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Robotic Mirror Therapy System for Functional Recovery of Hemiplegic Arms

Published: August 15th, 2016



1Department of Biomedical Engineering, Seoul National University College of Medicine, 2Department of Rehabilitation Medicine, Chungnam National University Hospital, 3Interdisciplinary Program for Bioengineering, Seoul National University Graduate School, 4Department of Rehabilitation Medicine, Seoul National University Hospital, 5Seoul National University College of Medicine, 6Institute of Medical and Biological Engineering, Seoul National University
* These authors contributed equally

We developed a real-time mirror robot system for functional recovery of hemiplegic arms using automatic control technology, conducted a clinical study on healthy subjects, and determined tasks through feedback from rehabilitation doctors. This simple mirror robot can be applied effectively to occupational therapy in stroke patients with a hemiplegic arm.

Mirror therapy has been performed as effective occupational therapy in a clinical setting for functional recovery of a hemiplegic arm after stroke. It is conducted by eliciting an illusion through use of a mirror as if the hemiplegic arm is moving in real-time while moving the healthy arm. It can facilitate brain neuroplasticity through activation of the sensorimotor cortex. However, conventional mirror therapy has a critical limitation in that the hemiplegic arm is not actually moving. Thus, we developed a real-time 2-axis mirror robot system as a simple add-on module for conventional mirror therapy using a closed feedback mechanism, which enables real-time movement of the hemiplegic arm. We used 3 Attitude and Heading Reference System sensors, 2 brushless DC motors for elbow and wrist joints, and exoskeletal frames. In a feasibility study on 6 healthy subjects, robotic mirror therapy was safe and feasible. We further selected tasks useful for activities of daily living training through feedback from rehabilitation doctors. A chronic stroke patient showed improvement in the Fugl-Meyer assessment scale and elbow flexor spasticity after a 2-week application of the mirror robot system. Robotic mirror therapy may enhance proprioceptive input to the sensory cortex, which is considered to be important in neuroplasticity and functional recovery of hemiplegic arms. The mirror robot system presented herein can be easily developed and utilized effectively to advance occupational therapy.

For patients with stroke, dysfunction of a hemiplegic arm has debilitating effect. The ability to perform bimanual activities is essential for daily life, but functional deficit of a hemiplegic arm often remains even a few years after stroke onset. Among various training programs in the hospital, an exercise to increase the range of motion or passive repetition of simple tasks have little effect on functional recovery of a hemiplegic arm. For this reason, training of meaningful tasks related to activities of daily living (ADLs) has been applied to occupational therapy in hospitals.

The effects of mirror therapy were proven by previous studi....

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 All of the procedures were reviewed and approved by the Institutional Review Board of Seoul National University Hospital.

1. Mirror Therapy Tasks

  1. Examples of 2-dimensional mirror therapy tasks (Figure 3)
    1. Freely move the healthy arm while looking in the mirror about 5 min for warm-up exercise.
      NOTE: One may utilize a metronome so that the patient can exercise the motion of the healthy arm in a rhythmic manner.
    2. On healthy side, dribble and place a sma.......

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Six healthy subjects conducted a 'pen marking task' (touching the two small boards alternately with a pen attached on the healthy hand as shown in Figure 17) 10 times which took on average 106 sec per subject. No adverse event was observed, and robotic mirror therapy was proven to be feasible.

In addition, a clinical study on rehabilitation doctors was conducted. We requested expert opinions to determine.......

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The primary purpose of this study was to develop a real-time mirror robot system for functional recovery of a hemiplegic arm using an automatic control algorithm. The effect of robot-assisted therapy on long-term recovery of upper-limb impairment after stroke was proven beneficial in previous studies12, and various kinds of arm robots have been introduced13-20. However, previous studies of upper extremity robots that realized bilateral arm movement applied mechanical connections without using a mirr.......

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This work was supported by the Brain Fusion Program of Seoul National University (800-20120444) and the Interdisciplinary Research Initiatives Program from College of Engineering and College of Medicine, Seoul National University (800-20150090).


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Name Company Catalog Number Comments
LabVIEW National Instruments System design software
24V power supply XP Power MHP1000PS24 24V Any 24V power supply should do
AHRS sensor receiver E2box EBRF24GRCV
AHRS sensors E2box EBIMU-9DOFV2 You will need total 3 sensors. Any AHRS sensors will do
EC90 flat motor module Maxon 323772 + 223094 + 453231 Any geared motor with higher than 30Nm should do. (For our custom machined parts, you will need these particular flat motor and gear module, but the gear ratio and encoder may vary) 
EC45 flat motor module Maxon 397172 Any geared motor with higher than 10Nm should do (For our custom machined parts, you should use the same gear module but the gear ratio, motor, and encoder may vary)
EPOS2 70/10 controller Maxon 375711 This can be replaced with EPOS 24/5 controller
EPOS2 24/5 controller Maxon 367676
Connector and cable set Maxon 381405 + 384915 + 275934 + 354045 You can also make these cables. Connectors and corresponding wire info can be found in "300583-Hardware-Reference-En.pdf" and "300583-Cable-Starting-Set-En.pdf"
Coupling- Oldham, Set Screw Type Misumi MCORK30-10-12 Type may vary
Coupling- High Rigidity, Oldham,
Set Screw Type
Misumi MCOGRK34-12-12 Type may vary
Shaft Collars Misumi SCWDM10-B   You will need 4 sets
Shaft Collars Misumi SDBJ10-8 You will need 2 sets
Precision Linear Shaft Misumi  PSSFG10-200 Any straight 10mm diameter shaft with at least 200mm length should do 
Bearings with housings Misumi BGRAB6801ZZ
Elbow motor force dispersion shaft  custom machined 3D CAD 
Lower elbow support custom machined Part Drawings
Elbow rooftop frame custom machined Part Drawings
Support wall custom machined Part Drawings You will need 2 frames.
Elbow coupling hollow cylinder cover  custom machined Part Drawings
Wrist motor force dispersion shaft custom machined Part Drawings
Wrist rooftop frame custom machined Part Drawings
Upper wrist coupling hollow cylinder cover custom machined Part Drawings
Lower wrist coupling hollow cylinder cover custom machined Part Drawings
Joint movement limiter custom machined Part Drawings
Handle 3D printed Part Drawings
Upper elbow support 3D printed Part Drawings
Friction reduction ring 3D printed Part Drawings
Acrylic mirror custom laser cutting Part Drawings
Task table custom machined Part Drawings
Silicone sponge
DOF limiter 3D printed Part Drawings
DOF limiter lid 3D printed Part Drawings
Healthyarm handle 3D printed Part Drawings
Ball rollers - Press fit Misumi BCHA18
Goalpost 3D printed Part Drawings
Circle trace 3D printed Part Drawings
Angled assist 3D printed Part Drawings Optional
Curved assist 3D printed Part Drawings Optional
Plain assist 3D printed Part Drawings Optional
Task board custom laser cutting Part Drawings

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