Wheelchair users needs in relation to safe, comfortable and efficient use of all transportation modes. The TRANSWHEEL (DE 3013) approach.
Prof. A. Naniopoulos
Aristotle University of Thessaloniki
Civil Eng. Dep., Lab. of Transport Engineering
54006, Thessaloniki
Tel.:+30-31-256033
Fax:+30-31-256037
E-mail: telis@hermes.civil.auth.gr
Dr. E. Bekiaris
TRUTh S.A., Alexandras Av. 28
10683 Athens, Greece
Tel.:+30-1-8253777
Fax:+30-1-8253780
E-mail: trnspcon@compulink.gr
1. Summary
TRANSWHEEL (DE 3013) user needs analysis started from a critical review of the relevant literature, devoting serious effort to the crash behavior and safety aspects. A thorough review of crash and strength tests of manual and electric wheelchairs as well as their components (tie-down mechanism, occupant restraint, headrest etc.) revealed that no wheelchair today is safe when compared to a standard vehicle seat and none is able to undergo the 20g vehicle homologation crash test. Wheelchair seat comfort was then also analysed and compared to the one of standard vehicle seats, proving once more to be inferior to the task, even for very expensive and advanced designs. Accessibility of the various transportation modes, in terms of use of their stations, ingress/ egress to the vehicles and access of various functions and elements (i.e. ticketing machine, window, etc.) within the vehicles has also been reviewed and the key problems have been identified per transportation mean. Existing vehicle adaptation and practices are also covered in detail.
The review has been supported by in-depth interviews with a moderate number of users to formulate a detailed travelling task matrix for wheelchair users, as well as by organisations with users in Belgium and Greece. These field applications have mainly revealed problems connected to the use of the transportation environment (i.e. pavements, rails, platforms, etc.) and use of adaptations.
The identified user needs have been translated to 50 system requirements, which form the basis for the realisation of TRANSportation WHEELchair with high impact safety and advanced sensor comfortability for people with mobility.
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2. Introduction
Extensive bibliography and numerous adaptations exist regarding the adaptation of public and private transport for E&D and particularly for wheelchair users. However, no existing wheelchair frame is crash-proofed and therefore can not be used with safety as driver's or passenger's seat. Also, there are some tailor-made solutions for car seats specifically designed to offer enhanced comfort to people with disabilities. However, the TRANSWHEEL prototype will be the first integrated approach in satisfying all safety, comfortability and maneuverability aspects of wheelchair users while using any transportation mean (car, bus, train, ship, plane) either as passengers or as drivers (in case of a car).
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3. TRANSWHEEL User Needs Analysis
3.1 Literature survey
Extensive literature survey has proven that currently there is no wheelchair frame that can resist the forces generated during a crash-test and therefore does not provide the same safety standards as a car seat. However, there are wheelchair restraint systems that are crash-proofed. For example the Permobil wheelchair models, which are multi-purpose electric wheelchairs, can be safely secured and transported within a van through the Permolock Tie-Down system, while the actual frame of the wheelchair has not been tested to withstand forces during crashes. Besides, these wheelchairs are not adjustable in height and therefore do not help the PSN ingress/egress and can not be used as driving seats.
Regarding manoeuvrability, various designs have been proposed to allow easier access to cars, like the Caro 1 wheelchair, which is a manual wheelchair combined with a turning base in the car. The chair is pushed in on gliding rails and then turned. Also, other examples are the Carchair and the "Autositz-Fahrstuhl" wheelchairs. In both cases, an electrically-powered mechanism fitted in the car lifts the wheelchair and its occupant and swings them into the car in place of the normal seat, which is removed. Once inside, the wheelchair is locked in position. However, this operation requires retraction of the wheelchair wheels once lifted off the ground, to reduce the height of the wheelchair, which is difficult for a person with weak arms. There are also wheelchairs with adjustable height, which could be used as driving seats, like the Zenith 4000 wheelchair, with a height ranging from 35 to 66 cms and a tailored made tie-down system for independent use, which however is rather expensive and the BALDER wheelchair, which moves too slowly.
Regarding comfort of car seats, there are a wide variety of transportation seats that are tailor-made for specific E&D users and are based on conventional mechanical layout or on highly complex electronic circuits. They are usually of high cost (as they are tailor-made) and moreover they are not wheelchairs, which means that the user has to transfer from and to his/her wheelchair to the special car seat (which he/she may not be able to autonomously perform in case of low force in upper limbs or limited co-ordination). Therefore, these seats have to be purchased in addition to a wheelchair, while the problem of wheelchair storage during transportation remains unsolved. Examples are driving seats manufactured by AMU, Sweden or the RECARO special drivers' seats.
From the above it becomes obvious that there is currently no wheelchair offering at the same time enhanced safety, comfort and manoeuvrability, so as to be used for transportation and driving.
3.2 Data Collection with Users
After this in-depth literature survey the main problems that wheelchair users face during transportation had been identified. However TRANSWHEEL further investigated some specific areas, not fully covered by the literature through some specific users and experts interviews. In this notion, TRANSWHEEL has developed a "Travelling Task Model", which classifies the travelling tasks for the various modes of travel. The "Travelling Task Model" was adopted from the TELSCAN project and was modified accordingly to include only the components relevant to wheelchair users specifically. This discerns around 150 prompts (simple tasks) and covers the full area of transportation means and user (driver and passenger). This was used as a data collection tool in the form of a questionnaire for interviews with wheelchair users. 29 specific interviews have been completed with users from various European countries. From this survey the main problems identified by the users refer mainly to difficulties in loading/unloading of the wheelchair, in adjusting the seat for comfort or for ingress/egress from the vehicle. Also it was pointed out that the car seat should be at the same height as the wheelchair, to facilitate the transfer from the one to the other. Also users of public transportation have noted that their mobility is limited because of the dimensions of the vehicles. Another problem identified by users was the need of autonomous lifting of the front wheels of the wheelchairs, in order to surpass situations like the one presented in the figure below.
Figure 1 : Problem identified in user observation, when using a drawbridge bus lift in a non-accessible pavement environment
Figure 2 : Problem identified in user observation, when trying to surpass a high inclination small ramp on top of the bus lift
3.3 Data Collection with Experts
A relevant questionnaire has been developed for individual interviews with experts, in order to gain greater insight in the field. 23 experts from various European countries have completed the questionnaire. Furthermore, two workshops have been organised, one in Belgium and one in Greece, with the participation of experts on wheelchair transportation as well as representatives from pubic transport and State authorities. Results that derived from this survey among others are that the wheelchair for transportation should have low centre of gravity during transportation and attachment points for wheelchair tie-down systems, enough space between front and rear wheels, air chambers in wheels to absorb shocks, small swiveling wheels to compromise with obstacle climbing ability. Regarding comfort experts have suggested the possibility to raise the wheelchair, so as to look out of the window and to easily reach and operate the various controls within the vehicle, while to lower it so as to be used as driver's seat.
Also, the TRANSWHEEL wheelchair should comply with the existing regulations and the CEN standard, and therefore should fulfil the same solidity standards as a car seat, the wheelchair fixation should resist the same forces as those prescribed for a car seat. Furthermore, the wheelchair seat should be equipped with a safety belt fastening, permitting the attachment of a three-point seat belt.
3.4 The TRANSWHEEL System Objectives and System Requirements Documents
The TRANSWHEEL wheelchair goals, functions and objectives as they result from the user needs analysis have been summarised as a checklist in a System Objectives Document (SOD). When considering the system objectives of TRANSWHEEL together with the trade-offs in the interface between wheelchair and transport infrastructure design, the result is the TRANSWHEEL System Requirements Document (SRD). It involves an inevitable compromise of the TRANSWHEEL elements and functions in relation to its objectives but nevertheless it is essential, since the TRANSWHEEEL model should be realistic and operable within the constraints of the existing transport infrastructure. Final priority has been given to electric wheelchairs, because the advance features of the TRANSWHEEL wheelchair will be compatible with the cost of electric wheelchairs.
The main requirements established according to the users needs analysis and literature survey have been can be attributed to 5 areas, which are Safety, Manoeuvrability, Comfort, Acceptability and Viability. The main System Requirements per area are :
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SAFETY
1. Ability of the wheelchair to lower to 25 cm from the vehicle floor, when anchored into the vehicle to be used as a driver's seat.
2. Wheelchair seat construction based on a crash-proofed standard car seat.
3. Ability of the wheelchair and the tie-down system to withstand a 20 g crash test.
4. Use of a standard safety belt when within a vehicle and use of a lap belt otherwise.
5. Wheelchair total weight in the range if 80-100 kgrs with the gravity centre not too far to the back.
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MANOEUVRABILITY
1. Wheelchair normal height of around 50 cm, with the ability to raise at 25 cm so that the user can look out of the window and operate the various controls within the vehicle.
2. Overall width of wheelchair about 60-65 cm.
3. Ability to overcome horizontal gaps of 10 cm, vertical obstacles of 5 cm and to climb ramps of 18% inclination (as many users are facing similar problems in embarking in trains and buses respectively).
4. Batteries and electric motor allowing for wheelchair maximum velocity of about 6km/h and autonomy of about 15 km.
5. Batteries recharging time of less than 3 hours with possibility of charging from the vehicle batteries.
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COMFORT
1. Suspension system with good vibration filtering properties for outdoors use.
2. Adjustable wheelchair seat according to the occupant's comfort sense.
3. Easy access to car control panel when used as driver's seat.
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ACCEPTABILITY
1. Joystick-based control for wheelchair motion and adjustment of seat height and shape.
2. Audiovisual feedback of crucial functions, safety warning and hep functions through the User Interface.
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VIABILITY
1. Final market price of about 10 kECU.
2. Use of low wear and high duration materials.
3. Capability of integrating other technological facilities (i.e. compatibility with M3S bus).
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4. Conclusion
After examining in great depth the problems that wheelchair users face when travelling (accessibility of transport modes, wheelchair stability, environmental accessibility), it is appropriate to conclude that a trade-off between wheelchair and transport infrastructure design is inevitable. The TRANSWHEEL wheelchair system requirements cover most of the system requirements of the SOD and therefore the functions of the prototype wheelchair to be developed will solve as many problems of wheelchair users as possible within the constraints of the existing transport systems.
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Literature:
RANSWHEEL project (De 3013) Deliverable No 3.1, 1997, Prof. A. Naniopoulos & A. Gateley (eds.)
Bekiaris, E., Naniopoulos, A., 1997, Towards the development of a Transportation wheelchair with high impact safety and advanced sensor comfortability for people with mobility problems, Adv. of Assistive Technology, G. Anoyiannakis, C. Buehler and M. Soede (eds.), IOS Press
DIN 75078, 1988 "Motor vehicle for the transportation of handicapped persons; restraint systems; concepts, requirements, testing"
UMTRI Research Review, 1996. Working toward safer motor-vehicle transportation for people in wheelchairs. University of Michigan Transportation Research Institute, July-September 1996, Vol. 27, Nr.3
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