Chico MacMurtrie / Amorphic Robot Works

 

Hand sketch Finger bones Work on hips Spine and hips Pelvis Hips up Right shoulder

An overview sketch of the mechanical and electrical systems needed throughout Skeletal Reflections' body.
Artwork: Chico MacMurtrie

The beginnings of the basic mechanical skeleton underlying Skeletal Reflections during fabrication in ARW's Red Hook studio.
Photo: ARW

The computer-controlled valve bank that creates the pneumatic-computational interface for the functioning of the piece.
Photo: ARW

A look inside Skeletal Reflections' pedestal, which houses the computational, mechanical, pneumatic and electrical components of the sculpture which are not the sculpture itself.
Photo: ARW

Skeletal Reflections: Fabrication

As with most of the works, the concepts gestate in the media of drawing and model-making until the resources can be gathered to realize the work in three dimensions. Prototypes of the most important mechanisms, the sculpture's environment, and interaction are explored and revised during this time, evolving the work on paper to the point of tackling the engineering challenges inherent in realizing a moving, sculptural piece. Once the work moves into three dimensions, additional challenges arise that become important in the final conceptual and physical form of the work.

The basic substructure of Skeletal Reflections is a hand-crafted aluminum support, which tightly mimics the form and function of the human skeletal system. The spinal column is made of conjoined plastic components which act as surrogates for disks and vertebrae and provide a support and flexibility similar to that of the human spine. The musculature consists of computer-controlled pneumatic cylinders of varying strengths and configurations, which are powered by a venous layer of electric, data, and pneumatic connections.

Skeletal Reflections' current face is constructed with 14 independently controlled RC servo-motors. As the humanoid robot mimics the physical gestures of the participant, unique facial expressions are composed as the 14 servo motors act independently, or in concert, to articulate the fabricated "bones" and "muscle" of the figure's face.

The motion capture and interpretation system currently consists of two PCs running video analysis software, and cameras directed at the viewer. Frames of the viewer are captured and compared to the images in a stored database of art historical poses. If the image captured matches one of the historical referents, the sculpture executes a smooth interpolated motion sequence to arrive at the desired pose.

The "brain" of Skeletal Reflections consists of a MediaMation/HRBOX servo controller computer which monitors and changes the position and movements of Skeletal Reflections' body. Specifically, HRBOX interprets the joint position commands for each art historical pose. This brain then generates electrical commands to drive a bank of Festo electro-pneumatic servo valves. The valves deliver precise, electrically controlled airflow to each of the sculpture's pneumatic actuators, which mechanically drive each joint. Position information for each joint is provided by Data Instruments linear potentiometers, which are connected back to the HRBOX's analog inputs.

Skeletal Reflections' computer, and valve bank reside in its pedestal, giving the installation a streamlined, elegant presence which supports a direct, face-to-face viewer interaction.

At this point in its evolution, Skeletal Reflections has taught Amorphic Robot Works a tremendous amount, and has expanded and solidified our interest in the dynamics of form, lightweight structures, and servo-pneumatic systems. This work has also allowed for the smooth integration of techniques previously untested by ARW in the creation of new installation and performance pieces. Another ARW work, Growing, Raining Tree, has benefit directly from the knowledge gained in building Skeletal Reflections. Skeletal Reflections continues to test our abilities, as we expand his.