Air Hockey Table With Robotic Defender

Have you ever been lonely?

PBS has found that 60% of people in America experience loneliness. As engineers, we've sometimes been in that 60%, and that's why we've created a solution.

Introducing The Robo-Rink, a custom-built mini Air Hockey Table equipped with a (removable) robotic defender to play with you if you have no friends.

Special thanks to Mark Rober and Thomastank for the inspiration behind this project along with Ms.Berbawy and Mr. Olson for their support along the way. This was made as our SIDE Project for Ms. Berbawy's PLTW Principles of Engineering Class.

This project was made by Vaibhav Jayakumar, Nathan Lintu, and Navish Sinha.

Here are the materials, tools, and resources we used to complete our project! (Hyperlinks to exactly what we used):

Tools:

• Table Saw
• Miter Saw
• Jig Saw
• File
• 180 Grit Sanding Block
• 3D-Printer (We used a PRUSA Mini and Mk3s+)
• Lasercutter
• Drill
• 1/16" Drill Bit
• Alligator Clamps
• C Clamps
• Caulking Gun

Table:

8 ft x 6" x 3/7" Pine Plywood (2)

Peg Board (2 ft x 4 ft min.)

12 oz. Black Gloss Spray Paint (2)

Behr Dynasty Semi Gloss paint sample

1.5 in. Flat Cut Polyester Paint Brush

Masking Tape

Wood Glue

AC Infinity Axial 1751 Fan (3)

2ft x 4f x 0.234375" Polycarbonate

2ft x 4ft x 3/16" MDF Maker Board

PLA Filament - White, Black

PETG Filament - LipStick Red

#8 x 1- 1.25" Wood Screws

White Felt

Black Felt

Individually Controlled LED Strips

Thin Extension cord

M4 Locknuts

Total Table Cost: approx. $400

Robot:

GoBILDA Speed Servo

REV Robotics Control Hub

Modern Robotics 12V Battery

22 mm Standoff Pack

14 mm Standoff Pack

M4 x 10 Screw Pack

Servo Frame

Servo Hub

Pillow Block

1/4" thick wood

Total Robot Cost: approx. $450

The first step to creating an air hockey table is to CAD it out.

Here are the different components of the air hockey table:

Bottom Plate:

The air hockey table functions by drawing in air from the bottom of the table. The table itself is raised by legs and the bottom of the table can be covered with a piece of draft board (with holes drilled into it) or a mesh cover (like chickenwire). We found the mesh cover to work best because it allows the most airflow. The purpose of this bottom plate is to make sure that nobody reaches into the table and that nothing will get caught inside of the table.

Fans and Fan Plate:

The fans that we use are screwed directly into the fan plate. Each fan has a CFM of 211 and intakes air from underneath the table and the gaps in the side of the table. The air from the fans is pushed into a chamber that is created by the top plate and the fan plate.

Air Chamber and Top Plate:

The air from the fans enters an air chamber where the air is equally spread throughout the table. The air then pushes up out of the holes in the top plate, allowing for gameplay to occur.

Walls and Puck Receiver:

The table is also equipped with side walls to make sure that the puck stays within the boundaries of the top plate. The table has two custom-designed puck receivers that allow you to easily retrieve the puck after it is scored.

The STEP files for all components are attached below, along with the entire CAD of the Table. The 3D-printed components are attached in a later step.

To cut out our wood, we received assistance from our district's woodshop teacher: Mr. Olson.

The engineering drawings for each of our pieces of wood are listed below.

You will need:

2 x Side Piece

2 x Front and Back Piece Bottom

2 x Front and Back Piece Top

4 x Puck Receiver Wall

2 x Side Walls

1 x Polycarbonate sheet

1 x MDF Board (Same Dimensions as Polycarbonate Sheet)

We cut these pieces with a table saw and a miter saw.

The next step in building the table is cutting the fan plate. If you are using the Axial Fans that are linked in our materials section, you will need three 6" holes for three fans(you can use more if you desire a larger table or more airflow). The middle fan is located at the very center of the board. The other two fans are 10" away from the middle fan (center to center). Start off by drawing the circle's outline with a compass and a pencil. Then, drill a hole large enough to fit a jig saw blade slightly inside the circle. Then fit the jig saw's blade into the hole and slowly go around the circle. Once you are done, place the fan on top of the cut hole and mark the screw holes. Drill the screw holes and repeat for each of the 3 circles. Finally, screw each fan in with two M4 screws provided and secure them in place with M4 Locknuts.

Creating the top board of the table is a tedious and long process. We found the easiest way to complete this process was to purchase a peg board that was the same size as the top plate or larger. The holes in the peg board are 1" apart from each other, which is exactly how far the holes on the top plate need to be. We then clamped the peg board to the polycarbonate and used a permanent marker to mark where the holes would be. The polycarbonate comes with a film on it so it doesn't matter if you draw on it. We then used a 1/16 " drill bit to drill all 576 holes. This took a good 4-5 hours so we'd recommend doing it with a friend and buying at least 4 drill bits since they often break due to the polycarbonate's thickness.

You can pick many options and types of paint when you decide to paint wood. We went with both spray paint and liquid paint. We thought that our table would look the best with glossy black paint. You can color your wood with any paint, or even wood stain.

We bought a semi-gloss paint sample from The Home Depot in the color: "Blackout" and a glossy black spray paint (see materials list). We also purchased a 180-grit sanding block, masking tape, and a 1.5" paintbrush.

We first started to sand each piece of wood so the paint would stick better and covered the edges of the wood with masking tape. We gave each piece 3 coats of spray paint. Afterward, we painted the inside of the wood with liquid paint. We did this because we could reach smaller areas with the brush. The paint dries a lot faster but is not as glossy as the spray paint. The glossiness of the paint would not matter on the inside since people would only see it through the top plate.

For the table, there are three different components that need to be 3D printed:

1) The Puck Receivers

2) The Puck Strikers

3) The Pucks

All the STLs for the three components are listed below. We printed each component on a PRUSA Mini. We chose the color scheme of our table to be black, white, and red. The puck receivers were printed in white (See images for settings) and the puck strikers were printed in black (See images for Settings). The parts can be any color, but if you are planning to build a robotic defender, the puck should ideally be red, green, or blue.

Note: We found that printing the puck in PETG (See images for Settings) was best since the puck was stronger and more durable. Printing in PLA is also a great option if you don't have PETG on hand, just note that the puck will only last 15-30 minutes.

It's time for the final step: assembling the table!

To stick the pieces of wood together, we used both wood screws and wood glue.

Step One:

Put the frame of the table together. Start with the "Front and Back Piece Bottom", "Front and Back Piece Top", and the 2 "Side Pieces". Hold these pieces together, for now, with masking tape. You should have a frame of the table, with one side missing. Slide in the middle fan plate for support.

Step Two:

Glue these pieces together with wood glue and hold them together with clamps. Finally, once every other part of the frame is glued and set together, glue in the second pair of the "Front and Back Piece Bottom" and the "Front and Back Piece Top". Then screw all the pieces together.

Step Three:

Use your caulking gun to caulk the underside of the fan plate. This will make it so that no air leaks. Next, stick your LEDS on the side of the "Air Chamber". Finally, Place your playing field on top, without the protective film, and caulk the sides to ensure no air escapes.

Step Four:

Place the puck receiver on either side and the walls alongside it. Epoxy all the top parts together and let it dry for a few hours.

Step Five:

With a deburring tool, deburr the holes on the top plate.

Note: The following instructions are for the defender. The table will work without the defender.

How it works:

The robot acts as an automated defender, blocking any incoming shots, and allowing for riveting single-player gameplay. The robot is designed for speed, stability, and durability. A webcam overlooks the top board and is able to track the puck using HSV color detection. Since the puck is red and everything else is white and black, the webcam is able to filter out all colors besides red. The webcam is connected to a REV Control Hub which is connected to a GoBilda Super Speed Servo. This Super Speed Servo is attached to a servo block and a laser cut frame. This servo block is connected to a 3D-printed arm, which defends about the robot's axis of rotation. The REV Control Hub is connected to a REV Power Switch and a 9V Battery. The REV Hub is connected to a Motorola Phone, which is our control station.

We used a REV Control Hub because that is what we had on hand. Our Control Hub is old and disconnects sometimes, so we opted to connect the Control Hub directly to the Battery.

The defender has a laser cut frame, a GoBilda Speed Servo Block, an arm, and a REV Control Hub set up.

Laser Cut Parts:

The Adobe Illustrator files for the parts are attached below. The two "Side Plates" should be made out of acrylic. Each piece should be 0.25" thick. The entire CAD of the defender is shown above.

Servo Block:

1 x 1908 Series Servo Hub

1 x 1603 Series Face Thru-Hole Pillow Block

4 x 14mm Standoffs

1 x GoBilda Super Speed Servo

1 x 1802 Series Servo Frame

4 x 22 mm Standoffs

1 x 10mm M4 Screw Pack

Arm:

The arm will need to be printed in PETG, it will have to be in a color aside from Red. The STL is attached below and the Settings are shown in the image above.

Assembly:

Assemble the frame of the robot together with wood glue. Let it dry for a few hours and hold the pieces together with clamps. Then, assemble the hardware and the REV Control Hub Set Up. Mount all the hardware and electronics to the wooden frame. Finally, attach the webcam to the REV Control hub by clipping a camera mount onto the indent in the top plate.

GitHub Repository

The control software was written in Java so that it can be run as an android application on the control hub. If you choose to use another microcontroller, the logic should be the same across other languages like Python and C

If you are using the REV Robotics Control Hub, follow the instructions below to install the project on your hardware.

1. Download Android Studio
2. Download the GitHub Repository by pressing the green button on the top right corner of the repository. Extract the zip file to a directory of your choice
3. Open the project in android studio (file -> open -> navigate to the folder that you extracted; the icon for the folder should show up as an android logo)
4. Connect the control hub to your PC using a USB-A to USB-C connection (USB-C to USB-C does not work!)
5. Go to the top corner of Android studio. The dropdown next to the green play button should say “Rev Robotics Control Hub v1.0”
6. Press play (the green button at the top right corner) to download the app onto the control hub.
7. Go to your wifi settings and connect to your control hub’s wifi network
8. Open a browser and navigate to 192.168.43.1:8080/dash
9. Go the the top left, click on the dropdown and select Main if it isn't already. Press INIT, wait a couple seconds (watch if the arm moves to the middle position of its range of motion).
10. Press start, and enjoy!

If you decide to recreate this project and have any questions while doing so, you can reach me at vaib.jay@gmail.com!

Enjoy the Robo-Rink!