The advancement in modern technologies, a wide variety of means equipped with more modern designed materials have been developed for patients. Such means have been developed in a way that they suit the patient's injury and the affected area.
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REPORT ON
DESIGN OF ECONOMICAL MEDICAL
BED WITH ADVANCED FACILITIES
SUBMITTED BY
GAURAV KUMAR YADAV 20163020
KANTREDDI TEJ KALYAN 201630301
DIPAK SHAH 20163092
Under the Guidance of
Dr PRAGYA SHANDILYA
ASSISTANT PROFESSOR
MECHANICAL ENGINEERING DEPARTMENT
MOTILAL NEHRU NATIONAL INSTITUTE OF TECHNOLOGY, ALLAHABAD,
PRAYAGRAJ, INDIA
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CANDIDATE'S DECLARATION
We hereby certify that the work which is being presented in the project report entitled "DESIGN
OF ECONOMICAL MEDICAL BED WITH ADVANCED FACILITIES" as our final year
project in Mechanical Engineering at MOTILAL NEHRU NATIONAL INSTITUTE OF
TECHNOLOGY, ALLAHABAD is an authentic record of our work carried out under the
supervision of Dr PRAGYA SHANDILYA. The matter embodied in the thesis has not been
submitted to any other University / Institute.
Signature of the Students
GAURAV KUMAR YADAV
KANTREDDI TEJ KALYAN
DIPAK SHAH
This is to certify that the above statement made by the candidates is correct to the best of my
knowledge.
Signature of Mentor
Dr Pragya Shandilya
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ACKNOWLEDGEMENT
We are grateful to Almighty for giving us the inner strength and vision to our journey of life where
this UG project is no less a milestone. We are thankful to the Director, Motilal Nehru National
Institute of Technology (MNNIT), Allahabad for providing this opportunity to carry out the project
work. We avail this opportunity to extend our hearty indebtedness to our guide Dr Pragya
Shandilya for her indispensable guidance, untiring efforts and meticulous attention at all stages
during my course of work. We would also like to convey my deep regards to our project panel
members for their contribution, constant motivation and regular monitoring of the work. We will
be further guiding us in the completion of this project. We express our gratitude to Prof. A. D.
Bhatt, Head of the Department for providing me with the necessary facilities in the department.
Last but not least, our sincere thanks to all who have patiently extended all sorts of help for
accomplishing this undertaking.
Name of Students
GAURAV KUMAR YADAV
KANTREDDI TEJ KALYAN
DIPAK SHAH
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ABSTRACT
A Medical bed defined as a specially designed bed used for patients denotes the "special design"
of such a device which has distinctive features meeting the needs of a bedridden patient. It is also
defined as an advanced device or mechanism used to provide comfort and move a patient easily,
which is typically developed to meet the patient's physical demands, such as mobility or
movement. A new method in rehabilitation for transporting an incapacitated patient is developed
and applied to avoid staying at the hospital with overpriced medical treatment and such obstacles,
therefore to conquer these problems, the proposed design of the bed is formulated based on
literature survey as well as consulting the medical staff. Though beds with reclining systems are
available in the hospitals, sanitation is still a problem. This report discusses the specification,
mechanism design and evaluating healthcare activities for the development of a new style of active
bed that provides mobility for bedridden persons with an integrated toilet, both manual & power
operated reclining system. It also can meet the demands of those who may be required to take
hospital beds to use at home particularly in the case of nursing disabled persons as this is going to
be economical and affordable for everyone.
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Table of Contents
1 Introduction 7
1.1 Overview 8
1.2 COVID
1.3 Design Standards 8
1.4 Food and Drug Administration Guidelines 9
1.5 Anthropometric Data 11
2 Methodology 12
2.1 Analysing all Existing Hospital Bed Designs 13
2.1.1 Evaluating Current Bed Designs 13
2.1.2 Selecting the Best Bed Design 13
2.2 Fabrication of our own Bed Design 15
2.2.1 Spatial and Angular Bed Dimensioning 15
2.2.2 Lower Leg Assembly Mechanism 16
2.2.3 The Slider-Crank Lifting Device 17
2.2.4 Worm Gear Acting as a Slider-Crank 18
2.2.5 Articulation of Back and Upper Leg Board 18
2.2.6 Mechanism of Guard Rails
3 DESIGNING PROCESS AND PREPARATION OF PROTOTYPING 19
3.1 Supporting the Overall Quality of Our Bed Design 20
3.1.1 Bed Safety 20
3.1.2 Mechanics Calculations of the Lower Leg Lifting Mechanism 21
3.2 Toilet Projected View 23
3.3 Toilet siphon 24
4 Cost Estimation 25
5 Timeline 26
6 Summary 27
7 References 28
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List of Figures
Figure 1 Anthropometric Data for Person Standing .……...........................................................11
Figure 2 Anthropometric Data showing human proportions ………............................................12
Figure 3 Crank-driven worm gear to lift the lower legs ..............................................................16
Figure 4 Complete Lower Leg Lifting Mechanism .....................................................................17
Figure 5 Backboard and Upper leg Board articulation system ....................................................18
Figure 6 Guard Rail Lifting Mechanism…………………….......................................................18
Figure 7 Solid Work Bed Model……….…………………….......................................................19
Figure 8 Link Mechanism…………………………………........................................................ 21
Figure 9 Reclining model……………………………………. ....................................................22
Figure 10 Lower part reclining height……...………………………………………………….23
Figure 11 Siphon, a clever use of gravity, cohesion and tension................................................. 24
Figure 12 Garden Sprayer….. ...................................................................................................... 24
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1. Introduction
1.1 Overview
Rural Health care is one of the biggest challenges facing the Health Ministry of India. With more
than 60 per cent of the population living in rural areas and low levels, health facilities, mortality
rates due to diseases are high. A majority of 833 million people live in rural areas where the
condition of medical facilities is deplorable. There is an alarming need for new practices and
procedures to ensure that quality and timely healthcare facilities reach the deprived corners of the
Indian villages. Due to non-accessibility to public health care and low quality of health services, a
majority of people in India move to the private health sector as of their first choice for care. If we
take a look at the health landscape of India, 92% of the healthcare visit to private players, of which
70% are urban population. However, private health care is overpriced, often unregulated and
inconsistent in quality. Besides being unreliable for the unlettered, it is also exorbitant by low-
income rural people. Special attention needs to be given to healthcare in rural areas.
Today in India, we have 1.6 million beds set up. The new healthcare policy, which was released
by the government in March 2017 mandates a minimum of 2 beds per 1000 people. According to
WHO standards, a minimum of 3 beds per 1000 people is required, but India aspires at least to
achieve two beds per 1000 people, which translates to 2.62 million beds over next decade, which
includes both replacement and new beds.
Due to the advances of modern technologies, a wide variety of means equipped with more modern
designed materials have been developed for patients. Such means have been developed in a way
that they suit the patient's injury and the affected area. The major motivation of carrying out the
present a number of the troubles encountered by bedridden patients and caregivers in the healthcare
scale. Many patients spend a long time at the hospital under unneeded special and costly medical
treatment, being far from their families and alone. What's worse is that they are encountered by
major problems related to posture changing, moving and sanitation problems when he/ she is
required to stay on the bed for a long time. Another motivation for conducting the present study
was that sometimes, such a hospital bed is needed by some people to be used at home and
particularly, for nursing disabled persons. To overcome such burdens and obstacles, we aim to
develop a new bed design concept for bedridden patients with a reclining system and integrated
toilet as well. Such features make the bed very flexible for patients to be able to overcome such
problems concerning their physical demands as it becomes possible for him/ her to rise up from a
lying to sitting position, and raise the legs up. Thus, such problems and obstacles were the reasons
motivated us to develop a new type of bed which can meet all patients' needs. Therefore, the major
aim of the study is to develop a prototype of a multifunctional hospital bed along by using basic
technological devices with an integrated toilet system for a bedridden patient and helping in taking
care of them with dignity and provide these facilities even for the rural areas at an affordable price.
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1.2 COVID-19 CRISIS
It has been facilitated by K VijayRaghavan, Principle Scientific Advisor to Government of
India.
These projections are based on a statistical model "COVID-19 Med Inventory"- an academic
intiative by Jawaharlal Nehru Center for Advanced Scientific Research, Indian Institute of
Technology, Bombay, Indian Institute of Science-Banglore and Armed Forces Medical
College-Pune.
In the worst case scienerio, mortality is projected to increase 38,000 from present 652, While the
number of positive patient is predicted to touch nearly 30 Lakh and over 76,000 ICU beds in
Hospitals will be required to handle the projected load.
❏ Locally manufactured medical meds can be a great help in situations of medical
emergencies.
❏ In the present situation, i.e., COVID crisis.
❏ This is the most basic necessity for quarantined people.
❏ Local manufacturing reduces both response time and product cost.
1.3 Design Standards
We have come up with a certain set of recommendations regarding the standards by visiting
nearby hospitals and studying the available market models. The standards cater to almost every
aspect of the bed must be strongly considered before design can begin to take shape. These
standards will influence our designs to specific measurements. These standards also govern the
degrees of patient movement within the bed, including the backrest, and the knee.
The parameters listed below in Table 1 will be the design specifications that we will work within.
As our bed is also going to be powered manually, the recommendations dedicate that the handles
should crank the bed into a sitting position rotating clockwise. We are deliberate in designing most
features of our bed with maximum values as our targets. We are deliberate in designing most
features of our bed with the maximum values as our targets. However, we will be designed to the
minimum values for the bed height as well as the weight capacity for the bed.
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Table 1:Recommended Standards for Hospital Beds
Maximum Value Minimum Value
Bed Length 200 cm 190cm
Bed Width 100cm 90cm
Bed Height N/A 48cm
Backrest (Inclined) 75° 0°
Knee Gatch 180° 120°
Weight Capacity N/A 240kg
Force Moment at Handle w/
no added weight 2 N×m 0 N×m
Guardrail Height N/A 35cm
Guardrail Length N/A 80cm
1.4 Food and Drug Administration Guidelines
Patient entrapment on hospital beds is a major issue. To ensure the highest safety factor for patients
in our bed design, we have implemented the guidelines provided by FDA to minimise the patient
entrapment risk while serving all medical function.
The FDA performed extensive background research of their own and sought the information to
find out which areas of modern hospital beds are most dangerous for entrapment, ergonomic data,
the number of entrapment occurrences over several years and the injuries that resulted.
According to FDA there were seven zones which were most dangerous and made size
recommendations for these seven zones to reduce the rate of patient entrapment. The combined
knowledge of these zones, as concluded from the hospital and bed manufacturers, as well from
ergonomic data.
The FDA has made the following 4-dimensional recommendation for these danger zones as can
be seen in the following Table 12.
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Table 12: Summary of FDA Hospital Bed Dimensional Limit Recommendations
As zone 5 to zone seven don't have a dimensional constraint, the FDA does recognise the
potential zone for entrapment and encourages the facilities and manufactures to report such
entrapment zones. For Section 5, patients may suffer neck/chest entrapment from the space
between the bedrails. A V-shaped rail has a chance/potential for entrapment by wedging. Section
6 imposes the risk of entrapment for face, neck or chest by means of wedging at the corner. FDA
also realises that different articulations for the bed may change the angle and spacing between
those gaps, so, therefore, encourages facilities and manufactures to report incidents of
entrapment and also find methods of minimising the changing dimensional schemes at different
bed articulations positions. In section 7 FDA recognises the area between the inside surface of
headboard/footboard and the end of the mattress. To counter the risk of entrapment FDA
recommends regular checkup to ensure headboard and legboard are in place and also not very
compressible.
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1.5 Anthropometric Data
Anthropometric data is a collection of measurements to determine the length of a person's various
supplement based on the height of that person. This data is determined by conducting the number
of measurements on a random sample of people. Anthropometric data is crucial to the success of
this project. Without the correct lengths of each section of our bed, about the human body, this
bed will be somewhat uncomfortable for the patient to use.
The specific anthropometric data that we will be dealing in this project will directly relate to the
parts of the body that we wish our bed to be adjustable at. Anthropometric data is available below
in Figure 1. This data is all with a person's overall height.
Figure 1: Anthropometric Data for a Person Standing (in m)
We have used the data from the top of the head to the lower back to calculate the length of our
backrest. To figure out this length, we have taken an overall length of our bed as that of person's
height. Using the table, we find that the length from the top of a person,s head to the bottom of the
person's lower back is 47% on the total heights. We have iterated this process by using
anthropometric data for a person's Gluteus Maximus, their thigh length and length of persons lower
leg with feet.
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The second style of anthropometric data chart that we have used is a person in a sitting position.
To determine the characteristic lengths for each design segment for a hospital bed, we have utilised
the data of a person in the seated position since it most closely resembles with the position one
will be set in on fully-inclined hospital bed. We used measurements 3.1, 3.6 and 3.9. Analysis 3.1
was used for the incline position of the back, 3.6 for the gluteus maximus slot and 3.9 was utilised
for the upper-thigh length and positioning.
Figure 2: Anthropometric Data showing various human proportions
2 Methodology
The mission of this project is to design a reliable hospital bed that can be manufactured locally.
With the completion of this project, we hope that our bed design could be widely used throughout
hospitals in India. We hope that by locally manufacturing the bed, the price of the bed will be
substantially get reduced and allow for affordable modern health care to be provided to a
significant portion of India's public.
Initially, we gathered literature from various resources regarding existing bed designs. Upon
collection of existing designs, we developed an outline of a reliable hospital bed with advanced
facilities. Once successful completion of bed model design is done, we proceed for analyses for
its structural stability, stress resistance and other mechanical properties to ensure the bed safety.
The team's final goal of designing a reliable domestic hospital bed which will be achieved through
the subsequent completion of the following purposes -
• To analyse the existing bed products and determine which are of the highest quality
concerning price.
• To manufacture or fabricate our design for use in rural/urban areas.
• To manufacture a prototype of our bed modifications.
• To determine and support the overall qualities of the hospital bed.
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2.1 Analysing all Existing Hospital Bed Designs
Today's technology offers various bed designs that are available for purchase in the medical
market. Different companies in various countries manufacture these beds. Each bed is designed
for a specific use, and the functions of that bed represent the situation that it will use in it. Our
main focus was on the basic beds that are currently being used in hospitals. Initially, we observed
the beds typically used by hospitals and available in the market. Our second task was to decide on
a bed design that gets closely fit the needs of the hospital at a reasonable expenditure.
▪ 2.1.1 Evaluating Current Bed Designs
The first step to evaluate hospital bed designs was to check out what various medical bed models
were currently available. We visited nearby hospitals and observed the available models of medical
beds and also referred to online sources. We studied the FDA standards for hospital bed patient
entrapment. According to FDA new models of hospital beds used must have components which
reduce the risk of entrapments including an emergency button for the patient to press and a warning
signal id any entrapment situation occurs.
The models present in the market and nearby hospitals do have elevating and reclining
mechanisms, many of the basic functions and components are similar. Some advanced models
even have integrated toilet systems, but all these features contribute to a higher price and increased
bulk.
▪ 2.1.2 Selecting the Best Bed Design
After the team had reviewed all the existing products and online sources, then it was time to select
a bed design. This bed will be one which closely fit our ideal design. We discussed and decided
the bed design by comparing the beds currently available and widely used.
To assess a bed design for the demands of hospitals, we had to develop an appropriate design for
evaluation. Each bed was pointed on a scale of 1-5, and each category had a certain percentage of
significance for the overall functions of the bed. The most important aspect was the satisfaction
of the standards of dimensions to minimise ambiguities between what the hospitals used and our
design. Quite frequently, the frame will crack, the articulating parts will fracture, and the cranks
will break off. So, durability and safety were given the second most important components for
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design intent because current beds produced are frowned upon for their proneness to failure. In
contrast, the safety of patients and staff is an obvious necessity.
Ease of manufacturing or opportunity to easily reproduce the bed is an important component so
that a higher number of beds can be mass-produced to meet the demand of all hospitals. The cost
of the beds is also an important aspect to not just save hospitals capital from bed purchases but
also to meet the needs of the rural people.
Considering out the items in the decision matrix where the ease of transportation, lower leg
mobility, electrically powered functions and other additional features. A summary of each measure
considered in the performance and determination of a good bed is as follows:
Industry Standards (20%): Includes recommendations for the articulated angles, height
variances for bed, size of safety rails and end rails. This is the most important feature because most
beds follow these standards, and they are a large component of hospitals preferring to purchase
certain medical/surgical beds.
Durability (15%): Durability includes the endurance and lifespan of the bed under normal
conditions, ranging somewhat from two years to twenty. Durability considers the material the bed
frame is designed from, the reliability of the type of motor used in automated beds and the cost of
repairing amongst other functions.
Safety (15%): The safety level of the hospital bed designs is a large important because if the beds
provided by hospitals do not promote a healthy body lifestyle for recovery the length of stay for
the patients may be somewhat longer, an injury may result to patient and/or staff and lawsuit
liabilities. The safety measures of each bed were determined by the material selections in referring
to FDA standards, stress analysis on the weakest sections of the beds and the functions provided
in case of emergency.
Ease of Manufacturing (12%): Ease of manufacturing is a very important factor to consider in
bed design for a number of reasons, most notable factors are the net profit margin that would result
from the production ratio, development of unique parts, number of workers needed etc.
Manufacturability was determined by the reproducible components for each bed, difficulty in
assembly, the estimated number of workers to complete each bed and approximate lead time for
manufacturing completion.
Cost (12%): Bed cost were considered in two dimensions. The first element was the actual cost
of bed assembly and purchase, whereas the second element as the cost of shipment to the hospital
or logistics costs.
Ease of Operation (10%): Today's the fast-paced world requires to accelerate the processes as
much as possible and in the hectic and crowded hospital environment. One of the ways to reduce
the nurse to patient time ratio is to make the beds easy to operate and easy to learn how to work.
Although electronic beds have many advantages because the motors can move faster and easier,
the hand-cranked beds should be simple to handle and as quick and efficient as possible.
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Ease of Transportation (5%): The ability to relocate a bed for medical emergencies, room
changes and other necessities are very important. Transportation is considered not only the ease
in moving a particular bed but also the space required to move each bed.
Leg Mobility (5%): Recent medical studies have revealed that articulation of the lower leg along
with the upper leg portion of the body can help patient to get recover in an exponential manner,
will allow for patients to be more comfortable and also reduces the number of pressure scores in
long term patients.
Electric Functions (4%): The inclusion of electric functions in beds makes it easier for patients
to achieve more comfort as they can adjust their beds to the patients' comfort levels. So, both
electric and manual operation should be available. The opportunity helps to change the bed from
manually cranked to electrically driven, and the power required for all articulating parts can be
taken from various energy sources.
2.2 Fabrication of our Bed Design
We aim to provide all the basic functions of medical beds along with an integrated toilet system,
both manual and power operated and an alternative power source (solar) for the reclining system.
So, to incorporate all these facilities, we need to come up with a new design. So, we have designed
this model on Solidworks and performed stress and force analysis on the model.
▪ 2.2.1 Spatial and Angular Bed Dimensioning
Based on the available standards of medical beds through online sources and inspection of models
present in hospitals, we selected the angular restraints for bed. Mostly every significant hospital
bed has an upper-body articulating mechanism, and its recommended that it moves a maximum
angle of at least 60 ̊. Based upon current bed features with patient concerns, we felt that that angle
must be at least 75 ̊ and high up to 80 ̊ would be in an ideal case. To establish length for bed, we
took into account both anthropometric data and industry standards. From both data sets, we have
established a nominal length in between 2000 to 2100 mm for the length of the entire bed frame
and also determined the length of the articulating back mechanism to be 90 cm base upon 95% of
the anthropometric data researched.
The minimum angle may have occurred between the stationary buttons and upper leg assembly
position. We found that angle 60 to be satisfactory and adopted it for our design and used
anthropometric data in sitting position, which most closely relates to the position of the articulated
hospital bed and found the length of our upper leg segment to be around 35 cm. To ensure the
lower leg mechanism which could achieve an angle parallel to the ground for a range of motion of
upper-leg assembly. Thus most extreme angle which upper leg assembly is inclined to its full and
a height of 30.3 cm.
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2.2.2. Lower Leg Assembly Mechanism
The first point of consideration we wanted to deal was the adjustment of the lower leg mechanism
Beds that are electrically powered had been found to frequently short out at lower leg assembly.
The reason behind power failure is that the designer accounted only the weight of the patient,
neglecting the other factors such as the presence of other visitors who often sit on the bed.
Subsequently, the motor tries to exert too much power to compensate the visitors at the foot of the
bed, and the motors burn out.
2.2.2.1 Slider Crank Lifting Device
One of our considered iterations was a slider-crank mechanism which lifts the lower leg
independently of the upper leg movement. The mechanism would have been designed such that as
the upper leg was cranked while the lower leg mechanism would move along as a slider so that it
remained grounded and could be independently changed. Upon completion of the articulation od
upper leg mechanism, the lower leg could then be cranked too. Before any mathematical
calculation, we realised that this concept was good in theory, but on the application, in order to
raised, it would have a great deal of force in the x-direction to initiate articulation.
2.2.2.2 Worm Gear Acting as a Slider-Crank
What then makes our design to offer ?
Our final design combines the mechanics of
the slider-crank mechanism with the rolling
devices at the end of the lower leg portion. To
minimise the manufacturing cost, the lower
leg mechanism of our bed, just same as slider-
crank lifting device. The crank attaches to the
platform that lower leg of the paramount
currently rolls along. A support beam cuts
across then bed to which the worm gear is
attached.
Figure 3: Final Design, crank-driven
worm gear to lift the lower legs
The crank rotates the worm gear, allowing the slider to move along with the gear. As the slider
traverses, the link attached to it will rotate freely, thus lifting the lower leg section of the bed. Our
preliminary sketch in figure 3, shows how the bed will articulate. The only portion of the platform
that rises is the two links where the wheels for lower assembly is supported. The other portions of
the platform provide a cover over crank mechanism and will remain fixed.
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Figure 4: Complete Lower Leg Lifting Mechanism
The sizing determination of the set was based upon simple trigonometry. We first calculated the
height that the upper leg device would achieve when in full articulation condition at 60 degrees.
Based upon that data, we found that the maximum vertical height of the upper leg mechanism
would be a distance of 30 cm from the platform that the assembly rests upon. The roller bar had
to achieve that same vertical height, but to minimise the risk of breaking; we determined the piece
should maintain a slight angle of 20 ̊ when it was in maximum position. Once we had the sizing
calculations determined, the design of the screw and nut pair and the support beams we had to
determine if the assembly could be packaged and fit accordingly into our bed design.
2.2.3 Articulation of Back and Upper Leg Board
Further in design consideration must be given to both the backboard adjustment as well as the
upper leg board. The linkages for the articulation of the backboard and the upper leg board are of
identical design. The major consideration for this design was the amount of space that is available
underneath the bed. This space is used by mechanisms that raise and lower the upper bed frame
and the linkages that articulate the lower leg board. For saving space, our design employs a
universal joint, a screw and worm gear. This system will allow for a straight connection between
the crank handle and the back and upper leg boards.
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The parts are articulated by manually
craking at the foot of the bed. Both the
background and upper leg board are driven
by separate cranks and will not move at the
same time unless both handles turned
together. These handles then transfer
motion to a universal joint. The joint
rotates and turns inside the worm gear. The
worm gear is then attached to a shaft which
is connected to backboard/upper leg board,
as shown in figure 5. Depending on the
direction the handle is cranked in, and the
skew will elongate or retract within worm
gear shaft and thus procures a motion that
either pushes back/upper leg board or pull
it down.
Figure 5: Handle System
2.2.4 Mechanism of Guard Rails
In the design of guard rails, the safety of the patient is one of main importance. The distance of
rail is considered to be 220 mm based on the design standards. The rails are designed so that only
minimal gaps and no slots were left to prevent entrapment of patients. Also, the rails are attached
to the bed frame so that no gap larger than 120 mm is present between the mattress and the rail.
Figure 6: Guard Rail Lifting Mechanism
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3 Designing Process and Preparation of Prototyping
We started by setting the bottom frame of the bed as the fixed part that all the other parts would
move around. Next, the bed raising mechanism described in Section 3.1.2. Bed Raising and
Lowering Mechanism was attached to the lower frame. The upper bed frame, including the
guard rails, litter, head and footboard, were attached to the lifting mechanism. The lower leg
lifting assembly was pinned in place on the bed frame. After that, all the cranks, universal joints,
screws, and worm gears were installed and attached to their corresponding parts.
Figure 7: Solidwork Model
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After the successful completion of the entire bed design, we needed to determine if the bed would
work. We ran a considerable analysis in Solidworks, and all indications show to be a successful
bed design. However, the only way that we would find out if the design would work realistically
was to machine the parts of our bed and create a prototype. Much of our complete bed had been
adapted from the current design so we are confident that they would work. Lower Lifting
Mechanism, however, is an entirely new design, and thus far unproven. It was this reason we felt
it was necessary to prepare the design for prototyping.
3.1 Supporting the Overall Bed Quality design
. We need to prove why our bed is better than the rest of the beds that are currently being used in
hospitals. If we could produce satisfactory bed for the hospital which was our team ultimate goal
of this project.Our team had to prove beyond a reasonable doubt that our bed was indeed better
than the paramount design currently in use. To validate our bed designwe turned to design that
we created as prt of section 3.1.2. The important feature of our bed design is its compliance with
the Industry Standards. Our design meets all the measurements that can be found in Table 1:
Industry Standards for hospital beds. The backrest has inclination capabilities up to 75°, and the
upper leg board inclines no more than 120° from the gluteus board as recommended. Additionally,
our bed supports greater than 240 mandatory kg load. Our articulation systems also require a force
no greater than 2N×m to operate, and our bed requires a maximum torque of the only 0.69N*m.
3.1.1 Bed Saftey
The saftey provided by the bed of hospital staffand patients are alike was a major consideration in
the development of our bed. Our bed not only took into account the industry standards described
above , but it also utilizes information publish by FDA on patient entrapmentwithin the beb. Our
guard rails were designed so that no space within the rails has distance greater that 120mm. The
guard rails are desined with minimum gaps and unlike the paramount beds, there are no slots which
would more easily get the patient entrapped. The rails are attached to the bed frame in a way that
ensures gap<120mm between the mattress and the rail.A gap<60mm between rails and the
headboard and footboard. Our bed design also features a headboard and footboardnthat can be
removed in a medical emergency quickly eith patient arise. The design maximizes the patient
saftey zone by ensuring minimum trapping zone. With all these saftey, we performed stress
analysis of the parts of bed which would be under pressure to ensure bed would not bend or break.
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3.1.2 Mechanics Calculations of the upper body Leg Mechanism
The first check performance was simple calculations of the degree of freedom of the entire lower
lifting assembly. We wanted to make simple sure that screw pair would rotate and allow the
raising and lowering of roller bar.
Figure 8:Recling Mechanism
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Figure 9: Solid work Reclining Model
Bed Front Reclination
Hmax=max height of front reclination Hmax = a= b*sin(Omax)
O max=Max Angle of reclination Hmax =760*sin(60)=658 mm
We found that was just one degree of freedom in the lower leg assembly device, revealing that
our projected movements were satisfied and the roller bars only movement would be in the radial
direction, therefore articulating the lower leg as desired.
Our second check which then had to be performed to ensure the safety of our device was a
mechanics determination of the lower leg lifting device, including a static analysis to determine
the maximum force felt by the device and the moment imposed at the pin of the link. As previously
described in our selection process, our rejected iterations failed as a result of the requirement of
too high a moment or inability of account for translation of lower leg board.
For Lower leg lifting device the mechanics analyse the force to be about 578 N. From that
determination we were able to calculate the torque required to rotate crank as only 0.69 N*m at
maximum, far less than 2 N*m maximum that is allowable as governed by CIS.
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3.2 Toilet Projected View
Figure 10 : Lower Part reclining height
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3.3 Toilet Psiphon Effect
Figure 11: Toilet Phison Model
When we pour a huge volume of water at once in the bowl, it rushes into the siphoning tube where
due to difference in height, a pressure difference is set. At which inlet, i.e. at point 1 there is a high
pressure, and at point 2 and in the tube, the pressure is low. This pressure difference creates a flow
in the pipe until it sucks down all the water in the bowl with wastes. Siphoning breaks when air
enters the tube after all water from the bowl is sucked out.
Pressure at point 1 = Pout + d g h1
Pressure at point 2 = Pout + d g h2
Since h1>h2,
P1 is greater than P2
● Garden sprayer is capable of producing sufficient water pressure that is capable
of properly rinsing and flushing for at least four times just with 5 litres of the
water tank.
● A cheap but yet best alternative for rinsing and flushing
Figure 12: Garden Sprayer
1
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4. COST ESTIMATION
Component Unit cost
(INR)
No. of
Units
Total Cost (INR)
18650 Li-ion 6000mAh 14.8v 4S3P Protected Battery Pack 2799.00 1 2799.00
Square Gearbox Motor - 480RPM 1281.00 4 5124.00
10W 12Volts 36-cell Solar Panel (41 x 30 cm) 997.00 1 997.00
280 Diaphragm 3.7V Self-Priming Small Micro-pump Tea
Fitting Metering Pump
259.00 1 259.00
550 Diaphragm Pump 12V Water Pump for Water Spray Fish
Tank Reflux Pump
639.00 2 1278.00
DC6-12V MINI Aquarium water Pump R385 304.00 2 608.00
350mm Trapezoidal 4 Start Lead Screw 8mm Thread 2mm
Pitch Lead Screw with Copper Nut
490.00 2 980.00
628ZZ Bearing 8x24x8 Stainless Steel Shielded Miniature
Bearings (4Pcs)
199.00 1 199.00
Motor Controller 24V for MY1016 350W 1330.00 1 1330.00
EasyMech M3 X 15mm CHHD Bolt, Nut and Washer Set-20
pcs.
59.00 1 59.00
DC Motor PWM Speed Regulator 1.8V, 3V, 5V, 6V, 12V-2A
speed control switch function
240.00 3 720.00
1 Meter UL1007 18AWG PVC Wire (Black) 49.00 20 980.00
Cytron 10A Dual Channel DC Motor Driver Shield for Arduino
Uno
1720.00 1 1720.00
MAQ 1/2 Inch x 10mtr (33'feet) Industrial Quality Nylon
Braided Hose PREMIUM QUALITY NYLON BRAIDED
HOSE Hose Pipe
472.00 1 472.00
KSTARENTERPRISE Attach A Touch Hanging Trash Bin
Holder Plastic Kitchen Garbage Bag Plastic Dustbin
254.00 1 254.00
Royal Indian Craft FT28 Bidet Nozzle 188.0 1 188.00
Naulakha Bed Pan, Vomit Basin (Pack of 2) Urine Pot 450.00 1 450.00
Mufasa Universal Flexible Plastic Waste Water Outlet Pipe
Hose Hose Pipe
199.00 1 199.00
Medical Mattress 1099.00 1 1099.00
Bed pan 671.00 1 671.00
Hot and cold Hose pipe 299.00 1 299.00
NEMA 23 30.61kg-cm hybrid stepper motor 3769.00 1 3769.00
Heating bag 1913.00 1 1913.00
Hospital castar wheel 250.00 4 1000.00
Brass ball valve 253.00 3 759.00
Grey cast iron 70 35 2450.00
Racron polyester synthetic cotton fiber(500gm) 200.00 8 1600.00
Plywood (7X4)feet 6mm 1260.00 1 1260.00
Shipping charges 1500.00
Total ₹34,936.00
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6 Summary
While working on this project, we were made aware of the medical situation in an industrialising
nation. There is still much the Indian government can do to advance their health care system. Our
project team was able to gain valuable first-hand experiences of the current status of the hospital
through various interviews and hospital visits. We were able to take the information that was
obtained through these visits and apply it in our project design. Our project team visited the nearby
Narayan Ashram hospital, and one of our teammates visited hospitals in Nepal to get an idea of
what beds they were currently using. Indian hospitals need to start buying domestically produced
beds. As of now, the advanced beds are imported from Japan or the United States. Our bed is just
one step that will allow India to begin producing its quality medical pieces of equipment and also
domestically produced. This will allow quality health care to become more affordable and
accessible to many Indian citizens.
Our bed design is based on the best features of a few bed designs and includes our modifications
and additional design features. Aside from having more features then the old beds it will allow
rural, smaller and less wealthy hospitals to afford and implement modern healthcare equipments.
Our design still needs to be perfected to accommodate the toilet system. To articulate the lower
legs, we used a crank driven worm gear that would be attached to slider type linkage. Our design
ultimately has as an integrated toilet system, articulating backrest, upper leg board, and lower leg
board. Our team feels that with a minimal amount of additional work, this bed design would be an
economical and effective alternative to the beds that are currently being used.
The last part of our project was the validation of the reliability of our design. This took us back to
the design model that was used to evaluate the original designs. We then analysed all the major
linkages within our bed to determine their reliability. Our bed design is a viable option for use in
Indian hospitals as a replacement for their current beds. Our task was to design a reliable hospital
bed that could be domestically produced for use in India, and that is what we have done.
A working prototype of the lower leg mechanism must be manufactured and tested. Additionally,
work must be done in the manufacturing area of the design. Appropriate material must be selected
for each part, and a complete prototype of this bed design must be constructed. Our team feels that
these steps would be worth pursuing and that this bed design would allow for the continued
expansion of India's developing health care industry.
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7 References
1. Wikipedia. Hospital Bed. https://en.wikipedia.org/wiki/Hospital_bed
2. Economic Times Article. WHO report on Demand of Medical Beds.
https://health.economictimes.indiatimes.com/news/industry/the-new-healthcare-policy-
mandates-a-minimum-of-2-beds-per-1000-sumeet-aggarwal/62992210
3. Food and Drug Administration. Anthropometric Data. https://www.fda.gov/medical-
devices/general-hospital-devices-and-supplies/hospital-beds
4. Dr Abhay Yadav, Sri Narayani Ashram Hospital, Allahabad.
5. Guzide Guzelbey Esengum, Cem Alppay (2018). A Study on Examining User Comfort in
Hospital Beds. Department of Industrial Product Design, Faculty of Architecture, Istanbul.
Technical University, Instanbul, Turkey.
6. Kolcaba, K.Y. Comfort Theory and Practice: A Vision for Holistic Health Care and
Research. Springer, New York (2013).
7. Hortom L.M, Mehta, R.K., S., Agnew, M.J., Nussbaum M.A. Effects of alternate hospital
bed design features on physical demands. In Proceedings of the Industrial Engineering
Research Conference, pp 937 – 942 (2009).
