# WaveTable: a Table Cut From Radio Waves or Sound Waves Using Real Augmented Reality Haptics

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## Introduction: WaveTable: a Table Cut From Radio Waves or Sound Waves Using Real Augmented Reality Haptics

Let's use AR (Augmented Reality) and haptics to design and make furniture!

I live in Palo Alto but collaborate with my colleagues at MIT, University of Toronto, University of Waterloo, etc., so we needed a way to do collaborative CAD/CAM and haptic augmented reality was our answer.

Fusion 360 is the best way to share designs while they're being worked on, so we're doing our collaborative haptic augmented reality computer-aided design and manufacture while trying to come up with clever ways to control or interact with Fusion 360, in order to make things together....

Specifically a table carved from nature itself, i.e. actual electromagnetic radio waves or sound waves permanently recorded in wood, granite, or stainless steel.

The world's first wearable augmented reality computer was built in 1974 to visualize radio waves using simple physics to ensure exact alignment between the real and virtual worlds, and you can make one cheaply and easily as reported in a previous Instructable.

Here we're going to use phenomenal (phenomenological) augmented reality to visualize the otherwise invisible waves around us, and to inscribe these waves into real physical objects, and in particular, use the waves to cut the materials to make furniture.

Specifically we're going to make a workbench and shelves out of a waveform and its harmonics.

The sound source is a violin mechanically actuated (driven) by a transducer connected to a Fourier signal generator, and the note is A440 (440 cycles per second) for which we can select (sculpt) with various harmonics.

The sounds are sculpted using the T-SWIM (Tactile Sequential Wave Imprinting Machine).

The note A440 has a wavelength

= speed of sound / frequency

= (343 meters/second ) / (440 cycles/second)

=.77955... meters.

So the wavelengths is about 78 centimeters, which makes a nice wavy shape that's actually quite space efficient, i.e. 78 centimeters is enough space for a nice indentation to sit at and have the table "wrap around" you locally, while a couple of other people can sit at the table in the other recesses of subsequent waves of the periodic waveform.

The table (work benchtop) is the fundamental, and each shelf above it includes the next harmonic in the naturally occurring Fourier series of the sound wave.

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## Step 1: Catch the Wave

This first step is to capture the wave.

You can capture your own wave, or you can use an existing wave from this Instructable or grab one from http://wearcam.org/swim/ or newSWIM

You can also simply jump ahead to Step 3 of this Instructable and use the .step file HARCAD_HARCAM_WaveTable.step .

If you're using an existing wave, you can skip this step and proceed directly to the next step.

Waves are captured using the concept of a "sitting wave", i.e. where waves are made to "sit still" so that we can see them.

An easy way to do this (child's play in terms of difficulty) is with a lock-in amplifier, a microphone, and a speaker. Connect the speaker to the oscillator output of the LIA (Lock In Amplifier), and the microphone to the signal input, and move one with respect to the other, along a sliderail, and your "sitting wave" emerges as a position-varying voltage at the output of the amplifier. It should be only a function of position, not time, i.e. you trace out the same wave no matter how fast or slow you move the speaker or microphone.

The simplest way to capture the waves is photographically with a long-exposure photograph in a darkened room. Wear black and use a black cloth behind the SWIM for best results.

Waves can also be captured using a datalogger at the output of the LIA, assuming you move at a constant speed (or separately record your position).

A better way to do this is with the a linear array of LEDs as a dotgraph, as shown in the pictures above (following my earlier Instructable). Add a mechanical transducer to the hand-grip of the SWIM so you can feel the wave you're sweeping through.

Once you capture the wave (or select a pre-recorded wave), bring it into a CAD program such as Fusion360.

In many of my earlier experiments with haptics and waves, I used X-Y plotters and this makes it easy to share waves and experiences among multiple people at the same time. Consider the plotter like a ouija board where multiple people can press and pull on the various Fourier coefficients of real physical waves!

## Step 2: CAD (Computer-Aided Design) of the WaveTable Using Fusion 360

Once you catch the waves, bring them into Fusion 360.

The process of catching the waves can also be shared, e.g. two people at different locations can "SWIM" out a wave and share it over Fusion, e.g. through features like "press pull" and modify the wave.

Begin by creating a shared wavetable and modifying Fourier coefficients in the table.

Some ideas for improvements to Fusion 360: implement better handling for Fourier series representations.

Functionality specific to Fourier series representations is on my wish-list for future versions of Fusion 360.

Once you have some waves, you can create a toolpath for cutting out the patterns on a CNC machine such as the Shopbot.

## Step 3: CAM (Computer-Aided Manufacture): Defining Toolpath for ShopBot CNC Router

If you want to skip ahead and just make the WaveTable, simply download the .STEP file above.

You'll end up with a table that has a nice wavy shape that's very comfortable to sit or stand at.

Mount it about 2 feet (24) inches up for sitting, or 3 feet (36 inches) for standing and then use higher chairs or lab stools for sitting. With A440 you get about 3 indentations along a typical 8 foot table.

For economy of material I used a 4 by 8 foot piece of 1 inch apple ply.

Three of us can sit or stand and work nicely at this table/workbench.

The shelves above it are made from waveforms that have more harmonics.

Enjoy, have fun, and remember that this is the Real Augmented Reality™.

## Step 4: Put It to Good Use

I've brought this table with me to various locations to setup in San Francisco, Palo Alto, Toronto, etc., and it has served us well.

It works well in narrow hallways too, where space is limited.

The insets allow 3 people to work at the same time, and still have room for others to fit past us.

The insets in the shelves also nicely match, due to phase-coherency.

Have fun and enjoy being one with waves!

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