Interactive Garden: Frequently Asked Questions

You’ve seen the building process and the final result, but there’s still more to say about the project. These are some of the common questions I got asked as visitors came around the garden and interacted with it. If you’re wondering something, and the answer isn’t here, please leave your question in the comments.

How does it work?

There are fourteen boards and each has a vibration sensor attached to the bottom. Each vibration sensor has a single blade of plexiglass glued to it. When that piece of “grass” moves, the vibration sensor reads its vibration. The Phidget interface kit converts the analog signal to a digital signal and sends the value into a MAX6 program.

In the program we scale the input so it reads between 0 and 1. This value is used to set the brightness of the light, so the more vibration, the brighter the light. When the value is over 0.5, a bell chime sound is triggered.

There are sixteen capacitive touch sensors, one on the end of each aluminum pole. When someone touches the pole, the capacitance changes and the sensor/interface kit sends a signal of about 1000 to the program. When this happens, a chime sound is triggered. Along with this, the LED connected to the interface kit’s digital output is switched on.

How come each grass blade doesn’t respond?

Vibration sensors are used to detect vibrations, and they’re connected to one rod near the edge of each LED board. Vibration sensors are about 2 inches by 1 inch, and they’re not cheap enough to put 175 of them on each piece of grass. Besides, the programming would get a little intense at that point.

Where do the sounds come from?

The sounds are coded into the MAX6 program. When the sensors hit a certain value, they trigger a sound.

Phidgets' Interactive Garden Program Segment

Is it fibre optics?

No. Optical fibre is more transmissive than the plexiglass we’re using, it’s also thinner, and more expensive. Because the lengths of plexiglass rod are quite short (18 inches), they are able to carry the light as we need.

Who made this?

Me, Kat Dornian, with a lot of help. I came up with the idea. Chester (Phidget CEO) helped a lot with the design and construction, along with other hands here and there.

Building the Interactive Garden

How long did it take to make?

It probably took about 135 hours, or about 3 solid work weeks for one person. I’ve been planning this for nearly 6 months though, with work here and there.

How is it powered?

We used a regular power supply this year, but maybe next time we’ll hook up some solar panels.

What is it used for?

The design came out of a challenge to use MAX6 with Phidgets, and, I thought, why not make something cool for Beakerhead while we’re at it? So, I came up with something very interactive and eye-catching. It’s mostly just decorative, not intended for anything in particular, but hopefully it inspires some people to make something cool.Sensory Interactive Garden at Beakerhead

If you missed it, check out more posts about the interactive garden and check out the lovely pictures of videos from the big show.


Math lover. Engineering communicator. Mad-lib enthusiast. Total nerd.

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