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

2. 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 simulated haptic probe Haptic Interface: device for touch interactions in real and virtual worlds End-effector (pen, thimble, surgical instrument, …) Motors, cables, actuators, position sensors, …

3. Human vs Machine Haptics:

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

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

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

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

8. 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 of repair and maintenance tasks Haptic Feedback for Collaborative Engineering Design Applications

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. Stylus Tip Virtual Finger Tip

12. Haptic Rendering with a Force Display Collision Detection Collision Response Geometry Material Object Database Position Orientation Contact Information Force 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) Proxy (displayed position) HIP (stylus tip: actual position!) Spring with stiffness k F = k * d (Hooke’s Law) d: Proxy to Tip distance (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. actual shape Haptic Display of Surface Details Haptic smoothing of object surfacesding)(similar to Phong shag Rendering of haptic textures Haptic rendering of surfaces with friction ( displayed shape

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

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

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)