PDF of Presentation

Links:

Japanese Soft Robotics Hand and Sushi

Programmable Material

A material whose properties can be programmed to achieve specific shapes or stiffnesses upon command.

Planning phase

generating creasing patterns

Fabrication phase

-materialize plans with three main parts: composite sheet, thin-foil actuators and flexible electronics

Composite Sheets

• A single sheet of sixteen-layer E-glass fiber impregnated with RS-30 resin
• Has high strength, light weight, ease of machinability, material compatibility with silicone-based elastomers
• The composite cured at 140C for 4 hours
• Magnets are used to create the potential wells
• Elastomeric joints : RTV-2 GI-1100 ( need to stretch and bend)

Thin foil actuators

The researchers used (100 μm) foil Nitinol shape memory alloy (SMA) for the actuator material. The planform geometry is formed with a pulsed ultraviolet laser micromachining system. The micromachined foil is tinned, fixed in a jig to hold a desired (folded) shape, and annealed at 420° C for 30 min. This annealing process resets the undeformed martensitic state such that when unfolded, the actuator will “remember” its folded shape when heated above its transition temperature of 70° C

• Should be low profile, simple to assemble, and easy to make for mass production
• Thin fold Nitinol shape memory alloy
• 100um thick
• Annealed at 420C for 30 min to hold a desired shape
• It remember its desired shape when heated above its transition temperature of 70C

Stretchable electronics

• Bridging the elastomer flexure creases
• Should be able to bend and stretch
• The connectors are micromachined from a sheet of copper-laminated polyimide
• All actuators are grouped according to the crease plan, and each group is actuated sequentially

Limitations

• Actuator size and  torque considerations
• Inability to move back to the initial flat form
• Control and coordination constraints for multiple actuators
• A finite set of shapes

Improvement

Applications

Animated Lamps

The one above is designed by Romolo Stanco and the below was designed by a Japanese design group, Nendo. It uses shape-memory alloys to change the shape of the lamp when the lamp is on. The change is initiated with heat from the light bulb.

“Oricalco” shirt with Nitinol fabric

The sleeves fabric could be programmed to shorten immediately as the room temperature became a few degree hotter. The fabric can be screwed up into a hard ball, pleated and creased then just by a flux of hot air (even a hairdyer) pop back automatically to its former shape.

Octopus-like Soft-Robotic-Arm Freely Moving in water

Basically composed of silicone, driven by cables and shape memory alloys

See the video here:

Octopus-like Robotic Arm grasping Human Hand.avi

Suppliers

Shape memory alloys are widely available to consumers. Nickel-titanium (nitinol) alloys have been found to be the most useful of all SMAs and can be easily purchased online. Other shape memory alloys include copper-aluminum-nickel, copper-zinc-aluminum, and iron- manganese-silicon alloys. There are no hazardous health risks associated with using this material.

There are several websites where you can obtain SMA for your projects inexpensively.

Inventables

Teachersource

Edmund Scientifics

How EACs work:

A basic dielectric EAC, like that explored in “Fabrication and analysis of dielectric-elastomer minimum-energy structures for highly-deformable soft robotic systems,” uses the electrostatic forces between two capacitive plates, to compress and deform an elastic dielectric polymer. To generate the strong deformations seen above, several thousand volts need to be applied across polymer.

Electroactive Polymers, Un-actuated (fat) and actuated (thin)

First, just to get you excited, a teaser video, by a group out in Switzerland, that has a done a number of beautiful things with EACs:

EAP Tests EMPA 2010/08/19 from materiability on Vimeo.

Fabricating the actuators is a bit messy, but basically straightforward. The components are (mostly) inexpensive and readily available (see Supplies below). Essentially speaking, the process is as follows:

(1) Mount the polymer to a flexible frame, so that when actuated, it moved in a structured way. Otherwise it’ll just contract and wriggle like a worm on a wet sidewalk.

(2)  Coat both sides of the polymer with a conductive substrate. Many examples use a kind of conductive carbon grease, that while effective, is messy. Conductive powders, etc., also work. Essentially, you’re trying to turn the polymer into a capacitor, so the conductive coating applied to its sides are the capacitive ‘plates’.

(3) Hook up each side to a high-voltage power supply or transformer.

(4) Watch the magic happen.

And a video from the same Swiss group above, showing their fabrication process. It involves some fancy equipment, but that’s really just so that they can do it in a clean way. They encapsulate the conductive powder that is brushed on the polymer, so that it doesn’t make a mess.

ShapeShift from materiability on Vimeo.

Safety

WARNING. This stuff can kill you pretty good if you don’t know what you’re doing.

To generate the electrostatic forces necessary to actuate a dielectric polymer, voltage potentials on the order of thousands of volts are used. This is not unto itself dangerous (regular static-electric sparks can be in the tens of kilovolts), but much of the equipment used to generate such voltages can easily produce unsafe current and power levels. The large potential alone means that the electricity can arc through air, damage equipment (cell phones, etc.) and give you a nice buzz even if the current is limited. And if the current levels are high enough, it can really zap you. So make sure that you’re limiting the power to something super-low, a few hundred micro-amps. Beware of any elements (capacitors, etc.) that might be storing charge.

Real Jacobs ladder from Alex on Vimeo.

Suppliers:

Most of the supplies are available through Digikey. 3M VHB acrylic tape is widely available. Digikey has it available here, as in carbon conductive grease. The greatest challenge is in safely supplying the 1-5kV required for actuating the dielectric polymers. Industrial and scientific high-voltage power supplies are available: this would probably be the easiest, most controllable, and safest way of playing in this space. Specialized high-voltage components are available from EMCO high-voltage. There are other ways of generating low-current, high-voltage, of course–one could use a Van de Graf generator or a commercial flyback transformer–a transformer typically used in conventional CRT displays. Unfortunately, such transformers can draw large currents and require some care in use. They can make

Paper:

Petralia, M.T. and Wood, R.J. Fabrication and analysis of dielectric-elastomer minimum-energy structures for highly-deformable soft robotic systems. 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE (2010), 2357-2363.

Presentation:

Electroactive Polymers Presentation (here)

For this assignment, you’ll research different material actuators in small teams. Each team is assigned a type of actuator and a paper that should provide a foundation for further research. For Tuesday’s class you should prepare a 3 minute presentation (note the change in time) and a blog post (on this site) that documents your research.

Your talk should include:

• An explanation of the basic properties of the actuator, how it works, and how it’s constructed.
• Brief reflections on how you might use the actuator in your own practice.

Your blog post should include:

• The material covered in your talk, plus:
• Identification of at least one supplier of the actuator (or its constituent parts). Provide information about cost and any safety concerns. You should be able to reasonably acquire material from this supplier.
• A link to a pdf of your research presentation.

Add your blog post to the the Actuators Research category.

Groups, materials, and starter papers are given below:

Group 1. Jamming
Adedoyin Ogunniyi
Sara Hendren
Jill Sherman

Brown, E., Rodenberg, N., Amend, J., et al. Universal robotic gripper based on the jamming of granular material. Proceedings of the National Academy of Sciences, (2010).

Group 2. Pneumatics and Soft Robotics
Oz Agar
Jason Wee

Ilievski, F., Mazzeo, A.D., Shepherd, R.F., Chen, X., and Whitesides, G.M. Soft Robotics for Chemists. Angewandte Chemie International Edition 50, 8 (2011), 1890-1895.

Group 3. Thermochromic Inks and Paints
Nicole Tariverdian
Dena Molnar
Daekwon Park

Siegel, A.C., Phillips, S.T., Wiley, B.J., and Whitesides, G.M. Thin, lightweight, foldable thermochromic displays on paper. Lab on a Chip 9, 19 (2009), 2775.

Group 4. Electroactive Polymers
Timothee Boitouzet
Sam Jacoby
Farre Nixon

Petralia, M.T. and Wood, R.J. Fabrication and analysis of dielectric-elastomer minimum-energy structures for highly-deformable soft robotic systems. 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE (2010), 2357-2363.

Group 5. Shape Memory Alloys
Shan Gao
Fangbing Qiu
Woong Ki Sung

Hawkes, E., An, B., Benbernou, N.M., et al. Programmable matter by folding. Proceedings of the National Academy of Sciences, (2010).