The MULOS project, funded by the EU Telematics Programme, involves the development of a 5-degree-of-freedom powered orthosis for the upper limb. The basic configuration allows the powered movement of the joints of the shoulder (3 degrees of freedom), the elbow, and forearm. The applications of this system are threefold:
The orthosis consists of three modules-shoulder, elbow and forearm. The shoulder is a 3-degree-of-freedom mechanism having intersecting axes to allow it to behave as a spherical joint with a center approximately coincident with that of the user's shoulder. We have shown, in experimental studies that, provided there is sufficient compliance, this mechanism will allow a full range of motion at the shoulder. In addition, the shoulder joint mechanism has been oriented in such a way as to minimize the problems of singularities. Power to these three joints is applied by cable drives in such a way as to keep the electric motors as near to the first joint as possible. This keeps the required torques to a minimum. The elbow joint mechanism is a self-contained unit having its own gearbox and electric motor as is the pronation/supination mechanism. Control hardware is mounted at the back of the wheelchair.
At the current stage of development, work has concentrated on the Assistive mode version, and three wheelchair-mounted prototypes are under construction.
Clearly, this is one of the key issues in rehabilitation robotics. It has been decided that, depending on the mode of operation, the orthosis should be controlled by one of the following modes:
The project has not been concerned with the design of control interfaces except for the development of the 4-degree-of-freedom joystick. We have shown in experimental studies that many people with severe disabilities have the ability to use such an input device. However, the modes of control described above should, in the long term, be suitable for control from a number of interfaces. Such work is outside the scope of the current research program.
A working demonstration prototype has now been completed and two further prototypes are at an advanced stage of construction. Over the next three months, extensive safety testing will be carried out, followed by initial user studies.
The work is being performed by a European Consortium under the EU TIDE Programme. The lead partner is the Centre for Rehabilitation and Engineering Studies (CREST), University of Newcastle upon Tyne, UK. The other members are: 1) University of Abertay, Dundee, UK, 2) TVI Europe Ltd., Dundee, UK, 3) SM Scienzia Machinale, Pisa, Italy, and 4) Free University of Berlin, Germany.
Written by Garth Johnson, Centre for Rehabilitation and Engineering Studies, University of Newcastle upon Tyne
For more information, contact: Professor Garth R. Johnson, CREST, Stephenson Building, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU email: firstname.lastname@example.org, tel: +44 191-222-6196 fax: +44 191-222-8600, URL: http://www.ncl.ac.uk/~ncrest
URL of this document: http://www.asel.udel.edu/
Last updated: November 1997
Copyright © Applied Science and Engineering Laboratories, 1997.