MOTION CONTROLLED MOBILE ARM SUPPORT McARM

Introduction
Persons challenged by weak arm muscles commonly are limited in their execution of all kinds of activities of daily living. This may include the important tasks of independent eating and drinking but also numerous other tasks like selfcare, mealtime preparation, vocational activities, hobbies and so. Lacking arm and hand function plays an extremely important role in the decrease of independence and social participation, and therefore in one’s quality of life. Well known groups of people that are extremely challenged in these respects are persons with muscular dystrophy, progressive neurological disorders, stroke and high level spinal cord injury.

Today many potential users avail themselves of good- quality products, but there definitely is a need for the further research and development leading to advanced products for demanding users. The McArm project is a major project that should bring forward a robotized dynamic arm support for daily life as well as for trainig purposes. 

focal The use of dynamic am supports is known in rehabilitation practice, but not very widespread. This above all has to do with the complexity of the human arm.  Its kinematics and coordination are complex and the functional demands for an effectively supported human arm and hand are extremely high.  The idea of assistive devices for this purpose has been appreciated  for many decades. Although not very well documented, there is a long history of research and development illustrating this queeste. From 1936, the Georgia Warm Spring foundation developed several versions or arm supports, from the foot-operated feeder, operated by voluntary foot extension to the the corset-based feeder in 1953 (Bennett, The evolution of the Georgia Warm Spring Foundation Feeder). In the fifties the first assistive devices to support the human arm against gravity were developed at a bigger scale. This was at the time of the polio epidemia and first developments were done in the United States. These devices were then called ‘feeders’ after their application for the purpose of independent feeding. Also their usage in training was known. Afterwards development of Balanced Forearm orthosis (1965), Rancho Golden arm (1969) and Burke orthosis (1975) took place. These non- powered devices proved to be functional for certain user groups but their application never was wide- spread. No further development of the ‘mobile arm support’, now called dynamic arm support due to the fact that they can also be used from a fixed position, took place.

It was in 1992 that Focal Meditech came into existence. This firm always had its full focus on dynamic arm supports and practically started the re- invention of this type of Assistive Technology. This resulted in a product range including Top/Help, Sling, and very recently Darwing.

Until now only the clinical application of non- powered dynamic or electrically powered dynamic arm supports is known. What they have in common in their basic design is the application of a balancing mechanism – either springs or counterweights. Electro-motors serve as an add-on for challenged users who have too weak muscles for non- powered devices or have problems in performing complex movements against gravity -  e.g. going to the mouth- all by themselves. Dynamic arm supports provide ‘support a needed’, their working principle is based on the philosophy that its users should perform their physical activities themselves as long as possible. Supporting technology supplies additional power when needed to perform a meaningful and manageable activity, but not more than strictly needed. This ‘use it or lose it’ approach through Assistive Technology that adapts to its users and their task execution is an approach in which the McArm project members strongly believe and an important direction for the future development of Assistive Technology in general.

Until now dynamic arm supports are not ‘smart’ and therefore not able to adapt to changing user and usage conditions. In this respect it is also important to mention that a large part of its users suffer from progressive disorders. Present dynamic arm supports are not self- adaptive and therefore their performance may decrease in the course of time. 


Already in 2005 Focal Meditech realized that in order to be able to fulfill the needs of very challenged users, a smart dynamic arm support should be developed that recognizes the user’s intentions and movements. This would lead to a new generation of supporting devices that is more functional, adaptive and truly able to supply ‘assist as needed’. From 2005 until 2007 first developments were done and in two projects Focal together with regional partners did first research. Developments were based on robotics technology. Basic assumptions were that its use should be truly intuitive and the device should be used without any need for fixations, bandages or other inconvenience for its application in daily life. These first two projects, already named McArm, resulted in  a proof of concept indicating the feasibility of this type of advanced dynamic arm support, built as an exoskeleton for the human arm. The present project McArm is inspired and on these earlier developments.
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Goals
The goals of the McArm project are threefold:

  1. Backgrounds 2 html 7f8ee52aTo develop and evaluate one or more prototypes of a sensor guided and actuated dynamic arm support for the performance of Activities of Daily Living. The devices will use a very innovative arm scale, up to date sensor technology and embedded software to let the technical aid understand the user’s intentions. It should therefore always be able to optimally support and when needed replace the user ’s arm, still respecting the user’s own forces and capabilities. It should support all possible manual activities at home, in institutions, at the workplace or at school.
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    Investigate and develop first models for use of such an exoskeleton for training purposes of the human arm. This work is partially based on knowledge acquired in research on training applications for Muscular Dystrophy patients as gained by project partner Radboud. Further, this work is based on knowledge and experience from the Focal project ‘Armada’ which dealt with training in Virtual Reality for stroke victims. Therefore the focus is now primarily on the rehabilitation of two patients groups: stroke and MD. Keywords of additional knowledge areas for this goal are requirements on effective training, haptics (force feedback) and virtual reality.





  3. focal The application of new light- weight materials such as carbon fiber for the above described developments. Present dynamic arm supports and rehabilitation technology in general often is too bulky, heavy or has too big volumes. Especially the application as a wheelchair mounted device requires the application and therefore knowledge of developments and manufacturing processes of new types of strong materials. A better knowledge of the application of modern lightweight materials has to contribute to the advancements of the medical device industry in the Netherlands in general.

 

Intended users
McArm is to be developed for persons who only have very limited muscle power available to move their arm and hand. To these persons very small forces make a big difference. The aid especially is intended for persons with severe neurological disorders or suffering from advanced forms of muscular dystrophy still having some ability to grasp. McArm should be very suitable for users who are notable to cover the last part of the trajectory to their mouth when feeding themselves or drinking, or cannot cope with changing weights or heavy clothes. McArm use avoids the operation of expensive stand alone robots (manipulators) for those who still have some grasping function. It allows them to use their remaining motor functions (with all positive side effects on the user’s health and condition) for a very prolonged period. A second user group are rehabilitation professionals like Rehabilitation Physicians, Occupational and Physical Therapists working with its training version in rehabilitation environments.

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Running period:

April 2011 – March 2014

Partners:
FocalMeditech BV, Tilburg
ZuydUniversity, Heerlen
M2Control, Uden
Maastricht University Medical Center+, Maastricht
Radboud Rehabilitation, Nijmegen
Eindhoven University of Technology, Eindhoven

In cooperation with:
Moog,
Marcel Bastiaans

Funding
The project McArm is a national Dutch ‘Pieken in de Delta’ project. It is  partially funded by:

Agentschap.nl, an agency of the Dutch Ministry of Economic Affairs, Agriculture and Innovation
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Province of Noord Brabant
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Province of Limburg
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