A PID control system achieves tilt stability. Tilt angle is calculated from sensor fusion of LSM6DS3 accel/gyro readings passed through an Extended Kalman Filter. Propulsion is done with 3A stepper motors with CUI AMT10 encoders for wheel position and velocity. Steppers were used for their high torque at low RPM and zero backlash, so near flawless stand-still response is achieved. The Kalman filter, LSM6DS3 anti-alias filters, and in-code butterworth filters mitigate the mechanical vibration effects of the steppers.
This test video demonstrates near perfect stand-still response.
The second test video demonstrates motion control while maintaining balance.
A Teensy 3.1 was used for a DIY security token. The functions inlude Trusted Platform Module (TPM) for Integrity Measurement Architecture (IMA) attestation, signing files, and ssh remote login. Some of the features include private keys generated on the token and a physical presence required to reprogram.
The token was simply constructed using the housing from a USB thumb drive and some epoxy to keep it all together.
Forum user whannah built a nifty MIDI joystick so that he could control a synthesizer from his organ.
This joystick solved a couple of problems for whannah. He wanted to control a synthesizer from his organ, but wanted a physical control for pitch bend and modulation, which the organ doesn’t have. Also, he couldn’t plug the organ into the synthesizer because the MIDI control change (CC) messages are sent to the synth when he didn’t want them to be. He couldn’t disable the sending or receiving of MIDI on either instrument. Normally he would need to bring a second keyboard to control the synth, which is a pain. So he built this little joystick box to give him a physical control and also filter the MIDI messages.
You wouldn’t know by looking at it, but whannah said that the hardest part about the project was drilling the holes in the right place.
Sammy Kamkar created an amazing sound reactive LED wall
This 4×4 wall has 1,728 addressable LEDs and tracks anyone in front of it via Kinect. Samy does smart background subtraction by creating a “depth window” in 3d space as the Kinect can provide me full depth data. The software is a combination of code he’s developed in OpenFrameworks, Syphon and Quartz Composer for sound reactivity. The panels are driven by a $19 micro-Teensy board using Direct Memory Access.
Andrew used a MSGEQ7chip to turn incoming audio and break it down into seven frequency bands. The data is sent to a Teensy 3.6 to control and assign colors to the LEDs lighting up the cubes. The result was an art installation that translated orchestra sounds into colors – blues purples for bass frequencies with higher frequencies in red. Each cube will also get brighter or dimmer depending on the volume level of the music.
This article gives a great overview of the project as well as instructions for building your own. Addtionally, all the code is available on GitHub.
Check out this video showing the LEDs in dancing action.
Some of the technical details ditigall11 provided on this project include:
5 Teensy’s running OctoWS2811 (Probably went a little overboard here, as I wanted the Teensy’s as close to the strips as possible, so I’m not using OctoWS2811 to its fullest, but I’m sure PJRC doesn’t mind :P)
Ableton Live/Max4Live/Jitter handling the music playing & video generation. Wrote a serial external for Max that basically generates a bytestream formatted for OctoWS2811 from a jit.matrix, so any video can be piped in realtime to the Teensy’s, with whatever fx/beat syncing is desired (Major props to nlecaude for the foundational work on this.)
Custom OSX app to monitor Twitter, queue up the requested songs, and update a tv display showing the song queue, available songs, and currently playing song.