Transcript

SASTECH 107 Volume 11, Issue 1, Apr 2012

Design of Multipurpose Wheel Chair for Physically Challenged and Elder People

Mohan Kumar R.1, Lohit H. S.2, Manas Ranjan Mishra 3, Md. Basheer Ahamed4. 1-Student, M. Sc. [Engg.], 2- Asst. Prof., 3- Asst. Prof.

Department of Design, M. S. Ramaiah School of Advanced Studies, Bangalore 560058. 4- Technical Director, M/S Sidhi Vinayaka Fab Engineering Pvt. Ltd, Bangalore

Abstract

Wheel Chair is a mobility device designed for shifting patients, moving physically challenged people from one place to another with the help of attendee or by means of self propelling. The wheel chair is divided into two different types based on the power used for mobility: 1. Manually powered wheelchairs. 2. Electric powered wheelchairs. Manual powered wheelchairs are driven by manual power which are again classified into foldable and non-foldable with or with out commode design. Electrical powered wheel chairs runs with electric power however manual operation is required to operate the joystick for the movement of the chair. The redesign of manual wheel chair was considered for this project.

The design of wheel chair started by means of literature review to know its evaluation from earlier to the present generation. Market study was carried out to know the present competators available in the market with cost analysis of the existing product. Ethnography study was done to observe the need, the importance of the existing product and to address the design gap in the existing product to the user need through questionnaries. The feed back was taken from different users and attendees, concept generation and design execution was done by the implementation of design methodologies like Quality Function Deployment, Mind mapping, Product Design Specification.

The final output is a wheel chair which gives multiple option to the user and attendee by providing ease of defecation, cleaning and changing of clothes. Adjustable back rest, arm rest, leg rest provides comfort for the patient while resting. The adjustable arm rest provide ease of shifting the patient from chair to the bed or to the vehicle. Facility provided for keeping plate while having food, reading and keeping water bottle. Additional to this alarm facility is provided to inform the attendee that there is a need of his / her presence to the patient. Validation of the prototype is done and usage is found satisfactory.

Key Words: Mobility Device, Wheel Chair, Ethnographic Research, QFD, PDS. Abbreviations

ID Industrial Design NPD New Product Design PDS Product Design Specifications QFD Quality Function Deployment RSI Repetitive Strain Injuries VOC Voice of Customer 1. INTRODUCTION

1.1 Product Design Product design is the concept of systematic

approach in understanding the user requirement, existing deficits, possible improvement and inventing new designs through idea generation, concept development, and concept realization thereby bringing newer products and solutions for the better quality of life.

1.2 Wheel Chair A chair with wheels designed as a replacement for

walking is known as wheel chair. This is used for movement of physically disabled, elder people, children who have difficulty and are unable to walk. This device comes in many variations like self propelled, propelled by the motor or with the help of an attendee to push. Figure 1 & 2 shows the parts of rigid frame and X frame wheel chair and its parts [1].

1.3 Nomenclature of a Simple Rigid Frame Wheel Chair

Fig. 1 Nomenclature of a rigid frame wheel chair

1.5 Need for New Design in a Wheel Chair At present patients are facing problem while defecating. Patients needs to be lifted up and helped to remove the dress and make them defecate, which is discomforting to the patients in emergency condition. The design of back rest in the existing wheel chair creates repetitive stress injury if the patient is sitting for a long time. The present design of brake needs to be improved for better impact and application of brake in slope area. Arm rest creates obstruction while shifting the patient from wheel chair to vehicles, no solution in the existing design to make ease of shifting of patient to transportation vehicle.

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1.4 Nomenclature of a simple rigid frame wheel chair

Fig. 2 Nomenclature of a Foldable wheel chair

2. LITERATURE REVIEW

2.1 History and Evolution of Wheel chair The first wheel chair was invented in the 1595

called as invalids chair was made for the king of Spain called Phillip. Later in the year 1655 Stephen Farfler built a self-propelling chair on a three wheel chassis as shown in figure 3 [1]. In the year 1783 John Dawson of Bath Town England invented a wheel chair named as bath wheel chair. The chair was with two large wheels and one small one as shown in figure 4 [1]. In the year 1869 patent for a wheel chair with rear push wheels and small front casters were invented, in the year 1881 the push rims for self propulsion wheel chair was invented as shown in figure 4 [1]. In 1900 the first spoked wheel chair was invented and in the year 1916 first motorized wheel chair was invented by British Engineers as shown in figure 5 [1]. In the year 1932, Harry Jennings built the first foldable wheel chair as shown in figure 5 [1].

Fig. 3 Wheel chair owned by King Philip II and self

propelled wheel chair

2.2 Different Types of Wheel Chairs There are various types of wheel chairs, we are

differentiating the wheel chair based on the mode of power used for drive. These wheel chairs are differentiated in to two types as below [3]:

• Manual wheel chair • Electric powered wheel chair

2.3 Manual Wheel Chair Manual wheel chairs are driven with the help of man power as source of energy for moving the chair, these are self propelled or propelled with the help of attendee [2]. The self propelled wheel chairs (Figure 3) are

driven by the user by using the rear wheels (diameter of 20-26”) which resembles to that of bicycle but has an additional rims know as hand rims are for the movement of the chairs by means of pushing forward or backward. The hand rims are of diameter lesser than the rear wheels. Use of two hand rims at a time gives straight movement of the chair, use of one of the rim gives the turning movement to the chair towards left or right [3].

Fig. 4 Bath chair by John Dawson and wheel chair

designed in 15th century

Fig. 5 Wheel chair by an Indian and first foldable

wheel chair

Fig. 6 Different types of wheel chairs

Attendant propelled wheel chairs (Figure 4) are those wheel chairs which are known as transport wheelchairs that require attendees help for the movement. The wheel chair is designed such that there is no big rear wheels with rim for the moving, moulded seating, light weight, push handles, support backrest, hand brake system. These chairs are commonly seen in airports to move passengers in to the seats [3]. Manual wheel chair are again classified into two types as shown in below (Figures 5 and 6) [3]

o Rigid wheel chair o Foldable wheel chair

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2.4 Electric Powered Wheel Chair The wheel chair that runs by means of

Electric motor is known as electric-powered wheelchair, this wheel chair requires navigational controls, usually a small joystick mounted on the armrest. For users who cannot manage a manual joystick, head switches are provided and chin-operated joysticks are provided, other specialist controls may also be provided for independent operation of the wheelchair. Motorized wheelchairs are useful for those unable to propel manually or who require travelling for a long distance which creates difficulty for manual operation. These wheel chairs are not only used by traditional mobility impairments but also by cardiovascular patients [3]. Different types of electric and hydraulic power driven wheel chairs are as shown in Figure 7 [13].

Fig. 7 Different types of motorised wheel chairs

2.5 Product Survey Product survey is carried out to understand the

usability, functionality, need of the product, market strategy, different class of users, where used, when used and why used. With the help of Mind Mapping process we can find out the usage of the product Mind Mapping is carried out by process as listed below,

Why Used Where and who are the Users When Used Different types of wheel chair

available in Indian market

2.5.1 Why Used Wheel chairs are used to shift the patients from

one ward to another in hospitals and from one room to another at home, as a walker for the people who are unable to walk. Figure 8 shows few situations where wheel chairs are used.

2.5.2 Different Applications of Wheel Chair o In Hospitals, Nursing homes o In Houses o In Pilgrim places o In Travelling o In Sports o In Beaches

Fig. 8 Applications of wheel chair

Figure 9 shows the some places where wheel chairs are used in common.

Fig. 9 Common places of wheel chair use

Fig. 10 Users of wheel chair

2.5.3 When Used During Emergency like: o Road Accidents o Fire Accidents o Air Accidents o Maternity emergency o Physical disorders

In day to day life by: o Physically challenged people o Old people unable to walk o Physically challenged children

2.6 Market Study Market study is done to understand the product market segment, to know the competitors in the market, to study their product capacitance and market strategy, to bench mark the product. Following are some of the competitors present in the Indian market:

i. M. TECHNOLOGIES Manufacturer of Hospital Equipments, Hospital Supplies, Hospital Furniture, Medical Furniture, Hospital Beds, Hospital Trolley, Wheelchairs,

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Bunk Beds, Office Furniture, MDF Furniture, Hospital Blankets and Garments Haryana.

ii. ANAND MEDICAL EXPORTS Manufacturer, Trading Company of Hospital products New Delhi.

iii. SAYANI SURGICALS Manufacturer, Trading Company, Distributor/Wholesaler of Physiotherapy, Rehabilitation, Orthopaedic application, Walking Aids, Wheel chair, Gym, Obesity, Health Care, Hospital Furniture, Surgical Instruments.

iv. PARAMOUNT SURGIMED LTD Manufacturer of Hospital Equipments, Surgical blades, Wheelchairs, Surgical Gloves, Walking Stick, Hot water bottle, Walkers New Delhi.

v. VISSCO INDUSTRIES Manufacturer, Trading Company of Hospital Furniture's and Wheel chairs Pune.

vi. MANISH STEEL INDUSTRIES Manufacturer, Trading company of Hospital products like Wheelchairs, Tricycle, Walker, Hearing Aid, Crutches, Sticks, Folding Commode, Cycle Rickshaw, Handicap Moped Madhya Pradesh.

2.6 Problems Identified in the Present Wheel Chair Gemba study shows that the two main types of wheel chairs used in hospitals and houses are rigid frame wheel chair and foldable X frame wheel chair with and without commode design. Problems identified are as listed below:

1. Observation shows that there is no adjustable arm rest, knee rest and foot rest the identified problem is as shown in Figure 11.

Fig. 11 Identification of problem 1

2. Observation shows that there is difficulty in shifting the patient from wheel chair to auto rickshaw and other vehicles due to bad braking system provided identified problem is as shown in Figure 12.

Fig. 12 Identification of problem 2

3. Shortage of the height of the back rest, no adjustable and cushioned back rest, no head rest in the existing design, identified problem is as shown in Figure 13.

Fig. 13 Identification of problem 3

4. Observation shows problem in defecation shifting of patient to the commode in case of non commode wheel chair, removing and cleaning problem in case of existing commode wheel chair, identified problem is as shown in Figure 14.

Fig. 14 Identification of problem 4

5. Observation shows that problem in reaching

the table and non adjustable height of table for ease of work which increases repetitive stress injuries like wrist, back, shoulder injuries; identified problem is as shown in Figure 15.

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Fig. 15 Identification of problem 5

2.7 Advantages of Rigid Frame Wheel Chair • Low cost, Easily affordable • Low maintenance cost as the parts are made

of aluminum alloy. • Heavy weights can be accommodated. • Less weight

2.8 Disadvantages of Rigid Frame Wheel Chair • Non foldable, requires more space. • Non adjustable back and arm rest • No stopper for backward moment • Non adjustable food rest

2.9 Advantages of X Frame Wheel Chair • Foldable accommodates less space • Ease of transportation as it requires less space • Cushioned back rest and adjustable foot rest • Commode design for defecating

2.10 Disadvantages of X Frame Wheel Chair • Cause repetitive stress injury due to flexible

back rest • Heavier in weight as it is made of stainless

steel body • Less durable as it comes in contact with

environmental disorders • Maintenance cost is more • Attendees face problem in cleaning the

patient after defecation

3. HUMAN DIMENSION AND ERGONOMIC STUDY Ergonomics is the scientific discipline concerned to understand the interaction between human beings and elements of the system where he is living. Ergonomics is employed in fulfilling the goals of health and productivity

3.1 Ergonomics with Wheel Chair Users Study of ergonomics of the wheel chair is the interaction in relation to aspects of vehicle mechanics and the user's physical condition. Ergonomically designed wheel chair will reduce the strain that is caused due to longer use of the product [11]. Ergonomics in wheel chair considers four key criteria like force, repetition, duration, posture.

3.2 Human Dimensions for Wheel Chair Design These figures are at a median value between the 95th percentile male (largest) and 50th percentile female (smallest).

Fig. 16 Human dimensions

The seat is the part which takes plays very important role in a wheel chair. So that maximum of concentration is given to the seat design to achieve the best comfortableness in any wheel chair.

Fig. 17 Mid thigh-thigh distance

Fig. 18 Human leg folding dimension

Fig. 19 Dimensions for hand grip design

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Fig. 20 Dimensions for frame design

This thumb rule is used for both designing the seat for both male female, this standard is mainly used for determining the dimensions of a seat. In this standard it is explained that 95th percentile for male and female are found to be 449 to 529mm respectively and combined 95th percentile value i.e. 479mm for general purpose seat design [11].

4. CONCEPT GENERATION

4.1 PDS and QFD Based on the Gemba study, data analysis and questionnaires, the below list briefly illustrates essence of customer voice.

Fig. 21 Quality Functional Deployment

Table 1. Quality Functional Deployment

Table 2. Product Design Specification

4.4 Concept 1 Concept 1 was generated with the PDS structure implemented on the basic design of wheel chair. The design was developed as a combined solution in a basic wheel chair model with commode design for ease of defecation for the patients and elder people. Sliding arm rest was provided for the ease of shifting the patient from chair to the bed or to the vehicle, cushioned foot rest for the cushioning feel to the foot. A good improved brake system provided to stop the wheel chair when moving down stairs in inclined angle. Figure 22 shows the wheel chair with foldable x frame design, cushioned seat with head rest that allows the patients to rest the head and back comfortably (Neck injured, back injured, stomach operated, shoulder injured people). The opening of the commode is provided at the front portion of the wheel chair so that the patient can open the commode before defecating and close after the defecating. Water tank with flush gun provided for ease of cleaning after defecation. The back rest, commode seat can be dismantled and the chair can be folded which helps in ease of transportation. Additional features like support plate for keeping plates while having food, keep books & laptop in case of student using the wheel chair, bell provided for indication of help required by the patient at the time of attendee away from him.

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Fig. 22 Concept 1

4.5 Concept 2 With the help of the PDS structure Concept 2 of wheel chair was generated. The design was developed with improved commode design for ease of defecation for the patients and elder people.

Fig. 23 Concept 2

Sliding arm rest was provided to provide comfort to the arm while resting and for the ease of shifting the patient from chair to the bed or to the vehicle. A good improved brake system provided to stop the wheel chair when moving down stairs in inclined angle. Figure 23 shows the wheel chair with foldable x frame design, cushioned seat with head rest that allows the patients to rest the head and back comfortably (Neck injured, back injured, stomach operated, shoulder injured people). The commode is provided with hinge type swinging opening and closing system, commode opening is provided at the back side of the wheel chair. Cushioned leg rest to provide cushioning effect for the leg injured patients, adjustable backrest and leg rest with screw lock system with angular rotating design as shown in figure 4.2 provided for rotating the seat and leg rest to inclined angle (from 90° to 180°) as required by the patient while resting. Water tank with flush gun provided for ease of cleaning after defecation. The back rest, commode seat can be dismantled and the chair can be folded which helps in ease of transportation. Additional features like support plate for keeping plates while having food, keep books & laptop in case of student using the wheel chair, bell provided for indication of help required by the patient at the time of attendee away from him.

4.6 Concept 3 Concept 3 was generated with the help of PDS structure implemented on the design of wheel chair. The design was developed with improved commode design for ease of defecation for the patients and elder people. Swinging arm rest as shown in figure 4.3 was provided to provide comfort for the patient while resting the arms and for the ease of shifting the patient from chair to the bed or to the vehicle, the arm rest can be rotated to comfortable angle as per the patient requirement. A good improved brake system provided to stop the wheel chair when moving down stairs in inclined angle. Figure 4.3 shows the wheel chair with foldable x frame design, cushioned seat with head rest that allows the patients to rest the head and back comfortably (Neck injured, back injured, stomach operated, shoulder injured people). The commode is provided with hinge type swinging opening and closing system, commode opens towards side similar to the windows in houses. Cushioned leg rest to provide cushioning effect for the leg injured patients, adjustable backrest and leg rest with spring operated lock system with angular rotating design as shown in figure 4.3 provided for rotating the seat and leg rest to inclined angle (from 90° to 180°) as required by the patient while resting. Water tank with flush gun provided for ease of cleaning after defecation. The back rest, commode seat can be dismantled and the chair can be folded which helps in ease of transportation. Additional features like support plate for keeping plates while having food, keep books & laptop in case of student using the wheel chair, bell provided for indication of help required by the patient at the time of attendee away from him.

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Fig. 24 Concept 3

4.7 Concept 4

Fig. 25 Concept 4 Concept 4 was generated with the help of the PDS structure implemented on the design of wheel chair. The design was developed with improved commode design for ease of defecation for the patients and elder people. Sliding arm rest was provided to increase the

comfort for the arms while resting by sliding to the arm rest to comfortable height & for the ease of shifting the patient from chair to the bed or to the vehicle. Deign is provided with a good improved brake system provided to stop the wheel chair when moving down stairs in inclined angle. Figure 25 shows the wheel chair with foldable x frame design, cushioned seat with head rest that allows the patients to rest the head and back comfortably (Neck injured, back injured, stomach operated, shoulder injured people). The commode is provided with hinge type swinging opening and closing system, commode opens towards back side of the wheel chair. Cushioned rotatable leg rest to provide cushioning effect for the leg injured patients, adjustable backrest and leg rest with spring operated lock system with angular rotating design as shown in figure 25 provided for rotating the seat and leg rest to inclined angle (from 90° to 180°) as required by the patient while resting. Water tank with flush gun provided for ease of cleaning after defecation. The back rest, commode seat can be dismantled and the chair can be folded which helps in ease of transportation. Additional features like support plate for keeping plates while having food, keep books & laptop in case of student using the wheel chair, bell provided for indication of help required by the patient at the time of attendee away from him.

4.8 Concept 5

Fig. 26 Concept 5 Concept 5 was generated with the help of the PDS structure implemented on the design of wheel chair. The design was developed with improved commode design for ease of defecation for the patients and elder people. Rotatable arm rest was provided to increase the comfort for the arms while resting by rotating the arm rest to comfortable angle and for the ease of shifting the patient from chair to the bed or to the vehicle. Design is

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provided with a good improved brake system provided to stop the wheel chair when moving down stairs in inclined angle. Figure 26 shows the wheel chair with foldable x frame design, cushioned seat with head rest that allows the patients to rest the head and back comfortably (Neck injured, back injured, stomach operated, shoulder injured people). Open commode with bottom cover plate for opening and closing is provided. Cushioned rotatable leg rest to provide cushioning effect for the leg injured patients, adjustable backrest and leg rest with spring operated lock system with sliding design as shown in figure 26 provided for rotating the seat and leg rest to inclined angle (from 90° to 180°) as required by the patient while resting. Water tank with flush gun provided for ease of cleaning after defecation. The back rest, commode seat can be dismantled and the chair can be folded which helps in ease of transportation. Additional features like support plate for keeping plates while having food, keep books & laptop in case of student using the wheel chair, bell provided for indication of help required by the patient at the time of attendee away from him.

5 CONCEPT SELECTION, FINALIZING AND MODEL MAKING

5.1 Concept Selection After the generation of concepts, the sketching and rendered images of different types along with depiction to understand the working principles were prepared. A total of 5 concepts were generated. These were explained to various people in the community. Based on the explanation and their understanding of the concept through these images, various feedbacks were collected from them. The feedbacks were analyzed and categorized according to design parameters through which the pros and cons of each concept were studied and the best concept for chosen for this study by PUGH method.

5.2 PUGH Method Using the PUGH method, concepts are analyzed for various parameters of each model against the fixed rating for each parameter, its pluses and minuses in terms of its usability, performance, unique features, etc are counted. Based on the overall rating, concept # 5 is selected as final trolley design.

Table 3 Pugh chart

5.3 Selected Concept

Figure 27 Final concept

5.4 Working Model After selecting the final design, mock up model is prepared to get the touch and feel of the actual product. In consultation with the study following specs are finalised;

Material • Frame –25mm x 1mm thick hallow pipe of

stainless steel 304 • Body – 1 mm thick Stain less steel 304 sheet • Wheel rim – 304 stainless steel • Tyre – hard nylon rubber • Seat & Back rest – cushioned foam seat • Brake – mechanical operated disc brake • Commode – rigid plastic Scale – • 1: 1 for working prototype • 1:3 for Mockup model Place of execution – M/S Sidhi Vinayaka Fab Engineering Pvt. Ltd., Bangalore Finish – External surfaces glossy finish & internal surfaces polished to Smooth curvature Color – Stainless steel frame, foam cushioned seat, disc braking system, plastic commode seat frame, rigid nylon tyres. Accessories – Water gun with hose for flushing

5.6 Working Model Preparation Process After finalizing the pre requisites for model preparation using cad drawings following activities has been done to complete the final model

1. Procurement of Raw materials. 2. Raw material marking & cutting 3. Removing of burr, Stitch welding to built

chassis assy 4. Preparation of development drawings of the

outer body 5. Laser cutting , shearing & bending 6. Tack & Full welding 7. Grinding & polishing 8. Final buffing 9. Acid pickling & Cleaning 10. Cushioning Seat 11. Assembling of seat, flush gun, rest plate

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Figure 28 shows the cutting of raw material in the working space.

Fig. 28 Raw material cutting model making Figure 29 shows the tack welding and full welding of joints in the frame.

Fig. 29 Outer body welding during model making

Figure 5.4 shows the semi finished product in the shop floor.

Fig. 30 Semi finished final model

Figure 5.5 shows the complete assembled product and inclined product to 0° back rest and leg rest .

Fig. 31 Final finished model

Figure 5.6 shows the water tank, flush gun, disc brake, alarm system with battery and alarm plug provided in the final finished wheel chair.

Fig. 32 Rear view of the finished model

6 CONCEPT VALIDATION 6.1 Validation Validation is done to know whether the designed product according to the specification is successful or not. Validation is obtained by doing feasibility test, usability test and desirability test. The final design product was subjected to feasibility, usability and desirability with different patients and feedback was taken in the form of documentation, pictures and video’s. The model was tested with the patients in Peenya 2nd stage, and different patients in M. S. Ramaiah Hospital. The figure shows different patient using the working model. Figure 33 shows the patient who is using the wheel chair in the house from many years, the feedback was taken based on the performance of our product and the previous product which was used by them in their house.

Fig. 33 Validation from user at home

The wheel chair was taken to the hospital and feedback was taken from different user Figure 6.2 shows the patient who is using the wheel chair in the hospital. The patient and attendee was allowed to use the wheel chair at the end of the day the feedback was taken from the patient and the attendee by means of pictures and video’s suggestion was taken for the improvements in the existing product.

Feedback was taken from the Chief Administrator, Administrator, Doctors, Nurses and Attendees. The feedback was collected verbally and through video. The collected data was accumulated and incorporated as future work.

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Fig. 34 Validation from user at hospital

The above methodology was adopted to generate the new concept which is believed to provide good performance, usability, economic and good in aesthetic when compared to the existing models in the market. The combination of unique feature in a single system will be a successful and will help to sell this product in the market. The response obtained by the users and attendees was good, there is full hope that this design will going to be a real time. The product was sponsored and fabricated in M/S Sidhi Vinayaka Fab Engineering Pvt. Ltd., it is an ISO certified company in manufacturing of stainless steel sheet metal fabrication in Bangalore. The difference between the existing product and the concept generated product is shown in table 4.

Table 4 Comparison of existing model with new

design

7. CONCLUSIONS The knowledge gained from product design education is used to analyse the existing wheel chair product by means of detailed Market research, GEMBA study, product study, problem identification, concept generation, concept finalization, detailing, and mock up modeling of the finalised concept. Validation of the prototype is done and usage is found satisfactory.

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[2] Croteau, C. (1998), “Wheel chair mobility hand

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[3] Cooper, R. A., PH.D. (1998) “Wheel chair

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[4] Bechtel, R., Certified Rehabilitation Technology

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[5] Chitale, A. C., Gupta, R. C. (2002),“ Product

design and manufacturing”, Prentice-hall

[6] Lal, G. K., Vijay Gupta (2010), “ Fundamentals

of design and manufacturing”, Narosa Book

[7] Chakrobarti, D. (1997), “Indian Anthropometric

dimensions for Ergonomic design Practice”,

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[10] Ulrich. K. (1995), “Product Design &

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[13] Anonymous. (Dated 20-05-2011), “http:

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[15] Anonymous. (Dated 20-05-2011),“http:

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