Animals are classified, plants are classified, why not controllers? There are dozens of controllers available on the market, and many have very similar functionality and characteristics. Some system of organization seems necessary and inevitable, in much the same way that synthesizers are classified(subtractive, FM, physical modeling, etc).

By no means am I suggesting that a scholarly method for organizing controllers should be mandated, but putting some sort of order in the controller kingdom may be useful in determining which controller should be used for a particular performance style and potentially aid in the development of new controllers.

The following is my system of classification, with examples, based on observations of controller functionality.

Keyboards: M-Audio Keystation 61es, Akai LPK25

Knob boxes: Evolution UC 33e, Allen & Heath XONE:DX

Button grids: Monome, Akai MPD18, Midifighter

Surfaces: Apple iPad, JazzMutant Lemur, Korg Kaoss Pad

Percussive controllers: Roland Octapad SPD-30, Alesis ControlPad, malletKAT

Kinetic controllers: Alesis AirFX, Microsoft Kinect

Acoustic controllers: Moog Piano Bar, Roland GR-55/GK-3, Alesis Trigger|iO, Yamaha Wx5

Tangible controllers: Reactable, BeatBearing

Hybrids: M-Audio Axiom 49, Akai MPK25

The above list, at the very least, reveals the variety of controller styles available today. Hopefully this list will inspire the development of new hybrids and entirely new species of controller.