Introduction: Parasitic Urban Furniture
Over View and motivation
The goal of the project was to design urban furniture which could be easily attached to an existing infrastructure within an urban context. Our material of choice was steel, in order to take advantage of its flexible qualities and the urban infrastructure chosen, were the existing perforated unistruts (used as bus stop posts) to take advantage of their strong structure and perforated surface that allowed us to connect the furniture with ease.
The process taken to develop the furniture
was through a computational pipeline which began from a parametric model of the design that was fed into a computational compiler. The compiler aided us in the fabrication and assembly of the final product.
Step 1: Parasitic Urban Furniture
Step 2: Case Study
The following case studies were used to research existing designs of parasitic urban furniture and materials used for fabrication.
Step 3: Aim and Challenge
Step 4: Experiment a : Strip
The images above show an experiment to understand how multiple strips can be fabricated and assembled to develop curved forms. The following object you see is made of paper strips that have been scored and folded to allow maximum flexibility.
Step 5: Experiment B : Panel and Joint
Experiment B looks at multiple panels that could be attached to one another using tabs as joints. The design was developed through a parametric model that developed tabs based on the angle of the panels.
Step 6: Experiment C : Double Layer
Experiment C was undertaken to understand double layer assembly of curved objects using adjoining tabs placed over one another.
Step 7: Experiment D : Sitting Position With Kinect
Using a Kinect we were able to create 3D models of various sitting positions in 3ds max.
Step 8: Experiment E Anthropocentric Design Simulation for Chair and Compiler
Using the 3D models extracted from the kinetic sensor we were able to simulate a surface manipulation that took the shape of a person’s sitting position.
Step 9: Parametric Model for Chair
The parametric model used to design the parasitic seat was developed using the grasshopper plugin for rhino. Various parameters such as seat height, width and angles can be adjusted based on anthropometrics and functionality as well as the connection of the seat to the unistrut.
Step 10: A Parasitic Urban FurnitureCompiler
The fabrication compiler was developed using python and c# add-ons for the grasshopper plug-in, in Rhino 3D. The compiler aids in the fabrication and assembly of the final product by extracting two dimensional drawings of the 3-D strips. The process is divided into four steps. Pass A takes into account the geometric rationalization of the design. This means that it takes a given mesh or surface and converts it into an unrolled two dimensional representation. Pass B inputs joints, seams and tabs on to the two dimensional drawing for assembly and Pass C lays out the drawings into a boundary for fabrication. Finally Pass D gives the instructions that aid in the assembly process.
Step 11: Example and Demo Video of the Compiler
The images and video above show examples of the compiler from pass A to pass D.
Step 12: Material Waste
An important aspect of the entire process was to lay out the strips on the 4' x 8' steel sheet such that minimum amount of material would be wasted. The diagram above shows the layout of strips in white and the material that can be used after the steel strips have been cut in light grey. However an interesting fact to note is that the OMAX water-jet has a 'saw' function that allows the user to cut out maximum amount of pieces from the steel sheet. Thus, technically almost all the pieces left over could be utilized for future fabrication if needed.
Step 13: Material Test and Cut
The strips were fabricated out of two, 4’x8’, 16 gauge steel sheets using an OMAX water jet.
Step 14: Fabrication
The steel strips and tabs were bent at specific locations using a brake machine. Tabs that were obstructed by the rest of the steel strips were bent manually using clamps and hammered at a 90 degree angle.
Step 15: Physical Model
The final design of the chair fabricated and connected to a unistrut. One of the obvious realization during the entire process were the complications that unfolded once the design was taken out of the digital phase and implemented into real life fabrication. Bending steel at the correct angles was a challenge as well as rationalizing the assembly process in terms of nuts and bolts. A thorough research of material properties and behavior through test cuts and simulations is always advisable so that one is able to grasp the possibilities and limitations of the assembly process.
Step 16: Digital Mockup
Animation for digital mock-up of the design.
Step 17: Future Work
We intend to further refine the compiler so that the assembly can be a more efficient process. The use of steel has been a challenging but fascinating experience and we intend to explore the material and its possibilities for fabrication in the future.