Orthosis - PowerPoint PPT Presentation

1 / 13
About This Presentation
Title:

Orthosis

Description:

Definitions Powered Locomotion Devices Orthosis: a rigid, non-moving brace for weak or ineffective joints or muscles 2. Prosthesis: an artificial device to replace a ... – PowerPoint PPT presentation

Number of Views:106
Avg rating:3.0/5.0
Slides: 14
Provided by: joaquinbl
Category:

less

Transcript and Presenter's Notes

Title: Orthosis


1
Definitions
Powered Locomotion Devices
  • Orthosis
  • a rigid, non-moving brace for weak or ineffective
    joints or muscles
  • 2. Prosthesis
  • an artificial device to replace a missing part of
    the body
  • 3. Functional Electrical Stimulation (FES)
  • Surface or surgically implanted current
    electrodes that active groups of muscles
  • 4. Gait
  • Sequence of foot movements, walking

2
Orthosis
Powered Locomotion Devices
  • Comparison of hybrid walking systems for
    paraplegics analysis of study methodology
    (Ijzerman 1999)
  • Moorong Medial Linkage Orthosis (Moorong MLO)
    (Middleton 1998)
  • Arcuate sliding link centered on the hip joints
    with roller bearings
  • Walkabout Orthosis (Middleton 1997)
  • Medially-mounted hinge joint linking two KAFO
  • Self-Fitting Modular Orthosis (SFMO) (Popovic
    1993)
  • Three modules to support patient, FES-aided gait
  • Project has been abandoned
  • Weight Bearing control (WBC) orthosis (Yano 1997)
  • Consists of rigid frame for support,
    reciprocating hip joint gas powered foot device
    that varies sole thickness and push button
    sequential control system

3
FES and Hybrid Walking Systems
Powered Locomotion Devices
  • Advantages/Disadvantages
  • Effects of SCI, muscles used, training
    requirements, cost, spasticity reduction,
    reliability (Solomonow 1992)
  • Builds muscle mass and stroke volume (Merati et
    al 2000)
  • High energy expenditure
  • Oxygen demand is above 50 of the VO2 peak
    (Merati et al 2000)
  • Slow ambulation
  • tenfold less than wheelchair (Merati et al 2000)
  • Cosmesis and difficult to don/doff
  • 14 subjects, 3 using RGO, 4 using only FNS
    (Merati et al 2000)
  • Parastep System, Sigmedics Corp. (Frank Zeiss)
  • Only commercially available FES system
  • Cleveland FES Center and Case Western Reserve U
    (CWRU) (feswww.fes.cwru.edu)
  • 16-channel FES with implanted electrodes and a
    walker. Surface are impractical for everyday use
    (Kobetic 1999)
  • Using a switch initiated gait, paraplegic could
    stand for 8 minutes and walk for 20 meters
  • Isocentric reciprocal gait orthosis (ISO-RGO) vs.
    FNS or orthosis only (Marsolais 2000)
  • Slower walking (.2 m/s) and increased energy cost
    (.5 Kcal/m)
  • Better stability and walking distance
  • Self-Fitting Modular Orthosis (SFMO) (Popovic
    1993)
  • Separate knee, hip and ankle modules placed on a
    pair of jeans

4
Advanced Gait Orthosis
Powered Locomotion Devices
  • Hydraulic system (Seireg et al 1981)
  • Five degrees of freedom (2 at hip, 1 at knee, 2
    at ankle)
  • Good and simple design and analysis
  • Bulky and unusable because of the current state
    of technology
  • Powered Gait Orthosis (PGO) 4 bar linkage and
    CAM system (Ruthenberg et al 1997)
  • One degree of freedom run by a linear DC motor
  • More of a research tool than a a practical means
    for paraplegic gait
  • Battery pack and control system can be fastened
    to the back of the corset
  • Mechanized hip and knee with cam-modulated
    linkage for knee function
  • Peak power usage is the same as human walking
  • History of active exoskeletons (Vukobratovic
    1990)
  • Hydraulic powered exoskeleton (1968)
  • Two pneumatically driven exoskeletons (1970-1973)
  • Electrical exoskeleton using servoelectric D.C.
    drives (1974)
  • Compact, computer controlled active suit for
    dysthrophics (1980)
  • Dynamic Knee Brace System (DKBS) (Irby 1999)
  • Allows flexion during swing, restricts it during
    stance
  • Footswitches are inputs, finite state controlled
    linear solenoid to control knee
  • Intelligent Orthosis (IO) (Suga et al 1998)

5
Current Useful Technology
Powered Locomotion Devices
  • 1. Biped robots
  • MIT leg lab spring flamingo (Pratt 1999)
  • Have a 6 degree of freedom biped robot walking on
    unknown sloped terrain
  • Applied a neural network mechanism for a stable
    adaptive control
  • Anthropomorphic biped robot BIP2000 (Espiau 2000)
  • Bipedal robot with 15 active joints include hip
  • Can walk and turn in unknown sloped terrain
  • 2. Feedback controllers
  • Sensory nerve signal to predict EMG signal for
    FES (Strange 1999)
  • EMG control of actuators (Fukuda 1998)
  • 3. Shape memory alloy (SMA) actuated arm and hand
    prosthesis (Mavroidis 1999)
  • Early stages of development, hasnt been applied
    to locomotion
  • Advantages small size, high force to weight
    ratio, low cost
  • Disadvantages low strain, limited life cycle,
    non-linear effects, low bandwidth and efficiency
  • 4. DARPA exoskeleton project (http//www.darpa.mil
    /dso/thrust/md/exoskeletons/program.html)
  • This program will be used to develop
    technologies, such as actively controlled
    exoskeletons, to enable a soldier to handle more
    fire-power, wear more ballistic protection, and
    carry more ammunition and supplies

6
Powered Actuators
Powered Locomotion Devices
  • 1. Shape Memory Alloys (SMA) Actuators
  • Frequency of actuation 5 Hz w/o cooling 15-20
    Hz w/ liquid coolant
  • Low efficiency and cyclic abilities due to heat
    transfer
  • Not a feasible option for actuation
  • 2. Pneumatic Muscle Actuators (PMA) (Caldwell
    1998) McKibben Artificial Muscle (Tondu 2000)
  • Highly flexible, soft actuators
  • Strains of 30
  • Max. bandwidth for antagonistic pairs is 5 Hz
  • Active stress is 3 MPa
  • Has built orthotic devices out of and controllers
    for MIMO
  • 3. Series Elastic Actuators (Pratt 1995)
  • Advantages greater shock tolerance, lower
    reflected inertia, more accurate and stable force
    control, less inadvertent damage to environment
    and capacity for energy storage
  • Disadvantages low zero motion force bandwidth
  • 4. Electroactive Polymers (Dr. John Madden, MIT
    Newman Lab)
  • Safe stress is 3 MPa, Specific power of 39 W/kg
  • Can survive 100,000 cycles at 2 (work being
    done on fatigue characteristics)
  • 3 Efficiency (could be as high as 20 if can
    recover stored electrical energy)
  • JPL's NDEAA Technologies Group (ndeaa.jpl.nasa.gov
    /nasa-nde/lommas/eap/EAP-web.htm)

7
(No Transcript)
8
Ankle
Powered Locomotion Devices
  • The Odstock Dropped Foot Stimulator
    (http//www.mpbe-sdh.demon.co.uk/fes.htm)
  • single channel FES that corrects dropped foot by
    stimulating the common peroneal nerve using self
    adhesive skin surface electrodes placed on the
    side of the leg
  • Clinical study finished in 1995, 178 patients
    have been treated 25 have stopped
  • Cost is for 1 year is 830
  • Peroneal Nerve Stimulator (PNS) (Voigt 2000)
  • Creates an exaggerated dorsiflexion with
    excessive subtalar eversion
  • Could not find any excessive and potential
    harmful mechanical loads
  • Spring-Type AFO (Brunner 1998)
  • Stiff AFO with a 10-15o cut at the ankle
  • Showed that allowing the ankle joint to move
    facilitates normal gait
  • Dorsiflexion Assist Controlled by Spring AFO
    (DACS-AFO) (Hachisuka 1998)
  • Generates a dorsiflexion assist moment during
    plantar flexion and no moment during dorsiflexion
    using a spring located at the calf
  • The initial dorsiflexion angle of the ankle
    joint is adjustable and three springs with
    different moments are available.
  • None of the five subjects that they tested said
    that they preferred the DACS-AFO
  • Spring-assisted dorsiflexion AFO (Lehmann 1986)
  • Effective in ground clearance, but not stiff
    enough for lengthening contraction after
    heel-strike

9
Rehabilitative Devices
Powered Locomotion Devices
  • Walking Assistance and Rehabilitation Device
    (WARD) (Gazzani 1999)
  • Treadmill with Body Weight Unloading apparatus
  • Six of seven patients improved score on
    ambulation scale
  • Modified crank and rocker mechanized gait trainer
    (Hesse 2000)
  • Simulates gait, supports subjects and controls
    their center of mass
  • Two subjects improved dramatically
  • Lokomat robotic gait Orthosis (http//www.aut.ee.e
    thz.ch/jezernik/research.msql)
  • Supported by a harness, robotic orthosis driven
    by DC electric motors moves the patients legs
  • Currently performing gait-pattern adaptation
    experiments

10
Control Systems
Powered Locomotion Devices
  • Bipedal walking robot using Cerebellar Model
    Articulation Controller (CMAC) (Hu 1999)
  • Adaptive CMAC neural network control is stable
    and accounts for disturbances
  • Modified crank and rocker mechanized gait trainer
    (Hesse 2000)
  • Simulates gait, supports subjects and controls
    their center of mass
  • Two subjects improved dramatically
  • Comparison of machine learning (ML) techniques
    (Jonic 1999)
  • Adaptive network based fuzzy inference system
    (ANFIS)
  • Minimal number of and most comprehensible rules
  • Entropy minimizing inductive learning (IL) and
    radial basis function (RBF) neural network
  • Best generalization
  • Finite state control of FES (Sweeney 2000)
  • Systems receive feedback from sensors on body or
    from the bodys own natural sensors
  • Neural network controlled FES maintains high
    accuracy with two force sensors under foot (Tong
    1999)
  • Fuzzy Walking Pattern (FWP) controller for SMA
    biped robot (Tu 1998)

11
Physiology
Powered Locomotion Devices
  • Paraplegic Standing (Matjacic 1998)
  • Paraplegic standing with ankle stiffness of 8
    Nm/o
  • Models the torque around the ankle for a two-link
    inverted pendulum
  • Did not look at lateral stability
  • Feedback control of unsupported paraplegic
    standing (Hunt 1999)
  • inputs are ankle torques and body inclination and
    outputs a FES signal to the plantar flexors
  • Passive stiffness increases in paretic patients
    (Lamontagne 2000)
  • Use stiffness as an energy storage for toe-off
  • Proves that orthotic should help
  • Ankle moment is linear with angle
  • Biomechanics of the Foot (Mann 1997)
  • Lower Limb Orthoses (Michael 1997)
  • Normal and Pathological Gait (Perry 1997)
  • Improved Muscle-reflex actuator for large-scale
    neuromuscular models (Winters 1995)
  • Model of the intrinsic and reflex contributions
    to ankle stiffness dynamics (Kearney)
  • Lower joint powers during stair climbing at
    different slopes (Riener et al 1999)

12
Power Sources
Powered Locomotion Devices
  • Fuel Cells
  • Methanol-powered alkaline fuel cell used to power
    piezoceramic actuator (Leo 1999)

13
Sensors
Powered Locomotion Devices
  • Overview (Veltink 1999)
  • Describes body-mounted sensors for muscle
    activation, force and movement
  • Using the natural sensors of subject as feedback
    signals to control FES (Haugland 1999)
  • Replaced heel switch with implanted electrode for
    a peroneal stimulator
  • Provided a hand grasp FES system with sensory
    feedback from fingertips
Write a Comment
User Comments (0)
About PowerShow.com