ACADIA

Robotic Rod-bending digital drawing in physical space

ABSTRACT Parke MacDowell

This paper details preliminary project-based design research that emphasizes the

Macdowell, Tomova

development of tools and processes in tandem with the development of ideas and forms. Amid increasingly mechanized fabrication processes, this project injects

Diana Tomova

t h e h u m a n a s c o d e - w r i t e r a n d t o o l - b u i l d e r, a s s e r t i n g a u t h o r s h i p w i t h i n t h e m o d e s

Macdowell, Tomova

of production themselves.

T h e i n i t i a l o u t p u t f r o m t h i s f o r a y, w a v e P a v i l i o n i s a n a r c h i t e c t u r a l i n s t a l l a t i o n generated by computer algorithms and built using custom digital fabrication t e c h n o l o g y. C o m p l e t e d i n J u n e 2 0 1 0 , t h e p r o j e c t i s l o c a t e d o n t h e g r o u n d s o f t h e U n i v e r s i t y o f M i c h i g a n Ta u b m a n C o l l e g e o f A r c h i t e c t u r e a n d U r b a n P l a n n i n g . wavePavilion has a footprint of 20x30 feet and stands 14 feet tall, containing over a kilometer of 1/4-inch diameter steel rod.

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Fig. 1

Fig. 2

1 Con c e pt Since the Renaissance, traditions of drawing have remained central to the discipline of architecture, contingent on a belief in the ability of the architectural l i n e t o r e p r e s e n t s p a c e . I n r e c e n t d e c a d e s , h o w e v e r, c o m p u t e r m o d e l i n g h a s largely supplanted the power of line with that of surface. The trend towards increasingly complex three-dimensional form-making highlights the centrality of surface modeling as both initiator and response within the feedback loop between software and design. While the ramifications of this shift are widespread, expressed i n e v e r y t h i n g f r o m t h e d r a f t i n g t a b l e t o t h e s k y s c r a p e r, t h e d o m i n a n c e o f s u r f a c e

Fig. 3

is especially apparent in the still-nascent domain of digital fabrication. Digital f a b r i c a t i o n h a s e m e r g e d a s a w a y t o b u i l d c o m p l e x v i r t u a l f o r m s , u s i n g c o m p u t e rcontrolled

machines

to

accurately

produce

highly-variable

parts.

Prevailing

digital fabrication practices break down virtual surfaces into these discrete parts through mediating strategies like sectioning and paneling. wavePavilion bucks this trend, discarding contemporary strategies of mediation and instead harnessing the potential of algorithmic computing to re-empower the line as a driver of architectural form.

Surface-derived

projects

demand

an

intermediate

step

between

design

and

fabrication to rationalize calculus-dependent shapes into parts that can be built with manufactured sheet-goods such as plywood, metals, and plastics. wavePavilion supports an alternative way of thinking about complex form, one that embeds material and fabrication constraints within the initial logics of formation. In wavePavilion, there is a resonance between the linear character of extruded steel rod and design a l g o r i t h m s r o o t e d i n l i n e a r g e o m e t r y. T h e d i r e c t n e s s o f t h i s r e l a t i o n s h i p p r o p e l s t h e line from what is now a comprised role within architectural representation to a critical role as an agent of built form. Here, the crude but variable base unit of the line, deployed within an assembly through complex relational logics, evokes qualities of

Fig. 4

surface and atmosphere. In so doing, the line challenges the ubiquity of the “blob� within scripted/parametric form-making—geometric composition supplying all the complexity and nuance for which we have become enamored of calculus-dependent surface modeling.

Figure 1. wavePavilion, top view, with occupant

Digital fabrication has the potential to collapse the long-standing divide that separates ideation and representation from construction. As the relationship between design and built form becomes more fluid, the scope of architectural practice might be expanded and strengthened as the designer acquires greater control over the means o f p r o d u c t i o n . T h e i n c r e a s i n g r e l i a n c e o n d i g i t a l f a b r i c a t i o n precipitated by complex architectural form foregrounds the significance of tools, processes, and the biases and tendencies they embed. Investing an ethic of design within the modes of production themselves c ap i t al i z e s

Figure 2. wavePavilion, in situ Figure 3. Strong sunlight multiplies the graphic qualities of the piece, reversing the translation from drawing to built form Figure 4. As the Pavilion form constricts, the lengths of the components diminish, and structural pattern becomes aesthetic gesture

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Fig. 9

Fig. 10

Fig. 12 Figure 5. Two program nodes generate a field of forces that effect how the pavilion grows Figure 6. The primary curve of the structure tracks a line between the nodes, making two zones with specific characters - The one on the right is more intimate, the one on the left more expansive, which reflects the different forces that the nodes project Figure 7. A secondary line of reinforcing structure develops with respect to the first curve, making a layer of pochĂŠ space Figure 8. A network of 3-dimensional polylines emerges from the curves on the ground plane Like the initial curves, the polylines develop with respect to their own tendencies and the effects of the critical nodes Figure 9. These polylines are the ancestor geometry for the final pavilion form - While the ancestor geometry is relatively simple, their descendants take into account more complex issues like structural integrity and user occupation Figure 10. The descendant geometry displays greater awareness of its neighbors, becoming a form-society through the relationships between discrete parts Figure 11. Within this form-society, there is broad structural connectivity but also a high degree of local diversity - There are gradients of change but also moments of strangeness which highlight the complex processes driving the evolution of wavePavilion Figure 12. Within two critical zones, the longitudinal gesture of wavePavilion morphs into seating - A pattern ‘phase-shift’ accompanies this change in functionality - In these zones, the length of the original polyline segments diminishes below a certain threshold, forcing the weaving behavior to adapt a new pattern - A convenient side effect of this shift is increased structural rigidity in the seating areas of the pavilion

o n o p p o rt un itie s late n t with in th is tre n d. To th is e n d, wave Pavi l i on (F i g ures 1- 3) emp has i zes th e de ve lopme n t of tools an d proc e sse s, in tan de m with th e de ve lopme nt o f i d eas and form, as a me an s of win n in g au th orsh ip for th e de sign e r amid in c re asin gly mechani zed fabric ation prac tic e s.

2

Co mputati o nal Desi g n

The structure and aesthetic of wavePavilion was developed through a scripted strategy of geometric evolution. This Rhinoscript code combined programmatic influences with intrinsic formal tendencies to produce an architectural object that manifests its logics of formation with respect to a specific set of spatial demands. This computational process can be described in a series of phases, as seen in the adjacent diagrams.

The virtual environment in which the pavilion form-script operates is established in Rhinoceros. This meta-site is seeded with critical nodes (Figure 4), which embed information tied to real-world spatial and programmatic requirements.

This process generates a field of vector impulses, influencing the innate tendencies of the form-script. The script then tracks a course within the data-environment of the established vector field, demarcating a curve of primary structure that describes two zones, each with distinct views and orientation (Figure 5).

The resultant spaces are simultaneously connected and autonomous, a perception reinforced by the modulating density of the developing pavilion form. A secondary array of geometry acknowledges the primary curve but follows its own logic (Figure 6).

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Fig. 13

Fig. 15

Fig. 14

In the specific instance of wavePavilion, this new layer delaminates from the primary form at the end of its trajectory. This expression highlights the internal variation invested within a single form-making strategy.

A network of three-dimensional polylines grows from the preparatory geometry on the ground plane (Figure 7).

The length and orientation of each segment of these polylines is dependent on its proximity to the critical nodes and the logic of the form-script. W ithin a certain range of the critical zones, seating elements develop. Beyond this range, echoes of the same geometric tendency are retained as merely vestigial forms. Collectively, these forms read as a single undulating gesture that runs the length of the pavilion. As a kind of ancestor geometry for the final pavilion form, the three-dimensional polylines are the simple progenitors of a lineage from which more complex descendants evolve. The ancestor geometry establishes the broad morphological characteristics of the pavilion (Figure 8), but lacks the sophistication to address issues of structural integrity and user occupation.

Figure 13. A custom CNC rod-bending device operates in tandem with a multi-use 7-axis robotic arm to shape the steel components - The behavior of this toolset is driven by a communication script which translates 3D computer geometry into robot / bender choreography Figure 14. Prototype tooling was developed over multiple iterations to deliver the high precision required in the custom CNC bending process: Clockwise from top left: waterjet-cutting parts, bender_v1.1, gripper_v1.0, bender_v1.3, bender_ v2.0, bending die fabrication, welded gripper mandibles Figure 15. A custom communication script evaluates 3D virtual geometry and outputs a command file for the robot/bender toolset

135 fabrication and prouction techniques

The descendant geometr y (Figure 9) takes the crude form of the ancestor geometry and augments it with a more nuanced understanding of proximity and spatial relationships.

New behaviors manifest, wherein individual components engage in physical exchange with their neighbors, forming aesthetic and structural alliances toward the development of a cohesive society of form. The late stage form-society displays broad networks of structural affiliation while maintaining a high degree of local diversity (Figure 10).

Behavioral gradients read across the breadth of the pavilion, but moments of eccentricity—phase shifts (Figure 11), vestigial phenotypes, dormant features— reveals the complex relational processes of the underlying system. Through this process of formal evolution, the wavePavilion manifests an index of its own p h y l o g e n y, p h y s i c a l l y e x p r e s s i n g i t s i n t e r n a l l o g i c s w h i l e s a t i s f y i n g t h e p r a g m a t i c requirements of built, occupiable form.

3

Ro bo ti c F abri cati o n and Assembl y

To s u p p o r t t h e c o n c e p t u a l a i m s o f t h e p r o j e c t , a m u l t i - u s e 7 - a x i s r o b o t i c a r m w a s paired with a bespoke CNC rod-bending device (Figure 12) to bend Âź inch steel rod into unique (non-repeating) three-dimensional shapes. This precision toolset (Figure 13) and the communication codes that control its behavior were designed and built/coded by the authors to resolve highly specific fabrication requirements beyond the capacities of conventional CNC tools.

A cus t o m s cript was de ve lope d to an alyze th e digital ge ome tr y of th e wave Pavi l i on and t rans l at e t h at in formation in to a se rie s of ope ration s for th e be n de r an d robot. This co d e b reaks in pu t ge ome tr y in to lin e s an d arc s an d re c ords data su c h as le n gth a nd o ri ent at i o n for e ac h e le me n t (F i g ure 14).

The d at a i s e xporte d as a se rie s of c omman ds in ku kaCode (for th e robot) an d h ex b as e machi n e c ode (for th e be n de r). T h e se c omman ds c h ore ograph th e ac tion s of t he ro b o t and be n de r in orde r to re c on stru c t th e origin al digital ge ome tr y ou t of ste e l r od ( Figu re 1 5 ).

The bent components were organized with a simple indexing system (Figure 16) and transported to the site, where they were manually assembled and welded (Figures 17, 18).

The mul t i -p lan arity of e ac h c ompon e n t is c ritic al to th is asse mbly proc e ss, e limin ating t he need fo r position in g jigs be c au se e ac h c ompon e n t c an on ly align with its n e igh bo rs i n a s i ng l e, spe c ific orie n tation . As part of th is se lf-in de xin g asse mbly, e ac h e le me n t f it s p reci s el y again st th e pre viou s pie c e s wh ile gu idin g th e position in g of th e su bse qu e nt .

Once p o s i t ion e d, th e rods we re man u ally we lde d in plac e .

Fig. 16

4

C o ncl usi o n and Pro j ecti o n

wavePavilion was a quick, two-month investigation that has initiated an ongoing trajectory of research. Both scripting and customized robotic fabrication embed a sometimes daunting learning curve that inhibits the potential of these tools and processes within an academic setting. With this in mind, the physical and computational tools developed for wavePavilion have been shared with designers both at the University of Michigan and other institutions in hope of accelerating the research through increased accessibility and open-source participation. Experimentation by the authors and others continues in 1/4-inch and 3/ 8i nch met al rod. Re fin e me n ts to th e toolse t are also on goin g (F i g ure 19) , an d th e n e x t g enerat i o n be n din g de vic e c u rre n tly in de ve lopme n t will e xpan d th is e xpe rime n tat ion t o l arg er diame te r mate rials. Compu tation al improve me n ts, su c h as visu alization s o ft ware t o be tte r pre dic t fabric ation c h alle n ge s, e xpan ds both th e ope rability of th es e p ro ces s es a n d th e ir c apac ity for broade r applic ation .

Figure 16. The command file outputted by the translation script is executed as a series of actions to precisely replicate the input digital geometry

As a p ed agogic al de vic e , wave Pavi l i on h as se r ve d as lau n c h in g-pad for stu dent p ro j ect s at th e Un ive rsity of Mic h igan with in th e c on te xt of fabric ation an d c ompu tation s emi nars . L ike wise , th e sc ripts an d tools from th e proje c t we re th e foc u s of Robot ic

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Fig. 20

C o n st r u c t s, an i nt ens i ve d es i g n wo rks ho p i nvolvin g stu de n ts an d fac u lty at Prin c e ton U n i v e r s i t y and i ns t ruct o rs fro m t he Uni vers i t y o f Mic h igan . In Fe bru ar y 2011, Mic h igan ’s FA B L a b p l a yed ho s t t o s t ud ent s and p ro fes s o rs from th e Arc h ite c tu ral Assoc iation an d L o n d o n M e t ro p o l i t an Uni vers i t y who t ravel ed to An n Arbor for a we e k-lon g visitin g s t u d i o o r g ani zed aro und ro b o t i c ro d -b end i ng . T h is e xpan din g re pe rtoire of proje c ts f o r e g r o u n d s a d es i g n i d eo l o g y i n whi ch t ect o nic s an d ge n e rative logic s are in timate ly l i n k e d t h r o u g h t he med i um o f t he l i ne.

Fig. 19

T h e v i a b i l i t y o f t hes e p ro ces s es , as evi nced by wave Pavi l i on, su gge sts th e pote n tial f o r m o r e refi ned archi t ect ural ap p l i cat i o ns : Me c h an ic al attac h me n ts migh t re plac e w e l d e d c o n nect i o ns t o i ncreas e as s emb l y s p ee d. Se c on dar y me mbran e syste ms may b e d e v e l o p ed t o p ro vi d e envel o p i ng cap aci t i e s. T h e be n t ste e l of wave Pavi l i on may e v e n b e p ai red wi t h wi re mes h and s ho t cret e t o produ c e h igh ly c u stomizable stru c tu ral f o r m s ( F i g u re 2 0 ). Cri t i cal l y, wavePavilio n o p en s th e domain of digital fabric ation to a h o s t o f no n-co nvent i o nal p ract i ces i n whi ch c on c e pt an d in stan tiation are lin ke d w i t h o u t t h e need fo r rat i o nal i zi ng s t rat eg i es t o me diate de sign in te n t an d fabric ation c o n s t r a i n t s . The exp ans i o n o f t hi s p rel i mi nar y e xe rc ise th rou gh kn owle dge -sh arin g b e t w e e n m ul t i p l e d es i g ners wi l l channel t hi s pote n tial toward n e w mode s of spatial d e sc r i p t i o n and t ect o ni c o p p o rt uni t y.

A c k n o w l e dge me n ts O u r t h a n k s t o Wes McGee [mat t er d es i g n s t udio] an d Dave Pigram [su pe rman oe u vre ], w h o se c r i t i ci s m and exp ert i s e were p i vo t al i n t h is work.

Figure 17. Individual components are CNC precision-bent and indexed prior to transportation and manual onsite assembly Figure 18. Carefully placed welds reinforce the structural pattern and allow the entire pavilion to act as a single moment frame Figure 19. Bender_v3.0, fabricated by Wes McGee, is a more robust version of the toolset used for the wavePavilion - This bender can be easily dismounted from its frame, and can be replaced with a hydraulic bender (currently in fabrication) for bending larger diameter metal rods and pipes Figure 20. The prototype bentSteel_chair02, by macdowell.tomova, employs an alternative attachment strategy - The bundled 3/8-inch steel rods are welded within waterjet-cut fasteners to deliver a cleaner aesthetic

137 fabrication and prouction techniques