Ping Pong Ball Launcher

Our team (Molly, Christian, Ian, Joey, and Parker) created this instructible page to make a ping pong ball launcher. for our ME 208 class.

This project is a very simple and semiautomatic ping pong ball launcher. It relies on a servo to drop a ping pong ball onto a wheel with four spoons to launch a ball to play ping pong by yourself.

Supplies List:  

4' x 4' sheet of cardboard 

4 plastic spoons  

Tape  

Scissors  

From Sparkfun Inventors kit: 

1 breadboard  

1 ultrasonic sensor 

1 motor controller 

1 gear motor 

1 Arduino Uno  

3 resistors 

1 red LED 

1 yellow LED  

1 green LED 

25 wires 

1 Arduino wheel  

The first step is to create the circuit on Tinkercad to better understand how it works before proceeding with the physical construction. The diagram provided above shows the complete circuit for the electronic components. The only modification needed is the motor controller. The one available in Tinkercad is different from the one included in the SparkFun kits. While both motor controllers function the same way, the SparkFun version has a slightly different wiring order.

The code needed for this to work is available for download below. It is quite simple, consisting of a single if statement that controls when the servo moves and the wheel spins. This if statement is triggered based on the distance detected by the sensor.

To properly be able to use the project the motor controller needs to be changed from the one in Tinker Cad.

Motor hookup 

Vm – needs to be hooked up to a separate battery 

Vcc – power for driver -5V 

GND – ground -GND 

A01red(+) output to motors red motor wire 

A02black(-) output to motors black motor wire 

PWMA – speed motor 1 - D11 (needs PWM) 

AIN2 – direction motor 1 - D12 

AIN1 – direction motor 1 - D13 

STBY– for internal Hbridge - 5V 

These are the proper hook ups for the sprakfun motor controller that corilate to the propper spots on the board.

Building the main housing for the launcher is simple. The measurements are provided on the notebook paper. The structure uses three pieces of cardboard. The front and top are made from a single piece measuring 8 x 4 inches, which is bent in the middle at about 4 inches. This piece is then taped to two additional pieces, each measuring 4 x 4.5 inches, to create a box with four sides. On the front side, cut a hole for the ultrasonic distance sensor and three smaller holes for the LEDs.

The side supports are a simple part of the build, consisting of three pieces. On the left side, there is a long rectangle measuring 11 inches by 3 1/4 inches, which is attached to a 2.5 x 3 inch piece of cardboard at the bottom to connect to the main box. On the right side, there is a support piece measuring 8 3/4 inches by 4 inches, which is bent at 6 inches to create a base and provide support for the funnel at the top.

The top funnel is made from three pieces of cardboard: one long rectangle and two squares. The long rectangle measures 11 inches and is bent into three sections, with a small rectangular cutout in the middle for the servo. The piece is folded into a U-shape, and two square pieces are taped to the sides to form a cube with no top.

The servo is easily attached to the funnel, allowing one ball to enter at a time. The wire runs smoothly down the side of the supports and connects to the circuit.

Using a sharp knife or one side of a pair of scissors, carefully cut four evenly spaced slits into the tire. The slits should be wide enough to insert the tops of four spoons, but not so wide that they fall out. This setup creates an effective way to launch the ping pong ball as far as possible.

This shows how to attch the gear motor to the main box so the fly wheel has room to spin to throw the ball.

ME 208 Project Movie.mp4

This video shows on how to build the structure.