"A Kestrel Manoeuvres in the Dark", or "A Kestrel for a Rave"

I made this project for fun and to learn about stepper motors.

It's debut performance took place at a New Year's Eve party in Dorset, in the same place and exactly one year after the Badgermin was revealed.

The kestrel sculpture is connected to a box of electronics, at the heart of which lies an arduino board. The arduino is a little microprocessor onto which you can load a program, which it then executes continuously until you switch it off. Various inputs and outputs on the board can be configured to do different things - in this case the arduino was used to turn on a number of outputs in a sequence, to make the kestrel dance in time to the music. The arduino outputs turn a series of oscillators on and off, the frequency of which can be set by turning a knob. This sets the speed of the kestrel's dancing, while the arduino controls the timing of the dance moves.

The oscillators send pulses to the motor driver boards, which distribute a higher voltage to the stepper motors and control the current supply. Stepper motors are a special type of motor that move in steps rather than continuous rotation. Electrical pulses are used to tell the motor how many steps to advance - useful for robotics, printers, CD players etc. where accurate positioning is required. The arduino also controls the timing of the smoke machine, strobe and lasers. A second arduino board runs an MP3 player "shield" to supply the music in sync with the dance moves.

I had started putting some of the electronics together at the beginning of the project when I heard Modeselektor's track "Kill Bill Vol 4". The track seemed to be perfectly divided into sections that could correspond to the dance moves of a kestrel. I imagine this was what Gernot and Sebastian had in mind when they composed the track. The first step was to open the track in an audio editing program and add markers to define each section. The length of each section was then noted, and added to the arduino program as a series of times in milliseconds. The code basically then says "Wait for 44300 milliseconds then turn on motor no. 2" etc, which means that the kestrel starts moving vertically after 44.3 seconds. My brother helped me with the code as usual, as he's very good at it.

A more detailed description of how everything works, including more photos of the mechanism and details of mistakes made along the way, can be found here.

Technical description and more photos

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