Out House: Actuated Active Bending Structure

MIT 2021
Course: 4.154 / IN HOUSE

Instructors: Zain Karzan, Catie Newell and Virginia San Fratello
TA: Joel Austin Cunningham

Out House is at once habitat and inhabitant, space and object. It originated as a hack of a desktop CNC milling machine and can be understood as a cable-driven robot, however, whereas cable-driven robots are typically suspended from a frame or elevated structure, Out House relies on the restoring forces in three 3/8” GFRP rods to counter gravity. The cables are wound by three winch stepper motor actuator modules, which are controlled by a TinyG that receives G-code generated in grasshopper from CNCJS. When Out House is positioned on an impenetrable surface, the three nodes at its base are fixed to three steel strut channels. When outside on grass or soil, it can be staked to the ground.

Out House is an exercise in thinking about the expressive potential of a machine. When designing a CNC machine, typically a high degree of stiffness is desirable in order to accurately execute a set of instructions. In the absence of a need for accuracy, bending can be embraced as a material property. Here, bending is not the enemy of stiffness but rather the source of character for an emoting machine.

Suspended within the frame of the bending-active structure is a truncated square pyramid sewn from fluorescent orange ripstop nylon and open at top and bottom. As the structure dances between configurations, faces of the pyramid become more or less slack or taut, producing a reading of the pure geometric figure with varying degrees of clarity. In this way, the fabric serves as a register of the forces in the GFRP rods communicating the internal state of the structure as a kind of active ornament.

The fabric also serves as a shifting boundary between interior and exterior, producing a space that varies in its habitability based on the pose of the structure. As the machine bends between configurations, it produces a varying set of attitudes towards its occupants and onlookers. Over the course of a sequence of poses a person might encounter Out House from the outside as an object, enter as an occupant, be forced to sit as the structure compresses, and be expelled when the structure strikes an oblique pose.