No Slide Title

Smart Vehicles – Summary

Leyla Nazhand-Ali, Ph.D.

Assistant Professor

IEEE member

Michael Henry

Graduate Student

This Talk

•We will review some topics that we discussed lastweek

–Autonomous vehicles

–Embedded microprocessors

–Programming an autonomous toy car

–Infrared sensors

–Square waves

•We will also talk about some new concepts:

–Closed loop control

–Design tradeoffs

Decision

Output

Input

Environment

Review: Why We Need AutonomousVehicles?

young-african-wildlife-safari-2-young-giraffe-w-michael-poliza-b.jpg

Review: What are AutonomousVehicles?

•A fully(semi)-autonomous vehicle can perform all (some) ofits actions without any human control.

•Commercial vehicles already perform many automaticactions such as anti-lock brake, cruise control, lanedeparture warning, …

•Research vehicles have been able to drive themselves inurban-like areas.

Review: How is Autonomy Achieved?

•In a car, autonomy achieved similar to the way it isachieved by humans:

–First, we sense the environment

–Second, we process the data we collected through oursenses (Yes, we do use our brains, at least sometimes!)

–Third, we act based on the decision we made

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\S5QU03FX\MCj04038930000[1].wmf$

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\XGZ1J8G8\MCHM00376_0000[1].wmf$

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\S5QU03FX\MCHM00378_0000[1].wmf$

sensors

Controller(microprocessor)

actuators

Review: Embedded Microprocessors

•Embedded microprocessors are thebrains of real-time systems, whichexecute deadline-based tasks.

•They are usually smaller, cheaper,easier to program and develop, andconsume less power compared togeneral-purpose microprocessors thatare used in PCs.

•They are more reliable and failureresistant, which is crucial inembedded systems.

•You probably own dozens, maybemore than a hundred of them.

Review: State Table

•State tables are a way ofmaking decisions.

•They are used for programmingand are heavily used indesigning digital hardware.

•For every possible input,specify the output.

•With the car, the input is theinfrared sensors and the outputis the motors.

•Good for problems with a smallamount of input.

Input

(IR sensors)

Output(Motors)

Left

Right

Left

Right

White

Forward

Full

Forward

Full

Black

Reverse

Full

ReverseFull

Black

White

Forward

Half

Reverse

Half

White

Black

ReverseHalf

ForwardHalf

Review: Infrared Sensing

•Infrared (IR) is invisible light.

•IR sensor on car transmits IR lightand measures how much bouncesback.

•Black surfaces absorb a lot of lightand reflect little.

•White surfaces reflect a lot of light.

•Based on how much is reflected, theprocessor can determine whatsurface the sensor is over.

IR transmitter

Black Surface

White Surface

Other Sensors Similar to IR Sensor

•With IR sensing, you are sending outIR light and measuring its response.

•RADAR works by sending out radiowaves and measuring the response.

•LIDAR and SONAR work like RADAR,but with light and sound, respectively.

•Barcode readers detect black andwhite, similar to your project, but theyuse visible light.

Review: Square Waves

•Square waves are used tofeed the motor and make itturn.

•Period is the length of time ittakes to complete one cycle.

•Frequency is how many timesper second the wavecompletes a cycle.

•Duty Cycle is the ratio of timethe wave spends being highand the period of the wave. Itis usually expressed as apercentage.

One cycle

Period

1 / Period = Frequency

50% duty cycle

75% duty cycle

Other Wave Shapes

•Waves come in differentshapes.

•Sound travels in a wave.

• AM radio uses changes inamplitude of the wave tosend data.

•FM radio uses changes infrequency to do so.

•We use the sameprinciples to use squarewaves for controllingmotors.

Sine

Sawtooth

Triangle

Square

Voltage

Closed Loop Control

•Control of the car can be simplified by thinking of thecontrol as being a closed loop.

•The sensor provides data from the environment to thedecision maker that starts an action, which in turn, affectsthe environment.

Output using Actuator

Input from Sensor

Decision

Environment

Think, Pair, Share Activity

•Consider the automatic thermostat in your home, which isresponsible to keep the temperature at a certain point.

•Come up with the closed loop that governs this system.

•Identify the input, the output, the decision maker and theenvironment variable.

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\08Q1BVGH\MPj03058250000[1].jpg$

Decision

Output

Input

Environment

Design Tradeoffs

•Most engineering problems involvedesign tradeoffs.

–Cost vs. Time: More expensiveequipment will sometimes get the jobdone faster.

– Cost vs. Reliability: Expensive partsbreak less.

– Time vs. Quality: A project that’srushed will not be as high of quality.

•Recognizing and controlling designtradeoffs is one of the mostimportant tasks of an engineer.

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\EK5FIH5V\MCj03418380000[1].jpg$

Design Tradeoffs in AutonomousVehicle Project

•In Task #3, there is a tradeoff between the “accuracy(quality)” of your solution and the speed.

•Drive the car too fast and it will frequently go off courseand need correction.

•The fastest speed setting does not necessarily achievethe fastest completion time!

Design Tradeoffs in AutonomousVehicle Project

•In some design problems, we have to sacrificespeed, quality and all other design objectives inorder to achieve dependability and reliability.

•With task #4 we sacrificed navigation speed byusing the right hand rule, but made the problemsolvable and guaranteed reaching the destination.

Even Discoveries Involve Tradeoffs

•For the Infrared discovery activity, you tried tomeasure the reflectivity threshold of the sensors.

•Trying to do the measurement quickly by movingthe car on the fastest setting results in a lessaccurate number.

80% 70% 60% 50% 40% 30% 20% 10%

Back to Autonomous Vehicles

•Everything you learned andapplied is involved in theautonomous design process.

–Sensor input (IR sensors)

–Controlled output (Motors andWaves)

–Decision Making (State Tables)

–Reliability/Fault Tolerance(Embedded Systems)

Some other Thoughts

•By now you should have realized that theautonomous design process includes manydiverse engineering topics.

•A successful design benefits fromcollaboration of many different fields.

$C:\Documents and Settings\leyla\Local Settings\Temporary Internet Files\Content.IE5\B443WCXL\MPj04068100000[1].jpg$

Closure Cooperative Writing Pairs

•Form pairs

•Using the blank screen provided, write a fewsentences describing the major point you learnedin this project and the main unanswered questionyou still have.

•Please write your names on the screen

•We will collect it electronically in DyKnow