GPS Research

Research into GPS Systems for wheelchairs.

Currently there are several wheelchairs that are already equipped with GPS systems. However, from an analysis of these it is apparent that they are primarily designed for more active users, who are looking for an ‘off-road’ wheelchair and corresponding GPS systems.

One of these systems, developed by the Fraunhofer Institue for Information and Data Processing IITB incorporates some of the features that we are planning on developing, including a GPS system and electronic health monitoring with emergency call systems.[1] However, this system is designed for a rugged four wheel drive wheelchair, and offers just a standard GPS system, so user can fin their position, rather than a system to navigate wheelchair friendly routes.

One interesting research paper provides a good review of various Assistive Device Technology (ADT) developments.[2] Whilst this paper mainly focuses on the first of the three stages in a system such as this (the stages being; inputs (e.g. joysticks, buttons); control systems (systems to convert these inputs to motor functions) and finally outputs (such as motors and displays)), it raises some interesting points about limitations of mobility for controlling a wheelchair. Obviously our system is to be designed for those who need some help walking around, however this paper cites research that shows that mobility is whole body, in that an elderly person who has trouble walking, would also have much trouble operating devices such as switches and joysticks. Thus, it would be sensible to make much use of touch-screens within these systems, to aid ease of use.

One piece of research which is of much interest is that of Monash Universities Robotics Department.[3] In this research, an indoor system for automated wheelchair guidance has been developed. Using cameras and a topological map, the system identifies key points as it moves, and calculates where it has seen these before. Using the map the system can then ascertain where it is. Whilst our system is to use a futuristic GPS system that can work inside, this shows that our initial idea of using the GPS system with a map of the user’s home to show location within the home is a feasible reality.

This idea is taken up again by Cornford of Weber State University.[4] Having already developed a motorised wheelchair that can take a user to a pre-programmed destination, his current research is in looking at methods for indoor GPS. Citing a different approach to Charkravarty, this method involves the use of radio transmitters to help position a chair. One limitation that Cornford’s current system has though is one of object detection. There is currently no method in place to detect any objects that may be in the path of the chair. This should therefore be included in our proposed system.

One are of research that is not necessarily for GPS but would be of use is that of Fitt’s Law. This effectively maps the time taken for a user to point to a target. This broadly relates the time taken to press the button (in our case) to the log of the distance from the starting position of the user and the width of the target, relative to the movement of the user. We can basically take this as meaning that the buttons should be close to the user and there should be no great physical distance for the user to cover between buttons. This would fit in with Andy’s proposal that the screen be the size of an A5 piece of paper.

[1] Unkown, (2007), “The Four Wheel Chair Drive Hybrid Wheelchair” [online] available; http://www.gizmag.com/go/5538/ Accessed 06/02/07.
[2] Arshak, K. Buckley, D & Kaneswaran, K. (2006), “Review of Assistive Devices for Electric Powered Wheelchairs Navigation”, in Journal of the Institute of Technology Blanchardstown. 13, pp13-23.
[3] Charkravarty, P. (2005), “Vision Based Indoor Localization for a Motorized Wheelchair” [Online] available http://users.monash.edu/~pcha25/indoor%20GPS.htm Accessed 07/02/07
[4] Unknown, (2005), “WSU Students Develop GPS Guided Wheelchair” [Online] available
http://weber.edu/WSUToday/050905gpswheelchair.html Accessed 07/02/07