25-07-2012, 02:10 PM
3D Haptics and Robotics
Haptics.ppt (Size: 325 KB / Downloads: 26)
Haptic Interfaces
“Haptic” - an information processing perceptual system that uses inputs from the receptors embedded in the skin, as well as in muscles, tendons and joints (Loomis and Lederman, 1986)
“hap.tic (hap’tik) adj. of or having to do with the sense of touch; tactile” (Webster’s New World Dictionary)
“haptic interfaces” - devices that measure the motion of, and stimulate the sensory capabilities within, our hands (as used in human interface technology )
Unique Characteristics of Haptics
Haptics relies on action to stimulate perception.
The haptic system can sense and act on the environment while vision and audition have purely sensory nature.
Being able to touch, feel, and manipulate objects in an environment, in addition to seeing (and hearing) them, provides a sense of immersion in the environment that is otherwise not possible (Srinivasan, 1995)
Other Topics
Actuators (electrical, hydraulic, pneumatic)
Sensors
Tactile Feedback Interfaces (sensors, texture, slip, surface temperature)
Control of Haptic Interfaces (distributed computation, quality)
Physical Modeling (collision detection, surface deformation, mechanical compliance, smoothness, physical construction)
Applications
Enhancement of GUI’s (graphical user interfaces) - enable users to feel where the buttons on their programs are.
Computer Games - engaging touch interactions, cost-sensitive market.
Simulation for training humans - to perform tasks that require sensorimotor skills (surgery, training for naval personnel).
Interaction with computer-generated 3D data - users of CAD/CAM, data visualization and other engineering and scientific applications.
Medicine, Entertainment, Telerobotics.
Human Haptics System
Tactile Sensory System - distinguish vibrations up to 1 KHz; detection threshold on smooth glass plate - 2 m high single dot, 0.06 m high grating
Kinesthetic Sensory System - bandwidth 20-30 Hz; JND (just noticeable distance) - 2.5o for finger joint, 2o for wrist and elbow, 0.8o for the shoulder
Motor System - human bandwidth for limb motions is between 1-10 Hz as a function of the mode of operation
Active Touch with all three systems - stiffness > 25N/mm is needed for an object to be perceived as rigid
Functions of Haptic Interfaces
to measure the position and contact forces (and time derivatives) of the user’s hand (or other body parts).
to display contact forces and positions (or their spatial and temporal distributions) to the user.
Alerting function - vibrations.
Premise: The sense of touching simple shapes could be evoked by programming computers to control electromechanical master devices. We can build devices that give us a sense of feel when controlling remote actions with a high degree of dexterity.
Categories of Haptics Interfaces
1. Free motion, in which no physical contact is made with objects in the environment
2. Contact involving unbalanced resultant forces (like pressing an object with a finger pad)
3. Contact involving self-equilibrating forces (like squeezing an object in a pinch grasp)
Additional consideration - we can touch, feel and manipulate the objects directly or with a tool
Currently Available Haptic Interfaces
Ground-Based Devices
joysticks/ hand controllers
Body-Based Devices
exoskeletal devices
flexible (gloves and suits worn by users)
rigid links (jointed linkages affixed to users)
Tactile Displays
shape changers
shape memory actuators
pneumatic actuators
microelectromechanical actuators
vibrotactile
electrotactile
Haptics Research in Universities
MIT AI Lab
Salisbury (design of high performance mechanisms and sensors)
MIT Human-Machine Systems Lab
Srinivasan (understand human haptics, enhance human-machine interaction)
Sheridan (tactile and auditory substitution of force feedback for teleoperation)
MIT Media Lab
Margaret Minsky (tactile feedback from a graphics simulation, home haptics)
Plesniak (haptics and holographic systems)
Harvard University
Rob Howe (tactile display of shape and vibrations)
UNC
Taylor, Fred Brooks (nanomanipulator force feedback, medical research)
CMU
Baraff, Vedula (force feedback in interactive dynamic simulation)
University Research (cont.)
Stanford University
ME Dept., Cutkosky (force feedback grasping, multi-finger manipulation)
CS Dept., Khatib, Ruspini (haptics library, force control, dynamics)
CCRMA, O’Modrian (grand piano simulation, haptics for the blind)
UC Berkeley
Canny (optimum stability of grasp, dynamic simulations)
Northwestern University
Ed Colgate (dynamically effects like mechanical impedance)
Japan
Iwata (6 dof stewart platform joystick Haptic Master, mechanical design)
University of New Mexico, University of Virginia, University of Colorado, Rutgers University, Georgia Tech, McGill University, Naval Postgraduate School, University of Washington, Simon Fraser University, ...
Industrial Research and Development
SensAble Devices (PhanTom)
Immersion Corp. (Impulse Engines, Joysticks)
Cybernet Systems Corp. (CyberImpact Joystick, Steering Wheel, Flight Yoke)
Microsoft (formerly - EXOS Inc. Power Stick, Surgical Simulator, SAFiRE)
Boston Dynamics (Tangible Reality, Interactive Humans)
VTT, Finland (virtual prototyping)
Interval Research Corp., MERL, GE Corporate R&D, High Techsplanations Inc., Army, Navy, ...
Existing Graphic Systems
Capable of displaying a large number of simple polygons at interactive rates (>20,000 polygons at 30Hz)
Intersecting polygons & gaps common
Topology seldom available (Polygon Soup)
Gourand/Phong Shading & Texture
Video on Roaches
before that - color slides on xylophone, roaches
after that
color slide on staircase
slides from the HL talk
goals
bounding sphere covering
bounding sphere hierarchy
simulating smooth surfaces
results
Issues
How to display (and compute) elemental sensations such as impact, friction, softness, motion and constraint.
How to involve more complicated interactions (the Phantom concentrates on forces at the fingertip or tool tip). Those include pressure distribution, temperature and high-frequency vibration.
Solutions
Penalty Based Haptic Systems
Bounding Sphere Hierarchy
Virtual Proxy Model
Surface Properties
Force Shading/Texturing
HL Library with Application Programmers Interface similar to GL