Lorenzo Masia

Modular Device for Hand Rehabilitation

 DESCRIPTION OF TECHNOLOGY
Recent results in the literature have proven that Robot Therapy promotes recovery of the patient with neurological diseases
-    MIT’s patent “Interactive Robotic Therapist”, U.S. Patent #5,466,231 dated 1995 by Hogan, Krebs, Charnnarong and Sharon is  a 2DOF Planar Robot developed for rehabilitation of human subject; it includes also a  3 DOF wrist module but not a device for rehabilitation of the hand. In patients affected by stroke loss of finger movements is one of the main effects of the neurological injury.

The purpose of this device is to deliver therapy to patients affected by neurological injury, orthopedic accident or arthritis, recovering their abilities to grasp. Besides it can be used to collect data on patient hand grasping level and helping therapist in quantifying some biological parameters and comparing the results between effects from different therapies. Due to the reduced dimension, the above mentioned device can be developed in a portable version, able to be used by patients directly at home. Another use of the Modular device for Grasping rehabilitation can be a tool for studying and monitoring the grasping level during various tasks.

Rehabilitation of Grasping also means to increase the dexterity and augmenting significantly the ability of a peatient to perform task of daily living. With this assumption the shape of the mechanism was chosen in order to imitate the most common shape a human needs in the simple grasping task: cylindrical one.
The kinematic structure of the device is simple but efficient;  it consist in 1 DOF mechanism able to convert a rotary motion of an electric motor in translational displacements disposed in multiple different radial directions.


 
 
Fig 1: kinematic structure of the mechanism (click for video on youtube)

PLAY THE VIDEO HERE


The Grasping Rehab Device is a High Force backdrivable haptic 1 DOF robot; the rotational motion is delivered by a commercial electric motor which works in a very novel fashion: without a fixed  ground frame. In this way rotor and stator are free to mutually rotate around their common axis.  This particular configuration allows to the motor to work as torque source damper and as a torsion spring.

DSC 3549

Fig 2: view of the prototypes.

PLAY THE VIDEO HERE ON YOUTUBE

The Device has a maximum angle or rotation of 180° before reaching a singular position where the equation of motion has two different solutions; in order to avoid the singularity of the mechanism a mechanical stopper has been introduced; the maximum diameter reached by the mechanism at 180° is 80 mm while the minimum value in close configuration is 40 mm .
The Device also includes a passive mechanism in order to compensate for Hypertonia of the patient’s hand; this solution allows to add a parallel torque source to the one delivered by the electric motor, creating a torque and displacement offset. For this purpose a titanium torsion spring is used; it is rigidly connected to the shaft of the motor and to a ratchet which is grabbed by a pawl linked to the stator; in this way turning the ratchet in a certain verse of rotation (the same of the opening verse of the mechanism) and blocking it by the pawl,  the motor shaft is forced to rotate in order to balance the torque delivered by the spring.

 
Fig 3: view of the prototype.

PLAY THE VIDEO HERE
The alpha prototype version of the mechanism uses a 200 Watt DC brushless motor an it is able to deliver by a 14:1 reduction a 2.4 Nm  maximum torque; in this way the maximum force exerted on one shell is approximately 150 N. The device will be covered by a rubber cylinder in order easy adapt the hand shape; the shell moving according their linear trajectories expand the rubber cylinder opening the hand of the patient. Due to the simple shape of the device, it is possible to perform different types of rehabilitation therapy.

For more information visit the INTERACTIVE MOTION TECHNOLOGY Website PLAY THE VIDEO ON YOUTUBE

 

 REFERENCE

MASIA L., KREBS H.I., CAPPA P., HOGAN N. DESIGN AND CHARACTERIZATION OF A HAND-MODULE FOR WHOLE ARM REHABILITATION FOLLOWING STROKE. IEEE TRANSACTION ON MECHATRONICS VOL.12, N°4, AUGUST 2007
MASIA, L., KREBS, H.I., CAPPA, P., HOGAN, N., “DESIGN, CHARACTERIZATION AND IMPEDANCE LIMITS OF A HAND ROBOT”, IEEE ICORR2007, INTERNATIONAL CONFERENCE ON REHABILITATION ROBOTICS, 13-15 June, Noordvijk, Netherlands.
MASIA L., KREBS H.I., CAPPA P., HOGAN N. (2006). WHOLE-ARM REHABILITATION FOLLOWING STROKE: HAND MODULE. IEEE BIOROB2006 INTERNATIONAL CONFERENCE ON BIOROBOTICS, PISA FEBRUARY 2006.
MASIA L, KREBS H.I. (2005). “AN APPARATUS AND METHOD FOR CONVERTING ROTATIONAL MOTION INTO RADIAL MOTION” MIT, USA. PATENT PENDING

 

 

Conference

IEEE BIOROB 2016 (clickhere)

 

Editors

  • L. Masia, Nanyang Tech. University
  • S. Kukreja, National University of Singapore

 

 


New Journal on Rehabilitation Technology

Journal of Rehabilitation and Assistive Technologies Engineering (click here)

Lorenzo MASIA (Associate Editor)

 

 

Journal Topics

Research Topic (click here)

 

 

Red

IEEE ICORR 2015

International Conference on Rehabilitation Robotics

Singapore 11th-14th August 2015 Hosted by NTU

General Chair: Wei Tech ANG

Program Chair: Lorenzo MASIA

 

Conference

Lorenzo MASIA Editor of Biorob 2014

 

 

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