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A Novel User-Controlled Assisted Standing Control System for a Hybrid Neuroprosthesis

Dodson, Albert (2018) A Novel User-Controlled Assisted Standing Control System for a Hybrid Neuroprosthesis. Master's Thesis, University of Pittsburgh. (Unpublished)

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Spinal cord injury (SCI) is a serious condition with 17,000 new cases each year and an estimated
total of 282,000 people in the United States who have SCI. Some people with SCI who have
paraplegia suffer from paralysis, muscle spasticity, bone changes, chronic pain and other
problems. Active orthoses such as the ReWalk, EXPOS, and Ekso have improved the quality of
life of people with SCI. The hybrid neuroprosthesis is an active orthosis that uses functional
electrical stimulation (FES) at the quadriceps and has two main purposes: restoring mobility in
people with SCI and providing physical therapy for the user outside of a clinical setting.
To mobilize people with SCI, the neuroprosthesis must provide assisted movement for a
sitting to standing motion. A standing control system developed by the Pitt Neuromuscular
Control and Robotics Laboratory (NCRL) before this proposed system did not give enough
control of the movement to the user and FES alone did not provide enough torque at the knees
for standing. The NCRL neuroprosthesis was modified to include a harmonic gearmotor at the
knees, a thumb joystick for user control, and a force sensing walker.
A control system using a finite state machine (FSM) was designed to perform hybrid
standing in the neuroprosthesis. The FSM is divided into 3 states and uses 5 separate controllers:
a tracking controller for forward leaning during sitting, a tracking controller to synchronize the
knees, a tracking controller to lock the knees during standing, a hip tracking controller, and openloop
Four experiments were performed on subjects to analyze control performance, power
usage, and energy consumption during motors only and hybrid standing. A subject with SCI
successfully performed several trials of hybrid standing. The controllers performed sufficiently
accurately, and several minor control problems were fixed. The highest average energy
consumption at the knee motors was 88.4 joules during experiment 1. The hybrid standing
experiment demonstrated a modest energy reduction of 15% in a subject with SCI. The hybrid
standing demonstrated a high energy reduction of 74% in the right knee in experiment 2, through
hybrid actuation and a slower standing speed.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Dodson, Albertaed55@pitt.eduaed55
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSharma, Nitinnis62@pitt.edunis62
Committee MemberDicianno, Braddicianno@pitt.edudicianno
Committee MemberClark, Williamwclark@pitt.eduwclark
Date: 24 January 2018
Date Type: Publication
Defense Date: 30 October 2017
Approval Date: 24 January 2018
Submission Date: 17 November 2017
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 133
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering and Materials Science
Degree: MSME - Master of Science in Mechanical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Robotics Robot Mechanical Engineering Mechatronic Spinal Cord Injury SCI Medical Rehabilitative Rehabilitation Therapy Exoskeleton Hybrid Neuroprosthesis Functional Electrical Stimulation Finite State Machine FSM Active Orthosis Standing User Controlled Control System Electromechanical Computer Aided Design CAD Pitt FSR Power Energy End Effector Human Machine Interaction HMI Quality of Life QOL PID RISE Harmonic Gear Joystick Disability Neuromuscular
Date Deposited: 24 Jan 2018 19:44
Last Modified: 24 Jan 2019 06:15


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