The SDRdrum is constantly tracking the mallets in space -- not just detecting percussive attacks -- and then sending this position data to the MechDrum. This allows us to give the robotic percussion "psychic" powers—it knows when it’s about to be struck. This leads to an interesting mirroring between human and machine that we explore as much as possible. Thus, the robotic player is a mirror of the human performer, as you can see from the video.

sonicpair #n is a series of duos involving robotic percussion. sonicpair #1 is for viola and radiodrum-controlled robotic percussion. This piece, sonicpair #2 is unique in that the robotic player is a "mirror" of the human percussionist. Using a new 3D capacitive sensor called the SDRdrum, the percussionist's gestures are exactly mimicked by the MechDrum, including gestures above the surface. This mirroring creates a unique visual and auditory experience that is different from all other percussive interfaces, because the robotic percussion is not “waiting” for a noteon to be received; rather it is continuously following all the gestures of the percussionist as they happen.

The SDRdrum employs a truly unique and innovative capacitive sensing technology for motion tracking with respect to a left and right striking implement. The core technology is built using state of the art Software Defined Radio and capacitive sensing. The primary components of the SDRdrum includes an 11.5” x 13” x 0.5” flat panel antenna and two electrically tethered striking mallets (transmitters), and a custom circuit board containing the Software Defined Radio electronics, and firmware. Additionally, the system is connected to a dedicated laptop through an ethernet cable for communications and a USB cable for power.

The impetus and original concept for the SDRdrum stems from the work of Max Mathews and Bob Boie, dating back to the 1970's at Bell Labs, when Boie was pioneering research into capacitive sensing. For many years, Max Mathews continued working on the concept of the Radio Baton or Radio Drum, later working with Tom Oberheim to create various prototypes. The SDRdrum uses exactly the same technique of capacitive sensing, in which the drumsticks transmit at frequencies around 120 kHz, and the pad is an antenna, but now we are using the technology of software defined radio to do the tracking of the sticks. This allows us to make a drum that can "laugh before it's tickled," since it knows when the drumsticks are approaching the surface before it is actually struck.