Beats Into Bots: GlueMotor Drives PWM Servos with Smartphone Audio

Robotics Technology
Beats Into Bots: GlueMotor Drives PWM Servos with Smartphone Audio

This exhibit will be appearing at the 10th annual Maker Faire Bay Area. Don't have tickets yet? Get them here!
This exhibit will be appearing at the 10th annual Maker Faire Bay Area. Don’t have tickets yet? Get them here!

One of my favorite aspects of editing projects at Make: is seeing how other people approach technology. It’s truly energizing to see someone use a basic component in a way you’d never think of doing yourself.

Such an experience is exactly what happened when I first saw Kazu Terasaki’s GlueMotor — a method of controlling servo motors with PWM via a phone or tablet over a 3.5mm audio cable.

Recently, I caught up with Terasaki to see what motivates him to create projects and learn what he has planned for Maker Faire Bay Area.

Kazu Terasaki creator of GlueMotor
Kazu Terasaki, creator of GlueMotor

Make: What gave you the idea to use a 3.5mm jack to control motors?
Kazu Terasaki: After I made a series of stupid YouTube videos, “iPhone Walking Robot” and “iPad Walking Robot,” I decided to make an iPod Nano (a tiny one like a watch) to walk for the next video. But it was too small, even smaller than the CPU board that I have used for the last 2 videos. Then I came up with the idea to “directly” connect the servo control line to the headphone jack. I tried with iPhone first with special software and it worked! Then I modify the software to generate an MP3 file instead, and then put the MP3 file to an iPod Nano that connects to two servo motors.

Glue Motors using a TRS port to control two servo motors
GlueMotors use the audio jack (aka TRS jack) to control servo motors with PWM.

M: What inspires you to build projects and share what you make?
KT: Well, since I was a child I love to make people laugh. Initially it was just stupid story telling, but I quickly realized that I need to come up with some unique story that other people never think of. This idea leads me to do unique things, and concludes “doing the same thing as other people is not interesting!” That is why I always try to come up with a “different way” even if I’m doing the same thing as others such as “control servo motors with smart phones.” Yes, you will still be able to do exactly the same thing by using Arduino, but GlueMotor is way cheaper than Arduino :-)

M: Is there anything new you are going to be showing off this year?
KT:Yes! For the last 3 years at Maker Faire Bay Area, I always use Lego bricks (and double sided tape) for kids to easily & rapidly prototype some stuff with GlueMotor. But this year I will NOT use any Lego bricks, but other materials. Currently I am focusing to use balloons to build some bigger stuff, then move them with GlueMotor.

M: Do you have any tips for aspiring makers?
KT: Make something very easy and stupid, then make other people to laugh!

M: Thanks and see you at the Faire!
KT: I look forward to see you at the Faire! Please please stop by my GlueMotor booth!

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If you can’t wait till the Faire to see more of Kazu’s work, check out his project in Make: Vol. 34 and the TRS Drawbot, a drawing robot that uses two servo motors operated by any audio player.

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4 thoughts on “Beats Into Bots: GlueMotor Drives PWM Servos with Smartphone Audio

  1. Nigel Tolley says:

    Cool stuff. There’s also the Peachy 3D printer that does the same, but with galvonometers, so allowing very cheap control systems. These things will catch on fast soon, I predict.

    1. David Scheltema says:

      That sounds rocking, Nigel! Do you have a link to the Peachy 3D handy?

      1. Nigel Tolley says:
        Originally here, also at now.
        Meant to have been out last year, but they are still fiddling. Personally, I bought one for the hackspace and one for the galvonometers – things have moved on since then – they should release now it is working and let the community sort out further improvements.

    2. BMCVFI says:

      ☛✈4 You can get it HERE





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I love to tinker and write about electronics. My days are spent building projects and working as a Technical Editor for MAKE.

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