Artificial IntelligenceArtificial IntelligenceArtificial IntelligenceArtificial Intelligence

Lecture 11Lecture 11

Computer Science Robotics

& AI

Outline• What does a computer scientist

do?• Robotics• Artificial Intelligence

What's a Computer Scientist?

• Let's ask Jeeves first:– Jeeves' answer

• Answer:– Computers are a new, complex kind of tool– Computer scientists figure out how to do useful

things with computers:• graphics & medical imaging• networking• sharing information (the web)• robotics & artificial intelligence!

Where do CS ppl. work?• There are basically three places that use

computer scientists:– Academia - colleges and universities for

teaching and research– Research institutions - NASA, plus other

companies that do research (Microsoft, Bell Labs, etc.)

– Industry - programmers (writing the software that people use on their computers)

Robotics• A robot is basically a mechanism

that operates under computer control

• The main purpose they serve these days is to do boring, repetitive tasks

• The fun ones are research robots

Basic Robot• Has three parts:

• Reads sensors to understand environment• Computes what to do based on sensors• Uses actuators to do it

Sensors Computer Actuators

Sensors & Actuators• Many possible sensors:

– video cameras– tilt sensors– force sensors

• Many possible actuators:– Electric motors– Hydraulics– Pneumatics

Mobile Robotics• All the stuff done in the field called Mobile

Robotics.– means that robot can move around on its own

power– as opposed to most industrial robots, which are

giant arms bolted to the floor

• There are two types of mobile robots:– walking robots– wheeled robots

Examples, examples• We'll do this by example…• Robots at Carnegie Mellon:

– Daedalus– Lunar Rover (Nomad)– Black Widow

• Robot at NASA:– Dexter

Daedalus• Designed to be a planetary

explorer

Daedalus• an example of a frame walker

Frame 1:

Frame 2:

Legs

Nomad• Designed to test ideas for a

commercial trip to the moon (LunaCorp)

Nomad• Went to the

Atacama desert of Chile

• Searched for meteorites in Antarctica

• Is a wheeled robot• Super-cool

collapsible steering mechanism

Dextre• Dextre is a two armed robot which is

part of the Mobile Servicing System on the International Space Station (ISS), and extends the function of this system to replace some activities otherwise requiring spacewalks. It was launched March 11, 2008 on mission STS-123.

Dextre

Black Widow• A research project

Black Widow• Patterned somewhat after an insect (leg

length, number of legs)• Patterned somewhat after a crab

• Purpose was to try out walking algorithms.

• Used neural networks for training method

Artificial Intelligence• Attempts to understand and build

intelligent entities• Four different definitions of AI:

– acting humanly (the Turing Test)– thinking humanly– thinking rationally– acting rationally (this is the goal of

robotics)

Problems that require AI

• Natural Language Processing– make a computer understand English

• Machine Learning– change behavior based on experience

• Perception of a visual scene– be able to pick out people, objects, etc.

• Robotics!– navigation, accomplishing tasks, etc.

AI Techniques• Some that you've probably heard of:

– Neural Networks– Genetic Algorithms– Fuzzy Logic

• Others that are popular:– Reinforcement learning– Probabilistic reasoning– Search techniques

Neural Networks• Based on animal nervous systems:

Neural Network Neuron

Input Links(from other neurons)

WeightedSum

ActivationFunction

Output Links(to other neurons)

A Simple Neural Network

Output

Input

Input

Training Neural Networks

• That was Black Widow's neural network to keep the body level.

• To train (decide the weights to use in the weighted sums) a NN, you have to give it LOTS of examples

• Traditionally, these are generated in simulation or by people– It made the robots do the work...

Questions & Answers

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