1. Electronics and Robotics Merit Badges
Class 4 – Robot Subsystem Mechanics or
Building Robot Bases and Drive Trains
In this class, we’ll talk about that “other part of a robot” (versus the Electronics Merit Badge stuff we just covered). That is, we will now cover “Mechanical Systems” and “Mechanical Engineering” aspects required to build these complex systems - especially as to how it applies to building robot bases, their drive trains, power systems and (back to electronics!) controls. In the BSA Robotics Merit Badge Pamphlet this is called
THE CHASSIS SUBSYSTEM
THE MECHANICAL SUBSYSTEM
THE POWER SUBSYSTEM THE CONTROLS SUBSYSTEM
Our robot is the Parallax SumoBot that is based upon a simple steel base and Radio Control (R/C-type) airplane servos that have been modified to act as drive motors for locomotion of the robot. We will build these mechanicals as we discuss this aspect of robotics.
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Electronics and Robotics Merit Badges - Class 3

2. Electronics and Robotics Merit Badge Class 4
Our kit! The SumoBot Kit
Our kit! Open up the zip lock bags and spread out the components.
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Electronics and Robotics Merit Badge Class 4

3. CHASSIS SUBSYSTEM
2. Robotics industry. Lets discuss the following (with your counselor):
The kinds of things robots can do and how robots are best used today.
4 D’s – Dangerous, Dirty, Dull, Difficult
b. The similarities and differences between remote-control vehicles, telerobots, and autonomous robots.
“R/C” Models (Heli), UAV’s (semi-autonomous), Autonomous Robots (Sumobot)
c. Three different methods robots can use to move themselves (other than wheels or tracks). Describe when it would be appropriate to use each method.
Walk, Fly, Crawl
When to use each? Muddy/Wet/Rough Terrain (Tracks – think bulldozer or tank), Smooth road/some rough – wheels, very very rough (Big Dog Video here) or humaniod (Sony)), Fly
Write this stuff on your Robotics Workbook (2 a/b/c)

4. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #1
Install the Battery Box
Parts Required:
• Battery Box
• (2) 4/40 3/8" long
flat-head countersunk
machine screws
• (2) 4/40 nuts
• SumoBot chassis
Stand the SumoBot on its PCB mounting ears. Install the plastic battery pack using two 4/40 3/8” flat-head screws and nuts. The screws will be countersunk into the battery pack when tightened and should be out of the way of the batteries.
This is our robot base. It is a simple steel cutout that holds all the other components of the Sumobot together.
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Electronics and Robotics Merit Badge Class 4

5. MECHANICAL SUBSYSTEM
4. Design, build, program, test. Do each of the following:
a. (With your counselor's approval) Choose a task for the robotic subsystem that you plan to build. Include sensor feedback and programming in the task. Document this information in your robot engineering notebook.
b. Design your robot. The robot design should use sensors and programming and have at least 2 degrees of freedom. Document the design in your robot engineering notebook using drawings and a written description.
c. Build a robot or robotic subsystem of your original design to accomplish the task you chose for requirement 4a.
d. Discuss with your counselor the programming options available for your robot. Then do either option 1 OR option 2.
(1) Option 1. Program your robot to perform the task you chose for your robot in 4a. Include a sample of your program's source code in your robot engineering notebook.
[We will not do flowcharting] (2) Option 2. Prepare a flowchart of the desired steps to program your robot for accomplishing the task in 4a. Include procedures that show activities based on sensor inputs. Place this in your robot engineering notebook.
e. Test your robot and record the results in your robot engineering notebook. Include suggestions on how you could improve your robot, as well as pictures or sketches of your finished robot. Sumobot Competition Night!!!

6. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #2
Install the Servo Motors
Parts Required:
• (2) Parallax
Continuous Rotation
Servos
• (8) 4/40 3/8" long
pan-head machine
screws
• (8) 4/40 nuts
• SumoBot chassis
Using four 4/40 3/8” pan-head machine screws and 4/40 nuts, attach each servo motor
to the chassis. The easiest way to do this is to hold the nut with one finger while
turning the screwdriver with the other hand.
Hacking a Servo
The theory behind this hack is to make the servo think that the output shaft is always at the 90 degree mark. This is done by removing the feedback sensor, and replacing it with an equivalent circuit that creates the same readings as the sensor being at 90 degrees. Thus, giving it the signal for 0 degrees will cause the motor to turn on full speed in one direction. The signal for 180 degrees will cause the motor to go the other direction. Since the feedback from the output shaft is disconnected, the servo will continue in the appropriate direction as long as the signal remains.
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7. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #3
Install the Rear SumoBot
PCB Stand-offs
Parts Required:
• (2) 5/8" round
standoffs
• (2) 4/40 3/8" long panhead
machine screws
• SumoBot chassis
Using a 4/40 3/8" pan-head machine screw, attach each stand-off to the rear of the
SumoBot chassis.
Back to work!
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8. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Install the Front SumoBot
PCB Stand-offs
Parts Required:
• (2) 5/8" round
standoffs
• (2) 4/40 1" long panhead
machine screws
• SumoBot PCB
Using a 4/40 1" pan-head machine screw, attach each standoff to the front mounting holes of the SumoBot PCB.
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9. CONTROLS SUBSYSTEM 5. Demonstrate. Do the following:
a. Demonstrate for your counselor the robot you built in requirement 4.
b. Share your robot engineering notebook with your counselor. (NEXT TIME!!) Talk about how well your robot accomplished the task, the improvements you would make in your next design, and what you learned about the design process.

10. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #5
Mounting the PCB
Parts Required:
• SumoBot PCB
• (2) 4/40 3/8" long
pan-head machine
screws
• (2) 1-1/4" round
stand-offs
• (2) Nylon washers
• SumoBot chassis
Feed the ends of the 1" long pan-head machine screws through the front mounting holes on the SumoBot chassis. Secure the rear side of the SumoBot PCB to the 5/8“ standoffs with two 3/8" pan-head machine screws. Holding the chassis upside-down, place a nylon washer onto the end of each 1" long pan-head machine screw, then secure by threading on the 1-1/4" round standoff.
Now its beginning to look like something…
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11. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #6
Prepare the Wheels
Parts Required:
• (2) SumoBot wheels
• (2) SumoBot rubber tires
Stretch a "tire" of each wheel and adjust so that the"tire" is centered across the wheel.
What where those other modes of movement again? FLY CRAWL WALK?
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12. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #7
Mount the Wheels
Parts Required:
• (2) Prepared
wheels/tires
• (2) Black servo-horn
screws
• SumoBot chassis
Carefully press each prepared wheel onto the servo splines. Secure each wheel with the small black Phillips head screw.
Almost there!
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13. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #8
Mount the Scoop
Parts Required:
• SumoBot scoop
• (2) 4/40 1/4" long panhead
machine screws
• (2) 4/40 nuts
• SumoBot chassis
Using two 4/40 1/4” pan-head machine screws and 4/40 nuts, attach the scoop to the SumoBot chassis. Carefully center the scoop before tightening the screws and nuts.
Review sumo rules here?
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14. SumoBot Rules The Match:
1) Flip a coin to determine who positions their robot first in the ring
2) Place the ‘bot in the ring as directed by the referee
3) Press the start button on the bot when directed by the referee.
After 5 seconds the bot may begin moving (sound/light indicates robot working).
4) Move back at least 3 feet from the edge of the ring
5) Catch any bot that is out of the ring and turn it off
6) Place the bot back in a holding area between matches. A contestant may
make adjustments between matches, but may not leave the holding area.
Basic Rules:
One match will consist of three rounds, within a total of 3 minutes each.
The team who wins two rounds out of three wins the match.
2) The match will be stopped and a rematch will ensue when it is apparent
that neither bot is making any progress for duration of about 4 seconds (as
determined by the referee).
3) If a part on the bot comes off that is less than 5 grams, the round will
continue.
4) A player has 30 seconds to correct a problem between rounds.
5) The referee has the final decision in a match.
Electronics and Robotics Merit Badge Class 3

15. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #9
Install Line Sensor
Wires
Parts Required:
• (2) 10" 3-pin
extension cables
• SumoBot chassis
Carefully feed each 10" 3-pin extension cable through the center chassis slot.
Sensors? Which members of the Patrols (KIAH-1 and JACOB-2) will program the sensors?
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16. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #10
Install the QTI Line
Sensors
Parts Required:
• (2) QTI line sensors
• (2) 4/40 1/4" long
pan-head machine
screws
• SumoBot chassis
Using two 4/40 1/4” pan-head machine screws, attach the QTI line sensors to the 1-1/4" round stand-offs. Connect the ends of the 10" 3-pin extension cables to the QTI line sensors, noting the polarity markings B[lack]-R[ed]-W[hite] on the QTI sensors.
And how will they design the sensors? (Have to have these for the edge, but placement of the opponent sensors is varied).
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17. POWER SUBSYSTEM
We use standard AA batteries to run our SumoBot. Usually made of Zinc–carbon or Alkaline (Capacity under 500mA constant drain mAh/ mAh/1.5 V). We may also experiment with newer high-power Lithium (Li-Ion) batteries used in Electric Cars (or “EV’s” as we call them at Eaton – Electric Vehicles).

18. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #11
Make the Connections
Plug the servo motors and QTI
sensors into the SumoBot PCB
connectors as indicated below.
Note that the "B" pin on each
connector is for the black wire.
X7 = Left Servo Motor
X6 = Right Servo Motor
X5 = Left QTI Line Sensor
X4 = Right QTI Line Sensor
Connect the battery pack wires to SumoBot PCB connector X1. The battery pack's white-striped lead connects to the + terminal.
Hook up the power (don’t forget to load the batteries).
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19. Electronics and Robotics Merit Badge Class 4
LET’S BUILD THE SUMOBOT
Step #12
Powering the SumoBot
The SumoBot PCB has a three-position power switch. The state of each position is shown below. The three-position switch has a middle position that powers the entire circuit except the servos. A complete schematic of the SumoBot PCB follows. Also note the new Li-ion Boe-Bot Power Pack-Charger.
Position 0 – No Power
Position 1 – Power PCB
Position 2 – Power PCB & Servos
TURN IT ON – does the LED light? Success!!! Ready to install sensors and program the robot base/drive train…
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20. Electronics and Robotics Merit Badge Class 4
COMPLETE SUMOBOT CIRCUIT DIAGRAM
APPENDIX A – Circuit Diagram
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21. Electronics and Robotics Merit Badge Class 4
Robotics merit badge requirements
       
Safety. Do each of the following:
a. Explain to your counselor the most likely hazards you may encounter while working with robots and what you should do to anticipate, mitigate and prevent, and respond to these hazards. Describe the appropriate safety gear and clothing that should be used when working with robotics.
b. Discuss first aid and prevention for the types of injuries that could occur while participating in robotics activities and competitions, including cuts, eye injuries, and burns (chemical or heat).
Robotics industry. Discuss the following with your counselor:
a. The kinds of things robots can do and how robots are best used today.
b. The similarities and differences between remote-control vehicles, telerobots, and autonomous robots.
c. Three different methods robots can use to move themselves other than wheels or tracks. Describe when it would be appropriate to use each method.
General knowledge. Discuss with your counselor three of the five major fields of robotics (human-robot interface, mobility, manipulation, programming, sensors) and their importance to robotics development. Discuss either the three fields as they relate to a single robot system OR talk about each field in general. Find pictures or at least one video to aid in your discussion.
Design, build, program, test. Do each of the following:
a. With your counselor's approval, choose a task for the robot or robotic subsystem that you plan to build. Include sensor feedback and programming in the task. Document this information in your robot engineering notebook.
b. Design your robot. The robot design should use sensors and programming and have at least 2 degrees of freedom. Document the design in your robot engineering notebook using drawings and a written description.
c. Build a robot or robotic subsystem of your original design to accomplish the task you chose for requirement 4a.
d. Discuss with your counselor the programming options available for your robot. Then do either option 1 OR option 2.
(1) Option 1. Program your robot to perform the task you chose for your robot in 4a. Include a sample of your program's source code in your robot engineering notebook.
(2) Option 2. Prepare a flowchart of the desired steps to program your robot for accomplishing the task in 4a. Include procedures that show activities based on sensor inputs. Place this in your robot engineering notebook.
e. Test your robot and record the results in your robot engineering notebook. Include suggestions on how you could improve your robot, as well as pictures or sketches of your finished robot.
Demonstrate. Do the following:
a. Demonstrate for your counselor the robot you built in requirement 4.
b. Share your robot engineering notebook with your counselor. Talk about how well your robot accomplished the task, the improvements you would make in your next design, and what you learned about the design process.
Competitions. Do ONE of the following.
a. Attend a robotics competition and report to your counselor what you saw and learned about the competition and how teams are organized and managed.
b. Learn about three youth robotics competitions. Tell your counselor about these, including the type of competition, time commitment, age of the participants, and how many teams are involved.
Careers. Name three career opportunities in robotics. Pick one and find out the education, training, and experience required for this profession. Discuss this with your counselor, and explain why this profession might interest you.
APPENDIX B – Merit Badge Requirements
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