Session: 05-06-01 Biomedical Devices I

Paper Number: 73668

Start Time: Friday, 12:15 PM

73668 - Electro-Mechanical Design Toward an Open-Sourced Robotic Hand Exoskeleton for Management of Neurological and Neurodegenerative Disorders 

Neurological and neurodegenerative diseases, such as Friedreich’s Ataxia (FRDA) and stroke, often lead to impaired muscle coordination, gradual loss of strength and sensation in the extremities, and significant muscle stiffness, resulting in progressively diminishing hand-motor function. Patients living with FRDA often struggle to open their hands independently, with stiffness in the forearm muscles causing the hand to rest in a clenched position. Similar impairments to independent hand grasping are experienced following stroke and the onset of other neurodegenerative diseases. While modern mechanical braces and prosthetics used in clinical settings assist individuals in the performance of daily living activities, most are static by design and bypass the hand open and close functions. The lack of repeated hand grasping movement causes the patient’s hand to become even more stiff as the muscles, joints, and tendons are under-utilized over time. Most existing robotic prosthetic systems that provide grasping assistance rely on high-cost components and complex mechanical designs, limiting their utility to patients away from the clinical setting and disproportionately affecting those in lower socio-economic groups. To address this growing need, the market lacks a simple, affordable, and portable robotic hand exoskeleton assistive device that could be developed using readily available off-the-shelf components. Leveraging 3D printing and other maker movement technologies, a low-cost solution based on open-sourced hardware and software would increase access to the resulting technologies outside of the clinical setting and aid affected individuals worldwide. Furthermore, improvements to the system by the open-source community would allow for rapid innovation in this space. Here we present an affordable and open-sourced robotic hand exoskeleton system for assisting patients in the management of FRDA and similar neurodegenerative conditions, focusing on the development and testing of the open-sourced modules of the system. The aim of our device is to primarily assist individuals in daily living activities away from the clinical setting, thus allowing a higher degree of independence. Our iterative patient-oriented design process resulted in a design that consists of two core modules: an on-arm electromechanical device intended to be worn by the patient and an electrical subsystem which encapsulates power delivery, sensor management, and motor control in a single off-board package. The on-arm electromechanical device consists of a 3D-printed and lightweight arm splint that combines with a compliant sliding spring mechanism to allow for mechanically assisted opening and closing of the fingers. The lightweight arm splint has been subjected to finite element analysis (FEA) simulation to determine the long-term durability of the current design. Likewise, a physical prototype of the compliant sliding spring mechanism has been analyzed. An experimental setup was devised, consisting of the on-arm electromechanical device and its associated electrical subsystem mounted to a standard lab bench. Progressively heavier loads (varying from no load to maximum required load) were applied to test points on the sliding spring mechanism correlating to key finger joint locations. This approach was taken in an effort to compare performance of the mechanism with force data collected from the collaborating patient early in the design process. Trials to determine range of motion and force transferred to the fingers have been performed. Preliminary results suggest that a single sliding spring mechanism is capable of opening and closing an individual finger. Control of the individual sliding spring mechanism was accomplished with an embedded force sensing resistor (FSR) sensor. Based on force input, the FSR sensor directs the opening and closing of the mechanism via a miniature linear actuator controlled with an Arduino Nano microcontroller. Moving forward, a set of sliding spring mechanisms will be tested to determine whether this design can be expanded to enable more complex actions such as pinching and grasping objects. Preliminary results from single mechanism trials suggest that enabling such actions is possible. If achieved, the full exoskeleton will assist individuals in performing daily living activities with a higher degree of everyday independence, resulting in an improved quality of life.

Presenting Author: James E. Bednar Wentworth Institute of Technology

Authors:

James E. Bednar Wentworth Institute of Technology
Matthew L. Schwartz Wentworth Institute of Technology
John Woo Wentworth Institute of Technology
Douglas E. Dow Wentworth Institute of Technology
Gloria Ma Wentworth Institute of Technology
Marisha Rawlins Wentworth Institute of Technology
Filip Cuckov Wentworth Institute of Technology