1. Introduction to LEGO RCX robotics and Robot Sumo
Workshop Day 3
CJ Chung
Associate Professor of Computer Science
Lawrence Technological University

2. Workshop Third Day Improved Sumo program Mini Competition
Tips and Ideas to improve your Robot!
Advanced Topics in RCX code (optional)
Team Pictures
Planning

3. Review: Basic Sumo Repeat the following forever: Problems?
Go forward until the edge
Backward slightly (in Big block)
Turn right
Problems?
Same behavior all the time!
Touch sensor was not used

4. Improving the Sumo program
Introduce a random wait value for turning
Introduce a touch sensor watcher – whenever the bumper is hit, change the direction

5. Improved Sumo Program Random between 0.5 ~ 1.2 seconds
If your opponent is pushing
Your back, then change your
direction

6. Mini Sumo Competition 1 Without Unknown Problem
Every team will compete with every other team
Team picture time!!!
Team 1
Team 2
Team 3
Team 4
Team 5 X

7. Team Picture
The team picture will be printed on your personal certificate
Please submit the following for each team:
Team name
Team member first and last name
Team member grade
Team member gender

8. Mini Sumo Competition 2 With Unknown Problem:
The robot must wait until touch sensor is pressed
Wait 5 seconds, then start to move
You cannot use the previous way using a touch sensor watcher! Why? Whenever the touch sensor is pressed, the robot will spin…
Team 1
Team 2
Team 3
Team 4
Team 5 X

9. Better Program for the competition 2
A nested loop
Repeat Until that will terminate the loop immediately when the termination condition is met
Unknown
Problem
solution

10. Is this a perfect program?
No, there are still some problems
One example:
The robot detects the edge line.
Move backward.
Turn right around 90 degrees.
Then the robot must see the outside of the ring which is very dark!!!

11. Ideas to improve your SumoBot
Improve (debug) your program!
Applying Theories learned in Physical Science
Mass, Newton’s laws
Friction
Gearing
Wheel size
Power level
Detecting the opponent (can be done later)
Touch sensor
IR and light sensor

12. Ideas to increase weight of your Robot
What is the max weight of each division?
Add more Lego blocks, if you have some at home
Add Coins, Used Batteries, or others – make a holder using cardboards
Put your team name on the robot. An idea: make a team flag

13. Ideas to increase friction of your Robot
Use rubber bands
Add more wheels later for Worlds

14. Gearing Ideas Use gear train to increase gear ratio
Considering resources, this is not allowed for the school qualifier
The winner from the school qualifier may consider this idea later

15. Changing Wheels? Using bigger wheels
Considering resources, this is not allowed for the school qualifier
The winner from the school qualifier may consider this idea later

16. Make sure the Power! RCX power level: 1 ~ 7
Voltage of your batteries should be around 9V
How to check the voltage level
In RIS, click on Settings
LTU will provide fresh batteries for all the teams on the competition day

17. Changing the shape of the Robot
Make it sturdy
Front part may need some changes (After the school qualifier)

18. Height of the robot matters?
Consider the “center of gravity”

19. Ideas using 2 Touch Sensors
A touch sensor –front left
Another touch sensor – front right
If left sensor is pressed – turn left and push hard
If right sensor is pressed – turn right and push hard
If both left and right sensors are pressed, push straight hard

20. What is next? - Meet with your teacher at least twice before the school qualifier
Improve your programs
Add stuff for the max possible weight for your robot
Review what you have learned for the unknown problem. If you do not solve the unknown problem, you lose automatically
Signed Media Release form must be ready before the qualifying competition date at your school

23. Implementing Proximity Sensor to detect opponent (optional)
Use a Lego Light sensor and Infrared message sending capability of RCX
RCX is continuously sending IR messages
Using another light sensor facing forward, measure fluctuations in the light intensity that is reflected from objects
The higher the fluctuation, the closer the robot is to an object

24. How to detect the light fluctuation??
You need to store previous sensor reading(s)
Compare with current reading
If the difference is more than threshold value, some thing is in front!

25. preval becomes the value of Light 3
preval = preval + 3
If the current light sensor
reading is greater than (previous value + 3), then some thing is close.

26. Sumo with proximity sensor
Repeat forever:
Scan until find the opponent
Go forward until the edge
Backward slightly
Turn right

27. My Blocks (optional topic)

28. Opening a saved program (optional)
Never use File | Open! There is a bug involving MyCommands
Use Main Menu | Program | Vault