Erik Von Burg

Mesa Public Schools

Gifted and Talented Program

Johnson Elementary School

elvonbur@mpsaz.org

Water Sabers (2008)*

High Heelers (2009)*

Helmeteers (2009)*

Cyber Sleuths (2009)*

LEGO All Stars (2010)*

SQUAD (2011)

Team A-maize-ing (2011)

Multi-Colored Monkeys (2011)

Quacking Cats (2011)*

Jet Packs (2012)

Team Fusion (2013)*

TBD (2014)

Workshop Agenda

Do: • Work in teams of up to 3.

• Note observations and ask questions.

• Collaborate.

• Fail. And try again.

• Take risks.

• Expect some frustration.

1. Foundations of problem

solving

2. Moving Straight

3. Turning 4. Sensors

Don’t: • Give up.

• Expect to be spoon-fed an answer.

• Be silent.

• Be afraid to play.

Robot

Structure

Mechanisms

Automation

Fundamentals of Problem

Solving

1. Determine problem.

2. Gather information.

3. Think of possible solutions.

4. Pick a solution.

5. Implement.

6. Test and revise.

How might I move the robot accurately, consistently, and predictably?

Select

Button

Back or

Cancel

Button

Directional

Buttons

Motor Ports

Sensor

Ports

USB Cable

Port (used to

download

program from

computer) Charger

Recently Run

Programs

Menu

Programs

Menu

Port View

Menu

Settings

Menu

Challenge: Move the robot forward in a

straight line.

Programming Lesson

1. EV3 interface.

2. Using the move block.

Block = Command

3. Downloading the program to the brick.

error = NOT accurate, NOT

consistent, or NOT predictable

Where do errors arise?

Errors of translation:

English Programming Language

Errors of the messiness of the real world:

Perfectly Controlled Programming

Environment Randomness/Variability of

the Real World

What is causing the error?

How can we determine the

origin of the error?

How can we eliminate/mitigate

the error?

Movement Problems

Observed Behavior Possible Root

Problems

Possible Reasons

for Problems

Curving/Turning

-Tires are different sizes.

-Tires are not turning at

the same speed.

-Tires improperly seated.

-Tires are rubbing

against motor.

-Manufacturing error.

Fishtail/Swagger Motors are moving at

different speeds. Unmatched motors.

Initial Jump Motors start moving at

different times. Gear slop varies.

Doesn’t Move

-Program problems.

-Miscommunication

between motors and

brick.

-Loose wire connections.

-Motor port problems.

-Wires incorrectly

connected.

How might I move the robot accurately, consistently, and predictably?

Fundamentals of Problem

Solving

1. Determine problem.

2. Gather information.

3. Think of possible solutions.

4. Pick a solution.

5. Implement.

6. Test and revise.

Problem Solving Process

1. What’s the specific or root problem?

2. What information is out there? What do I

need to know?

3. What are some ideas?

4. Which idea should I go with?

5. What steps do I need to take?

6. What worked? What didn’t? What can I

improve?

Challenge: Park the robot between the

lines.

Bonus Challenge:

Park the robot as

close to the wall as

possible.

And, oh by the way,

succeed the

first time!

• Does changing the wheel size affect your program?

• Repeat the challenge over a greater distance. Does this

change your approach?

• How does the power setting (speed) affect the robot?

• How could you create a formula to determine the number of

rotations for any given distance?

• How might you move past the parking space and back into

the spot?

• How does the initial placement affect where the robot ends

up?

Follow-up

Questions/Challenges

Please stop

working and

be ready to

discuss.

Math Behind the Moves

The distance the robot travels (Dt) is determined by the number of

rotations (n) and the circumference of the tire (C).

Dt = n × C

Knowing this, we can use this solve for the tire circumference using

the following equation.

C = Dt ÷ n When you know the tire circumference, you can determine the

distance the robot will travel in one rotation.

You can also distance travelled (Dt) by using the speed of the robot (S)

and the time the motors are on (t). This is not recommended because

speed is not constant.

Dt = S × t

Scaffolding Instruction

In what ways could you determine the number

of rotations necessary to move a certain

distance?

Concrete Abstract

Let’s add some

turns.

Turning

Pivot Turns

One wheel turns while the

other is stationary.

Tank Turns

One wheel turns forward

and one turns backward.

Measuring Turns

Turn Calibration Exercises

360° Turn Calibration Program the robot to complete the following

three actions:

1.Move forward about 2 rotations.

2.Turn 360°.

3.Move forward about 1 rotations.

Four Turn Test Program the robot to drive in a square using

move block and a loop.

This will help determine accurate 90° turns.

Perfect Turn Parameter

Over steer (decrease turn)

Under steer (increase turn)

Under steer

Over steer

Please stop

working and

be ready to

discuss.

Predictable Turn Angles

r

Tire

Rotations =

Path Length

Tire Circumference

Number of

Rotations =

(Desired Turn Angle/360°)(2πr)

Tire Circumference

Questioning Strategy

Question Sequence-

– How many rotations did it take to complete a 360°

turn?

– How might you use this to determine how many

rotations it would take to make a 90° turn?

– How many rotations will it take to have the robot

complete a 1° turn?

– If this is true, how many rotations would it take to

make a 149° turn?

Tire Rotations

Visualizing Turn Mechanics

Turning Jig

One wheel turns while the other is locked into position.

Motion Mapping

Obstacle Course Race

First Robot Across Finish Line WINS!!

4

3

1 1

2

5

Step Measurement Rotations

1 F 16” 2.3

2 R 45° 0.48

3 F 8.5” 1.2

4 R 90° 0.96

5 F 30” 4.3

Challenge: Park

the robot in the

parking space.

Challenge: Park the robot in the

parking space.

Starting Line

Parking Space

No part of the EV3 can be out of

the parking space.

Bonus Challenge:

Move your robot

through the maze.

Challenge: Navigate the Maze

Starting Line

Move the robot from the beginning of the maze to the end.

NXT can not

touch the wall.

Finish Line

Challenge Time

Challenges:

1. Turn to Parking Spot

2. Navigate the Maze

3. Create your own challenge

(with straight lines and

turns).

Want to explore more? Try

some of these changes.

• Try different speeds.

• Try different directions.

• Add more movements.

• Move in a figure 8.

• Navigate an obstacle course.

• Retrieve an object.

• Use your imagination.

Discussion Questions

– How does the initial placement affect the ending

position?

– How can you accurately place the robot in the

beginning?

– Does wheel size affect turn parameters?

– Castor wheels and sliders – which is better?

– How do surfaces effect turn accuracy?

– Does weight placement affect the turn? Where

should the weight be placed on a robot?

How might we use sensors to move the robot more accurately, consistently, and predictably?

How might we use sensors to find reference points or landmarks to move the robot more accurately, consistently, and predictably?

Sensors allow the robot to gather

information to find intermediate

reference points or landmarks.

Shorter move distances = Less error

Dynamic information gathering = Larger margin of error

EV3 Sensors

Touch

Gyro Light

Ultrasonic

Rotation

Programming Logic

1. turn on motor D to 50

2. wait until rotation

sensor gets to 4

rotations

3. stop motor D

Programming Logic

1. turn on motor D to 50

2. wait until rotation

sensor gets to 4

rotations

3. stop motor D

Programming Logic

1. turn on motor D to 50

2. wait until rotation

sensor gets to 4

rotations

3. stop motor D

Programming Logic

1. turn on motor D to 50

2. wait until…distance?

touch? angle? color?

3. stop motor D

Challenge: Use

sensors to park

between two lines

without knowing

the starting line.

Challenge: Use

sensors to

move within two

cm of a wall.

Challenge: Use

sensors to solve

the maze.

Sensor Challenges

1. Park between two lines without knowing the starting line.

2. Stop the robot within 2 cm of a wall without knowing starting line.

3. Solve the maze.

4. Invent your own.

5. BONUS: Have robot continuously explore room without getting stuck.

6. SUPER EXTRA BONUS: Follow a line.

7. EXTRAORDINARILY HUGE BONUS: Solve the maze regardless of starting point.

Start

Finish

Task: How might you program your robot to move through the obstacle course.

Constraints:

-You must use at least two sensors.

-You may not use any fixed duration move blocks to move the robot forward.

You may use them on turns.

Obstacle Course Challenge