Objective

The goal of this project was to create a box that emulates the feeling of different objects inside as the box is rotated. I collaborated on this project with a partner where I completed the physical design and fabrication and assisted with the high-level programming. We had only two weeks to complete this project, so creating a minimum viable prototype was the main goal.

Operating Principles

Assumptions:

• The box is perfectly rigid

  • If the box is perfectly rigid, all the walls should vibrate the same. This assumption allows us to use just one actuator to emulate vibrations anywhere inside the box.

• Weight transfer inside the box can be neglected

  • In preparation for this project, we guessed the contents of 8 sealed boxes with different objects inside (ping pong balls, wood beads, etc.), and we found that vibrations from objects rolling and slamming into the sides of the walls were the most useful in determining the object.

The components inside the box are a Nintendo Switch JoyCon for accelerometer data, and a voice coil actuator for the vibrations. The digital twin of the box is simulated in Unity with the object inside (for this project it was only a ball), and vibration signals were sent to the voice coil based on the ball's state.

Physical Design

I designed all of the laser-cut parts in Adobe Illustrator without the use of 3D CAD software. This approach required a lot of mental visualization, but I really enjoyed how quick this prototyping process was.

Vibration Actuator

My favorite aspect of this design is the simplicity of the vibration actuation. It consists of a voice coil with a magnet fixed to a piece of rubber. The leads from the voice coil go into an audio amplifier which then plugs into a computer through a 3.5mm headphone jack. This was the best solution for a quick prototype because we could set up the vibration signals as an audio output in Unity rather than involving an Arduino in the project.