DESIGN AND FABRICATION OF ATTACHABLE WHEELCHAIR AUTOMATOR

1.1 Introduction

An automatic wheelchair or electric-powered wheelchair is a wheelchair that is propelled by means of an electric motor rather than manual power. Automatic wheelchairs are useful for those who are not able to impel a manual wheelchair or who may need to employ a wheelchair for distances or over terrain which would be strenuous in a manual wheelchair. They may also be used not just by people with conventional mobility impairments, but also by people with cardiovascular and fatigue based conditions.

As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.

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1.2 Background of Study

Today, worldwide there are around 600 million persons aged 60 and over; estimated one billion people live with disabilities. It is estimated that 16 million people in Bangladesh are living with disability (Norek et al., 2013), whereas the actual scenario is much more acute. This is very frightening news, since aged people suffer from partial paralysis, trembling and usually unmovable problem.

Manual wheelchair and Automatic/Electric power wheelchair are available in current situation for assisting handicapped people. Manual wheelchairs can be operated by persons who have the use of their upper body or someone available to assist. But it only can move in limited surface only. In order to propel a manual wheelchair, a user not only has to move their weight, but they have to move the weight of the wheelchair as well. Some disabilities problems do not permit to move wheelchair manually. Most automatic wheelchairs are implemented by modifying existing Powered Wheelchair systems. Examples include the Bremen Autonomous Wheelchair (Röfer et al., 1999) and the Maid (Mobility Aid for Elderly and Disabled people) robotic vehicle (Prassler et al., 1999). These approaches arrange sensors and computing hardware around an existing infrastructure. They are able to take advantage of pre-built control and motor systems. One such project, the Tin Man wheelchair (Miller et al., 1994), uses servomotors to control the host chair through an unmodified joystick. Wheelchair equipment has also been designed from scratch. These devices enhance traditional designs in order to increase the possibilities of travel in challenging environments. They present complex control problems but can yield impressive results. One such project (Lawn et al., 2001) proposes four hydraulic, wheeled, robotic legs. It aims to produce a device capable of ascending multiple stairs and lifting itself into vehicles. Another model (Fioretti et al., 2000), being developed by a commercial concern, can reputedly raise and balance itself on its rear wheels alone through the use of sophisticated gyroscopes and multiple Pentium processors.

Automatic wheelchairs, by their nature, demand specialized user interfaces. Whilst many projects do not address this issue directly, invariably using joysticks (Fioretti et al., 2000), others do. One wheelchair (Trahanias et al., 1997) uses a visual display that shows a sequential scanning of commands (left, right, increase speed, stop, and etcetera). A highlighted command can be selected by pushing a button. Another design uses natural language commands, such as “move forward” or “move left”, though a headset microphone. More ambitious groups (Miller et al., 1994) have proposed commands such as “go to the kitchen” or “stop at the next door on the left”. Other groups (Katevas et al., 1997) have opted for voice recognition based on a user defined vocabulary and voice print techniques.

User uses the traditional wheelchairs need help from others or their own body power. Moreover physically weak users also face problems to grip joystick for moving the automated wheelchairs. In this circumstance, this project aims to design an automatic prototype wheelchair with button control which is fabricated from locally available resources and cheaper technologies that would be viable for disable person in the developing country like Bangladesh.

This project’s wheelchair is distinguished from most other similar projects in its attempts to produce practical results using a minimum of equipment and computing power.

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1.3 Statement of Problems

Investigation reveals the problem of the existing Design and Fabrication of Attachable Wheelchair Automator system;

1. A lot of aged people suffer from partial paralysis, trembling and usually unmovable problem,
2. Driving a manual wheelchair or crutches is a difficult task and past invented automatic wheelchair are not available in present market that can be bought and used for physically disable persons.
3. Due to high sustainable stress, low cost and availability, Mild steel has been chosen over Aluminum, Cast iron, Stainless steel for frame material. The constructed wheelchair has a frame; four rear wheels with two shafts units; two front caster wheels for smooth turning and a chain driven gear train for power assist to rear wheel from motor shaft. The Sprocket gear is joined with chain which is connected with another smaller cassette that is mounted directly on motor shaft.
4. Current wheelchair models which can be driven from one place to another are on a higher price range. So, not everyone can afford them. Scooter side wheels are also costlier as they are an actual set of extra wheels and they are costly. Existing wheelchair models have very little to no suspension. This can cause spinal cord injuries to the disabled person. Spinal cord injuries can lead to death within two years. Hand driven mechanisms in wheelchairs can also lead to continuous pain in shoulder, elbow, wrist and hands. This can lead to loss of motor nerve functions among these body parts and can cause the person to be paraplegic. The disabled person has to depend on someone to put them in the wheelchair if they want to move around. This leads to less mobility and decreased mobility causes Pressure sores and Osteoporosis that can lead to 3.73 times higher risk of limb fracture compared to people with good mobility.

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1.4 Aim and Objectives of Study

The aim of the study is to Design and Fabricate an Attachable Wheelchair Automator. In achieving this aim, the following objectives were set out as follows;

1. To guarantee easy and comfortable wheelchair driving,
2. To facilitates learning to handle the chair and obtaining maximum efficiency,
3. To make the electronic system open to future additions.
4. To provide the ultimate easy movement & effortless independent operation without assistance by handicapped.

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1.5 Scope of Study

The study focuses on the Design and Fabrication of Attachable Wheelchair Automator.

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1.6 Limitations of the Study

During the course of this study, many things militated against its completion, some of which are:

1. Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
2. Research material: availability of research material is a major setback to the scope of the study.
3. Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
4. Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, and literature or information.

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1.7 Significance of Study

A power-assist automatic wheelchair prototype that effectively meets the various transportation needs of individuals with hemiplegia or physical disabilities has been designed, manufactured, and tested.

1. Intricate design detail and execution resulted in a visually simplistic design that promotes low cost and low maintenance.
2. The modular aspect of the components allows the system to be retrofit to most manual wheelchairs with only minimal modifications.
3. The main goal of replacing power lost by a user affected arm while maintaining maneuverability and transportability was successfully achieved.
4. The overall dimensions of the constructed wheelchair and therefore maintains its ability to be transported in the trunk or backseat of a full sized car. The minimization of expense is pretty affordable for most of the people of Bangladesh and it can be even cheaper when taken for mass production.
5. Cost Effectiveness: This wheelchair will benefit the most individuals if the cost is not prohibitive. This factor is currently controlled by using locally available material and technology.

1. It must use practical components: Components should consider total system weight and dimensions. They should seek to maximize on-board battery life through power efficiency and minimize maintenance concerns through simplicity and durability.
2. This project can also be counted as a brilliant initiative for the betterment of physically handicapped and disabled people's lifestyle.

Besides, the study will serve as reference material for subsequent researcher in the field or related topics.