Arduino Rube Goldberg "Do Nothing Machine" for Teachers

Most of the projects in early Arduino classes only use one sensor or one actuator (e.g. Blink or servo). While this device has no practical purpose, the motivation was to provide teachers a device to demonstrate how a single Arduino can use multiple(6) sensors and actuators acting together to make more interesting constructions.

The motivation was Rube Goldberg's "Do Nothing Machines." Rube Goldberg was a popular cartoonist in the early 1900's that drew ridiculously complicated gadgets to perform trivial tasks using very convoluted mechanisms.

This project Arduino-based "Do Nothing Machine" is shown in the second figure. But there is nothing special about the physical configuration, and the controlling software sketch is pretty basic. The hope is not to make exact copies, it is that the idea will inspire beginner Arduino Makers to make their own crazy Rube Godberg inventions.

This Do Nothing Machine is also used in a second Instructable about Using Arduino in Project Based Learning Projects.

Supplies

Arduino Uno

Ultrasonic Sensor

IR Sensor

Servo Motor

Piezo Buzzer

Red and Green LED

LCD Display

Paper clip that is bent and attached to the servo to act as a paddle.

Ping Pong or 1" foam ball

Kite string or thread to hang the ball

Brad size nail or pin to attach the ball to the string with hot glue added

Super structure frame made from foam core, pop sickle sticks, or Lego parts of your own choice

Step 1: Finished Construction

Here is a YouTube video of the finished construction.

Step 2: The Do Nothing Sequence

This Do Nothing Machine includes 6 different functionalities. When there are no nearby observers the device just sits there and blinks. An Ultrasonic sensor detects a person has approaches. A two-line LCD display that shows the distance measured by the ultrasonic sensor of an approaching observer. When a person is closer than 75 cm it triggers the device to become active. First, the LEDs change color and blink differently. Then an IR obstacle/beam-break sensor detects when a hanging ball is hanging still. If not moving, it triggers a servo to move a small paddle to tap a hanging ping-pong ball to make sure it is not swinging. Then the servo rotates back, and swings to hit the ball. That causes the ball to swing back and forth. As it swings, it breaks the beam of an IR obstacle sensor on each swing. This causes the LED to blink and a piezo buzzer to buzz on each swing.

A simplified pseudo code sequence of the Arduino sketch program is shown in the first figure. The second figure shows a TinkerCad wiring diagram of the components connected to the Arduino.

In a later version a speaker is added that plays a tune when an observer gets near.

Step 3: Structural Framework

There is nothing special about the structural framework for this project, so use your own ingenuity! The only requirement is an overhead frame that can hold a suspended ping-pong ball, the servo motor, and IR sensor.

The structural components in the image on the left are parts from a Thames & Kosmos kit. The second image is made with Snap Cubes. But any type of structural construction can be adapted, including foam core, Lego, ErectorSet, etc.

The ping-pong ball (or other foam ball) can be attached to thin string or thread about 6" long. That can be done with superglue or poking a pin or brad-nail into the ball and tying the string around the pin.

LEDs, the piezo buzzer and (optional speaker) can be mounted anyplace.

In this construction the Arduino is mounted under the frame holding the ball, but the Arduino could be mounted anyplace as long as the connecting wires reach.