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Introduction to Computer Haptics

Introduction to Computer Haptics

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Introduction to Computer Haptics

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  1. Introduction to Computer Haptics Chris Harding charding@iastate.edu

  2. 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 Haptic Rendering: process of displaying synthetically generated 2D/3D haptic stimuli to the user Motors, cables, actuators, position sensors, … End-effector (pen, thimble, surgical instrument, …) simulated haptic probe Haptic Interface: device for touch interactions in real and virtual worlds

  3. Human vs Machine Haptics:

  4. Machine Haptics: Types of Haptic Devices Tactile Displays (skin) Force feedback Displays (Kinesthetic: position)

  5. Force Types of Haptic Devices Active Passive keyboard, trackball, mice, etc.

  6. Types of Haptic Devices Grounded Attached Hulk strong – crush Coke can !! combined

  7. Applications Haptic Feedback for Molecular Simulation Haptic Feedback for Medical Simulation and Training force molecule Haptic Display Visual Display

  8. Applications Haptic Visualization Haptic Feedback for Collaborative Engineering Design haptic display collected data tangible data • Tangible Interfaces • buttons • dials • slider bars • folders • layers • force fields Simulation of repair and maintenance tasks Haptic User Interface (HUI) Haptic Feedback for Crew Training

  9. Geometry • Color • Stiffness • Deformability

  10. 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

  11. Virtual Finger Tip Stylus Tip

  12. Position Orientation Object Database Collision Detection Geometry Material Contact Information Collision Response Force Haptic Rendering with a Force Display virtual wall F = stiffness * dist

  13. point-object interaction HIP = Haptic Interface Point: True (real world) position of stylus tip Hand: always drawn outside the sphere Assumption: Stiffness = 1.0

  14. Haptic Rendering of 3D Objects via Proxy (point-object interaction) d: Proxy to Tipdistance HIP (stylus tip: actual position!) F = k * d (Hooke’s Law) Spring with stiffness k Proxy (displayed position) (If in doubt: the visual sense will override the sense of touch …)

  15. Haptic Rendering of Polygonal Surfaces HIP = actual tip position IHIP = Proxy point

  16. Haptic Display of Surface Details • Haptic smoothing of object surfacesding)(similar to Phong shag • Rendering of haptic textures • Haptic rendering of surfaces with friction ( actual shape displayed shape

  17. s t Haptic Texturing • image-based two-stage mapping Bier & Sloan, 1986 • procedural bump mapping h(x,y,z) Blinn, 1978; Max and Becker, 1994

  18. Force-Reflecting Deformable Models: Surgical Simulation F F Haptic Sculpting/painting

  19. 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

  20. 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?)

  21. 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)