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COMPUTER AIDED WHEELCHAIR PRESCRIPTION SYSTEM (CAWPS)

Steven A. Garand M.S., Nigel Shapcott M.S. School of Health and Rehabilitation Sciences, Department of Rehabilitation Science and Technology, University of Pittsburgh Pittsburgh, PA U.S.A.

ABSTRACT

Keeping up with the growing list of wheelchairs and current prescription methodologies is a daunting task for the individuals responsible for prescribing this equipment. A computer aided wheelchair prescription system (CAWPS) is under development. The proposed system will use a computer program to help match the mobility needs of people with disabilities to a wheelchair that meets their specific requirements and, assist with the generation of the required reports. The expert system will use information based on the recent ANSI/RESNA wheelchair standards and input from leading experts in the field. The computer program will aid in the gathering of consistent, relevant client data through the use of question prompts, help menus, and graphics. A prioritized list of wheelchair recommendations will be provided. A related program will also help train individuals in the use of current wheelchair prescription methodologies.

BACKGROUND

To date, the use of current literature and other information sources in helping therapists to develop an effective standard approach to match a client's needs with the most appropriate, currently available wheelchair has been limited by five major problems.

The first problem is, until recently, dimensional wheelchair data may not be measured similarly between manufacturers nor would a complete and standard set of objective information be available. Another problem is the rate at which new wheelchair types, accessories, and features are becoming available soon makes current knowledge obsolete. A third difficulty is developing a standard prescription process that can accommodate the wide range of possible client needs and also accommodate the ever increasing complexity of existing wheelchair features. Another difficulty is the cognitive overload placed on the therapist in trying to evaluate the complex relationship between existing wheelchair features and prioritized client goals. The final problem is the ever increasing amount of time spent on information retrieval and report generation required by the various agencies involved in the prescription process.

The ANSI/RESNA Wheelchair Standards Committee is working on the inconsistent wheelchair data problem by developing a set of standards to allow manufacturers to make available consistent and complete wheelchair information. Axelson et al. (1) published a guide to help explain how to use the ANSI/RESNA wheelchair standards in selecting an appropriate wheelchair. To help address the problem regarding the increasing rate of wheelchair features becoming available, Axelson (2) publishes an annual survey of light weight wheelchairs based on the ANSI/RESNA standards. Denison et al. (3) present a standard prescription process that focuses on providing the best possible manual wheelchair for an individual. Cognitive overloading and report generation time problems are being addressed for occupational therapy functional assessments by a computer program titled OT FACT (4). Another program titled FIESTAS (5) addresses funding information eligibility. These programs however, do not provide a specific tool for aiding in the prescription of wheelchairs. Two such prototype programs specifically targeted for wheelchair prescriptions were developed by Arnold et al. (6) and Hammel et al. (7). Both prescription software projects were abandoned and are not commercially available.

STATEMENT OF THE PROBLEM

Determining the most appropriate combination of current wheelchair features that best match user's goals in a cost effective and timely manner is becoming increasingly difficult, particularly amongst first time inexperienced wheelchair users. An expert system designed to aid a therapist or RTS in the prescription of wheelchairs appears to be the best solution to this problem. As of present, no such commercially available expert system was found.

RATIONALE

In order to provide an aid to a therapist or RTS in the current wheelchair prescription process, a unique computer program is under development. Based on advice from leading experts in the field and a national survey (8), system goals were established and are given as follows.

The system must be easy to use in order to accommodate the wide variation in computer skills amongst therapists. The program must therefore run on both platforms the users are most familiar with, Macintosh and Windows. The program must have a graphical based intuitive means of operation and obtaining help. The system must be affordable to the users. In order to achieve this third party software with little or no run time or royalty fees must be used. The use of the program must decrease the time required for the prescription process by assisting in the preparation of written reports and justifications necessary to obtain funding. The software must also provide quick access to current, accurate, and standardized wheelchair information.

DESIGN

The basic expert system design is modeled after Denison's three step approach to wheelchair prescription. The first stage is to gather the necessary information to determine a client's goals. This includes proper fit, safety, personal preference, and activity goals. The goals are further categorized into primary, secondary and optional priorities. The second stage is to create an ideal model wheelchair that meets the individual's needs. Finally a rating is given to existing wheelchairs based on how well the device can meet the client's goals. The ratings are influenced or "weighted" by the priority of a given goal.

In addition constraints can be used to create a second rated list of wheelchairs. Possible constraints include, available funding, approved vendor lists, and local vendor support. The effect on clients' goals of both the original rated list and the constrained list of wheelchairs is presented. Information to aid in the preparation of written reports and justifications necessary to obtain funding is also provided. Digital video was used as one method to illustrate a broad concept of wheeled mobility. A diagram of the systems' functional blocks is given in Figure 1.

A graphical tool is also available to help the therapist "build" a typical day or days in the life of a client at work or school, week end, and vacation. Objects representing daily activities such as negotiating ramps, transferring in and out of a van, toileting, and performing pressure relief can be added to the screen thus providing a graphical representation of the clients' environment. Details about the environment such as the ramp angle can then be added.

After a question is answered the goals are effected which in turn modify a computer model of the ideal wheelchair. Any conflicts are identified and presented to the user for resolution. A graphical representation of the model is reflected by this modification. The effect any answer has on the ideal wheelchair can be seen on the screen as the answers are entered. This gives immediate feedback on the ramification any answer has on the ideal wheelchair.

<PLACE FIGURE 1 HERE>

Once all necessary questions are answered the ANSI/RESNA based wheelchair information and manufacturers' information is automatically rated in terms of meeting client goals. The wheelchairs can also be rated prior to this stage based on available answers, but the lack of a complete answer set will be noted in the report. The matching algorithm first translates wheelchair data base parameters to actual goal values. The difference between the actual goal values and the ideal goal values are used to generate a "relative level of matching" number from a predefined fuzzy surface. The fuzzy numbers are weighted by the clients' priority level to produce the number used to rate a wheelchair. The results of this complex process will be presented in an easy to understand graphical format.

DEVELOPMENT

The system requirements were defined through input from experts and results from a national survey. Based on these design requirements, software development tools were identified. The programming language chosen is C++, an object oriented language that facilitates a modular and easy to maintain design. The graphical user interface, data base interface, and rules based inference engine were purchased as cross platform C++ libraries. This approach allowed the development and testing of a single set of source code that can be easily ported to other platforms i.e. Windows, Macintosh and PowerPC. A program was developed to demonstrate the initial concept to our team of experts. Based on the feedback of this meeting a second user interface was developed to demonstrate the revised concept. To prove the feasibility of using the software libraries together, a small graphical expert system was developed which determined the wheelchair type required by an individual. The next stage is to develop a small scale working system to prove the design feasibility of generating an ideal model based on user input.

EVALUATION

The program can run on both platforms the users are most familiar with, Macintosh and Windows. The program has a graphical based intuitive means of operation and obtaining help. There are no run time fees and a low royalty cost for the inference engine library. Assistance in the preparation of written reports and justifications necessary to obtain funding is provided by the generation of a text file containing all pertinent information. This file can be loaded into most popular word processors for further customization. The proposed system should provide quick access to current, accurate, and standardized wheelchair information due to the system components chosen and the matching algorithm used.

DISCUSSION

The proposed CAWPS system should prove to be an effective easy to use, and affordable, wheelchair prescription aid to a therapist or RTS. A teaching aid program, based on a similar design but focusing on teaching wheelchair prescription methodologies, is also under development. The effectiveness of the expert system will be evaluated by September of 1996 followed by commercialization of the system in the following two years.

REFERENCES

(1) Axelson P. W., J. Minkel, and D. Chesney "A Guide To Wheelchair Selection." Washington, DC: Paralyzed Veterans of America, 1994

(2) Axelson P. W. "Chair & Chair Alike." Sports'n Spokes 21 (1995): 26-61

(3) Denison I., J. Shaw and R. Zuyderhoff "Wheelchair Selection Manual." Vancouver, BC: BC Rehab, 1994

(4) Smith, R.O. "OT FACT" The American Occupational Therapy Association, 1994

(5) Winnegar, A. and B. Newroe "FIESTAS" Sante Fe, NM: New Mexico Technology Assistance Program, 1995

(6) Arnold, J.A. and P. Wood "Wheelchair Selection Program." Perrysburg, NY: J.N. Adam Development Center and Buffalo, NY: SUNI Buffalo, 1988

(7) Hammel, J.M., J. Weis, and I. Perkash "MacClinic: Wheelchair Prescription" Palo Alto, CA: VA Medical Center, 1992

(8) Saur T., S.A. Garand, and N. Shapcott "Computer Aided Wheelchair Prescription Questionnaire." Submitted for RESNA'96 Proceedings

(9) Walker N.A. and N. Shapcott "Incorporating Video Into a Software Based Expert System." Submitted for RESNA'96 Proceedings

ACKNOWLEDGMENT

Funding for this project was provided by Department of Veteran's Affairs, VA Rehabilitation Research and Development Service, Project #B485-DA, housed at the VAMC Highland Drive Pittsburgh and the University of Pittsburgh RERC on Wheeled Mobility and Seating. The authors wish to acknowledge the fact that this project has been aided by valuable input and assistance from many experts and others in the field of assistive technology too numerous to mention here.

Steven Garand VA Medical Center 7180 Highland Drive, 151R-1 Pittsburgh, PA 15206 U.S.A. (412) 365-4864 FAX: (412) 365-4858 E-Mail: SGARAND@pitt.edu

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