SoftRobotics

Introduction: What is Soft Robotics?

Robotics has experienced a huge growth in the last few years, but most of the robots are still made of hard rigid components, being too heavy and dangerous to interact with humans.

In order to solve this issue, there have been several studies in flexible robotics, resulting in robots with some flexible parts that allow them to collaborate with people. Finally, Soft Robotics arose as the last step in this evolution: robots whose main structure is made of soft materials, allowing a total cooperation with humans.

Hard Robotics

Flexible Robotics

Soft Robotics

Generally, these soft robots are actuated by air or another pressurized fluid. However, some other materials enable the construction of this kind of robots. Take the case of SMA (Shape Memory Alloys), which deform under temperature changes, or electroactive polymers (EAP), which react to some external stimuli (e.g. electric fields).

Hydrogels, which are the materials that we will use in our research, are included in the last category (EAP).

Our research: Hydrogels in Soft Robotics

Hydrogels

A hydrogel is a polymer network capable of absorb large quantities of water. What makes these materials so interesting is that the amount of water contained inside the gel defines its physicochemical characteristics. In this way, we can tune these features with the appropriate chemical design. Furthermore, the hydrogels have a strong resemblance with human tissues, so its use in collaborative robotics is really interesting.

The deformation of hydrogels under external stimuli (electric fields, magnetic fields, etc.) makes them useful as actuators in Soft Robotics.

The only drawback is their low mechanical resistance. To solve this problem, nanocomposed hydrogels are being developed. These hydrogels contain nanoparticles of other materials (metals, polymers, graphene...) to strengthen them. Moreover, these nanoparticles can also regulate the stimulus that the gel reacts to.

Henceforth, our first goal is to develop a hydrogel with suitable mechanical resistance and good response under stimuli to be used in Soft Robotics as actuators, sensors or structural elements.

To make it possible, given the chemical nature of the material, we count on the support of MSOC-Nanochemistry research group. Thanks to them, we are synthesizing hydrogels with good response under electric fields, making serious progress in this area.

Modelling, instrumentation and control

Once we have the material defined, the next step is the adaptation to use it as an actuator or sensor. For that purpose, we must develop the following principles of modelling (M), instrumentation (I) and control (C):

MIC principles for flexible links with variable rigidity. Having a link with controllable rigidity would be very profitable, because it would have the advantages of both rigid and flexible components.
MIC principles for actuated soft structures, with the objective of develop robotic links whose deformations could be controlled.
MI principles for soft sensors in order to obtain feedback of forces, contacts or slips, data of great interest in robotics or biomechanics.
MIC principles for intelligent skins with self-healing or variable stiffness.

Robotic manipulation

Having obtained the previous principles, the final goal will be the design and fabrication of a soft robotic hand to validate the technologies previously developed.

This hand must be able to hold different objects thanks to his variable stiffness. In addition, it must be light and soft to interact with humans and it will have intelligent skin and advanced sensorial capabilities. Furthermore, we pretend to use 3D printing to fabricate it at low cost.

Source: Wikipedia

To design and develop this robotic hand, we will take as references the taxonomy of human grasping and some previous research studies of our group in this area. This soft hand will be the next evolutionary step to these flexible robotic hands that we have developed previously.