Development and Biomechanical Analysis toward a Mechanically Passive Wearable Shoulder Exoskeleton

Shoulder disability is a prevalent health issue associated with various orthopedic and neurological conditions, like rotator cuff tear and peripheral nerve injury. Many individuals with shoulder disability experience mild to moderate impairment and struggle with elevating the shoulder or holding the arm against gravity. To address this clinical need, I have focused my research on developing wearable passive exoskeletons that provide continuous at-home movement assistance. Through a combination of experiments and computational tools, I aim to optimize the design of these exoskeletons. In pursuit of this goal, I have designed, fabricated, and preliminarily evaluated a wearable, passive, cam-driven shoulder exoskeleton prototype. Notably, the exoskeleton features a modular spring-cam-wheel module, allowing customizable assistive force to compensate for different proportions of the shoulder elevation moment due to gravity. The results of my research demonstrated that this exoskeleton, providing modest one-fourth gravity moment compensation at the shoulder, can effectively reduce muscle activity, including deltoid and rotator cuff muscles. One crucial aspect of passive shoulder exoskeleton design is determining the optimal anti-gravity assistance level. I have addressed this challenge using computational tools and found that an assistance level within the range of 20-30% of the maximum gravity torque at the shoulder joint yields superior performance for specific shoulder functional tasks. When facing a new task dynamic, such as wearing a passive shoulder exoskeleton, the human neuro-musculoskeletal system adapts and modulates limb impedance at the end-limb (i.e., hand) to enhance task stability. I have presented development and validation of a realistic neuromusculoskeletal model of the upper limb that can predict stiffness modulation and motor adaptation in response to newly introduced environments and force fields. Future studies will explore the model\u27s applicability in predicting stiffness modulation for 3D movements in novel environments, such as passive assistive devices\u27 force fields

Robot Assisted Shoulder Rehabilitation: Biomechanical Modelling, Design and Performance Evaluation

The upper limb rehabilitation robots have made it possible to improve the motor recovery in stroke survivors while reducing the burden on physical therapists. Compared to manual arm training, robot-supported training can be more intensive, of longer duration, repetitive and task-oriented. To be aligned with the most biomechanically complex joint of human body, the shoulder, specific considerations have to be made in the design of robotic shoulder exoskeletons. It is important to assist all shoulder degrees-of-freedom (DOFs) when implementing robotic exoskeletons for rehabilitation purposes to increase the range of motion (ROM) and avoid any joint axes misalignments between the robot and human’s shoulder that cause undesirable interaction forces and discomfort to the user. The main objective of this work is to design a safe and a robotic exoskeleton for shoulder rehabilitation with physiologically correct movements, lightweight modules, self-alignment characteristics and large workspace. To achieve this goal a comprehensive review of the existing shoulder rehabilitation exoskeletons is conducted first to outline their main advantages and disadvantages, drawbacks and limitations. The research has then focused on biomechanics of the human shoulder which is studied in detail using robotic analysis techniques, i.e. the human shoulder is modelled as a mechanism. The coupled constrained structure of the robotic exoskeleton connected to a human shoulder is considered as a hybrid human-robot mechanism to solve the problem of joint axes misalignments. Finally, a real-scale prototype of the robotic shoulder rehabilitation exoskeleton was built to test its operation and its ability for shoulder rehabilitation

Design of Trans-humeral Prosthetic Mounting System for Use in High Load Activities

High load activities are difficult for trans-humeral amputees due to inadequate mounting methods. The goal of this project was to design, analyze, and manufacture an upper arm exoskeleton for trans-humeral prostheses to allow one to perform high load activities. The prosthesis attachment connects the prosthetic limb to the mechanism transferring loads to a custom vest. Tests have been formulated to confirm functionality of the design. From those tests and problems encountered throughout the design process, recommendations have been made

A Cost-Effective Haptic Device for Assistive and Rehabilitation Purposes

With the growing population of elderly, the need for assistance has also increased considerably especially for the tasks such as cleaning, reaching and grasping objects among others. There are numerous assistive devices in the market for this group of people. However, they are either too expensive or require overwhelming user effort for manipulation. Therefore, the presented research is primarily concerned with developing a low-cost, easy to use assistive device for elderly to reach and grasp objects through intuitive interface for the control of a slave anthropomorphic robotic arm (tele operator). The system also implements haptic feedback technology that enables the user to maneuver the grasping task in a realistic manner. A bilateral master-slave robotic system combined with the haptic feedback technology has been designed, built and tested to determine the suitability of this device for the chosen application. The final prototype consists of primarily off the shelf components programmed in such a way as to provide accurate teleoperation and haptic feedback to the user. While the nature of the project as a prototype precluded any patient trials, testing of the final system has shown that a fairly low cost device can be capable of providing the user an ability to remotely control a robotic arm for reaching and grasping objects with accurate force feedback