8. Soft robotics¶

Research¶

Soft robots are a category of robots built with flexible and deformable materials that mimic the softness and adaptability of biological tissues. Unlike traditional robots made of rigid components, soft robots are developed using materials such as silicone, elastic polymers, or textiles, which allow them to move and adapt to complex environments without causing damage. These characteristics make them ideal for applications in fields like medicine, rehabilitation, and handling fragile objects, enabling safer and more efficient interactions in delicate scenarios.

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References & Inspiration¶

The following video shows a real octopus interacting with a robotic octopus. This type of content is a great inspiration for developing soft robots. Octopuses are ideal for soft robotics design due to their flexible bodies, adaptable tentacles, and fluid movement. These robots aim to replicate the octopus's abilities to manipulate objects precisely and adapt to complex environments, which is especially useful in medicine and exploration. The interaction between the octopus and the robot highlights soft robots' ability to coexist safely in natural environments.

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Process and workflow¶

My workflow involved visualizing the necessary procedures to achieve the desired results. First, I identified the steps to follow, which were:

Design in software (SolidWorks)
G-code generation
Manufacturing
Assembly
Repeating or adjusting a process as needed.

Vynil¶

Inflatable Soft Robots are an intriguing branch of robotics that use flexible and deformable materials instead of traditional rigid ones. In this case, textile vinyl is an excellent option for their fabrication due to its durability and flexibility, which allow for structures that inflate to change shape and return to their original form when deflated.

Why Textile Vinyl?:

-Flexibility: Textile vinyl is flexible enough to withstand cycles of expansion and contraction, which is essential for inflatable soft robots.
-Airtightness: The material is relatively impermeable, allowing it to retain air or fluids within inflatable chambers.
-Ease of Fabrication: It’s easy to laser-cut or assemble with heat-sealing, adhesives, or sealed stitching, which facilitates the creation of complex shapes and compartments.

How Do They Work?¶

The concept behind inflatable soft robots is to create air chambers (also known as actuators) that change shape when inflated. Depending on the design of these chambers and the control of airflow, various movements can be produced, such as bending, twisting, or stretching.

Key functional aspects include:

Air Control: Using valves or micropumps, each compartment can be inflated or deflated to achieve the desired movement.
Chamber Patterns: The shape and layout of the inflatable chambers dictate the movement; for example, an asymmetric layout creates bending motions, while a symmetrical pattern could lead to uniform extension.
Applications in Digital Fabrication Soft robots with textile vinyl can benefit from digital fabrication techniques such as laser cutting or vinyl plotting for creating the piece patterns. Additionally, heat-sealing techniques can be helpful to create airtight compartments.

This type of inflatable robot is widely explored in Textile Academy and Fabricademy because it allows for research into the design of soft and organic interfaces, which could have applications in wearables, haptic interfaces, or even medical assistance devices.

Cut studio¶

Roland CutStudio is software designed to simplify cutting tasks on Roland plotters. It’s ideal for those looking to create and manipulate vector graphics for projects like vinyl, textile graphics, labels, and stickers.

Plotter Setup¶

Pressure and Speed Adjustment: Set the blade pressure and cutting speed based on the thickness and type of vinyl.
Material Positioning: Place the vinyl in the plotter, ensuring it is well-aligned and secure to prevent shifting during the cut.

Cutting Process¶

Sending the File to the Plotter: Send the design from the cutting software to the plotter. Monitoring: It’s important to monitor the process to ensure the cut is consistent and to correct any issues.

Weeding¶

After cutting, perform the "weeding" process, which involves removing the excess vinyl that is not part of the design. Tweezers or a spatula are usually used to make this task easier. Then, the adhesive backing of the textile vinyl will help hold the design together, keeping the pieces aligned.

Heat Press Setup¶

Set the heat press according to the specifications of the vinyl you are using. Generally, textile vinyl adheres at temperatures between 150-180°C (300-350°F), and we’ll set a time of 5 seconds since it’s a small piece.

First pieces¶

In these pieces, the air only acts as a relief without generating significant movement. Therefore, I will create other pieces that allow for greater airflow to achieve a more pronounced movement effect.

Second pieces¶

In these pieces, a change in movement can be observed, beyond just a relief, as they perform bending movements according to their shapes. This model ¹

Silicone¶

For my experimentation, I used soft robots made with silicone as a basis. Thanks to my colleague Aristarco, I gained a better understanding of how they work. These soft robots are a category of robots that use soft, flexible, and deformable materials to mimic the behavior of biological organisms, enabling complex and adaptive movements. Silicone is one of the most commonly used materials in the creation of these robots due to its exceptional characteristics, which include flexibility, durability, biocompatibility, and resistance to various environmental factors.

Design¶

I created the 3D design in SolidWorks because this software has an option to calculate solid properties based on a materials library; in this case, I selected rubber. The design focuses on replicating the suction cup parts found on octopus arms, which allow them to adhere to various surfaces. This model ² This model ³

3D Print¶

Silicone casting in 3D-printed molds is a useful process for creating flexible and durable parts. First, the mold is 3D-printed, typically in materials like resin or PLA, ensuring it is well-sealed to prevent leaks. A release agent is applied inside the mold to ease demolding. The silicone is then mixed and poured into the mold, with bubbles removed through degassing or vibration. Finally, it is left to cure for the recommended time before carefully removing the silicone piece from the mold.

Silicone casting¶

To use Ecoflex™ 00-30, begin by wearing vinyl gloves and ensuring ventilation. Pre-mix Part B, then mix equal parts A and B for three minutes. Optional vacuum degassing can remove air bubbles. Pour into molds and allow the silicone to cure at room temperature. Use a release agent if desired, especially for intricate molds. Store at 73°F/23°C and avoid contaminants that could inhibit curing, like latex.

Using the Vacuum Chamber:¶

Place the container in the vacuum chamber and turn on the pump.
Watch as the mixture bubbles and expands, releasing trapped air. This takes about 3 to 5 minutes. When the bubbles decrease and the mixture stabilizes, turn off the pump and release the vacuum.
Pouring: Remove the degassed mixture and pour it into the mold carefully to avoid introducing new bubbles.

This process eliminates bubbles and ensures a smooth finish in the silicone.

To prevent the air from escaping the chambers, it’s necessary to add a seal. For this, the silicone is prepared; in my case, I used 5 grams to cover two molds. I then poured the silicone onto a surface and placed the molds on top, creating a layer that acts as a seal and prevents air from escaping the chambers.