Wearable robot gives ALS patients a hand
Device helped patients in study with lifting, carrying
A wearable robot that detects small arm motions and helps support the shoulder can make it easier for amyotrophic lateral sclerosis (ALS) patients to pick up and carry things, a study showed.
ALS is a neurological disorder that causes progressive muscle weakness and eventual paralysis. Weak limbs make many day-to-day activities challenging for patients, resulting in poorer quality of life.
Researchers have been developing so-called wearable robots to help ALS patients and others with movement disorders improve their functionality. The general idea is for the robots is to take cues from the body and help it through its movements.
For their study, the researchers built on previous attempts at making wearable robots to support arm function. They designed a soft device that is positioned on the patient’s arm and along the side of the body. It inflates and deflates to help the patient lift and lower the arm.
The study, “Personalized ML-based wearable robot control improves impaired arm function,” was published in Nature Communications.
Device proves more accurate than other systems
The device uses sensors to detect small movements from the wearer’s arm. Advanced machine learning algorithms are used to interpret these signals and translate them into actions for the robot to help support the wearer’s intended arm movement.
“We selected sensors that do not require precise placement or a stable skin interface and a lightweight, transparent actuation method to support multi-day usability,” the researchers noted.
Tests showed that the system could help patients raise an arm, hold it, or move it down to the intended elevation more than 94% of the time. The researchers noted that this is better than other systems using sensors that detect electrical signals in muscles, rather than arm movements, which generally get about 85% accuracy.
The amount of time the system took to detect movements and respond accordingly also compared favorably to prior systems, the researchers said.
To evaluate the robot’s utility, the researchers tested it on nine people with arm weakness: four due to ALS and five due to stroke. In all nine participants, the system led to improvements in measures of joint mobility, lessened the need for the trunk to move to compensate for arm weakness, and increased the efficiency of arm movements.
The researchers noted that these improvements were generally more pronounced in ALS patients than in those whose limb weakness was due to stroke. Videos of the improvements enabled by the robot are available online.
To further test the system, two participants — one ALS patient and one who had a stroke — used it while going about day-to-day tasks at home. Both patients found the system made it easier to pick up and hold objects.
“Our at-home demonstration shows that the robot can allow individuals with impairments to lift weighted objects higher and for longer,” the researchers wrote.
Overall, the data suggest that the system could help patients with arm weakness. However, the researchers noted some limitations: The device only works for people who are able to move their arms, so it’s not suitable for those with more extensive paralysis. It’s also not possible for patients to put the system on without assistance. The device also supports only the shoulder. Future work could explore incorporating the system with others to support parts of the arm like the elbow and wrist, the researchers said.
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