9. Soft Robotics¶
RESEARCH¶
Soft robots are primarily composed of easily deformable matter such as fluids, gels, and elastomers that can match certain materials, in a process called compliance matching. Compliance matching is the principle that materials that come into contact with each other should share similar mechanical rigidity in order to evenly distribute internal load and minimize interfacial stress concentrations.
These types of interactions with soft materials are widely spread, as for instance with natural skin, muscle tissue, delicate internal organs, but also organisms, artificial replications of biological functionalities, etc. Due to this dramatic mismatch in mechanical compliance, it is easy to conclude that rigid robots are not adapted and even dangerous for intimate human interaction.
Therefore, there is a need of robots that match the elastic and rheological properties of materials and organisms found in nature, and this is where soft robots could bring the solution.
Designing soft robots calls for completely new models in their mechanics, power supply and control.
1. Actuation
Pneumatic Networks actuators are the most common soft robots, and are made up of a soft material, an elastomer, within which pressurized fluids can navigate through a series of channels and chambers. When these chambers are pressurized, the entrapped fluid generates stress from inside the material, causing the material to strain, to deform, and those enabling the motion of the actuator. The nature of this motion is controlled by modifying the geometry of the embedded chambers and the material properties of their walls. Generally, each segment of a fluidic elastomer robot bends, and this bending is due to material strain.
If a robot is composed of a single homogenous elastomer, most expansion will occur on the thinnest structures, and the motion of the robot will thus depend on the geometry of the microfluidic circuit. However, materials with different elastic behaviors can also be used to allow further control over actuator behavior.
Some more designs on how to create soft actuators.
REFERENCES & INSPIRATION¶
New Bending Actuator for Soft Robots
Soft robotic actuator/gripper
EXAMPLES IN LAB¶
HEAT-TRANSFER VINILE¶
TOOLS¶
EXAMPLE 1¶
As a first example to be able to understand how Soft Robotics works using heat-transfer vinyl, I wanted to use Adrina Cabrera's tutorial since I see it as excellent to begin to understand this concept.
You can see the rest of the steps in his tutorial here
The way in which the materials should be arranged is as follows, in the form of a sandwich.
These presses, also known as heat presses or thermal transfer machines, generate uniform heat and controlled pressure on the vinyl, facilitating its fusion. The procedure involves placing the sandwich that we created in the previous step, and then the heat press is used to apply heat and pressure for a specific period. This process activates the adhesive of the vinyl, allowing it to permanently adhere to the substrate. Temperature and time are critical factors, as they need to be adjusted according to the type of vinyl and the base material. Heat presses provide controlled precision, ensuring efficient and durable transfer.
After waiting for it to cool and removing the plastic from the vinyl, this is the movement it gives us.
EXAMPLE 2¶
For the next example I wanted to make the same body as the previous example but split it in half, so I proceeded to design it in my notebook and in AutoCAD.
When making the design I wanted to achieve the following movement.
Here is also a sample of what it looks like without trimming the edges.
EXAMPLE 3¶
In Adriana Cabrera's presentation, she shows us how by adding the shape of a diamond we can create the L-shaped movement.
Therefore, to the previous example I wanted to add these diamonds to be able to combine both movements, the spiral and in L.
Even though the shape of the diamonds was tiny, it stuck together properly after putting it in the heat press.
This was the final result, it can be seen that both movements have been achieved.
EXAMPLE 4¶
For this example I was inspired by Haneen Jaafreh, in which he joins a similar pattern to try to create the movement of a flower.
I really liked it so I designed a similar pattern in AutoCAD but applying the previous example. Using the laser cutting machine it was much faster to do this practice.
This was the final result.
SILICONE FILLED MOLDS¶
TOOLS¶
EXAMPLE 1¶
For the first example I decided to print an example of Emmy.Winks , and be able to see how the silicone behaves.
Using the 3D printer, it took around 2 hours to print this piece. Use PLA filament at a temperature of 215 degrees Celsius and hot bed at 60 degrees Celsius.
It is necessary when filling the molds with silicone to also spread a layer of silicone on a surface such as acrylic and then be able to use that thin layer to close the mold.
EXAMPLE 2¶
After the first test I was inspired by diamonds and wanted to achieve that movement with silicone so using Autocad I designed a gripper type mold.
I proceeded to fill it with silicone as in the previous example.
This was the final result, it was not a success as expected but I managed to find the fault.
In order for us to have more retraction power and be able to lift each limb, more air is necessary inside the conductors, so it would be necessary to correct the next section in the design.
