INTERIM PROGRESS REPORT - Memorial University …jmat/docs/reports/Interim Design Report.pdfincline to provide up to a 15-degree maximum incline will be accomplished via a slider-crank

ENGI 8926

PEDIATRIC HOSPITAL BED MODIFICATION

INTERIM PROGRESS REPORT

Matthew Pilling

200452332

Justin Pinksen

201014602

Ashley Sullivan

200211068

TeAndra Thomas

200915817

Overall Bed Incline Additional Bed Height Equipment Storage Bed Rail Modification

ENGI 7926 Research and Concept Selection Report

06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page i of iii

TABLE OF CONTENTS

Summary ......................................................................................................................... 1

1. Introduction .............................................................................................................. 2

2. Problem Definition .................................................................................................... 2

3. Background .............................................................................................................. 2

4. Literature Review ..................................................................................................... 4

5. Design Objectives and Constraints .......................................................................... 5

5.1 Design Objectives .............................................................................................. 5

5.2 Design Constraints ............................................................................................. 5

6. Early Testing ............................................................................................................ 6

6.1 Test Setup Design .............................................................................................. 6

6.2 Test Setup Deployment ...................................................................................... 7

6.3 Test Setup Construction ..................................................................................... 8

7. Design Concept Generation ..................................................................................... 9

7.1 Overall Height Adjustment ................................................................................. 9

7.2 Overall Bed Incline ............................................................................................. 9

7.3 Bed Rail Modification ....................................................................................... 10

7.4 Storage ............................................................................................................ 11

8. Concept Evaluation and Selection ......................................................................... 11

8.1 Overall Height Adjustment ............................................................................... 12

8.2 Overall Bed Incline ........................................................................................... 13

8.3 Bed Rail Modification ....................................................................................... 14

8.4 Storage ............................................................................................................ 14

8.5 Final Concept ................................................................................................... 15

8.5.1 Overall Height Adjustment ......................................................................... 15

8.5.2 Overall Bed Incline .................................................................................... 16

8.5.3 Bed Rail Modification ................................................................................. 17

8.5.4 Storage ...................................................................................................... 17

8.6 Miscellaneous .................................................................................................. 18

9. Conclusion ............................................................................................................. 18

10. Recommendations .............................................................................................. 18

Appendix A: Project Management Plan ......................................................................... I

Appendix B: Morphogical Charts .................................................................................. V


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page ii of iii

Appendix C: Evaluation & Selection Matrices ............................................................. VII

Appendix D: Invacare 5410IVC Hospital Bed Data Sheet ........................................... XI


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page iii of iii

TABLE OF FIGURES

Figure 1: Previous crib setup the family was using.......................................................... 3

Figure 2: Home hospital bed ontained through client medical inurance. ......................... 4

Figure 3: Trial demo installed on bed for overall bed incline and height adjustment. ...... 8

Figure 5: Illustration of final concept chosen for overall height adjustment. .................. 16

Figure 6: Illustration of final concept chosen for overall bed incline. ............................. 17

Figure 7: Illustration of final concept chosen for bed rail modification. .......................... 17

Figure 8: Illustration of final concept chosen for storage. .............................................. 18

ENGI 8926 Interim Progress Report

06-Feb-15 EN8926-W15-P1-RPRT-00-000-0002 Page 1 of 19

SUMMARY

J-MAT Consulting is tasked to provide a modified home hospital bed to suit the needs of

a four year old boy with cerebral palsy and his caregivers. The client was previously

using an inclined crib that did not fully suit the needs of him or his caregivers. An

existing Invacare 5410IVC home hospital bed was acquired that currently has the

functionality of head / foot incline and limited height adjustability electrically with a

manual override. To make this factory bed suit his needs it requires additional overall

height, an overall adjustable bed incline option, specialized protective bed railings and

storage for medical equipment.

To determine the required dimensions of the height and bed incline angle an early test

setup was designed, fabricated and installed at the clients’ home. It was determined that

the bed requires up to a maximum 6-inches of additional height and a total bed incline

angle adjustability of approximately 10-degrees. Through research, a literature review,

and brainstorming, design options were compiled into morph charts, from which final

designs were chosen from concept selection and scoring matrices. It was determined

that the additional height will be accomplished with an aluminum plug-like adaptor of

identical shape/size as the existing bed legs. To provide an adjustable overall bed

incline to provide up to a 15-degree maximum incline will be accomplished via a slider-

crank mechanism driven by an electrical linear actuator. An auxiliary frame of the

current bed will be created to provide a pivot point to connect the foot of the bed,

allowing the frame to rotate as it is inclined. To provide a clear enclosure that is safer for

the boys exaggerated limb movements an inside enclosure made of clear Lexan

fastened with aluminum pop rivets and nylon washers would be designed. To provide

storage that is easily accessible and visible, a wooden shelving frame underneath the

bed with width adjustable wooden walls along pilasters will be designed.

From this concept selection the detailed designs, purchasing of materials, fabricating

and testing final products will be required prior to final installation and testing for the

client. It is intended to have much of the material and labor costs donated. A project

website has been created that provides weekly progress of the project as it progresses:

http://www.engr.mun.ca/~jmat/project.php




1. INTRODUCTION

J-MAT Consulting was approached by the Tetra Society of North America, St. John’s

Chapter to modify a hospital bed for a client with a disability in our community. The end

client is a family of a four year old boy with cerebral palsy who requires a proper bed /

crib to suit his special medical needs and the needs of his caregivers on a daily basis.

An existing Invacare 5410IVC full electric high-low home hospital bed was acquired

through the familys medical insurance as a starting point of specialized modifications of

this factory bed to tailor it to his specific needs. It was found that to make this factory

home hospital bed better suited for the family it requires additional overall height, an

adjustable overall bed incline option, specialized protective bed railings and storage for

required important medical equipment. Final concepts were determined that are outlined

in this report. A full project management plan with project Gantt chart and budget can be

found in Appendix A. For the most current project status and documents, a project

website has been created that will be updated as the project progresses:


2. PROBLEM DEFINITION

To modify an existing home hospital bed to better suit the needs of a four year old boy

and his caregivers. The bed must be modified to allow an overall adjustable bed incline

and additional bed height. The bed rails must be modified to ensure the client is safe

within the bed from his exaggerated limb movements that hit against and get stuck in

the currently railing. Storage for pertinent medical equipment and linens is also required

that is easily accessible and visible. All while keeping all functionality of the current bed.

3. BACKGROUND

According to the Mayo Clinic, cerebral palsy is a disorder that affects muscle tone,

movement, posture, and motor skills that causes impaired movement associated with

exaggerated reflexed, floppiness or rigidity of the limbs and trunk, abnormal posture,

involuntary movements, unsteadiness of walking, or a combination of these. This

disorder can affect children in varying degrees, however in the case of the client he is

greatly affected which has led to very little trunk control, exaggerated movements of the

limbs, and mental impairments that have resulted in him being unable to stand or walk

and requires support while sitting or being held and is unable to communicate verbally.




Due to these complications he suffers from extreme reflux, difficulty swallowing, and is

currently fed through a feeding tube in his stomach. [1]

Previously the family is using a crib that they had modified with wood to give a slight

overall elevation. However, this setup was not suitable due to the boy sliding down the

bed from his movements and being constricted in a bent position at the end of the bed,

requiring caregivers to constantly move him back up the mattress. During various

hospital admissions that the boy has endured his family discovered that the beds used

in the hospital better suit their needs. However, the specific beds in the hospital are not

commercially available for individuals to purchase since the manufacturer deals directly

with health authorities. These particular beds are also not an option for the client due to

their extreme costs.

Figure 1: Previous crib setup the family was using.

What is required for the client and his caregivers is a bed with height and angle

adjustability (head, foot, and overall bed incline), special railing that would be safe for

the boys sporadic limb movement, and space to store equipment such as oxygen tanks,

saturation monitor, nebulizers, suction machine, etc that are medically important to be

easily monitored/controlled. A regular hospital bed would meet some of these needs

but would require modification to suit his needs.

A regular home hospital bed, an Invacare 5410IVC full-electric low-high hospital bed

with wood style bed ends, was acquired through the clients’ family insurance which can

be seen below. It is fully electric with a manual crank to use in the case of an electrical

failure. A specifications data sheet can be found in Appendix D which shows

specifications such as bed dimensions, head/foot incline capabilities, and current height



adjustment provided for the Invacare 5410IVC full electric high-low home hospital bed.

From this commercially purchased home hospital bed modifications will be made to

enhance this existing bed to better suit the needs of the boy and his caregivers.

Figure 2: Home hospital bed ontained through client medical inurance.

4. LITERATURE REVIEW

A review of the hospital beds produced by a number of manufacturers indicates that

many of these beds incorporate Trendelenburg features where by the entire bed is

made to incline such that the foot is above the head. Some beds also incorporate

reverse-Trendelenburg features that allow the bed to incline to a position where the foot

is below the head. Most hospital beds also provide height adjustment. While the trend

appears to be towards electrical actuation, lower-end models are actuated manually via

a hand crank [1]. Some hospital beds also provide height adjustment and head and foot

angle adjustment via pneumatics [2]. Virtually all hospital beds considered have either

polyethylene or metal hand rails. However, they provide very little space for storage of

equipment and other patient care items [1] [2]. Various trolleys are available to

supplement hospital beds, but these take up considerable amounts of valuable floor

space [3] [4]. Some literature review was performed by the client’s caregivers when

selecting a bed. However, there is very little literature available regarding modifying

existing hospital beds to add additional functionality. A review was conducted of

previous projects undertaken by The Tetra Society regarding modifying beds. Available

literature that has proved to be useful are the data sheet [5], user manual [6], and part

catalog [7] for the existing bed.



5. DESIGN OBJECTIVES AND CONSTRAINTS

The following sections detail the objectives that the design should achieve, and the

constraints that the project and the design will be subject to.

5.1 DESIGN OBJECTIVES

The objective of this project is to make specialized modifications to an adjustable

hospital bed. The objectives to be met by the selected design are to:

1. Increase height of bed to make it easier for caregivers to access the boy;

2. Keep the current features (both head and feet incline, limited height

adjustability) of the bed;

3. Adjustable bed angle (incline) of entire bed;

4. Provide space to store required medical equipment (oxygen tanks, saturation

monitor, nebulizer, suction machine, etc.) that must be visible and readily

available;

5. Provide a backup power supply in case of a power failure;

6. Provide transparent rails that are easily movable, or modify existing rails to

make them safer for the boys exaggerated limb movement.

5.2 DESIGN CONSTRAINTS

The specialized modifications of the hospital bed will have restrictions and limitations

that constraints include, but are not limited to:

1. Cost of the project is limited to $1500 which consists of $250 of supplied

material from faculty, donated materials and labour from MUN technical

services and the remaining costs covered by the Tetra Society;

2. Bed modification to be designed and fabricated in a three-month time frame;

3. Designs must allow the bed to grow with the client and provide enough space

for the client's mother to lie with him;

4. Bed modifications designed and operated such that no physical harm is done

to anyone;



5. Overall angle of the bed must be adjustable, up to a maximum incline angle of

15 degrees;

6. Adjustment mechanism should be motorized but incorporate a manual

override option in the case of power failure;

7. Equipment in removable storage should be readily accessible and visible;

8. Bed rails must be durable to withstand force from the client, but must also

ensure that the client is not hurt when striking the rails and can see through

material for maximum communication;

9. Designs must be simple to construct and fabricate in the time allowed;

10. Current features (both head and feet incline, height adjustability) of the bed

must be maintained.

6. EARLY TESTING

6.1 TEST SETUP DESIGN

In order to determine specifications for the overall incline angle and overall height of

the bed, a temporary test setup was designed. The entire bed was to be raised to

determine how much additional height was required. Furthermore, the head of the

bed was to be further raised to determine the required incline angle. The setup was

to be easy to install and uninstall in place such that both operations could be

completed in one to two hours, and without removing the bed from the home.

Based on initial conversations with the client’s primary caregivers, it was determined

that the test setup should allow the bed to be raised by approximately 12 inches.

Based on the incline provided by a previous mattress inclination setup employed, it

was determined that the test setup should incline the bed by approximately 10

degrees. The inclination would be achieved by raising the head of the bed above the

level of the feet.

A two-part wooden jacking setup was designed on which the head of the bed would

rest. The setup incorporated a side-wind trailer jack to raise and lower the head of

the bed. The two parts of the setup consisted of a base section and a top section.

The base section provides a landing area on which to bolt the base of the trailer jack



to and guides for the top section. The top section is used for raising and lowering the

head of the bed and is secured to the travelling portion of the trailer jack with a steel

pin. Landing areas are provided for the wheels on the head of the bed. Collapsible

support legs on hinges are provided on the top section; the free ends of the legs are

angled. As the top section is raised, these support legs fall into place and mate with

corresponding angled supports on the base section. Wedge-shaped blocks may

then be placed in front of the mated support legs in order to secure them. At this

point, the weight of the bed is no longer being taken by the trailer jack. However, it

should be noted that the collapsible support legs only mate with their corresponding

support blocks when the top section has reached the height of its travel. The total

travel of the top section is estimated at 15”. The landing area for the feet of the head

of the bed is approximately 12.5” above the floor. The majority of the base and top

sections were specified to be constructed from 2x6 lumber and 1/2" plywood.

The feet of the bed only needed to be raised to a static height; they did not need to

be raised and lowered. For the sake of simplicity, milk crates were used to raise the

feet of the bed such that one milk crate was placed under each side of the foot of the

bed. The open end of each crate was placed such that it was facing downward

(towards the floor) and rested on a sheet of anti-slip material. Plywood, 1/2" thick

was then placed on top of the closed end of each milk crate, with anti-slip material to

prevent the plywood from sliding. Anti-slip material was then placed on top of the

plywood to prevent the wheels on the foot of the bed from sliding. The top of the

plywood on each milk crate is approximately 11.5” above the floor. The overall angle

on the bed when the jacking setup is not raised is approximately 1 degree.

6.2 TEST SETUP DEPLOYMENT

The wooden jacking setup and footboard supports were deployed at the client’s

home on 28 January 2015. The setup was function tested to ensure that it worked as

expected. The amount of time taken to install and test the setup was approximately

3 hours. It was determined that that the addition of 11.5 inches in overall height was

too high. It was also noted that the provided overall incline angle of approximately 10

degrees was sufficient. Based on the results of this early test, it has been

determined that the overall height of the bed is to be increased by 6 inches, and the

overall incline angle of the bed is to be variable between 0 and 15 degrees.



The testing setup was left installed at the client’s home, with the permission of his

caregivers. It was agreed that the caregivers would provide feedback regarding

functionality that could inform the final product design. The test setup will be

removed from the client’s home at any time at the request of his caregivers. Barring

that, it will be removed when the final product is installed on the bed.

6.3 TEST SETUP CONSTRUCTION

The construction of the test setup had four phases. The first phase was cutting

individual pieces and organizing each into the proper section. The pieces were all

cut on a table saw except for a few angle pieces that were cut with the skill saw. The

two main sections were the Base Assembly and the Top Frame Assembly. The

second phase was to construct the base assembly that would hold the entire

mechanism in place. The base piece of plywood was laid on the ground to begin.

This involved cutting pieces to specified dimensions and assembling and securing

pieces as per developed drawings. The third phase is to construct the Top Frame

Assembly. Similar to phase two, this involved cutting the required pieces to specified

dimensions and assembling and securing them per drawings. The fourth and final

construction phase involved assembling the entire assembly, installing and securing

the trailer jack, and installing other outfitting components. It is worth noting that some

minor deviations from the original plans were made during the construction phases;

these were primarily due to availability of materials and were all approved. A set of

as-built drawings will be developed.

Figure 3: Trial demo installed on bed for overall bed incline and height adjustment.



7. DESIGN CONCEPT GENERATION

Potential design concepts were generated primarily by using a morphological chart. This

involved generating concept ideas for each section with various categories. These

sections included: incline mechanism, height adjustment, equipment storage and rail

enclosure. The morphological charts may be found in Appendix B. This generated a

very large number of possible design concepts.

7.1 OVERALL HEIGHT ADJUSTMENT

A morphological chart was developed after brainstorming exercises to develop

conceptual designs for raising the entire bed six inches. There were three different

criteria: material, mounting structure and location to the existing leg. Four different

materials were considered when deciding what to use for extending the legs of the

bed, these four choices were steel, aluminum, polymer, and composite material. The

options for the mounting location for the extension include mounting to the exterior

or exterior of the leg, or both. The structures chosen to permanently hold the

extension in place are a clamp, screws or pins. The full morph chart can be seen in

Appendix B.

7.2 OVERALL BED INCLINE

A morphological chart was developed and used in conjunction with brainstorming

exercises to develop conceptual designs. The morphological chart may be found in

Appendix B. Various parts of this morphological chart are presented and discussed

below.

Five mechanisms were developed for the overall angle adjustment of the bed. The

first mechanism uses a four-bar linkage whereby the follower link is pinned to the

bed frame and rocks back and forth. In this case the crank link could be attached to

either an electric motor (via gear reducer), or to a linear actuator. The next two

mechanisms make use of a slider-crank mechanism. In one case a power screw is

used as the slider, pushing/pulling a connecting rod that in turn raises/lowers the

bed. In the second case, a linear actuator is used as the slider, pushing/pulling the

connecting rod. The fourth mechanism uses a scissor lift mechanism to raise the

head of the bedframe; here the lift would be actuated by a power screw linked to an



electric motor. The fifth and final mechanism uses a linear actuator serving as an

extendable link between the bedframe and the base.

Three different power types were considered for providing the actuation motive force

for each mechanism. These power types were electric, hydraulic, and pneumatic.

Electric power would be applied via electric motors either directly to a power screw,

or to an electric linear actuator. It should be noted that both the hydraulic and

pneumatic power sources must make use of electric motors to run a hydraulic power

unit and/or an air compressor.

An auxiliary bedframe will be provided with which to support the existing bedframe.

The existing bedframe will be removed from the headboard and footboard and will

be stiffened by custom designed stiffening beams. The auxiliary frame will then be

attached to the existing headboard and footboard. This auxiliary bedframe will allow

the existing stiffened frame to rest in the horizontal position, and will provide a pivot

point about which to rotate the existing stiffened frame in order to achieve the

desired incline angle. Any existing actuators mounted to the headboard and

footboard will be removed and will be re-mounted to the auxiliary frame in the same

locations; any existing drive shafts will be lengthened using shaft couplings. These

modifications are intended to preclude altering the existing structure; the auxiliary

frame and components will be designed such that they can be removed and the

existing frame reassembled into the original bed.

Four types of materials were considered with which to manufacture the components

of the mechanism and the auxiliary bed frame: steel, aluminum, composites, and

polymers. For the sake of simplicity the mechanism links and auxiliary frame will be

constructed from the same material.

7.3 BED RAIL MODIFICATION

A morphological chart was developed after brainstorming exercises to develop

conceptual designs for creating a safe enclosure to incorporate for the bed rails. The

initial thought process for the rail enclosure was to use some form of clear, durable

plastic. Plexiglas glass was a viable option but is not as resistant to breaking as

Lexan. When considering various concept options, based on the problem definition



and design constraints a criterion was developed. The enclosure materials must be

durable, light weight, thin, easy to machine and transparent.

7.4 STORAGE

Various options for how to incorporate storage for medical equipment and linens

such as blankets and clothes were thought of through brainstorming sessions. The

main criteria for this section of the project involves the location at which the storage

would be placed/installed, material it would be made of, whether it would have

shelving dividers, the overall shape of the frame, and power source option.

The options for location were to incorporate the storage above the bed, under the

bed at the head or foot of the bed and under the bed along the full length. The

materials considered were aluminum, steel, plastic and wood. The shelving options

are to have the whole storage space an open concept with no shelf dividers, to have

permanently attached shelf dividers at pre-set widths along the length of the base, to

have an open concept with fabric storage bins, or adjustable width dividers that can

be adjusted to any drawer width. The frame shapes considered were combinations

of partial and full lengths and depths. The type of power source was also

considered, including the use of a regular power bar internal to the storage frame, no

power supply internal to the storage frame, power supply with surge protection

internal to the storage frame, and an uninterrupted power supply internal to the

storage frame.

8. CONCEPT EVALUATION AND SELECTION

Concept evaluation was used to screen concepts prior to selection. Concept selection

provided a scoring and ranking system in order to objectively select one of the concepts

that passed the screening process. Concepts were evaluated using a simple screening

system. A reference concept was chosen, and all other concepts rated against the

reference. All concepts were given ratings of plus (“+”), minus (“-“), or zero (“0”) in

comparison with the reference concept. The total of plus, minus, and zero ratings for

each concept were tallied, and the total number of minus ratings are subtracted from the

total number of plus ratings. Any concept with a score greater than or equal to zero was

then considered for selection.



A concept scoring matrix was developed to quantitatively identify the concept that would

be chosen to be fully developed and that would proceed to detail design. Appendix C

consist of the concept screening and/or scoring matrix for all sections. Here, each

selection criterion was given a weight as a percentage. Each concept was then rated on

a scale of 1 to 5 with reference to each selection criterion. Multiplying the weight by the

rating gives a score for each selection criterion. Adding the scores for all of the selection

criteria gives a total score for each concept. The concept with the highest score was

selected.

8.1 OVERALL HEIGHT ADJUSTMENT

From the morphological chart three concepts were developed that were put through

a screening matrix to see which concept was best. The type of material to use

underwent a separate screening matrix after the concept selection matrix was

completed.

The first concept, our reference concept, was to clamp six inches of identical tubing

to the existing legs. The second concept was to insert a smaller tube into the

existing legs and have another piece of identical to the leg tubing going over the

smaller piece of tubing and pinned in place on top and bottom. The third concept is

to just put a smaller piece of tubing inside of the existing leg and pin the two pieces

together. The concept that came out on top was the second concept, the inner tube

inside the existing leg and another leg extension the same size as the existing leg

and pinned together.

The material to use for the leg extensions was evaluated while taking into account

the strength of the material, the machinability, the durability, corrosion resistance,

cost, and compatibility with the existing material. The four different materials to be

put through the screening matrix are aluminum, steel, composite, and polymer. As

you can see from the screening matrix in Appendix C aluminum came out on top as

the best material to use. It is the same metal uses in the structure of the bed-frame

therefore there will be no corrosion caused by metal-to-metal contact. It is easily

machinable, it’s durable, and it is more than strong enough to withstand the weight

of the bed and the patient. The only concern we have is the cost. Aluminum is not

the cheapest material although, because of all of the other pros, it may save money

in the long run because of potential corrosion with other materials.



8.2 OVERALL BED INCLINE

Three concept scoring matrices were used in the selection process: one for the

adjustment mechanism, one for the material, and one for the motive power source.

These scoring matrices are presented in Appendix C.

An electric motive power source was selected, largely due to its lower cost and

increased safety; hydraulics and pneumatics both make use of fluids under high

pressures and potentially high temperatures. Hydraulics are also susceptible to

leaks and perforation of hydraulic hoses under pressure can result in catastrophic

damage. Pneumatics requires the use of an air compressor that is potentially quite

loud and an air receiver that would require a considerable amount of storage space.

Furthermore, hydraulic and pneumatic systems are notoriously non-linear, making

design and analysis quite difficult.

Aluminum was selected as the mechanism link and auxiliary frame construction

material. While aluminum is more expensive than steel, it is considerably more

resistant to corrosion and is likely more compatible with the existing material. Even

though its strength and elastic modulus are lower than those of steel, it is roughly as

durable. However, these consideration were deemed to be of lesser importance than

corrosion resistance and material compatibility. Composites offer relatively high

strength and durability have elastic moduli comparable to that of steel, but they are

anisotropic materials and are considerably more expensive than either steel or

aluminum. Polymers are highly corrosion resistant and will likely be compatible with

the existing bedframe materials; however, they are relatively expensive and offer

only modest strength, durability, and elastic moduli at best. However, the use of

polymers such as polytetrafluoroethylene (PTFE) may still be considered for use in

conjunction with aluminum for sliding surfaces.

The slider-crank adjustment mechanism making use of an electric linear actuator

was chosen as the adjustment mechanism. An actuator connected directly between

a base and the existing bedframe produces the simplest adjustment mechanism that

is easily maintained and operated, that does not make use of sliding motion.

However, it does not easily allow for manual operation in the event of a power-

outage; this criterion was deemed to be of very high importance to the client. The

four-bar slider mechanism is the most complicated concept to design and analyze.



While it does allow for manual operation, it also has the most pin connections and

requires sliding motion. As a result, future maintenance could be difficult and the

potential for wear of sliding components is high. The use of a power screw to actuate

the mechanism was rejected as it would require a considerable amount of

mechanical and electrical engineering that has already be conducted for pre-

assembled linear actuators. Electric linear actuators may also be purchased with

motor controllers and hand controls and are easily operated by hand. Furthermore,

this is the actuator type used in to actuate the existing bed.

Due to the relatively low linkage speeds expected in the bed, hydrodynamic and

magnetic bearing have been ruled out. The decision to use ball or roller bearing will

be made once the forces on the bearings have been determined. Rolling bearings

may also be rejected in favour of oil-impregnated PTFE or brass sleeve bearings. A

removable installation type that makes use of clamping was selected in order to

ensure that the existing bed components are preserved such that the bed can be

reassembled into its original configuration. The selection of control and sensing

functions were made indirectly be selecting an electric linear actuator, purchased

with a motor controller.

8.3 BED RAIL MODIFICATION

The final concept that was selected entails enclosing the rail on the inside only,

preventing the client hands from getting trap and injured in rail openings but also

allowing the care givers to firmly grip rails on the outside without any interference to

adjust if needed. The material selected Lexan fitted the criteria the best; it is a

polycarbonate that is light weight, transparent, easy to handle and manufacture. It is

strong and virtually unbreakable due to impact resistance. Lexan has all

the advantages of glass without the dangers.

8.4 STORAGE

The options for the location of storage for medical equipment were further evaluated.

The location of above the bed was determined to not be suitable due to the difficulty

to reach the space and the logistics of how to mount such shelving in the space

available. It would be difficult to incorporate into the bed frame itself, especially for

maneuverability of the bed, and it is not desirable to make permanent changes to the



home. Therefore, the option of installing the storage above the bed was not chosen

and it is desired to incorporate under the bed frame itself. Due to the smaller length

available at the head or foot of the bed and the lack of space available in the living

space the bed is used in, the under the bed head and foot storage option was also

not desirable.

The materials were considered in terms of their weight, costs, easily cleaned,

esthetics, availability, and ease of manufacture. Due to higher costs, extra weight,

and less esthetically appealing, the aluminum and steel options are less desirable

options. Wood was chosen due to being more lightweight, more locally available and

less costly since a lower grade plywood sheet can be stained to be more esthetically

appealing and it can be machined easily. The type of shelving options were

evaluated. To provide the most adjustability it was desired to incorporate an overall

base board with detachable wooden dividers that can adjust the width of the

shelves. It is also desired to provide the final storage layout to provide space for

each piece of medical equipment in front and have fabric storage baskets providing

space for linens behind each shelf section. It is also desired to make the underneath

storage easily moveable for cleaning and adjustment, six wheels are incorporated

into the design frame.

The medical equipment being used and stored is of vital importance to the health of

the client and therefore needs to be easily seen and accessible at all times.

Therefore a door or covering over the front of the shelving unit was not desirable.

Due to the importance of the equipment it is desirable to incorporate an

uninterrupted power supply to keep medical equipment functioning properly for a

certain amount of time in the case of a power failure to give the family time to

engage a generator for their home.

8.5 FINAL CONCEPT

From these separate mini-project designs concept evaluation and selection matrices

provided final concept designs that are outlined below.

8.5.1 Overall Height Adjustment



The final concept for the modification of the overall height of the bed will be

achieved by installing plug-like adaptors on the each foot of the bed. The castors

will be removed from their current installation point in each foot of the bed and

will be reinstalled in the base of each adaptor. One hole will be drilled through

each bed leg to allow a retaining pin to pass through in order to keep the adaptor

in place. Each adaptor will be constructed from aluminum. The individual pieces

making up each adaptor may be welded together; however, the adaptors will in

no way be permanently fixed to the existing bed. An illustration of the final

concept can be seen below.

Figure 4: Illustration of final concept chosen for overall height adjustment.

8.5.2 Overall Bed Incline

The final concept for the overall angle adjustment will be achieved via a slider-

crank adjustment mechanism, driven by an electrical linear actuator. The existing

bed frame will be disassembled and will be reassembled such that it is allowed to

rest on an auxiliary frame that is to be designed. The design intent of this

auxiliary frame is to prevent any permanent alterations to the existing frame: it is

to be completely removable. The auxiliary frame will provide a pivot point to

which the foot of the existing bed frame will be connected; this will allow the

existing bed frame to be rotated about its foot as it is inclined. The material of

construction for both the adjustment linkage and the auxiliary frame has been

selected as aluminum. Either ball bearing or roller bearings will be used in the

pivot point; hydrodynamic and magnetic bearing have been ruled out due to cost

and the low-speed service. Any electrical controls will be purchased in

correspondence with the electric linear actuator. An illustration of the final

concept can be seen below.



Figure 5: Illustration of final concept chosen for overall bed incline.

8.5.3 Bed Rail Modification

The final concept selected for the rail modification is an inside rail enclosure

using clear Lexan sheets that are fastened with aluminum pop rivets and nylon

washers. An illustration of the final concept can be seen below.

Figure 6: Illustration of final concept chosen for bed rail modification.

8.5.4 Storage

The final design for the storage of medical equipment incorporates a wooden

shelving frame along the side length of the bed with wooden shelving walls that

can be moved along pilasters running perpendicular to the base allowing various

shelving widths to accommodate different size equipment needs. The shelving

walls will not go all the way to the back to allow room for cords and wires, six

wheels are included and aluminum angles are incorporated along the left, right

and back sides to stabilize the side panels and to keep things from falling out of

the back section of the base frame. Fabric organization bins will be incorporated

to be stored behind any equipment or in front of the empty shelving sections for

storage of linens or blankets. An illustration of the final concept can be seen

below.



Figure 7: Illustration of final concept chosen for storage.

8.6 MISCELLANEOUS

Additional to the four main design changes it has been requested to incorporate a

detachable IV pole and it is desirable to incorporate a drop-down table to the head of

the bed and wire clips at various locations around/under the bed to keep wires tidy

and the end of the suction line clean.

9. CONCLUSION

A home hospital bed is to be modified to better suit the family of a 4 year old boy with

cerebral palsy. The required modifications involve additional overall bed height of 6-

inches, an adjustable overall bed incline option of up to 15-degrees, specialized

protective bed railings made from clear Lexan and storage for required important

medical equipment under the bed with an uninterrupted power supply. Final concepts

were determined that will lead to detailed design, fabrication and will be ultimately

installed for the existing hospital bed.

10. RECOMMENDATIONS

The next steps for this project involve fully defining detailed designs, purchasing

materials, fabricating designs and testing the final product prior to installation for the

client. It is desired to keep the permanent alterations to the existing bed to a minimum



REFERENCES

[1] Virtual Expo, "Medical Expo - Hospital Beds," Virtual Expo , 1 February 2015. [Online]. Available: http://www.medicalexpo.com/medical-manufacturer/hospital-bed-13.html. [Accessed 1 February 2015].

[2] Virtual Expo, "Medical Expo - Hydraulic Hospital Beds," Virtual Expo, 1 February 2015. [Online]. Available: http://www.medicalexpo.com/medical-manufacturer/hydraulic-hospital-bed-540.html. [Accessed 1 February 2015].

[3] Truelife, "Hospital Equipment," Truelife, Dublin, 2015.

[4] Paragon Care, "Materials Handling," WebMagnet, 2 February 2015. [Online]. Available: http://www.paragoncare.com.au/medical-equipment/acute-care/materials-handling. [Accessed 2 February 2015].

[5] Invacare Canada, "Invacare Canada Home Care Beds and Bed-Related Accessories," Invacare Canada, Mississauga, 2007.

[6] Invacare Canada, "Owner's Operator and Maintenance Manual: IVC Bed Series: Full Electric Beds," Invacare Canada, Mississauga, 2007.

[7] Invacare Corporation, "Parts Catalog: Homecare Beds (Manual, Semi-Electric, Full Electric)," Invacare Corporation, Elyria, 2014.

[8] M. C. Staff, "Definition," 16 April 2013. [Online]. Available: http://www.mayoclinic.org/diseases-conditions/cerebral-palsy/basics/definition/con-20030502. [Accessed 5 Febuary 2015].


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page I of XVI

APPENDIX A: PROJECT MANAGEMENT PLAN

SCOPE OF WORK

The scope of work of J-MAT Consulting for this project is the design and fabrication of

specialized modifications to a pediatric hospital bed. This includes the lifting

mechanism, inclining mechanism, rail enclosure and equipment storage. Design of the

existing home hospital bed including original rails, actuation systems, and remote

controller are excluded from the scope of work. Fabrication will be provided by MUN

Technical Services who will volunteer their time and part of the materials. The

modifications are to be designed and fabricated under this scope of work to include the

above mentioned components.


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TIME MANAGEMENT


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06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page IV of XVI

BUDGET MANAGEMENT

JMAT Consulting

PEDIATRIC HOSPITAL BED MODIFICATION

Feb-15

Project Manager - Ashley Sullivan

Income and Funding Income or Funding Source Amount

Faculty of Engineering $250

Tetra Society

Total Funding for Project $250

Expense Type of Expense Cost

Labor donated

Materials and Supplies $2,692

Misc. / 10% Contingency $269.15

Detailed Expense Type of Expense Cost

Test Setup Trial Building supplies, trailer jack, ancillary supplies $186

Total Bed Incline: Electric actuator & controls $600

Electric control box & hand controls $350

Aluminum rectangle tube $350

Aluminum rectangle bar $60

Bearings (including housing) $150

Shaft Couplings $200

Clevis Pins $15

Height Adjustment: Aluminum tubing (4') $30

Bed Rails: Lexan sheet (x2) $80

Aluminum pop rivets (x12) $2.50

Nylon washers (x12) $3

Storage: Wood (base x1 + shelves/ends x5 ) $200

Pilasters (x3) & Clips (x10) donated

Fabric organization bins (x4-5) $100

Uninterrupted Power Supply (UPS) $100

Aluminum angles (sides x2 & back x1) $60

Wheels (x6) $60

Miscellaneous: Wire Clips $20

IV Pole $75

Head board fold-down table (wood platform & hinges) $50

Total Project Expense $2,692

Total Project Budget $2,961

Note: This budget is current high level estimates of future costs, it is intended to acquire most building materials and all labor costs donated by local supply dealers and MUN Technical Services.


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page V of XVI

APPENDIX B: MORPHOGICAL CHARTS

OVERALL HEIGHT ADJUSTMENT

Table 1: Overall Height Adjustment Morph Chart.

Option 1 Option 2 Option 3 Option 4

Material Steel Aluminum Polymer Composite

Mount Location (leg)

Exterior Interior Both exterior &

interior

Mounting Mechanism

Clamp Screws Pins

OVERALL BED INCLINE

Table 2: Overall Bed Incline Morph Chart.

Option 1 Option 2 Option 3 Option 4 Option 5

Mechanism 4-Bar Slider Slider Crank w/ Power Screw

Slider Crank w/ Linear Actuator

Direct-Connected Linear Actuator

Headboard Scissor Lift

Material Steel Aluminum Composite (CF or fiber glass)

Polymer (HDPE, PTFE, etc.)

Motive Source Electric Hydraulic Pneumatic

Bearing Type Hydrodynamic Ball Roller Magnetic

Installation Removable Permanent

Installation Method

Bolt to existing Weld to existing

Clamp to existing

Angle Controller

Handheld, wired

Handheld, wireless

Bed-mounted

Angular Speed Control

Micro Controller

Personal Computer

Mechanical None

Angular Position Sensing

Optical Encoder

Limit Switches LVDT None

Torque/Force Limiting

Torque Switches

Limit Switches Shaft keys Frangible Shafts Press Fits

BED RAILS MODIFICATION


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Table 3: Bed Rail Modification Morph Chart.


Rail Enclosure

Cover inside of rail opening only

Cover inside and outside of rail opening

and rail handles

Cover outside of rail opening only

Cover inside and outside of rail

opening

Material Lexan

(Polycarbonate) Lexan (Polycarbonate)

& Rubber Acrylate Sheets

Clear Vinyl Sheets

STORAGE

Table 4: Storage Morph Chart.


Location of storage

Above bed Under foot Under head Along side

Material Aluminum Stainless Steel Plastic Wood

Shelving dividers

All open space – no dividers

Permanently spaced dividers

Open space with fabric storage bins

Adjustable width dividers

Shape of frame

Partial length & depth

Full length & partial depth

Partial length & full depth

Full length & depth

Power source Regular power

bar No internal power

supply Power supply with surge protection

UPS


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APPENDIX C: EVALUATION & SELECTION MATRICES

OVERALL HEIGHT ADJUSTMENT

Table 5: Material Selection Matrix for Overall Height Adjustment.

Aluminum Steel (REF) Composite Polymer

Weight Rate Score Rate Score Rate Score Rate Score

Strength 20.00% 2.5 0.5 2.5 0.5 1.5 0.3 1 0.2

Machinability 10.00% 2.5 0.25 2.5 0.25 2 0.2 2 0.2

Durability 10.00% 3 0.3 2.5 0.25 2.5 0.25 1.5 0.15

Corrosion Resistance 15.00% 2.5 0.375 2.5 0.375 5 0.75 5 0.75

Cost 20.00% 2 0.4 2.5 0.5 1 0.2 1.5 0.3

Compatibility with existing material 25.00% 4.5 1.125 2.5 0.625 4 1 5 1.25

Total Score TOTAL SCORE: 2.95 2.5 2.7 2.85

Table 6: Concept Selection Matrix for Overall Height Adjustment.

Concept 1 (REF) Concept 2 Concept 3

Weight Rate Score Rate Score Rate Score

Strength 20.00% 2.5 0.5 4 0.8 2 0.4

Machinability 10.00% 2.5 0.25 2 0.2 3 0.3

Durability 10.00% 2.5 0.3 3 0.3 2 0.2

Corrosion Resistance 15.00% 2.5 0.375 3 0.45 5 0.75

Cost 20.00% 2.5 0.4 1.5 0.3 2.5 0.5

Compatibility with existing material 25.00% 2.5 1.125 5 1.25 4 1

Total Score 2.95 3.3 3.15


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page VIII of XVI

OVERALL BED INCLINE

Table 7: Material Selection Matrix for Overall Bed Incline.

Selection Criteria

Weight

Steel (Reference)

Aluminum Composite Polymer

Score

Weighted Score

Score

Weighted Score

Score

Weighted Score

Score

Weighted Score

Strength 20% 2.5 0.5 2 0.4 1.5 0.3 1 0.2

Machinability 10% 2.5 0.25 2.5 0.25 1 0.1 2 0.2

Durability 10% 2.5 0.25 2.5 0.25 2.5 0.25 0.5 0.05

Corrosion Resistance

10% 2.5 0.25 4 0.4 5 0.5 5 0.5

Cost 20% 2.5 0.5 1.5 0.3 0.5 0.1 1 0.2

Compact. w/ Existing Material

20% 2.5 0.5 4 0.8 5 1 5 1

Availability of Manufacturing Resources

10% 2.5 0.25 2.5 0.25 0 0 0 0

Total Score 2.5 2.65 2.25 2.15

Table 8: Material Selection Matrix for Overall Bed Incline.

Selection Criteria

Weight

4-Bar Slider (Reference)

Slider-Crank Headboard Scissor Lift

Direct-Connected Actuator

Score

Weighted Score

Score

Weighted Score

Score

Weighted Score

Score

Weighted Score

Mechanical Simplicity

10% 2.5 0.25 4 0.4 4 0.4 5 0.5

Ease of Analysis

5% 2.5 0.125 4 0.2 4 0.2 5 0.25

Ease of Operation

10% 2.5 0.25 4 0.4 2.5 0.25 4 0.4

Ease of Maintenance

10% 2.5 0.25 3.5 0.35 2 0.2 5 0.5

Amount of Sliding Wear

20% 2.5 0.5 5 1 4 0.8 5 1

Compatibility with Hand Crank

25% 2.5 0.625 3 0.75 2.5 0.625 1 0.25

Actuator Cost

15% 2.5 0.375 1.5 0.225 2.5 0.375 1.5 0.225

Material Cost

5% 2.5 0.125 5 0.25 2.5 0.125 5 0.25

Total Score 2.5 3.575 2.975 3.375


06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page IX of XVI

Table 9: Mechanism Selection Matrix for Overall Bed Incline.

Selection Criteria Weight

Electric (Reference) Hydraulic Pneumatic

Score Weighted

Score Score

Weighted Score

Score Weighted

Score

Total Cost 20% 2.5 0.5 1 0.2 1 0.2

Safety 50% 2.5 1.25 1 0.5 1.5 0.75

Ease of Design & Analysis

15% 2.5 0.375 2 0.3 1 0.15

Availability of Space 15% 2.5 0.375 2.5 0.375 1 0.15

Total Score 2.5 1.375 1.25

BED RAILS MODIFICATION

Table 10: Concept Screening Matrix for Bed Rail Modification.

Selection Criteria

Concepts

C1 C2

(Reference) C3 C4

Weight + 0 - -

Ease of Manufacture 0 0 - 0

Size + 0 0 -

Complexity 0 0 0 -

Durability - 0 - -

Transparency 0 0 0 0

Cost + 0 + +

Sum of “+” [A] 3 0 1 1

Sum of “0“ [B] 3 8 3 2

Sum of “-” [C] 1 0 3 4

Total [A-C] 2 0 -2 -3

Rank 1 1 2 3

Selection Yes Yes No No

Table 11: Concept Scoring and Selection Matrices for Bed Rail Modifications.

Selection Criteria

Concepts

Weight C1 C2

Rate Score Rate Score

Weight 10% 4 0.40 3 0.30

Size (Thinness) 10% 4 0.40 3 0.30

Manufacturability 10% 5 0.50 4 0.40

Simplicity 20% 3 0.60 3 0.60

Durability 25% 4 1.00 4 1.00

Transparency 15% 5 0.75 5 0.75

Cost 10% 4 0.40 3 0.40

Total Score 4.05 3.75

Rank 1 2

Selection Yes No


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STORAGE

Table 12: Concept Screening Matrix for Storage.

Selection Criteria

Concepts

C1

C2 (Reference)

C3 C4

Weight + 0 + -

Ease of Manufacture

- 0 0 +

Size + 0 + -

Complexity - 0 0 0

Durability 0 0 0 0

Maintenance / Operation

- 0 + 0

Maneuverability - 0 - +

Cost - 0 0 0

Sum of “+” [A] 2 0 3 2

Sum of “0“ [B] 1 8 4 4

Sum of “-” [C] 5 0 1 2

Total [A-C] -3 0 2 0

Rank 3 2 1 2

Selection No No Yes Yes

Table 13: Concept Scoring and Selection Matrix for Storage.

Selection Criteria

Concepts

Weight C3 C4

Rate Score Rate Score

Weight 5% 5 0.25 5 0.25

Size 20% 4 0.8 5 1.0

Manufacturability 20% 5 1.0 5 1.0

Complexity 10% 4 0.4 3 0.3

Durability 10% 4 0.4 4 0.4

Maintenance / Operation

10% 2 0.2 5 0.5

Maneuverability 20% 1 0.2 4 0.8

Cost 5% 4 0.02 3 0.15

Total Score 3.37 4.4

Rank 2 1

Selection No Yes


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APPENDIX D: INVACARE 5410IVC HOSPITAL BED DATA SHEET


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06-Feb-15 EN7926-S14-P1-RPRT-00-000-0002 Page XVI of XVI

Documents

INTERIM PROGRESS REPORT - Memorial University …jmat/docs/reports/Interim Design Report.pdfincline to provide up to a 15-degree maximum incline will be accomplished via a slider-crank