Soft robots make virtual reality gloves feel

A soft robot that can support 40 times more weight

video: Current soft robotic hands can hold small objects, such as an apple. Because the robotic arm is soft, it can gently grasp objects of various shapes, understand the energy required to lift them, and become stiff or tense enough to lift the object, a task similar to how we grasp and hold things in our own hands. An electroadhesive coupling is a thin device that increases the stiffness of materials, allowing the robot to perform this task.
View more

Credit: Penn Engineering

Soft robots, or robots made of materials such as rubber, gels, and fabrics, have advantages over their harder, heavier counterparts, especially when it comes to tasks that require direct human interaction. Robots that could safely and gently help people with limited mobility shop, prepare food, dress or even walk would undoubtedly be life-changing.

However, soft robots currently lack the power needed to perform these kinds of tasks. This long-standing challenge—to make soft robots stronger without compromising their ability to subtly interact with their environment—has limited the development of these devices.

With the relationship between strength and softness in mind, a team of Penn engineers devised a new electrostatically controlled clutch that allows a soft robotic arm to hold 4 pounds—about the weight of a bag of apples—40 times more. before the hand could raise without clutch. Additionally, the ability to perform this task requiring both soft touch and force was achieved with only 125 volts of electricity, a third of the voltage required for current couplers.

Their safe, low-power approach could also enable wearable soft robotic devices that would simulate the sensation of holding a physical object in an augmented and virtual reality environment.

James Pikul, assistant professor of engineering and applied mechanics (MEAM), Kevin Turner, MEAM professor and chair with a secondary appointment in materials science engineering, and their Ph.D. students, David Levine, Gokulanand Iyer, and Daelan Roosa, published a study in Scientific robotics describing a new model of electroadhesive joints based on fracture mechanics, a mechanical structure that can control the stiffness of soft robotic materials.

Using this new model, the team was able to realize a clutch 63 times stronger than current electro-adhesive clutches. The model not only increased the force capacity of the clutch used in their soft robots, but also reduced the voltage needed to power the clutch, making the soft robots stronger and safer.

Current soft robotic hands can hold small objects, such as an apple. Because the robotic arm is soft, it can gently grasp objects of various shapes, understand the energy required to lift them, and become stiff or tense enough to lift the object, a task similar to how we grasp and hold things in our own hands. An electroadhesive coupling is a thin device that increases the stiffness of materials, allowing the robot to perform this task. A clutch, similar to a clutch in a car, is a mechanical connection between moving objects in a system. In the case of electroadhesive joints, two electrodes coated with a dielectric material are attracted to each other when a voltage is applied. The attraction between the electrodes creates a frictional force at the interface that prevents the two plates from sliding around each other. The electrodes are attached to the flexible material of the robotic arm. By energizing the clutch, the electrodes stick together and the robotic arm holds more weight than it could before. Disengaging the clutch allows the plates to slide over each other and the hand is freed so the object can be released.

Traditional clutch models are based on the simple assumption of coulombic friction between two parallel plates, where the friction prevents the two clutch plates from sliding past each other. However, this model does not capture how the mechanical stress is unevenly distributed in the system and therefore does not predict the clutch force capacity well. It is also not robust enough to be used to develop stronger couplings without the use of high voltages, expensive materials or difficult manufacturing processes. A robotic hand with a clutch created using the friction model may be able to pick up an entire bag of apples, but it will require high voltages that make it unsafe for human interaction.

“Our approach addresses the force capacity of clutches at the model level,” says Pikul. “And our model, a model based on fracture mechanics, is unique. Instead of creating parallel plate joints, we based our design on lapped joints and investigated where fractures might occur in these joints. The friction model assumes that the stress on the system is uniform, which is not realistic. In reality, stress is concentrated at different points, and our model helps us understand where these points are located. The resulting clutch is stronger and safer because it requires only one-third the tension compared to traditional clutches.

“The design and fracture mechanics model in this work have been used for the design of bonded joints and structural components for decades,” says Turner. “The novelty here is the use of this model for the construction of electro-adhesive joints.”

The researchers’ improved clutch can now be easily integrated into existing equipment.

“A model based on fracture mechanics provides fundamental insight into the workings of electroadhesive coupling and helps us understand them more than the friction model ever could,” says Pikul. “We can already use the model to improve current clutches just by making very small changes in geometry and material thickness, and with this new understanding we can continue to push the limits and improve the design of future clutches.”

To demonstrate the power of their clutch, the team attached it to a pneumatic finger. Without the scientists’ grip, the finger was able to hold the weight of a single apple inflated into a curled position; with her, a finger would hold a whole bag of them.

In another demonstration, the clutch was able to increase the strength of the elbow joint to be able to support the weight of the manikin’s arm at a low power consumption of 125 volts.

Future work that the team is excited to delve into includes using this new clutch model to develop augmented and virtual reality wearables.

“Traditional connectors require about 300 volts, a level that can be dangerous for human interaction,” says Levine. “We want to continue to improve our clutches to be smaller, lighter and less energy-intensive to bring these products to the real world. Ultimately, these clutches could be used in wearable gloves that simulate the manipulation of objects in a VR environment.”

“Current technologies provide feedback through vibration, but simulating physical contact with a virtual object is limited in today’s devices,” says Pikul. “Imagine both the visual simulation and the feeling of being in another environment. VR and AR could be used in training, remote work, or just simulating touch and movement for those who lack these experiences in the real world. This technology brings us closer to those possibilities.”

Improving human-robot interactions is one of Pikul’s lab’s main goals, and the direct contribution this research represents is fuel for their own research passions.

“We haven’t seen many soft robots in our world yet, partly because of their lack of power, but now we have one solution to that challenge,” says Levine. “This new way of designing clutches can lead to soft robot applications that we cannot imagine now. I want to create robots that help people feel good and improve the human experience, and this work brings us closer to that goal. I’m really excited to see where we go next.”


Source

Also Read :  First-ever AR art exhibition on view at Humanities Gallery

Leave a Reply

Your email address will not be published.