Robotic Exhalation

Collin Garnett & Elliot Smithberger, A. Alfred Taubman College of Architecture + Urban Planning

Robotic Exhalation is an interdisciplinary exploration at the intersection of robotics, sculpture, and building science. Using machine-assisted fabrication, open-source documentation, and computational design, the team will explore the aesthetic and technical affordances of concrete rheology, ultimately creating a building-scale facade mockup that will serve as a sculptural exterior cladding prototype for building construction applications.

Our process involves casting a concrete panel (dimensions ranging from 6” to 18”) and displacing the material while it is setting, using continuous compressed air running to a nozzle tool head. This tool head is controlled and positioned above the cementitious slurry via a CNC armature that allows for precise expulsion of air while maintaining alignment to prespecified points. Toolpaths are generated via a custom Grasshopper script, where drawn orthogonal lines are translated into points and parsed into Gcode.

Patterns are determined by 2D CAD drawings and implemented using a variety of factors, including spacing, nozzle height, air pressure, mix rheology, water temperature, and perhaps most importantly, dwell time. Once variables are determined for specific pattern sequences the process is infinitely repeatable, producing groups of panels that are consistent, but individually unique.

The inherent imprecision of injecting pulses of compressed air into a semi-plastic slurry produces highly variable local patterns in the concrete, yet when controlled and repeated is visually recognizable as coming from the same material genus. Achieving local variation within a global, highly reproducible process allows this research to establish a framework for form-finding that would otherwise require excessive expense, machine time, and specialized knowledge.

Our fabrication process allows for quick adaptations to rapidly shifting material characteristics, establishing a real-time feedback loop that allows for designs to be drawn, processed, and implemented on the fly. A panel created with this method can feasibly be designed digitally, sent to the machine, and produced in minutes, with formal characteristics that are not replicable with traditional means of concrete fabrication.

Contemporary methods of concrete panel production rely heavily on the design and manufacture of mechanical master molds produced from high-strength steel. These materials are extremely energy intensive to fabricate, needing highly specialized milling routines to achieve a mold with formal complexity. These molds are only able to be used for a single panel type but can produce many identical copies. If the design needs to change, or if additional panel types are needed, many more molds will need to be manufactured, a process that is often slow, expensive, and energy intensive.

With robotic exhalation, reusable molds, efficient material usage, non-subtractive fabrication methods, and readily adaptable tools all come together for a low-cost, minimally wasteful means of creating a unique concrete facade system.

The specific material quality of the resulting panels will be a major portion of this research, which can be divided into three parts:

(1) An exploration of the aesthetic affordances of robotic exhalation, with compelling textures resulting from the combination of seemingly disparate scales of spatial manipulation. On one hand, extremely precise point-orient patterns are controlled by computer input, on the other, an indeterminate form is produced from the dislocation, setting, and curing of cementitious material with bursts of air. This process produces a beautiful resultant product, one that speaks to the methodology of production and establishes a visual language of reciprocity between the material and those that interact with it.

(2) Analysis of panel performance as it relates to thermodynamic properties, panel stiffness, andpotential use as a cladding system in actual building construction. A formal study will be conducted regarding light and temperature control, and how the specificity of these qualities can be realized in a full facade mock-up.

(3) Addition of natural additives and aggregates to combine with and substitute for commercial grade portland cement products to reduce both the material consumption and carbon footprint of this research endeavor.

Further, this research pushes beyond the bounds of physical architecture and digital form-making; this often-indeterminate means of production has far-reaching implications regarding artistic intent and the generation of architectural form, centering the resultant object of this exploration as an expression of process-based thinking and material science.

This work builds on our fascination with said expression of form, but perhaps even more importantly it may serve as a foundation for future career development in terms of digital authorship, fabrication processes, and methods for sustainable practice + material systems.

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