Exoskeleton Archives - Page 4 of 5 - Neuromechanics & Mobility Lab

BC Conner, AM Spomer, SSPA Bishe, KM Steele, ZF Lerner (2022) “Soleus H-reflex modulation in cerebral palsy and its relationship with neural control complexity: a pilot study”

Katie JournalArticle, MotorControl, News, Publications June 25, 2022June 11, 2024Cerebral Palsy, Exoskeleton, H-reflex, Muscle synergy

Journal Article in Experimental Brain Research

Individuals with cerebral palsy (CP) display motor control patterns that suggest decreased supraspinal input, but it remains unknown if they are able to modulate lower-limb reflexes in response to more complex tasks, or whether global motor control patterns relate to reflex modulation capacity in this population.

Aim: To further elucidate the multifaceted effects of CP on inhibitory and faciliatory supraspinal pathways and global measures of motor control, providing novel information for improving targeted neuromuscular interventions in this patient population.

Methods: Eight ambulatory individuals with CP (12–18 years old) were recruited to complete a task complexity protocol, where soleus H-reflex excitability was compared between bilateral (baseline) and unilateral (complex) standing. We also investigated the relationship between each participant’s ability to modulate soleus H-reflex excitability and the complexity of their walking neural control pattern determined from muscle synergy analysis. Finally, six of the eight participants completed an exoskeleton walking protocol, where soleus H-reflexes were collected during the stance phase of walking with and without stance-phase plantar flexor resistance.

Results: Participants displayed a significant reduction in soleus H-reflex excitability (− 26 ± 25%, p = 0.04) with unilateral standing, and a strong positive relationship was observed between more refined neural control during walking and an increased ability to modulate reflex excitability (R = 0.79, p = 0.04). There was no difference in neuromuscular outcome measures with and without the ankle exoskeleton (p values all > 0.05), with variable reflex responses to walking with ankle exoskeleton resistance.

Interpretation: These findings provide evidence that ambulatory individuals with CP retain some capacity to modulate lower-limb reflexes in response to increased task complexity, and that less refined neural control during walking appears to be related to deficits in reflex modulation.

MC Rosenberg, BS Banjanin, SA Burden, KM Steele (2020) “Predicting walking response to ankle exoskeleton using data driven models”

Elijah JournalArticle, News October 20, 2020October 12, 2021Exoskeleton, Floquent theory, Gait, generalizable models, Modeling, Orthoses, Walking

Journal Article in The Royal Society:

This work highlights the potential of data-driven models grounded in dynamical systems theory to predict complex individualized responses to ankle exoskeletons., without requiring explicit knowledge of the individual’s physiology or motor control

Aim: Evaluate the ability of three classes of subject-specific phase-varying (PV) models to predict kinematic and myoelectric responses to ankle exoskeletons during walking, without requiring prior knowledge of specific user characteristics.

Method: Data from 12 unimpaired adults walking with bilateral passive ankle exoskeletons were captured. PV, linear PV (LPV), and nonlinear PV (NPV) models leveraged Floquet theory to kinematics and muscle activity in response to three exoskeleton torque conditions.

Results: The LPV model’s predictions were more accurate than the PV model when predicting less than 12.5% of a stride in the future and explained 49–70% of the variance in hip, knee and ankle kinematic responses to torque. The LPV model also predicted kinematic responses with similar accuracy to the more-complex NPV model. Myoelectric responses were challenging to predict with all models, explaining at most 10% of the variance in responses.

Interpretation: This work highlights the potential of data-driven PV models to predict complex subject-specific responses to ankle exoskeletons and inform device design and control.

NBC Learn: Exoskeletons and Engineering

Dr. Steele Media, Orthoses November 12, 2019October 12, 2021Cerebral Palsy, engineering, Exoskeleton, Orthoses, prototype

We partnered with NBC Learn to share some of our work on exoskeletons to help encourage students to consider a career in engineering. What can be more exciting than musculoskeletal modeling, exoskeletons, horses, and stuffed animals?

Check out the video – a lesson plan will also be posted soon for classrooms to use.

Go team!

Jessica Zistatsis Successfully Defends Her Master’s Thesis

Keshia Exams, Graduation, News March 6, 2018October 12, 2021Exoskeleton, Master's Defense, PlayGait

Jessica Zistatsis has successfully defended her Master’s Thesis here at the University of Washington, in Dr. Steele’s Ability & Innovation Lab.

To complete her Master’s in full, Jessica will be submitting and disseminating her thesis, A Passive Pediatric Exoskeleton to Improve the Walking Ability of Children with Neuromuscular Disorders.

To begin watching Jessica’s defense, you may view Part 1 on YouTube HERE, or directly below:

Our lab could not be more proud! To help celebrate her successful defense, the lab drafted a flyer depicting an empowered Godzilla wearing PlayGait, Jessica’s pediatric exoskeleton. Here’s hoping future children will use their newfound superpowers for good, unlike our friend in this picture!

AA Portnova, G Mukherjee, KM Peters, A Yamane, KM Steele (2018) “Design of a 3D-printed, open-source wrist-driven orthosis for individuals with spinal cord injury.” PLOSOne

Keshia JournalArticle, Publications February 26, 2018October 12, 2021Exoskeleton, Orthosis, SCI, Spinal Cord Injury, WDO

Journal article in PLOSOne: In collaboration with the University of Washington Prosthetics and Orthotics Division, a user-centered design approach was used to improve the design and wearability of a passive, wrist-driven orthosis. To read the article in full, click HERE. To access the open-source print files, click HERE.

Background: Assistive technology, such as wrist-driven orthoses (WDOs), can be used by individuals with spinal cord injury to improve hand function. A lack of innovation and challenges in obtaining WDOs have limited their use. These orthoses can be heavy and uncomfortable for users and also time-consuming for orthotists to fabricate.

Purpose/Methods: The goal of this research was to design a WDO with user (N = 3) and orthotist (N = 6) feedback to improve the accessibility, customizability, and function of WDOs by harnessing advancements in 3D-printing.

Results: The 3D-printed WDO reduced hands-on assembly time to approximately 1.5 hours and the material costs to $15 compared to current fabrication methods. Varying improvements in users’ hand function were observed during functional tests, such as the Jebsen Taylor Hand Function Test. For example, one participant’s ability on the small object task improved by 29 seconds with the WDO, while another participant took 25 seconds longer to complete this task with the WDO. Two users had a significant increase in grasp strength with the WDO (13–122% increase), while the other participant was able to perform a pinching grasp for the first time.

The WDO designs are available open-source to increase accessibility and encourage future innovation.