AirBeat 1.0

1. Introduction

Problem

A drum set is a huge piece of equipment and very hard to transport. This prevents a drummer to freely move and jam and have fun with his/her friend :( Electronic drum set is also available, but they are not much smaller.

Existing solutions and their shortcomings

Design requirements

1. Small... could be put in a backpack
2. Layout is similar to a regular drum set, to help ease the transition

Solutions

Requiring a traditional layout would mean putting a sensor where the drums should be, around the drummer. This would imply a large size, so it seems like the two requirements could not be satisfied simultaneously. One way to solve this is to put the sensors on the drum sticks themselves.

These devices are called "air drums," and there are a few that are already available today:

• Arduino Air Drums. One stick produces one sound. Good design, but quite limited.
• Mi Jam. Has buttons on the sticks to let the user choose what sound the hit would produce. Doesn't really satisfy the second requirement... you have to press different buttons when you would like to change the sounds. 
• V-Beat. Has 3 positions for each stick (flat, tilt, high) that could produce different sounds. Still doesn't satisfy the second requirement, since you could not, say, use two sticks on the same drum.

What I plan to do is to create a better version of the air drums. The major additional component I plan to incorporate is a magnetometer. This would allow the device to know which direction it is pointing at. So for the right hand, if the stick is pointing to the very left, that would be a hi-hat. If it's pointing to the very right, that would be a floor tom. All these headings would be relative to some reference direction that the user could set.

2. Design

Outputs

• Audio line out*
• USB MIDI
• 5-pin MIDI

* I decide not to include an amp/speaker because it would make the device too big, and the MIDI synthesizer in the VS1053 chip doesn't sound too good, so the line out is just for reference.

Power supply

• USB 

Materials

Controller unit 

1. Teensy microcontroller. This supports MIDI USB, unlike the Arduino.
2. VS1053 decoder
3. LED power indicator
4. 3-way switch to select output
5. 4x female RJ12
6. 4x RJ12 cable 
7. Female 5-pin DIN
8. Female 3.5mm jack
9. Housing 

Sticks (2x)

1. MPU-9150 9-axis IMU
2. Momentary switch 
3. LED indicator (optional)
4. Housing 

Pedals (2x)

1. MPU-6050 6-axis IMU
2. LED indicator (optional)
3. Housing 

Challenges

• How to best define where each drum is? Each drum is defined by the compass heading and a pitch (and perhaps a roll?)
• How to best capture the drum hits? Consider velocity, etc.
• Find a way to have haptic feedback... a vibration when the drum is hit?
• How to fabricate the housing to be used as a drum stick? 

Additional features

• Let the user define where each drum is, what sound it should produce, etc.

3. Project Timeline

7/30 - Get different sounds from different headings

8/4 - Finalize user interactions... how to set up, how to select sounds, etc.

8/10 - Work on hardware

8/16 - Presentation

8/18 - Documentation due

3. Backup Plans

The backup plan is just to have two sticks, two pedals, that would produce different sounds when hit. This is already done.