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Intelligent Robotics
Introduction
Thomas Hellstr
öm
Hellström
Umeå
Umeå University
Sweden
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© Thomas Hellström
““ROBOT”
ROBOT”
• Robot Industry Association (RIA):
“A re-programmable, multi-functional manipulator
designed to move material, parts, tools, or
specialized devices through variable programmable
motions for the performance of a variety of tasks”.
• A machine able to extract information from its
environment and use knowledge about its world to
move safely in a meaningful and purposive manner.
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Two major types of robots
Industrial robots
- Operates on the factory floor
(static, deterministic)
- Normally fixed or restricted mobility
- Performs actions independent of
the environment
Mobile robots
- Operates in “the real world”
(dynamic, non deterministic)
- Moves around
- Acts through close interaction with
the environment
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This course will be about:
• “Mobile robots”
• “Intelligent robots”
• “Autonomous robots”
• We will focus on Algorithms,
Behaviour and Sensors,
not so much on physical design
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What are they made of ?
Computer (“brain”)
Sensors
– distance meters
– “bumpers”
– cameras
Actuators
– “locomotion” (moves the robot).
Usually wheels, legs or tracked
– Manipulation (affect other objects) gripper,
“hand”, screwdriver,...
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Why Robots?
The 3 D’s:
1. Dirty
Money to make
2. Dull
3. Dangerous
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Typical applications
Manufacturing
•Spot or arc welding
•Die casting
•Surface coating
•Assembly
•Glueing
•Sealing
•Acid dipping
…
Other
• Cleaning pipes and pools
•
•
•
•
•
Rescue robots
Nuclear power plants
Space expeditions
Bomb disposal
De-mining (>100 Million land mines in the world )
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S
ervice Robots
Service
(Dull?)
• Helping
elderly/handicapped
• Post delivery
• Vacuum cleaning
• Lawn mowing
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k
Ok, so you don’t want
robots in the house…
USC surgeons perform surgical with robotic
assistance; No need for thoracotomy: splitting
the chest between the ribs
Hopefully
beyond all of
the 3 D’s
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Rotundus
a swedish robot
A sealed ball with no external
moving parts.
To move: the pendulum is lifted in the direction of travel, the centre of mass
gets displaced and the ball starts rolling.
To turn: Move the pendulum to either side.
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Research robots
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The future of Robots
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The pre history of Robotics…
Robotics…
Psychology
Psychology in the beginning of the previous century:
Behaviorism, John Watson:
The subject of study should be behaviors instead
of mental mechanisms.
Every behavior could be explained as stimulusresponse mappings.
Early 1930: Tolman found that a rat is building a
“cognitive map” of its environment.
Modern psychology admits the necessity of
internal representations. E.g.: psycho therapy
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The pre history of Robotics…
Robotics…
Cybernetics
Developed by Norbert Wiener in the late 1940s
A combination of biology, information science,
control theory.
Seeks to explain the principles behind control in
both animals and machines
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1953: Gray Walter’s tortoise
– Seeking light
– Head toward weak
light
– Back away from bright
light
– Turn and push
(for obstacle
avoidance)
– Recharge battery
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The pre history of Robotics…
Robotics…
Artificial Intelligence
Born August 1955:
Dartmouth Summer research Conference
Marvin Minsky:
“[an intelligent machine] would tend to build up within itself an
abstract model of the environment in which it is placed. If it were
given a problem it could first explore solutions within the internal
abstract model of the environment and then attempt external
experiments”.
Dominated AI and robot research for 30 years.
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The Classical AI Approach
(the ””hierarcical
hierarcical paradigm”
”)
paradigm
paradigm”)
Method: “sense-plan-act”
–
–
–
–
Interprete sensors
Model the world
Plan
Execute the plan
The components are FUNCTIONS:
– Perception
– Learning
– Planning
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The Behavior Based Approach
Brooks 1986, Braitenberg 1984, Walter 1953
The components are BEHAVIORS instead
of functions. E.g:
– Avoid obstacles !
– Explore !
– Follow the light !
Method:
– Each behavior module is a “reflex agent” mapping
inputs to outputs. (also called “reactive systems”)
– “Behavior fusion” if contradictions occour.
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Braitenberg
Valentino Braitenberg 1984: “Braitenberg Vehicles”
Excitatory (+) and Inhibitory (-) connections
between photocells and motors:
Light aversive (“ fear”)
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Braitenberg Vehicles
Light attracted (”aggresive”)
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Braitenberg Vehicles
Approaches and stops at strong light (“ love”)
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Braitenberg Vehicles
Approaches light, but always exploring (“ explorer”)
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Braitenberg Vehicles
Add various non- linear connections between sensor
and engines. Result: oscillatory behaviors
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Braitenberg Vehicles
Add various non- linear connections between sensor
and engines. Result: oscillatory behaviors
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Simulated versus Real robots
ADVANTAGES:
Experiments can be designed and repeated!
We can stay at our beloved keyboard!
(Accelerated execution time)
No need to recharge the batteries or to repair
Environment parameters can be modified:
friction, graviation, temperature, physical laws
DISADVANTAGES:
Requires an accurate MODEL of the world !
We will solve a simplified problem
:(
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Examples of tasks
Simple:
Not so simple:
Avoid obstacles
Wall following
Light following
Push things to the
corner
Collective behaviour
Soccer
Robot vacuum cleaner
Robot waiter
Planetary exploration
Rescue robots
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Robotics is Multidisciplinary
Classical AI
Knowledge representation, Natural language
processing, Planning, Searching, Perception
Machine learning
Model free techniques: Neural networks for
modeling, Kohonen nets for clustering of sensor
signals, Fuzzy logic for control,
Genetic algorithms to make the robot “evolve”
Computer Science
Software engineering, Architectures
Numerical methods
Optimization, Parameter estimation in models
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Robotics is Multidisciplinary
Neurophysiology
Human control systems
Ethology
Animal behavior
Psychology
Human behavior
Robotics
Path planning, Map making,
Obstacle avoidance, Tactile sensors,…
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Challenges
Perception
- Limited, noisy sensors
- Too much data / Hard to know what to care about
Control
- Limited capabilities of robot actuators/effectors
- Power consumption/support
Thinking
- Lots of unsolved problems
Environments
- Dynamic, impose fast reaction times
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