Building a Robot to Assist Individuals with Upper-Limb Disabilities
In This Article
- Investigators from Mass General and Harvard are developing a device to provide personalized movement assistance for people with upper-limb impairment
- A paper published in August 2025 details a major update to the software powering this inflatable, wearable shoulder robot
- In a study of nine ALS and stroke patients, the investigators found that the robot anticipated users' intended shoulder movements with 94% accuracy
Almost 20% of Americans have some type of disability. With the aging of the U.S. population, this figure is projected to swell in the coming decades. Keeping up with the growing demands will require impactful innovations in the nascent field of disability technology.
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ALS specialist Sabrina Paganoni, MD, PhD, co-director of the Massachusetts General Hospital Neurological Clinical Research Institute, and stroke and neurorehabilitation specialist David Lin, MD, director of Mass General's NeuroRecovery Clinic, are collaborating with professor Conor Walsh, PhD, founder of the Harvard Biodesign Lab, to advance the development of devices to assist individuals with upper-limb disabilities.
The three investigators are among the co-authors of a paper published in Nature Communications in August 2025 that details a major update to the software powering an inflatable, wearable shoulder robot. The device is designed to provide personalized movement assistance for people with upper-limb impairment, such as ALS or stroke patients.
"Because of our location and our relationships with investigators, universities, and industry in Greater Boston, Mass General Brigham is uniquely positioned to support the co-design of products like this," Dr. Paganoni says. "Whether it's in engineering or other areas of science, we help to translate these projects to the bedside much faster than if the work were taking place in silos."
Incorporating Machine-Learning and Physics-based Models
The device under development features a vest with sensors that track motion and pressure along with soft actuators underneath the arm. A portable actuation box, which can be worn at the waist or sit beside the user, houses the batteries and other elements that power and control the robot. The actuators inflate or deflate to support the user in performing various upper-limb movements.
For this latest iteration of the device, the investigators incorporated a machine-learning model to discern what movements the individual is trying to do based on data from the sensors. As described in the paper, they also used a physics-based model to "estimate the minimum pressure needed to support the arm and ensure transparency during lowering."
In a study of five individuals who had experienced stroke and four living with ALS, the investigators demonstrated that the robot:
- Identified the intended direction of shoulder elevation with 94.2% accuracy
- Reduced the amount of effort required to lower the arm by 31.9% compared to previous versions
- Improved movement quality, as evidenced by significant increases in shoulder elevation/depression as well as elbow and wrist flexion/extension
"Ultimately," Dr. Paganoni says, "we want to have a tool that's highly customized and personalized to fit the needs of people living with ALS, stroke, or other neurological conditions and can be deployed in the patient's home so that they can actually use it in their daily life."
Patient Involvement Central to Co-design Process
All nine of the study participants are patients of Dr. Paganoni or Dr. Lin. Mass General physical therapist Katherine Burke, PT, DPT, accompanied patients during visits to Dr. Walsh's lab. The individuals provided feedback on the device to the engineering team, and Burke offered her input as well.
"These patients have lived experience with ALS or stroke, which helps us to ensure every aspect of the tool is customized to fit their specific needs," Dr. Paganoni notes. "Their contributions enhance the co-design process and speak to the power of working collaboratively to expedite progress."
Dr. Paganoni and her colleagues plan to continue to conduct research informing further refinements to the device. She is optimistic that their initial work in ALS and stroke will eventually lead to solutions that benefit patients with other neurologic conditions and similar patterns of upper-limb weakness.
In the meantime, she hopes more researchers will initiate their own efforts to push forward the disability-technology field.
"A few great labs like the Walsh Lab have been pioneers in this space," Dr. Paganoni says. "But we need to do more when it comes to driving innovation in disability technology and scaling it up because there's an urgent need and not enough solutions out there."
Learn more about the Neurological Clinical Research Institute