Two mechanical-engineering assistant professors at the University of Iowa have created a robotic device to give people with limb impairment a wider range of motion. Right now, the pair is focused on the upper limbs and their first prototype increases mobility in the wrist.

The researchers, Venanzio Cichella and Caterina Lamuta, worked together to develop a flexible, lightweight device that can be powered with a small battery. Lamuta and her students are designing and developing the device itself and Cichella and his student are developing the controls of the device.

The device fits over the hand and wrist like a glove, and uses artificial muscles made from carbon fibers which are strong and flexible, Lamuta said. The muscles can lift 12,600 times their weight, and a lot of these artificial muscles can be used to reproduce the arrangement of human muscle. A small battery can be used to power the device, she said.

“So, the idea is to use this more flexible artificial muscle as an alternative for noisy and heavy traditional actuators like electrical motors or hydraulic or pneumatic actuators,” Lamuta said.

The current prototype can perform a few degrees of wrist extension and flexion, she said, but the researchers are working to increase the motion capabilities of the device.

The actuators the researchers are using are very inexpensive, Cichella said. This allows them to not only create a device that is portable and cheap, he said, but allows them to put more of the actuators in the device.

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With so many actuators, the question eventually became how to move each of them in order to get the desired action or movement, he said.

Cichella is developing robust control algorithms that can be implemented in the device. He and his student are developing theoretical tools that will help find the optimal controls for the device, Cichella said, and the goal is to implement the algorithms on the side of the device.

Amid spread of the novel coronavirus, some orders for supplies to build sensors have been delayed and working from home makes it so they can’t use larger machinery in the labs, Lamuta said, so they’re going to have delays in their work.

“Part of our research takes place in the lab, which now is the living room of our house and our students’ houses, and also on paper and pen, so it (the challenge) spans both for theoretical and experimental,” Cichella said.

Two UI Ph.D. students and a visiting scholar from Italy are helping with the development of the algorithms and prototypes of the device.

Thilina Weerakkody, a Ph.D. student, and Carlo Greco, the visiting scholar, are working with Lamuta to develop the device itself.

Weerakkody, who has a background in biomedical-device development, has worked on the device, which is similar to an exoskeleton hand, to control it with external feedback. Now, he’s in the process of developing external sensors for the device, he said.

The first prototype only had a single degree of freedom for the wrist, he added.

“Now in the second prototype, we’ve developed a 3D-printed prototype, so in this phase we are trying to elicit two freedom instances,” Weerakkody said.

Greco helped design the muscle used in the glove, choosing the dimension and length of the muscles and studying the schematics of the wrist, he said. The glove was initially able to move up and down in one motion, Greco said, but now they are working to improve movement in the other direction.

“Our testing now is done on a 3D-printed hand with a forearm and we can measure the displacement of the angle of rotation,” Greco said. “…[If] a person does a motion on his own hand and our hand [should] do the same motion in the same [amount of] time.”

Calvin Kielas-Jensen, a Ph.D. student, has worked with Cichella to develop the control algorithms for the device. They’re working with a motion-capture system to give them submillimeter accuracy for the positions of the wrist.

With a background in electrical engineering, Kielas-Jensen has helped with the electronics in the device. He is providing feedback for what kind of sensors should be used and what kind of algorithms should be used to read the data, Kielas-Jensen added.

“It’s a rehabilitation device, so there are plenty of rehabilitation doctors that say that it’s really good to have people do something with their hands,” he said. “It’s one thing to give a patient a stress ball to squeeze, but it gets tired — it gets boring.”