introduction to computer haptics
DESCRIPTION
Introduction to Computer Haptics. Chris Harding [email protected]. F. Haptic (adj.) ( from the Greek word haptesthai for to grasp or to touch) : related to the sense of touch.. Graphical Rendering : process of displaying synthetically generated 2D/3D visual stimuli to the user. - PowerPoint PPT PresentationTRANSCRIPT
Introduction to Computer Haptics
Chris Harding [email protected]
Haptic (adj.) (from the Greek word haptesthai for to grasp or to touch) :related to the sense of touch.
Haptic Rendering:process of displaying synthetically generated 2D/3D haptic stimuli to the user
Graphical Rendering: process of displaying synthetically generated 2D/3D visual stimuli to the user
F
simulatedhapticprobe
Haptic Interface: device for touch interactions in real and virtual worlds
End-effector (pen, thimble, surgical instrument, …)
Motors, cables, actuators, position sensors, …
Human vs Machine Haptics:
Tactile Displays(skin)
Force feedback Displays(Kinesthetic: position)
Types of Haptic Devices
Machine Haptics:
Types of Haptic Devices
ActivePassive
keyboard, trackball, mice, etc.
Force
Types of Haptic Devices
Grounded Attached
combined Hulk strong – crush Coke
can !!
Applications
Haptic Feedback for Medical Simulation and
Training
VisualDisplay
HapticDisplay
force
molecule
Haptic Feedback forMolecular Simulation
Haptic Feedback for Crew Training
Haptic User Interface (HUI)
collected data
haptic display
Haptic Visualization
tangible data
Tangible Interfaces• buttons• dials• slider bars• folders• layers• force fields
Simulation ofrepair and
maintenance tasks
Haptic Feedback for CollaborativeEngineering Design
Applications
Integration of Vision and Touch
HapticThread
HapticInterface
HUMAN OPERATOR
VisualThread
VisualInterface
SharedDatabase
MotorTorques EncoderPositions
DISPLAYFORCE STATE
~1 kHz
DISPLAYVISUALS STATE
Images ~ 30 Hz
•Geometry•Color•Stiffness•Deformability
Point-based Haptic feedback Problem:
simulating the Human hand (22 DOF) and tactile sensations (skin pressure) is very difficult (impossible) to simulate
Need very fast update rates (~1000 Hz) Need Interface acceptable to everyday users Affordable, with API for non-haptic specialists
Solution (Enter the PHANtOM): Use only a single point (3DOF): point with stylus (direction vector) GHOST API, ReachIn API, OpenHL
Stylus Tip
Virtual Finger Tip
Haptic Rendering with a Force Display
CollisionDetection
CollisionResponse
Geometry
Material
Object Database
PositionOrientation
ContactInformation
Force
virtualwall
F = stiffness
* dist
void calculate_force (Vector &force) { float X, Y, Z, distance; float R = 20.0;
X = HIP[0]; Y = HIP[1]; Z = HIP[2]; distance = sqrt(X*X + Y*Y + Z*Z);
if(distance < R) //collision check { force[0] = X/distance * (R-distance); force[1] = Y/distance * (R-distance); force[2] = Z/distance * (R-distance);
}
}
F
R
distanceHIP Hand
point-object interaction
HIP = Haptic Interface Point: True (real world) position of stylus tipHand: always drawn outside the sphere
Assumption:Stiffness = 1.0
Haptic Rendering of 3D Objects via Proxy (point-object interaction)
Proxy (displayed position)
HIP (stylus tip: actual position!)
Spring with stiffness kF = k * d(Hooke’s Law)
d: Proxy to Tipdistance
(If in doubt: the visual sense will override the sense of touch …)
HIPt
HIPt-1 HIPt-2HIPt-3
v2
v3
v1
HIPt+1
IHIPt
IHIPt+1
d
HIPt+2
IHIPt+2
d
Haptic Rendering of Polygonal Surfaces
HIP = actual tip positionIHIP = Proxy point
actualshape
Haptic Display of Surface Details
Haptic smoothing of object surfacesding)(similar to Phong shag
Rendering of haptic textures Haptic rendering of surfaces with friction (
Directionof movement
Fn
Ff
Ft
Fuser displayedshape
Haptic Texturing
s
t
• image-based
• procedural
h(x,y,z)
two-stage mappingBier & Sloan, 1986
bump mapping
Blinn, 1978;Max and Becker, 1994
Force-Reflecting Deformable Models:
Haptic Sculpting/painting
Surgical Simulation
FF
Reachin Display Phantom + Reachin
Display + Reachin API 3D stereo via mirror Integrates 3D Vision with
haptics After calibration:
real stylus = virtual stylus Uses proxy method 3D haptic user interface
(HUI) API: define VRML
scenegraph with graphics and haptics properties
Sensable Omni Phantom New, “cheap” version of
phantom line Stiffness: 3 - 4 N Firewire port Windows, Linux (?) OpenHL API: (low-level
OpenGL-like haptics) Demo of virtual clay
sculpting (splodge?)
Conclusion
Point haptics: Reduction of hand to point Separate Update loop at 1000 Hz Same geometry as graphics but additional
haptic properties Improvements in tool based interaction:
Surgical simulation and training assembly/repair planning Virtual clay sculpting (art, rapid prototyping) Sculpting of subsurface layers (saltdome modelling)