Special Topics in Computer Science
Computational Modeling for
Snake-Based Robots
Introduction
Week 1, Lecture 1
William Regli
Geometric and Intelligent Computing Laboratory
Department of Computer Science
Drexel University
http://gicl.cs.drexel.edu
1
Team 1
• Lead Institution: Drexel University
– PI William Regli, co-PI Michael Piasecki
• University of Maryland @ College Park
– SK Gupta
• University of North Carolina @ Chapel Hill
– Ming Lin and Dinesh Manocha
• University of Wisconsin @ Madison
– Nicola Ferrier, Vadim Shapiro, Krishnan Suresh
2
About the Team
• W. Regli
– CS, ECE and Mech E
– 1997 NSF CAREER
• M. Piasecki
– Civil
• SK Gupta
– Mech E
– PECASE, CAREER,
and ONR YIP
• M. Lin
– CS
– CAREER
• D. Manocha
– CS
– PYI, ONR YIP, Sloan
Fellow
• N. Ferrier
– Mech E
– NSF CAREER
• V. Shapiro
– Mech E, Math & CS
– NSF CAREER
• K. Suresh
– Mech E
3
Goals and Objectives
• Build and play with robots
• Course is fundamentally about modeling
– Mathematically model robot kinematics and dynamics
– Geometrically model robot design
– Virtually simulate robot behavior and performance
• Document experiences in GICL Wiki for
–
–
–
–
Use by future generations of students
Development of outreach materials (I.e. K-12)
Development of demonstration materials
Illustrate comprehensive, multidisciplinary, engineering
modeling
4
Course Outcomes
• The goal of this class is to build comprehensive
engineering models of biologically-inspired robotic
systems. Students completing this class will
– be able to identify problems resulting from the
interdisciplinary interactions in bio-inspired robots;
– perform system engineering to design, test and build biobots;
– be able to apply informatics principles to bio-bot design and
testing;
– gain experience using a variety of pedagogically appropriate
hardware (i.e. Lego Mindstorms, Roombas, etc) and
software tools (see above) for robot design/analysis.
5
Hardware Available
• Lego MindStorms Robot Kits, V1
– Note:
I will buy V2 or other modules as needed
• IRobot Roomba
• Sony Aibo
– ERS 7M3
• HP iPAQs
– 3800 and 5400 series
6
Lego Mindstorms Kits
• 12+ 1st
generation kits
• Motors,
sensors,
handyboards,
etc
• Many examples
on the web of
bio-lego designs
http://www.bea.hi-ho.ne.jp/meeco/index_e.html
7
iRobot Roomba
• Basic vacuum
cleaner robot, but
– Has USB port
– Hacker guides
•
http://www.roombareview.com/hack/
• Issues:
– Not particularly
bio-inspired
8
Sony Aibo
• Sadly, discontinued
• Happily, we have 2
• Fully programmable
– Quadruped motion
– Internal wifi,
cameras, etc
• Lots of tools on the
internet for hacking
Aibos
9
Also available: HP iPaqs
• More interesting behaviors
might require more
computational power
• Several late-model HP iPaqs
can be made available to the
class
10
Given the hardware,
What do we mean by modeling?
11
What do we mean by
modeling?
• There are several kinds we care about in this class
– System modeling
• Software, hardware, power, sensors and their interactions
– CAD/3D/Assembly Modeling
• Geometry, topology, constraints, joints and features
– Functional Modeling
• Intended use (or function) for the device (note, device may have other
unintended functions or uses)
– Behavioral Modeling
• System inputs/outputs, motion characteristic, etc that achieve the
function
– Physics-based modeling
• Statics, kinematics, dynamics and laws of physics
– Information Modeling
• Data, relationships, semantics (meaning)
12
Basic Engineering for
CS Students
• Statics: The branch of physics concerned with the analysis of
loads (force, moment, torque) on a physical systems in static
equilibrium, that is, in a state where the relative positions of
subsystems do not vary over time, or where components and
structures are at rest under the action of external forces of
equilibrium.
• Kinematics: The branch of mechanics (physics) concerned with
the motions of objects without being concerned with the forces
that cause the motion.
– Inverse Kinematics: The process of determining the parameters of
a jointed flexible object in order to achieve a desired pose.
• Dynamics: The branch of classical mechanics (physics) that is
concerned with the effects of forces on the motion of objects.
13
Physics-Based Modeling
• The creation of computational
representations and models whose
behaviors are governed by the laws of
the physical world
• In the context of bio-inspired robots:
create an virtual environment for
creation, testing and simulation of virtual
robot design
14
An example of a
multi-disciplinary engineering
model
15
Designing a “Windshield Wiper”
• From D. Macaulay,
“How Things Work”
• What are the models?
– Functional
– Behavioral
16
Models (1)
• Functional model
– The function of a windshield wiper is to remove
dirt from the surface of a car’s windshield
• Behavioral model
– Input: motor rapidly rotating around the z axis
– Output: oscillation in the yz plane with low
frequency
17
Models (2)
• CAD Models
– 3D models with joints
and constraints
• Typically consist of
– Part models
– Assembly model(s)
• Formats can be 3D
solid or 3D wireframe
18
3 Lego models of a wiper assembly
Models (3): Information
Windshield
Wiper
Referring
artifact
Sub_of
Sub
Gear Function
Rotation conversion
Inflow
Outflow
High speed
rotation
Oscillation Function
Motion conversion
Outflow
Rotation Function
Motion conversion
Inflow
Sub
Sub_of
Sub_of
Mechanical
Function
Wiping motion
Sub
Inflow
Outflow
Referring
artifact
Source
Destination
Referring
artifact
Low speed
rotation
Low speed
circular
motion
Referring
artifact
Source
Low speed
oscillating
motion
Destination
Shaft
Source
Worm and
Gear pair
Destination
Source
Arm with Peg
Destination
Slide Rocker
Wiper Arm
19
Models (3): Information
• Information modeling representations
– XML, OWL, FOL, UML…
• Information modeling tools
– Protégé, Ontobuilder, Rational, etc
• Information modeling tasks
– Knowledge engineering, ontology building,
creating a knowledge base, functional
modeling, etc.
20
Physics-based Models
• Kinematics (i.e. Animation)
– Just move the parts based on
joints & constraints
• Dynamics
– Incorporate forces, motor
torques, power consumption,
friction, etc
• Other issues:
– collision detection algorithms
that check for intersection,
calculate trajectories, impact
times and impact points in a
physical simulation
21
End Result of this Class
• 10-to-12 comprehensive engineering
models of bio-inspired robot designs
– Individuals, teams (1-to-2 people)
• All documentation in the Wiki
– “README.TXT”-like instructions so as to
make work reproducible
– Your audience: Projects could be
accessible to K-12 students or Frosh
design
22
Grading
• Three duties:
– 15%, Weekly scribe: everyone will get a turn scribing notes
and discussion from each week’s class into the Wiki. The
more details the better (i.e. scribe is encouraged to ‘back-fill’
discussion with links and references and to-do items).
– 35% Weekly progress: each person/group will set up a
project space in the Wiki to document complete design and
modeling project
• Instructor will use the ‘discussion’ mechanism to post feedback
and monitor progress; students welcome to comment on the
work of other students; vandalism harshly punished
– 50% Final project: due on or before finals week. Includes
walking robot, mathematical and physical models, and Wiki
pages.
23
Bio-Inspired Robot
Locomotion: Topics
• Explain motivation for bio-inspiration in mobile robot design
– What ideas can nature offer engineers?
– Can bio-inspired designs outperform traditional technology?
• Identify important design parameters in nature
– How can we quantify and evaluate nature?
– How can we measure maneuverability and the ability to navigate
various terrain?
• Show successful implementation of bio-inspiration in mobile
robot design
– How is the source for bio-inspiration chosen?
– How is the bio-inspiration implemented into the design?
– What advantages does the bio-inspired robot offer over the
traditional robot alternatives?
24
Some Concepts from Nature


• Scorpion
• Cockroach

• Stick Insect

• Crab

• Spider

• Lobster
25
Some Concepts from Nature
• Dog

• Snake

• Gorilla

• Gecko

• Human

• Dinosaur

26
Example: Snake Robot
Applications
•
Search and Rescue
– Urban environments
– Natural environments
•
•
•
Planetary surface exploration
Minimally invasive surgery / examination
Pipe inspection / cable routing
27
Example: Snake Robot
Applications
Snakes are also being used as inspiration for stationary robots that are
capable of complex manipulations.
• Bridge inspection
• Disarming bombs
• Construction/repair in space
http://voronoi.sbp.ri.cmu.edu/serpentine/serpentine.html
28
Design Problem
• Design requirements
•
Application: Search and rescue
•
Motivation
– Hazardous environments
• Further collapse
• Fire and toxic gases
– Narrow spaces
• Obstacles may be densely packed
• People, devices, or conventional robots may
not fit
– Small body diameter
– Small area required for
locomotion
– High maneuverability
– Ability to navigate
obstacles
– Locomotion through
various environments
•
•
•
•
Dirt
Rocks
Water
Obstacles
29
Conventional Robots
•
•
•
•
Require large cross sectional areas for passage due to wheels or legs
Cannot navigate through narrow spaces
Have limited maneuverability
Limited by terrain and obstacle height
30
Where do we start?
• Projects should focus on robot locomotion and gait
• Wheels are not allowed
• Identify bio-mimetic behaviors
– i.e. 4 legs, make a mathematical model of movement for each leg,
how many joints does each leg need, etc
• Build some bots
– Legos are probably easiest to start with
• Iterate between working in the physical world and enhancing the
virtual world
– Objective: create as complete and high-fidelity model as possible!
• When in the virtual world, you’ll need to learn about and teach
yourself a number of tools
– CAD/CAE, 3D, etc.
31
Project Examples
• 1-to-10 legged robot
– Turtle, ant, spider, etc.
• “Snake” that lifts its head
– i.e. climb up a stair step
• Jumping robot
– How high can you jump? How far (Frog)?
• Tumbling robot
– i.e. Star Wars
• Whatever your imagination can think up!
32
Software to Investigate
• Anything is fair game! Part of this
classes’ goals is to explore what works
best in the classroom
• Software is needed for
– Design
– Modeling
– Simulation
33
Modeling Software
• CAD Systems
– Pro/ENGINEER
– SDRC/UG I-DEAS
– AutoCAD, MicroStation, SolidWorks
• Lower level
– Models: OpenCascade, ACIS, Parasolid
– Rendering: OpenGL, DirectX
34
Simulation Software
• OpenSource
– Open Dynamics Engine
• Open Source dynamics & collision detection
• Game engines
– Havoc
• CAD
– Pro/MECHANICA, Adams, …
• Other
– Matlab, maple
35
Initial Data
• Lego Models
– http://gicl.cs.drexel.edu/repository/datasets
36
Discussion Topics
• Engineering Datatypes
– 2D/3D, standards, proprietary
•
•
•
•
How to represent an assembly
Role of the Wiki
Expectations of the scribe
Help spend money!
37
Other Events This Term
• Two talks sponsored by GRASP Lab
– Fridays at 11am
– THIS FRIDAY: Daniella Rus, MIT
– Oct 13: Dinesh Manocha, UNC
38
END
39
Issues in Physics-Based
Modeling of Bio-Robots
• One needs to algorithmically and
40
Engineering Design
41