3D Haptics and Robotics
Krasimir Kolarov
Interval Research Corporation
HCC Seminar, UC Berkeley, 12/3/98.
What is this talk about?
• Introduction to Haptics and Haptic Interfaces
• Commercial and University Haptics
• Force Feedback Devices
• 3D Haptics at Interval Research Corp.
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, costsensitive 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
History of Haptic Interfaces
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, ...
Immersion Corporation
Cybernet Systems Corp.
EXOS Inc.
SensAble Technologies Inc.
Video on Applications (SensAble)
• before that
• b&w slides from Web Page
• color slides from Hasser’s report
• after that color slides from VTT
Research Interests
Develop a cooperative graphic and haptic interface
that allows to manipulate and sculpture 3D objects
more effectively
Goals and Assumptions
• Provide a high level interface to haptic devices that:
Complements existing interactive graphic systems
Works robustly in multi-surface environments
Provide common framework to allow stable and safe haptic
control.
• Ability to perform tasks that are not possible with the current
technology
• The combined graphical and haptic interface to 3D objects will
allow us much richer and powerful interaction.
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
Questions
• How can you support a powerful and general set of
modeling 3D primitives.
• Allow the haptic server to operate with a great amount
of autonomy from the host computer and simulate a wide
range of virtual environments
•Explore issues like latency in manipulating large 3D
data sets
Basis for Research
• Test distance/collision
simulation.
calculation
and
dynamic
• Building a library to support arbitrary complex rigid
objects.
• Allow the developer to specify constraints between the
objects in the environment and control the motion of
objects in the virtual world.
• Model the contact forces caused by contact and
collisions between the objects in the environment
Stanford Students Projects
• The Virtual Xylophone.
• The Haptic Roaches.
• Haptic Exploration of rigid 3D objects.
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
Bounding Sphere Hierarchy
The Virtual Proxy
Virtual Proxy Description
• A representative
object that is constrained by
obstacles in the environment
• Proxy is reduced to a point (C-space). User
definable size of proxy.
•Constraint planes locally describe the range of
potential proxy motion.
• Proxy moves to locally minimize the distance to
user’s position
• Haptic device physically moves user to proxy’s
position
Force Shading
Haptic System Implementation
• HL library, syntax similar to GL
• graphic Client/Haptic Server Model
• Bounding Sphere Hierarchy
- O(log n) growth
• > 24,000 polygonal primitives on 200 MHz Pentium
- Stiffness 1800 Newtons/meter
- > 1000 Hz servo rate
Demonstrations
Sample References
• “Force and Touch Feedback for Virtual Reality”, Grigore
Burdea, Rutgers Univ., 1996, John Wiley & Sons.
• “The PHANToM User’s Group Workshop Proceeding”,
MIT September 1996, 1997, 1998 (published as MIT AI
Lab Tech Reports).
• Haptics Home Page at Northwestern Univ.:
http://haptic.mech.nwu.edu/
• Ruspini, D., Kolarov, K. and Khatib, O. "The Haptic
Display of Complex Graphical Environments", Computer
Graphics Proceedings, Annual Conference Series,
SIGGRAPH'97, Los Angeles, California, September 1997