A router end-effector has been designed with the hope to soon be utilizing the KUKA’s six axes for milling. This low budget router end-effector is assembled out of one $30 hand router from Harbor Freight Tools and a custom holder to be 3D printed in two pieces with our Form 1 printer. When finished, the router will be secured to the mounting assembly. This end-effector, although relatively crude, is a mean to understanding the KUKA’s capabilities for 6-axis milling and a temporary solution until a more refined end-effector can be produced.
Watch for more updates on the router end-effector in the future.
While assembling precedents for our research with the KUKA we found many examples of automated foam cutting with a robotic arm. A hot wire foam cutter end-effector looked as if it would require little expense to develop so we began designing and fabricating the tool. With steel angles, 1″ pipe, nichrome wire, a guitar string tuning mechanism, and a power supply we were able to fabricate the tool with less than $90.
The end-effector is designed to cut up to 40″ wide and 16″ deep in one motion. The most challenging aspect of the end-effector has been producing enough current to get the nichrome wire up to temperature for rapid foam cutting. Initial tests of the wire’s cutting temperature were done by hand. We found that the wire was capable of cutting the foam, but only at slow speeds. Attempts to wire through the foam more rapidly resulted in the wire dragging through foam and large deflection in the wire. Once we have a larger power supply we expect to have no issues with this.
Watch for more updates on the hot wire foam cutter end-effector in the future.
While fabricating the hot wire cutter end-effector we knew we would need a suitable work surface to shape our material. Research into industrial standards for work surfaces only revealed options that cost thousands. With little time and money to work with we set out to design and fabricate our own custom work surface.
Using Ball State’s Thermwood mill, the finished work surface was able to be constructed entirely of laminated and pressure fitted MDF pieces. A box raises the work surface 14″ above what the robot recognizes as the world plane. Here, material rests on a perforated surface that is itself above a vacuum chamber located inside the box. After a ShopVac is connected to the vacuum chamber material is held in place for the robot to begin work manipulating its shape.
Assembly and testing of the work surface has taught us a lot about where we could improve the design for the future. We hope to do so, but until then this inexpensive and efficient design should do just fine for some projects to come.
MIT’s Self-Assembly Lab, led by Skylar Tibbits, is on the bleeding edge of smart material research, pioneering efforts in self-assembling materials and components as well as programmable materials. From the Self-Assembly Lab website:
“Self-Assembly is a process by which disordered parts build an ordered structure through only local interaction. In self-assembling systems, individual parts move towards a final state, wheras in self-organizing systems, components move between multiple states, oscillate and may never come to rest in a final configuration.”
“Programmable Matter is the science, engineering and design of physical matter that has the ability to change form and/or function in a programmable fashion. 4D Printing, where the 4th dimension is time, is one recent example of PM that allows objects to be printed and self-transform in shape and material property when submerged in water.“
Both of these concepts are of great interest to us as we explore the relationship of form and time and consider how to design for changing conditions. In addition, these areas of research bridge the gap between our interests in robotics, composites and non-static form in the built environment. The Self-Assembly Lab’s section on Programmable Materials states that their “goal is true material robotics or robots without robots.” To that end they are exploring the following areas, among others, which are particularly relevant to our thesis development.
Programmable Carbon Fiber and Programmable Textiles
In partnership with Autodesk and carbon fiber supplier and material innovator Carbitex, the lab is researching flexible and self-bending carbon fiber fabrics. Carbitex already offers flexible fabrics, but the lab is looking at the possibility of programming this material to bend with the application of energy of some kind (for example, electrical current or heat).
A programmable textile would differ from carbon fiber in that it would offer different strength and rigidity characteristics and might not be able to change shape more than once, for example, after being immersed in water.
As described in the above quote regarding self-assembly, the lab is considering how parts in a system can come together in a specific fashion of their own accord with the simple application of an outside energy source. On some level the idea that such a system results in a “final state” is opposed to the concept of dynamic form, especially if parts are only able to come together in a single configuration. However, if we consider the possibility of a future material that is both self-assembling and programmable, allowing the parts to assume different configurations under different circumstances or stimuli, then the finality of a self-assembling system would simply refer to one of many states that the system can assume. It is in reference to such a possibility that we developed the final animation presented in the formeta 0.9 project.
A key influence throughout the development of our thesis work this semester has been the University of Stuttgart and the research pavilions jointly developed by the school’s Institute for Computational Design (ICD) and Institute of Building Structures and Structural Design (ITKE). The three pavilions developed from 2011 to 2014 all employed KUKA six-axis robot arms in the fabrication process, and two of them made use of carbon fiber weaving in structural and modular components. These projects were stimulating not only because they involved two key interests–robotics and composites–but also because of the rigor of the design process employed and quality of the documentation produced.
2012 Research Pavilion
Fabricated as a single unit, the 2012 pavilion uses a KUKA robot arm situated in a raised position to the side of the fabrication area to weave fiber tow onto a frame, which was removed after fabrication and installation. The design of the weaves reflects the structural forces at play in the overall design–a helicoidal crossweave is employed where strength is needed in various directions and a unidirectional weave is used to address axial forces.
This approach to weaving involving a temporary frame is of interest because of limited material required to shape the carbon fiber. A more typical approach to shaping composite materials involves single-use molds that can result in significant waste. We are interested in developing a fabrication method that will minimize waste while providing versatility and reducing the time and investment required to make use of composites.
2013-2014 Research Pavilion
The subsequent pavilion developed by the ICD/ITKE collaboration is another woven, carbon and glass fiber structure. In contrast to the 2012 pavilion, this design takes a modular approach, using a pair of robot arms to fabricate customized units for later manual assembly on site. Rather than using unique framing for each module, a single, adjustable framing system was employed, allowing for varied sizes and angles to be implemented.
In addition to the creative end-effector design, we were drawn to the design process, product and presentation of this project. It illuminates some of the technical details involved in carbon fiber weaving as well. For instance, in order to bond the carbon fiber tow to itself and to adjacent fiber tow, the tow had to be drawn through a resin bath continuously during fabrication. Unless we find an alternate form of fiber (such as “prepreg” resin pre-impregnated fiber) for any robotic weaving experiments of our own, we will have to design and construct a similar mechanism to prepare the fiber.
Both pavilions combine glass fiber with carbon fiber, using the carbon for structural reinforcement while at the same time creating a fascinating aesthetic. This approach is a more efficient use of materials, favoring the use of the more expensive carbon in areas where it is needed structurally.