Rehabilitation Robotics Newsletter

Project Showcase
Spring/Summer 1995

Robotics Lab at the Queen Alexandra Centre for Children's Health

Johanne Mattie, MASc

At the Queen Alexandra Centre for Children's Health (QACCH), rehabilitation engineering research is conducted alongside orthotics, seating, and prosthetics services. In 1991, it was recognized that a manipulative device could improve the quality of the lives of resident teen-aged boys with muscular dystrophy. These boys use electric wheelchairs and have varying levels of hand and arm function. The research department therefore became involved in rehabilitation robotics, with a goal of making available a low-cost manipulator arm to these boys.

To date, robotics research has focused on developing and implementing an evaluation procedure for various manipulators. Design work of our own has been initiated resulting in the "QA Manipulator," followed by preliminary designs for a smaller object manipulator. This work is now reported.

Development of an Evaluation Procedure

A standardized evaluation procedure is being developed to define an objective and quantitative method for assessing manipulator arms. The following protocol has been developed:
  1. A mechanical assessment of the arm is conducted to evaluate criteria such as maximum load, range of motion, reliability and power requirements.
  2. "Evaluation matrices" are constructed to evaluate the ability of the arm to perform tasks. Tasks and their priority ratings are listed as rows in the matrix; components required to execute the tasks as columns. Matrices are analyzed to evaluate user priorities for each component and define design weaknesses.
  3. Two pre-set tasks are repeated with new and experienced users (non-disabled) to evaluate ease of operation and accuracy.
  4. First impressions of the arm are elicited from users for aesthetics, noise, speed and other variables.
  5. Clinical trials are conducted (with electric wheelchair users) both in laboratory and "real life" settings, based on user priorities. Details of each trial are recorded and some sessions are video taped.
  6. Short-comings of the arm are defined as a basis for design modifications and improvements to the arm.
This procedure is being used to evaluate several manipulator arms.

Evaluation of the Inventaid Arm

In 1993, an InventAid Arm was purchased for evaluation. The InventAid Arm is a 6 degree of freedom pneumatic manipulator (based on the "Flexator" air muscle technology) developed by Mr. Jim Hennequin in England.

Results of the evaluation showed that the InventAid Arm can be of assistance to youth with muscular dystrophy. However, improvements to the aesthetics, noise, and control are necessary before the Arm becomes acceptable to the group surveyed.

Evaluation of the InventAid Arm was used to develop a hybrid manipulator - the QA Arm. The QA Arm has 6 degrees of freedom and is built from a combination of Flexator joints (slightly modified), pneumatic cylinders and a small d.c. motor. The Arm folds into a compact, tucked away position when not in use.

Evaluation of the QA Manipulator

The QA Arm is currently under evaluation. Initial impressions of users seem to indicate that although the Arm is easier to control and manipulate, further aesthetic improvements are required. A quiet source for pressurized air is still required.

Development of the Telescoping Object Manipulator

Feedback from users has indicated that they would prefer to have a smaller, less visible device. To try and fulfil this demand, a telescoping object manipulator is currently being developed. This manipulator will have four degrees of freedom and fold underneath the arm-rest out of view when not in use.

Future Work

Future work includes continuing to refine the evaluation procedure, and using it to evaluate other manipulator arms, including the Art Arm (developed by Dr. Malcom McAllister in North Carolina). Work will continue on the development and evaluation of the telescoping object manipulator. For a more detailed outline of the evaluation procedure or for more information regarding research at the QACCH, please contact:

Queen Alexandra Centre for Children's Health
2400 Arbutus Road
Victoria, British Columbia
Canada V8N 1V7
Phone: (604) 721-6732
Fax: (604) 721-6815

The Project Showcase is a regular feature of the newsletter in which a selected project or program is spotlighted. If you are interested in having your project showcased, contact Tariq Rahman or Julia Mercier at ASEL.

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Last updated: October 24, 1996
Copyright © Applied Science and Engineering Laboratories, 1996.