The Institute for Advanced Architecture of Catalonia (IAAC), based in Barcelona, has, for some time now, been exploring and investigating the potentials of additive manufacturing (3D printing) applied to the architectural field, therefore the implemented on a larger scale. In this framework, the Institute put together a team of researchers with the aim of re-elaborating 3D printing techniques so as to overcome these limitations.
SMALL ROBOTS PRINTING LARGE-SCALE STRUCTURES
Robotics offer great potential towards innovation within the construction industry. However, in their current implementation applied to the architectural field, in particular, construction robotics, these systems all share a specific limitation: the objects they produce are linked to and constrained proportionally to the size of the machine. This methodology of production and construction is not scalable. In this sense, to create a house, using current construction robotics, the machine needed must have a work envelope as large as the house itself.
Hence, the project here below elaborated aims to address this particular limitation through the creation of a technology that is both scalable and capable of fabricating structures using tools that are independent of the final products shape of size.
The objective was to develop a family of small-scale construction robots, all mobile and capable of constructing objects far larger than the robot itself. Moreover, each of the robots developed was to perform a diverse task, linked to the different phases of construction, finally working together as a family towards the implementation of a single structural outcome. Hence, instead of the implementation of one large machine, a number of much smaller robots were generated, working independently, but in coordination, towards a single goal.
Specifically, a family of three robots was developed, each robot linked to sensors and a local positioning system. These feed live data into a custom software which allows us to control the robots’ movement and deposition of the material output: fast setting artificial marble.
The first robot, the Base Robot, lays down the first ten layers of material to create a foundation footprint. Sensors are mounted inside the robot control the direction, following a predefined path. Travelling in a circular path allows for a vertical actuator incrementally adjust the nozzle height for a smooth, continuous, spiralling layer. The advantage of laying material in a continuous spiral is that it allows for constant material flow, without having to move the nozzle up at intervals of one layer.
To create the main shell of the final structure of the second robot, the Grip Robot, attaches to the foundation footprint. Its four rollers clamp onto the upper edge of the structure allowing it to move along the previously printed material, depositing more layers. The nozzle moves dynamically allowing for greater accuracy of the material output, to create a curved surface the material output will be incrementally offset. Heaters, integrated into the robot’s structure increase the local air temperature to influence the curing process. Controlled by custom software, the robot follows a predefined path, but can also adjust its path to correct errors in the printing process. Rotational actuators control height above the previous layer to maintain a consistent layer.
Another major limitation of today’s additive manufacturing techniques is linked to the unidirectionality of layer orientation, creating an inherent weakness. Additive manufacturing allows for heterogeneous optimised distribution of matter. To take advantage of this, and not succumb to this limitation, we used structural optimisation tools to create a second layer of material over the shell. The material is also closely aligned with the direction of stress, finally optimising both orientation and thickness of the shell structure.
The data derived from the structural analysis is then translated into paths for the third and final robot, the Vacuum Robot. Using a vacuum generator this robot attaches to the surface of the previously printed structure. Moving freely over the first shell on its tracks, depositing material on the surface of the shell, enhancing its structural properties. This task can be performed by one robot or a swarm of robots working in coordination.
Seven months of research were dedicated to the development of this project by IAAC, Institute for Advanced Architecture of Catalonia, in the framework of the Open Thesis Fabrication postgraduate programme in 2013, specifically by the researchers:
- Shihui Jin
- Stuart Maggs
- Dori Sadan
- Cristina Nan
And led by IAAC faculty:
- Saša Jokić
- Petr Novikov.
This project was also made possible thanks to the sponsorship of SD Ventures, culminating with the production of a large-scale print. A 1.5-metre high prototype structure was printed in the exterior exhibition space of the Design Museum of Barcelona (Dhub), proving to be a positive outcome for the research entailed.