1. EV3 Software EV3 Robot Workshop 2015
Instructor:
Assistants:
Lawrence Technological University

2. Course Overview 2015 Robofest competition Robobowl SPbot introduction
Using the SPbot to solve the Robobowl challenge

3. 2015 Robofest competition Video overview Key tasks
Key tasks
Measure the height of the rectangular shape
Compute location of pin 3 & 4
Follow the edge of the table
Find the bowl zone
Find a set of pins
Bowl a tennis ball
Return home

4. 2015 Robofest competition
Please note that bowling the tennis balls are outside the scope of this workshop

5. LEGO EV3 robot used – SPbot
Right Motor: C
Touch Sensor
EV3 Computer
Sonar Sensor
Left Motor: B
Color Sensor

6. Remember the connections!
Left Motor connects to B
Right Motor connects to C
If your motors are upside down forward will be backwards in your program
Color sensor connects to port no. 1
Touch sensor connects to port no. 2
Sonar sensor connects to port no. 4
Please note that the retail version of EV3 uses an infrared sensor, not a sonar sensor.

7. EV3 Versions Used
Examples use EV3 Educational Version or EV3 Home Edition 1.1.0
EV3 Firmware version: V1.06H
PowerPoint and all example programs are available at robofest.net under Tech Resources:
EV3 RoboFest Workshop Sp2015.pptx
RoboBowlWorkshop.ev3

8. Free EV3 Software Download
LEGO offers a home edition of the EV3 software
It is free to download and use, but has some limitations
No experiments
Limited built-in sensor support
You can download all sensor blocks
Main download page:

9. Move forward and stop when the rectangular shape is reached
Task 0
Move forward and stop when the rectangular shape is reached

10. Task 0: Example Solutions
Using wait block
Using loop block

11. Measure the height of the rectangle Watch the YouTube videos at:
Task 1
Measure the height of the rectangle
Watch the YouTube videos at:
(MeasureDistance)
(MeasureRectangle)

12. Measure Distances
Determine how far the robot travels while moving forward
Compute distance traveled by measuring the number of rotations of the wheel
Distance

13. Measure Distances Use the wheel geometry PI = 3.14
Circumference = Dia × PI
Diameter = 2 × Radius
Radius
How can use this information?

14. Measure Distances
For each rotation of the wheel, the robot will travel (Wheel Diameter) x (PI)
Distance = (Wheel Diameter) x (PI) x (# Rotations)
Distance = (55 mm) x (PI) x (# Rotations)
Distance = x (# Rotations)
Program: MeasureDistance.ev3

15. Measure The Rectangle Height
One method could be:
Go forward until the black rectangle is found
Reset motor rotation sensor
Go until the end of the rectangle is found
Read the motor rotations
Compute the distance traveled

16. Measure The Rectangle Height
Example of measuring the rectangle height
Program: MeasureRectangle.ev3

17. Compute the location of pin 3 & 4
Task 2
Compute the location of pin 3 & 4

18. EV3 Mathematical Operations
We can use math blocks to compute the location of pins 3 & 4
For example, assume
How can we compute this using our robot? mm

19. EV3 Mathematical Operations
We can use simple math blocks
Assumes that x = 200mm
Program: SampleMath1.ev3

20. EV3 Mathematical Operations
Here is another approach using advanced blocks
Program: SampleMath2.ev3

21. Follow the edge of the table Watch the YouTube videos at:
Task 3
Follow the edge of the table
Watch the YouTube videos at:
(LineFollowZZ)

22. Follow The Edge Of The Table
Use the zig-zag method to follow the edge of the table
Edge following is also referred to as line following
We need to determine when the robot is on or off the table
Right Edge
Left Edge
Table

23. Follow The Edge Of The Table
Get color sensor values to determine when the robot is on or off the table. We will use the color sensor in Reflective Light Intensity mode.
Off table = ______
On table = ______
On foil = ______
Color
Sensor
Reading

24. Follow The Edge Of The Table
Light sensor settings example
Off table = 10
On table = 40
Median threshold = (10+40)/2 = 25
Two cases
Light sensor reading > 25. On table.
Light sensor reading < 25. Off table.

25. Simple Line Following Algorithm
Right side
Program: LineFollowZZ.ev3

26. How to improve our line following algorithm
Zig-zag method can cause a bumpy response
To improve the response, you can use a 3-level line follower (concept shown below)
Off Table
On Table
Off Table
On Table

27. Watch the YouTube videos at:
Task 4
Find the bowl zone
Watch the YouTube videos at:
(LineCrossing)

28. Find The Bowl Zone
Assuming that the robot is in the no-bowl zone, we must enter the bowl zone in order to bowl a tennis ball to knock down pins
One method for finding the bowl zone is reach and cross the black line that separates the bowl zone and no bowl zone
This concept is called line crossing

29. Line Crossing How can we use our robot to detect lines?
Travel straight and look….
Off Line = waiting to cross line
On Line = reached line
Off Line = crossed line
Crossing
Lines

30. Line Crossing
Sample approach
Program: LineCrossing.ev3

31. Watch the YouTube videos at:
Task 5
Find a set of pins
Watch the YouTube videos at:
(TravelDistance)
(SpinSearch)

32. Find A Set Of Pins Couple methods Line follow for a given distance
Spin until the pins are detected with the sonar sensor

33. Line Follow For A Given Distance
First, we need to know how far to go
Let’s assume that the robot must travel 30 cm
How many wheel rotations is 30 cm?
Distance = (Wheel Diameter) x (PI) x (# Rotations)
Solve for # Rotations….
# Rotations = Distance / [ (Wheel Diameter) x (PI) ]
For our robot…
# Rotations = 30 cm / [ (5.5 cm) x (PI) ] = 1.74 rotations

34. Follow A Line A Given Distance
Example solution
Program: TravelDistance.ev3

35. Spin And Search
Here we are going to have the robot spin until it “sees” the pins with the sonar sensor
Program: SpinSearch.ev3

36. Task 6
Bowl a tennis ball

37. Bowl A Tennis Ball
Again, this task is outside the scope of this workshop
However, your robot should be in position to deliver a tennis ball if the previous tasks were completed successfully

38. Watch the YouTube videos at:
Task 7
Return home
Watch the YouTube videos at:
(FindHome)

39. Return Home
One method to have the robot return home is to line follow until home base is detected
Using the same principal as line detection, we can determine the threshold for detecting home base
On table / off home base = 40
On home base = 60
Median threshold = (40+60)/2 = 50

40. Return Home Two cases Light sensor reading > 50. On home base.
Light sensor reading < 50. Off home base.
Program: FindHome.ev3

41. Putting It All Together
In this course we learned how to
Measure the height of the rectangular shape
Compute location of pin 3 & 4
Follow the edge of the table
Find the bowl zone
Find a set of pins
Return home

42. Little Robots, Big Missions
Questions?