What We’ve Learned from DrumPants 1.0
We deeply care about capturing and expressing the musician’s true intention as accurately as possible. That’s why DrumPants is velocity sensitive. It is also why we’ve worked hard to give DrumPants 2.0 the lowest latency possible, and to make it easy to adjust the sensitivity settings so you can play the way that you want.
Designing an electronic musical instrument takes a lot of signal processing and testing. Designing a wearable instrument is even more involved, since users may wear it on different parts of their body, under thinner/thicker clothes, and play in different styles: meaning the design has to be open and easily customizable (just like a real drum set).
Here is some tech we developed in order to test the DrumPants as we built them and implemented feedback from our customers.
Rhythmic Robots
The key to making a reliable product is to test in the physical world. We needed to test our algorithms against real-world situations. Enter Robo Starr, our drumming robot, that helps us run tests in a controlled, reproducible manner.
Very few human drummers can hit a DrumPad the exact same way every time, but Starr is designed to do just that, at a steady pulse. This allowed us to test the latency in our algorithms, and make sure there were no hiccups in the chain from firmware to MIDI to Bluetooth to the app.
The robot is made from a solenoid, attached to an Arduino with a Relay Shield. A third-hand holds the solenoid in place above the DrumPad, (and anthropomorphises the little guy so it’s harder to get mad at him.)
When we apply current to the solenoid, electromagnetic coils that are wrapped around the solenoid rod suck it back into the solenoid body. The Relay Shield then interrupts the flow of current, and gravity brings the rod back down to hit the DrumPad. Tempo is adjustable by sending MIDI CC messages to the Arduino. He can play all day long and never get tired!
Artificial Drummer Intelligence
We wanted DrumPants 2.0 to be playable in a wide variety of applications. We ran tests to determine the best default settings so that DrumPants will work well in most common situations. We also added popular customizations as presets into the DrumPants 2.0 app so you can easily and quickly find a setting that works for you. Lastly, we allow you to individually customize the sensitivity of each trigger based on your playing style.
Since small changes in the DrumPants code could make big differences in expected output; the last thing we wanted was to fix one issue, just to have it not work at all for a different playing style. We made sure to check all the changes we made to sensitivity or the filtering equations against the many different ways you can play DrumPants.
For instance, one of the most common issues DrumPants users experienced was accidental foot pedal triggering. To fix this, we added in some special high-pass filter magic to get rid of those unwanted retriggers, and tested it with a wide variety of playing styles to make sure it was still responsive when worn in the shoe or mounted to the ground.
We wrote testing software we called our “artificial drummer” to help us visualize the inputs of the DrumPants sensors and how the various settings and algorithms changed the final output — which decides when a hit happens, and how hard the hit is:
Our testing app has recordings of real drummers playing the DrumPants in different styles along to the same song: wearing them in clothes, on top of clothes, with the foot pedal worn in the shoe or with the foot pedal placed on the floor. These recording are the raw sensor input from the DrumPads.
The “artificial drummer” app then runs the actual DrumPants algorithms (called the Sensorizer library) on the input, and shows you the results on a graph. You can adjust the sliders to tweak the algorithms in real time.
All these sliders are the same sensitivity parameters that you, the user, can customize in the DrumPants app. Visualizing the changes in the output lets you easily make a DrumPad more sensitive, or a foot pedal harder to accidentally trigger.
If you’d like to check out the test simulator app for yourself, you can download it for Mac here.
Stay tuned for Part 2, where we dive into the new MIDI over Bluetooth LE features of the DrumPants 2.0, and how we’ve improved wireless latency and what it means for the future of wireless instruments.
Our DrumPants 2.0 Indiegogo campaign ends Monday 7/13. Less than one week left to pre-order your DrumPants kit for this production run!
Special thanks to Lei Yu and the DrumPants team for editing.
