Introduction: Robo-Critters

Picture of Robo-Critters

The goal of this project was to travel to 13 remote communities across the Yukon and teach kids how to build their own robots. 200+ robots were built during the process!

This design was originally created by Bill Smart and Ian Elwood-Oates (www.mbrobotgames.ca) and is well suited for children in grades 4-6.

Components:

  • 2x 3/4.5 volt DC electric motors
  • 2x Rubber wheels
  • 1x Wire motor mount
  • 1x 2 channel controller (details outline in separate instructable)
  • 1x 5” x 10” piece of Fomecor.
  • Approx 12” PVC electrical tape or duct tape.
  • Hot glue gun & glue sticks.
  • Soldering iron & solder.
  • Sharp knife & cutting board.
  • 2x “AA” batteries.
  • Decorating supplies

Step 1: Design Your Robot

Picture of Design Your Robot
  1. Make a sketch of how you want your robot to look.
    • Will the robot have its wheels in the center, front or rear?

    • What do you want the robot to do best?

    • If the driving wheels are in the middle, be sure to add some skids to prevent it from falling forward/backward so that the robot will rock only slightly on its wheels. If the driving wheels are in the front (a tail dragger design) then keep the tail low. If the driving wheels are at the back you will probably need a wheelie bar to stop the robot flipping backward on full forward acceleration.

  2. When you have decided on a design, transfer your cutting plan to the Fomecor.

Step 2: Adding Wheels

Picture of Adding Wheels

  1. Put the wheel, large side down, on a hard surface and place the shaft of the motor in the center of the small side as shown. With the motor in an upright position, carefully push downwards on the back of the motor with both thumbs. Push as far as it will go to slide the wheel onto the shaft. If it is very hard to get the wheel onto the motor shaft, try repiercing the center of the wheel with a compass point or stick pin. Though it may be hard to see, the wheels have been pierced in the center of the wheel, from the small side.

Step 3: Mounting Motors

Picture of Mounting Motors
  1. Hold the formed wire motor mount so that the ends hang down.
  2. Place a motor underneath one of the ends so that:
    • the wheel is on the outside
    • the two solder tabs on the back of the motor are horizontal and parallel to the wire motor mount
    • the end of the wire motor mount acts as a stop to position the motor
  3. Use some PVC tape to secure the motor tightly to the wire motor mount.
  4. Do the same with the second motor.

Step 4: Complete the Body

  1. Cut out the body from the Fomecor, saving all the pieces as some will be used for skids and fins.
  2. Glue the axle to the underside of the Robot using a scrap of fomecor to ‘sandwich’ the motor mount to the body.

Step 5: Make the Electrical Connections

Picture of Make the Electrical Connections

  1. Make a small hole through the body of your robot just large enough to be able to pass the 4 wires through.
  2. Tie a knot in the wires so that the knot will sit at the hole but the ends of the wires will be long enough to reach the solder tabs on the motors.
  3. Connect the wires to the motors as shown.
  4. Strip about 10-12mm (1/2”) of insulation from the ends of the wires and twist the strands together.
  5. Thread them through the holes in the solder tabs and fold them back to make a “U”.
  6. At this point you can install the batteries and test that the wheels turn in the correct rotation.

Step 6: Solder the Connections

Picture of Solder the Connections

  1. When the soldering pencil is hot, wipe the tip an a piece of damp sponge or a piece of folded wet paper towel to remove any insulating oxides from the tip.
  2. Melt a small amount of solder on the tip and wipe again. The tip should now be a shiny silver colour.
  3. Touch the silvered part of the tip to both the wire and the tab on the motor- count slowly to three...
  4. Watch to see the solder melt, then flow between the wire and tab then slowly slide the tip away while still holding the wire in place. You can blow on it a little to help it cool.
  5. When the solder has cooled and set, give the wire a little tug to check that the connection is sound.
  6. Solder all four wires in the same way, then you will be ready to test your robot.
  7. Be sure to insulate any exposed wire joints that may touch another to avoid short circuits.

SAFETY NOTES:

  • Place a bowl of water in easy reach when using any hot tools such as hot glue guns and soldering equipment. Skin that has come in contact with a hot element should be cooled immediately in water to reduce damage to the tissues.
  • Solder is made from Tin which is food safe and Lead which is poisonous to humans, especially children. Children cannot expel lead so it is accumulated in the body. Lead poisoning reveals its self by the loss of melanin causing a whitening of hair, memory loss and can be fatal with sufficient exposure. Lead is easily absorbed into young bodies through contact with soft tissues. Be sure to wash hands thoroughly after handling/before eating and do not place Lead in the mouth.
  • When soldering, the rosin core becomes corrosive when heated and much of it is leeched off as smoke. Position yourself so that the fumes do not rise into eyes or nose. Do not wear a peaked cap when soldering. When using sharp knives... Always cut AWAY from fingers.

Step 7: Power Up!

Picture of Power Up!

  1. Install two “AA” size batteries in the controller. Be sure the + ends point in oposite directions. Close the battery cover and enjoy driving your new Robo-Critter!
  2. If your robot goes in circles when you push both levers forward, decide which motor is going in the wrong direction then de-solder the wires to that motor and reverse them.
  3. Congratulations! Your Robo-Critter robot is now ready for a test run.
  4. Have fun decorating to make your Robo-Critter unique!

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