Download - VR Technology TNM086 Haptics
![Page 1: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/1.jpg)
VR TechnologyTNM086
Haptics
![Page 2: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/2.jpg)
Synopsis
Haptics – background, motivation, research Haptics in computer science and VR The senses, important aspects Haptic devices Haptic rendering
![Page 3: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/3.jpg)
Haptics – Science of Touch
Haptics from Greek = touchable Scientific description of touch, the sense Self perception and perception of the world
Multi- and crossdisciplinary Old research area Psychophysics Control theory and system identification Computer graphics and applications
![Page 4: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/4.jpg)
Psychophysics
Applied biology and psychology Haptics' role in our self- and world-perception Limits of the haptic senses Haptic memory and processing
Computers are their tools Use computer to perform controlled experiments However: why simulate what you have in real?
![Page 5: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/5.jpg)
Control Theory
Robotic control Applied haptics in robotics Tele operations (remote control) Stability, performance, latency, etc
Development of hardware devices and haptic rendering
Network
![Page 6: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/6.jpg)
Motivation in VR
Increased body control Coordination Speed and precision
Guidance Pathways, tutoring Physical support
Information Additional channel Hardness, strength, position Reinforce visual impression
Realism Immersion and more
![Page 7: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/7.jpg)
Important Applications
Haptics is more important in some cases Where vision is poor or not available Where touch is of special importance
guidance, perception, …
Some examples Bone drilling Spinal anaesthesia Virtual prototyping Stroke rehab
![Page 8: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/8.jpg)
Bone Drilling
Poor visibility / no visibility
![Page 9: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/9.jpg)
Spinal Anaesthesia
Feel the tissues Push towards membrane Pop through and stop!
![Page 10: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/10.jpg)
Virtual Prototyping How will it work?
Cheap(er) realization of prototype Connect to CAD/CAM system Easy to update minor changes, adjust parameters
Test feel, ergonomics, assembly, accessability, etc
![Page 11: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/11.jpg)
Stroke Rehab
![Page 12: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/12.jpg)
...and (of Course) Gaming
For realism! The Void
![Page 13: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/13.jpg)
Two Haptic Senses
Tactile senses (cutaneous) Nerves under skin Pressure, shear, slip
Micro shape, vibrations, etc Temperature, pain
Kinaethetic senses (proprioception) Nerves in muscles and joints Forward kinematics Position, force, macro shapes, weight
![Page 14: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/14.jpg)
Building One Sense
A single whole Physically connected
also kinaesthetic devices give tactile stimulation Sensomotorically connected
multimodal integration sense of pose and body control E.g. force constancy theorem
Cognitively connected sense of surrounding and properties of objects
![Page 15: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/15.jpg)
Tactile Characteristics
Micrometer precision Feel a the edge of a paper on a flat surface Feel difference on directions and tilting
Vibrations Large range – sensing 20–1000 Hz Very small magnitude
Temperature Termoconductivity Heat, cold
Pain!
![Page 16: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/16.jpg)
Tactile HID
Feedback from computer Simulate sensations Indicate events No input, but put on mice, etc
Many types, for example Vibrotactile Surface Pin-based Electrocutaneous
![Page 17: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/17.jpg)
Vibrotactile Devices
Vibrating elements Based on motor or speaker On finger, a point or distributed over body Put into objects, e g input devices
![Page 18: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/18.jpg)
Vibrotactile Devices
Applications Indicate direction
Vibrations in sequence Intuitive perceptualization
Indicate event Warning och getting shot Simulate follow through on touch screens
Indicate closeness Varying magnitude Discrimination threshold is not very good
Frequency profile can be designed
![Page 19: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/19.jpg)
Surface-based Devices
Real surface Pushing, shearing
Simulate touch Pressure against surface Slipping Also closeness if you like
![Page 20: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/20.jpg)
Surface-based Devices
Reactive grip (Tactical Haptics) force and shear
![Page 21: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/21.jpg)
Pin-based Tactile Devices
Pins sticking out of surface Typically > 5x5 pins Pushing or vibrating Magnitude in millimeter range
Indicating shapes Ridges and edges can be simulated Moving vibrations can feel like slipping
Typically large Pneumatic, servos, electromagnetic, (piezoelectric) Hard to fit on mice or other devices
![Page 22: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/22.jpg)
Electrocutaneous Devices Electrocutaneous
HF electric stimulation of nerves Anodes and catodes
Feeling of touch, slipping Showing shapes, edges Sequences to represent motion
Small form factor Issues
Conductivity dependent Salt, sweat, pressure
Pain!
+ - + -
+- + -
+ - + -
+- + -
![Page 23: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/23.jpg)
Electrocutaneous Devices
Teslasuit
![Page 24: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/24.jpg)
Free Air Tactile Feedback
Focussed ultrasound (coming to market) interference pattern with peak(s) on skin
Air vortex cannon (research)
![Page 25: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/25.jpg)
Kinaesthetic Characteristics
Input/output Connection between motoric and sensory systems
Parietal cortex – sensing, data integration, manipulation Coordination Balance between inner and outer forces
Low resolution Precision in centimeter range
Dynamic system Manipulation at about 1–10 Hz Low cognitive attention below 1 Hz
![Page 26: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/26.jpg)
Kinaesthetic HID
3D input device with feedback Like a robotic arm that you interact with Degrees-of-freedom
Both input and output (typically 6→3 DoF) Important for what to simulate
Two control paradigm Impedance control – force feedback Admittance control – position feedback
Important characteristics (fidelity) Precision, strength Mechanical stiffness, Z-width
![Page 27: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/27.jpg)
Force Feedback Control Basics
![Page 28: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/28.jpg)
Force Feedback Control Basics
Closed loop control system Feedback force affects position Dynamic, hybrid non-linear system Require high update rates, typically 1 kHz
Warning For high loop gain
Stiff system causes instability Caused by high stiffness in simulation
For phase shifts Caused by feedback delay and low update rates Caused by low mechanical stiffness
![Page 29: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/29.jpg)
Force Feedback Wand/Stylus
Single mechanical arm Sensable
Desktop PHANToM Premium PHANToM PHANToM Omni
Multiple mechanical arms Force Dimensions
Delta, Omega Haption
Virtuose 6D
(http://haptipedia.org)
![Page 30: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/30.jpg)
Device Characteristics
Very high precision Required for stable interaction Measured in micrometers
Force feedback Light devices
Varying strength, typically < 8 N
6 DoF – torque feedback Low strength, typically < 0.5 Nm Limited motion
![Page 31: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/31.jpg)
Gaming Device
Novint + Force Dimension = Falcon Too small workspace Too low resolution Not enough stiffness (esp. joints) Good strength Very cheap
(Dead – no news since 2011)
![Page 32: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/32.jpg)
Dexmo
On market (development version)
![Page 33: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/33.jpg)
HaptX
DK1 released
![Page 34: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/34.jpg)
VRgluv
![Page 35: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/35.jpg)
Cyber Glove Systems
![Page 36: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/36.jpg)
Grounded / Ungrounded
Grounded devices Provide force/torque feedback relative world You can lean against a wall
Ungrounded Grounded to the body or using inertia
![Page 37: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/37.jpg)
Customization
3 DoF (x, y, z) → 3 DoF (τy, τ
x, z)
2 x 3 DoF → 5 DoF
![Page 38: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/38.jpg)
Position Feedback Control Basics
Admittance Force sensors and explicit position control
Handle virtual weight, dynamics Simulate acceleration from input force
Don't admit penetration of stiff walls Simulated stiffness limited by mechanical stiffness
Controller
Forces
Geometries
Constraints
Computer PVA
Human interaction
Position
Force
![Page 39: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/39.jpg)
Position Feedback Devices
Moog FCS Haptic Master
3 DoF Very big Very strong Very high stability
Dental Trainer, Eye Trainer Also strong and stable Smaller and more practical form factor
![Page 40: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/40.jpg)
Special Considerations in VR
Workspace size Haptic devices are typically small
Long mechanical arms have poor stiffness Levarage problem with precision and strength
Mobile haptic devices Wearable haptic devices (ungrounded)
Occlusion Mechanical arm might be in your way Interference with other tracking
Magnetic, sound or image-based
![Page 41: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/41.jpg)
Asynchroneous Rendering
Graphics rendering Traverse scene graph (@ 10–100 Hz) Much processing, graphics, events, etc
Haptic rendering High update rate, typically @ 1 kHz Shared or separate scene graph Separate, asyncroneous thread (process?) Synchronization issues
![Page 42: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/42.jpg)
Haptic Rendering
Software to generate haptic feedback (Here, we consider kinaesthetic force feedback)
Impedance control algorithm Position input – force output
Geometry rendering Penalty-based, god object-based, proxy-based Polygons, implicit surfaces, nurbs, etc.
Rigid-body simulation Proxy object (hand or tool) interaction
Volume haptics Haptic rendering of non-surface data
![Page 43: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/43.jpg)
Important Characteristics
Smooth surfaces No discontinuities (on a continuous surface)
Conservative Do not add or remove energy Passive behaviour Stable behaviour
No artifacts Only represent the surface's properties No vibrations, jitter or other misbehaviour
![Page 44: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/44.jpg)
Penalty-based Haptic Rendering
Penalty for penetration Find shortest way out Push haptic instrument out
Force dependent on penetration depth ”Stiffness” (N/m)
Issues Force discontinuities Pop-through Simplistic
no friction, texture, etc.
![Page 45: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/45.jpg)
God object-based Rendering
Point tracing the polygons Spring to calculate feedback
Stiffness (N/m) No pop-through Friction cone
Issues Fall-through ”between” polygons No contact size, only point
Hardware accelerated No topology information
![Page 46: VR Technology TNM086 Haptics](https://reader030.vdocuments.site/reader030/viewer/2022012415/61703e311cc9ee4bda0e3883/html5/thumbnails/46.jpg)
Proxy-based Haptic Rendering
Ruspini renderer Finite-sized proxy sphere
Configuration space Iteratively update proxy position
PD regulator Proportional – stiffness Derivative – damping No integration (PID) – why?