HOW-TOs How-To #1: Assemble DC-Motor Robot Chassis

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1 HOW-TOs How-To #: Assemble DC-Motor Robot Chassis HT Background: A chassis is the frame of a device. The components are attached to this frame. The chassis described in this How-To is for two geared DC motors with wheels, an Arduino with a motor controller shield, a battery pack, an H-bridge circuit board, and a rear wheel. This chassis is made from wood, although other materials will certainly serve. The wood is pre-cut into five pieces: the front panel, the rear panel, two side panels, and a deck. Modeling glue for wood is the recommended adhesive. For precisely rectangular construction a corner clamp is highly recommended, although it is not absolutely required. Materials: Included in Robot Body kit (part RB03) All the parts necessary to assemble the chassis and attach it to the Arduino, its navigation shield, the battery pack, and the DC motors are included in the kit. Quantity Part Image Notes Catalog Number Deck The top flat surface of the robot. The armadillo logo should be visible when the chassis is complete. Front Panel 2 Side Panels Rear Panel Rear Wheel Curved along the bottom. Attaches on each side to the end of the side panel with the large rectangular cutout. End with large rectangular cutout should be near the front panel. U-shaped opening, should be attached with the U opening downward. One-inch diameter wood ball with a hole through the center. RB03 Rear Wheel Axel 3-inch dowel. How-To # Assemble a DC-Motor Robot Chassis 22

2 Part Image Notes Catalog Number 4 Nylon Spacers 4-40 threaded for mounting Arduino Uno. 8 Nylon Pan Head Screws For attaching the Arduino Uno to the nylon spacers, and the spacers to the robot deck. 8 Stainless 4-40 Pan Head Screws For attaching DC motors to the side panels. RB03 8 Stainless 4-40 Hex Nuts For attaching DC motors to the side panels. Not included in kit: Quantity Quantity Part Image Notes Arduino Uno Motor Controller Shield Single-board computer. This board is delicate and should be handled with care. When you are not using it, keep it in a box or plastic bag. May be assembled from parts or purchased as a kit. Find How-To instructions can be found on LearnCSE.com. Catalog Number 302 MC0 2 DC Motors Geared DC motors, 6 volts. 332 Battery Holder with 2.mm connector. Holds 6 AA cells. May be assembled from kit or by following instructions on LearnCSE. com AA cells Alkaline or rechargeable Learn to Program in Arduino TM C: 8 Lessons, from setup() to robots

3 Quantity Part Image Notes Catalog Number HT 2 Wheels to match the geared DC motors Rubber-tired wheel to fit DC motors. 333 H-bridge May be assembled from parts or purchased as a kit. Instructions are in How-To #7 on LearnCSE.com. 307 Tools: In addition to the parts, the following tools aid in the assembly of the robot chassis: Quantity Small tube Tool Image Notes Modeling glue for wood Corner clamp (optional) Screw driver Most wood glues will work, but Testors Cement for Wood Models sets quickly and is sufficiently strong. It is available from most hobby stores. This device is an easy way to ensure 90- degree corners for the chassis. It is inexpensive and available from Home Depot and most other tools suppliers. The one shown here, purchased from Home Depot, sells for approximately $9. Phillips-head, suitable for the pan head screws. How-To # Assemble a DC-Motor Robot Chassis 223

4 Procedure: Follow the instructions for the type of glue. Drying and curing times are different. "Dry" often means the glued object does not need continued support. But the glue hasn't reached its full strength until it is "cured," that is, when the chemical reactions are complete. Curing usually requires several hours.. Glue the front and rear panels to the side panels as shown in Figure HT-. Figure HT-. Front, rear, and side panels of robot chassis Important In Figure HT- the panels are all upside down. It's important to ensure that: the assembly lies perfectly flat when put together as shown. the rectangle cutouts on the side panels are toward the front panel. each of the corners is as close to a perfect 90-degree angle as possible. the rounded corners of the side panels meet the rounded side of the front panel. 2. After the glue has dried and cured, turn the assembly over. 3. Glue the deck to the top. Important The location of the Armadillo image is critical. It must be on top and at the opposite end of the curved front panel. See Figure HT Learn to Program in Arduino TM C: 8 Lessons, from setup() to robots

5 HT Figure HT-2. Placement of chassis deck to front panel 4. Attach the rear wheel. This is accomplished by gluing the dowel, passed through the center of the wood bead, to the rear panel. Figure HT-3. Adding the rear wheel and axel to chassis How-To # Assemble a DC-Motor Robot Chassis 225

6 5. Turn the robot body over after the glue used to attach the rear wheel is dry and cured. Use the nylon screws to attach the four nylon standoffs to the top of the robot deck. Figure HT-4. Chassis with nylon standoffs Caution Use only nylon screws to mount the Arduino. Metal screws can damage the nylon standoffs and on some versions of the Arduino can cause an electrical short. 226 Learn to Program in Arduino TM C: 8 Lessons, from setup() to robots

7 6. Attach the Arduino Uno to the standoffs, again using the nylon screws. HT Figure HT-5. Arduino Uno attached to chassis body with nylon screws 7. Use the metal screws and hex nuts to mount the DC motors to the side panels of the robot body: Figure HT-6. DC motor mounted to side panel of robot chassis How-To # Assemble a DC-Motor Robot Chassis 227

8 8. Mount the wheels to the motors by first aligning them with the flat sides of the motor shaft and then pressing the wheels on gently. HT-7. Wheels mounted to DC motors The rolling robot body is now ready to be used. This robot is used in Lessons 5 and Learn to Program in Arduino TM C: 8 Lessons, from setup() to robots