties related to the way it feels. The third component, the haptic render- ing algorithm, joins the first two components to com- pute, in real time, the model-based forces to give the Figure 1: This polygonal model of a space shuttle is user the sensation of touching the simulated objects. made up of 616 polygons. This is an example of the [From J. Jacobs et al. , Proc. IEEE 3DUI , 2012.] This paper focuses o n a new haptic rendering al- complexity of objects the god-object algorithm can allow gorithm for generating convincing interaction forces the user to touch. for objects modeled as rigid polyhedra (Fig. 1). W e create a virtual model of the haptic interface, called a,ctions with simulated objects. The point interaction the god-object, which conforms to the virtual envir- paradigm greatly simplifies both device and algorithm onment. The haptic interface can then be servo-ed development while permitting bandwidth and force fi- to this virtual model. This algorithm is extensible to delity that enable a surprisingly rich range of interac- other functional descriptions and lays the groundwork tions. It reduces the problem of computing appropriate for displaying not only shape information, but surface interaction forces - haptic rendering - to one of tracing properties such as friction and compliance. the motion of a point among objects and generating 1 Introduction the three force components representing the interac- The process of feeling objects through a force- tion with these objects. In this paper the term haptic generating interface is familiar in the context of using interface point will be used to describe the endpoint teleoperator master devices to touch and interact with location of the physical haptic interface as sensed by remotely located objects [7]. Recent interest in en- the encoders. abling interaction with virtual objects [l] has led us to This work was done with PHANTOM-style device investigate devices and algorithms which permit touch with a max force of 18N (4 lbf). We have found this to and manipulative interaction - collectively, haptic in- be enough force to make virtual objects feel reasonably teractions - with these virtual objects. solid without, saturating the motors. While exploring The PHANTOM haptic interface [4] permit,s users virtual environments most users tend to use less than to feel and control the forces arising from point inter- 5N (1 lbf) of force. 146 0-8186-7108-4195 $4.00 0 1995 IEEE
[From M. Prachyabrued & C. W. Borst, IEEE Trans. Visualization & Computer Graphics , 2016.]
Summary • Wearable displays may very well be the future of consumer haptics Virtual and augmented reality applications have renewed the desire to touch virtual stuff - Many companies are now trying to develop haptic gloves - Still mostly vapourware as of today… - • The rendering techniques you learned in this course can be applied to many of these novel haptic displays We didn’t get into details of any specific algorithms here… - It’s still a very active area of modern haptics research! -
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