Elementary Robotics




Introduction: Elementary Robotics

Our students at Long Ridge School (www.longridgeschool.org) build robots that can accept basic navigational instructions. I spent a long time searching for the right platform for our students' robots that would support our learning objectives. Although there are many different educational robot systems most are snap and play, which do not explore fully the multi-modal nature of robotics. Our powered machine component demonstrates the electrical and mechanical modes of a robot and provide the necessary infrastructure to build an autonomous robot. Here is an article about the robot and the program we developed around it http://www.connecticutplus.com/cplus/information/n...

The process is split into 3 sections:

  1. Assembling the robot chassis using - Magician Chassis (http://sfe.io/p12866).
  2. Assembling the electronics. Our robots use an Arduino Uno, a motor driver board, and a membrane keypad.
  3. Downloading the firmware to the Arduino Uno and learning how to program the robot.

First step in building an robot is to review and gather your supplies. Engineers use BOM (Bill of Materials) that specify what tools and materials in what quantity they will need. In our project the students use the following materials:

  • Magician's Chassis for the robot body includes most of the screws and nuts (Sparkfun - http://sfe.io/p12866)
  • Arduino Uno for the mainboard (microcenter)
  • Motor driver board (Robot Shop)
  • Keypad (Adafruit)
  • Straight headers (Adafruit)
  • Angle headers (Sparkfun Electronics)
  • Five M3 37mm spacers (McMaster)
  • Nine 15mm screws with nuts (McMaster)
  • Two Jumper cables M/F and five M/M (Adafruit)
  • Styrene plastic 80 mm x 85 mm x 1.5mm
  • Six 6mm aquarium airline tubing

Step 1: Attach the Motor Holders

    Take the four M3*30 screws and two motor holders and attach to the body as seen in the picture. The T-part of motor holder is underneath the chassis.

    Step 2: Position the Motors Inside the Motor Holders

    1. The first picture shows the direction of the motors.
    2. Place the motor axle (shiny, metal axle in the picture) to the back of the chassis (straight edge is the back).
    3. Make sure that the yellow nub on the motor is pointing the outside of the chassis. See the third pictures.

    Step 3: Attach the Motors to the Motor Holders

    1. Put the top screw through the outside motor holder and motor first before pushing through the inside motor holder.
    2. Add a nut and finger tighten the screw.
    3. Add the bottom screw and nut using the screwdriver to tighten the screw.
    4. Go back and repeat steps 1 through 3 for the other motor. Again make sure the nub is pointing to the outside of the chassis.

    Step 4: Attach Encoders and Wheels

    1. Add one encoder to the inside axle.
    2. Add the second encoder to the other axle.
    3. Attach the wheels to the outside axles.

    Step 5: Assemble the Omni Wheel

    1. Attach the Omni Wheel with two L25 spacers and two M3*6 screws using your fingers. Tighten with the screwdriver.

    Step 6: Attach the Omni Wheel

    1. Flip the chassis over, so the motors are now facing the ground. Attach the screws to the holes in the picture where the fingers are pointing.
    2. Attach the omni wheel to the chassis using the screws.

    Step 7: Attach Battery Holder

    1. Take battery holder and two M3*10 flathead screws with m3 nuts and place the battery pack on the top, back of the chassis. The screws are placed inside the battery pack and the nuts on the bottom of the chassis.
    2. Tip: Add one screw before placing the pack on the chassis.
    3. Add and tighten the second screw before tightening the first screw completely to the chassis.
    4. Add the nuts to the battery pack bottom.

    Step 8: Attach Spacers to Bottom Chassis

    Looking at the second picture for positioning of the spacers, attach the five screws and spacers underneath the bottom chassis.

    Step 9: Attach Motor Controller

    1. Attach tape to the bottom of the motor driver.

    2. Attach the motor driver with two 16mm M3 screws, two white spacers, and two nuts on the top of the board. The spacers are cut from airline tube purchased at an aquarium store.

    Step 10: Attach Motor Wires

    1. Loosen the screw above the green terminal header, then insert the red wire to the MotorA outside green terminal header on the motor controller.

    2. Loosen the screw above the other green terminal header and insert the black wire from the SAME motor to the other MotorA green terminal header.

    3. Repeat for the other motor wires to the MotorB terminal headers. Make sure that the wires stay in pairs.

    Step 11: Attach Wires

    1. Attach one wire to VMS and one to GND on the motor controller.

    Step 12: Attach Keypad to Base

    1. Position the base with the off-centered holes at the top with the x and play triangle.
    2. Peel the back of the keypad and attach to the base, covering the holes.
    3. Mark the holes with a pin base side up.
    4. Turn over the keypad. Using the marks as guides, punch holes through the keypad using an awl.

    Step 13: Making the Keypad

    1.Print out the keypad_pdf onto Avery label paper 5165.

    2. Laminate the top of the label with clear packing tape. Do NOT cover the sticky peel side with tape.

    3. Holding up to a strong light, attach the keypad over the membrane with the X over the # and the play triangle over the *.

    Step 14: Attach the Keypad

    1. Put all four screws into the keypad and top chassis.
    2. Add nuts to the two screws by the ribbon cable.
    3. The other two screws will be attached to the spacers in two more steps.

    Step 15: Position Motor Wires

    1. Push motor wires through the center of the top chassis.

    Step 16: Add the Top to the Chassis

    1. Take five L37 spacers and attach from the bottom of the chassis with five M3*6 screws.
    2. Dress the cables from the motor through the center hole by the battery pack.
    3. Add the batteries to the power pack.
    4. Attach the top with five more M3*6 screws.

    Step 17: Attach the Arduino Uno

    1. Align the power and USB to the front end of the chassis.
    2. Push the screws through the board and spacers.
    3. Add the nuts underneath starting with the screw by the ribbon cable.

    Step 18: Attach Ribbon Cable to the Ardunio

    1. Add the straight pins of the connector into digital pin 1 through digital 7.
    2. The cable closest to the x inserts into the digital pin 1.

    Step 19: Attach the Motor Driver Wires to the Ardunio

    1. Attach the GND jumper to the Power GND on the Ardunio.
    2. Attach the Vin jumper to the Power VIN on the Ardunio.

    Step 20: Connect the Motor Driver to Logic Pins of the Arduino

    1. Attach the motor driver ENA through ENB to the cables.
    2. Attach the other end of the cables to the Ardunio from Digital 8 through 13. ENA on the motor driver goes to 13 on the Arduino.

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