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VISVESVARAYA TECHNOLOGICAL UNIVERSITY

BELGAUM-590014

A Project Report

On

“Automated Prosthetic Leg”

A project report submitted in partial fulfilment of the requirements for the award of the

degree of Bachelor of Engineering in Mechanical and Engineering of Visvesvaraya

Technological University, Belgaum.

Submitted by: ABHILASH P 1AM13ME004

ANUSHA P S 1AM13ME025

VENKATESH PAVAN M 1AM13ME078

PURUSHOTHAMA J 1AM13ME060

Under the Guidance of:

Prof. MADHU MOHAN R

(Asst.Prof, Dept of MECH)

&

Dr. GRISHA C

(HOD, Dept of MECH)

Department of Mechanical Engineering

AMC Engineering College, 18th K.M, Bannerghatta Main Road, Bangalore-560 083

2016-2017

AMC Engineering College, 18th K.M, Bannerghatta Main Road, Bangalore-560 083

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

This is to certify that the technical seminar work entitled

“Automated Prosthetic Leg” has been successfully carried out by Mr. ABHILASH P

(1AM13ME004), Ms. ANUSHA P S (1AM13ME025), Mr. VENKATESH PAVAN M

(1AM13ME078), and Mr. PURUSHOTHAMA J(1AM13ME060), bonafide students of

AMC Engineering College in partial fulfilment of the requirements for the award of degree

in Bachelor of Engineering in Mechanical Engineering of Visvesvaraya Technological

University, Belgaum during academic year 2016-2017. It is certified that all

corrections/suggestions indicated for Internal Assessment have been incorporated in the report

deposited in the departmental library. The project report has been approved as it satisfies the

academic requirements in respect of project work for the said degree.

Guide:

Prof. MADHU MOHAN R

(Asst.Prof, Dept of MECH)

&

Dr. GRISHA C

(HOD, Dept of MECH)

Dr. Girisha C Dr. T. N. Sreenivasa

(HOD, Dept. of MECH) (Principal, AMCEC)

Examiners: Signature with Date

1.

2.

ACKNOWLEDGEMENT

The satisfaction and euphoria that accompany the successful completion of any task would be

incomplete without mentioning number of individuals whose professional guidance and

encouragement helped us in successful completion of this report work.

I am glad to express my gratitude towards my prestigious institution AMC

ENGINEERING COLLEGE for providing me utmost knowledge, encouragement and the

maximum facilities in undertaking this project.

I have a great pleasure in expressing my deep sense of gratitude to the Founder

Chairman, Dr. Paramahamsa K. R. for having provided me with a great infrastructure and all

well-furnished labs.

I take this opportunity to express my profound gratitude to the principal Dr. T. N.

Sreenivasa, AMCEC for his constant support and encouragement.

I wish to express my deepest gratitude and special thanks to Dr. Girisha C,

H.O.D, Dept. of Mechanical Engineering, for all her guidance and encouragement.

ABHILASH P (1AM13ME004)

ANUSHA P S (1AM13ME025)

VENKATESH PAVAN M (1AM13ME078)

PURUSHOTHAMA J(1AM13ME060)

ABSTRACT

A prosthetic is an add-on that is provided to the amputees, replacing the missing limb. This

helps the patient to perform the day to day activities. Prosthetics are available only for

patients with amputated limbs, while patients with dysfunctional lower limbs use the help of

crutches or wheelchairs.

This requires a lot of upper body strength to travel. An automated prosthetic leg helps

patients to move around with dysfunctional limbs without that limb being amputated.

With the use of electromechanical devices and sensors, the movement the patient is

controlled based on the motion of the functional limb

TABLE OF CONTENTS

CHAPTER NO. TITLE PAGE NO.

ABSTRACT iii

LIST OF TABLES xiii

LIST OF FIGURES xiv

LIST OF SYMBOLS AND ABBREVIATIONS xvii

1 INTRODUCTION 1

1.1 Prosthetics 1

1.2 History 2

1.3 Polio 3

2 LITERATURE SURVEY 5

2.1 History of Lower extremity 5

2.2 Advancements 7

2.2.1 Myoelectric Prosthesis 7

2.2.2 Direct Skeletal Attachment 7

2.2.3 Stump and Stock Method 8

2.2.4 Microprocessor Control 8

2.3 Polio 8

2.4 Current Situation 10

3 CONCEPTS 11

3.1 Concept Generation 11

3.1.1 Concept 1 12

3.1.2 Concept 2 14

3.1.3 Concept 3 15

3.1.4 Concept 4 17

3.1.5 Concept 5 19

3.1.6 Concept 6 22

3.2 Concept Screening and Scoring 25

4 METHODOLOGY 26

4.1 Components Involved 27

4.2.1 Relay 27

4.2.2 MOSFET 27

4.2.3 Flex Sensor 27

4.2.4 Linear Actuator 28

4.2.5 Lithium Polymer Battery 28

4.2.6 Pylon 29

4.2.7 Socket 29

4.2 Software 29

5 MECHANICAL COMPONENTS 30

5.1 Socket 30

5.2 Prosthetic foot 31

5.3 Sleeve 32

5.4 Pylon 33

6 HARDWARE AND ALGORITHM 36

6.1 Hardware 36

6.1.1 Flex Sensor 36

6.1.2 Relays 38

6.1.3 Linear Actuator 40

6.1.4 MOSFET 42

6.1.5 Lithium Polymer Battery 43

6.2 Circuit Diagram 44

6.3 Algorithm 45

7 CONSTRUCTION 47

7.1 Pylon Rod 47

7.2 Tibia to Knee Connector 48

7.3 Hexagonal Nut 49

7.4 Cup Catcher 49

7.5 Cup support 50

7.6 Link 51

7.7 Bolt 52

7.8 Double ended screw 53

7.9 Knee joint 53

7.10 Socket 54

7.11 Foot 54

7.12 Linear Actuator 55

7.13 CAD Model views 56

8 ASSEMBLY PROCESS 58

9 TESTING 62

9.1 CAD Analysis 63

9.2 Results 63

9.2.1 Displacement 63

9.2.2 Strain 64

9.2.3 Reaction Forces 64

9.2.4 Von Mises Stresses 65

10 ADVANTAGES AND DISADVANTAGES 66

10.1 Advantages 66

10.2 Disadvantages 66

11 RESULTS AND DISCUSSIONS 67

12 CONCLUSION 68

13 SCOPE OF FUTURE WORK 69

14 REFERENCES 70

15 CASE STUDY 72

LIST OF TABLES

TABLE NO. TITLE PAGE NO.

3.1 Concepts and their Ranks 25

4.1 Specifications of Relay 27

4.2 Specifications of Linear Actuator 28

4.3 Specification of Lithium Polymer Battery 28

9.1 Cup angle and linear actuator position 62

11.1 Cost Analysis 67

LIST OF FIGURES

FIGURE

NO.

TITLE PAGE

NO.

1.1 Evolution 2

1.2 Paralytic poliomyelitis 4

2.1 Egyptian toes 5

2.2 Ancient prosthetic 6

2.3 Evolution of prosthetic 7

2.4 Polio virus case :1995-2012 9

2.5 Polio case in India 9

FIGURE

NO.

TITLE PAGE

NO.

2.6 Alternatives 10

3.1 Concept 1 12

3.2-3.3 Concept 1 13

3.4-3.5 Concept 2 14

3.6-3.7 Concept 3 15

3.8 Concept 3 16

3.9 Concept 4 17

3.10 Concept 4 18

3.11 Concept 5 19

3.12 Concept 5 20

3.13 Concept 5 21

3.14 Concept 6 22

3.15 Concept 6 23

3.16 Concept 6 24

5.1 Socket 30

5.2 Prosthetic foot 32

5.3 Sleeve 33

5.4 Pylon 34

6.1(a)-

6.1(b)

Flex sensor And resistance change 36

6.2 Relay 39

6.3(a) Linear actuator 40

6.3(b) Graph 41

6.4 MOSFET 42

6.5 Li-Po battery 43

6.6 Circuit 44

7.1 Pylon rod 47

7.2 Knee mechanism 48

7.3 Hexagonal nut 49

7.4-7.5 Cup support 50

7.6 Link 51

7.7 Bolt 52

7.8-7.9 Double ended screw and knee joint 53

7.10 Socket 54

7.11-7.12 Foot and liner actuator 55

7.13-7.14 Assembly isometric view and assembly back view 56

7.15-7.16 Assembly rear and assembly side view 57

7.17-7.18 Assembly front view and exploded view 58

9.1 Displacement analysis 64

9.2 Strain analysis 65

9.3 Reaction analysis 65

9.4 Von Mises stress 66

Automated Prosthetic Leg 2016-17

Mechanical Engineering, AMC Engineering College 1

Chapter 1

INTRODUCTION

1.1 PROSTHETICS:

A prosthesis is an artificial device that replaces a missing body part, which may be lost through

trauma, disease, or congenital conditions.

TYPES OF PROSTHESIS:

Upper extremity prostheses are used at varying levels of amputation: forequarter, shoulder

disarticulation, transhumeral prosthesis, elbow disarticulation, transradial prosthesis, wrist

disarticulation, full hand, partial hand, finger, partial finger.

A transradial prosthesis is an artificial limb that replaces an arm missing below the elbow. Two

main types of prosthetic devices are available. Cable operated limbs work by attaching a harness

and cable around the opposite shoulder of the damaged arm. The other form of prosthetic devices

available is myoelectric arms. These work by sensing, via electrodes, when the muscles in

the upper arm move, causing an artificial hand to open or close. In the prosthetics industry, a trans-

radial prosthetic arm is often referred to as a "BE" or below elbow prosthesis.

Lower-extremity prostheses provide replacements at varying levels of amputation. These

include hip disarticulation, transfemoral prosthesis, knee disarticulation, transtibial

prosthesis, Syme's amputation, foot, partial foot, and toe. The two main subcategories of

lower extremity prosthetic devices are trans-tibial and trans-femoral.

A transfemoral prosthesis is an artificial limb that replaces a leg missing above the knee.

Transfemoral amputees can have a very difficult time regaining normal movement this is

due to the complexities in movement associated with the knee. In the prosthetics industry,

a trans-femoral prosthetic leg is often referred to as an "AK" or above the knee prosthesis.

https://en.wikipedia.org/wiki/Myoelectric

https://en.wikipedia.org/wiki/Arm



A transtibial prosthesis is an artificial limb that replaces a leg missing below the knee. A transtibial

amputee is usually able to regain normal movement more readily than someone with a transfemoral

amputation, due in large part to retain the knee, which allows for easier movement. Lower

extremity prosthetics describes artificially replaced limbs located at the hip level or lower. In the

prosthetics industry, a trans-tibial prosthetic leg is often referred to as a "BK" or below the knee

prosthesis.

1.2 HISTORY:

Figure 1.1

Prosthetics have been mentioned throughout history. The earliest recorded mention is the warrior

queen Vishpala in the Rigveda. The Egyptians were early pioneers of the idea, as shown by the

wooden toe found on a body from the New Kingdom. An early mention of a prosthetic comes from

the Greek historian Herodotus, who tells the story of Hegesistratus,

Pliny the Elder also recorded the tale of a Roman general, Marcus Sergius, whose right hand was

cut off while campaigning and had an iron hand made to hold his shield so that he could return to

battle. A famous and quite refined historical prosthetic arm was that of Götz von Berlichingen,

made at the beginning of the 16th century. The first confirmed use of a prosthetic device, however,

https://en.wikipedia.org/wiki/Vishpala

https://en.wikipedia.org/wiki/Rigveda

https://en.wikipedia.org/wiki/New_Kingdom

https://en.wikipedia.org/wiki/Herodotus

https://en.wikipedia.org/wiki/Hegesistratus

https://en.wikipedia.org/wiki/Pliny_the_Elder

https://en.wikipedia.org/wiki/Marcus_Sergius

https://en.wikipedia.org/wiki/Iron_hand_(prosthesis)

https://en.wikipedia.org/wiki/G%C3%B6tz_von_Berlichingen



is from 950–710 BCE. In 2000, research pathologists discovered a mummy from this period buried

in the Egyptian necropolis near ancient Thebes that possessed an artificial big toe. This toe,

consisting of wood and leather, exhibited evidence of use. When reproduced by biomechanical

engineers in 2011, researchers discovered that this ancient prosthetic enabled its wearer to walk

both barefoot and in Egyptian style sandals. Previously, the earliest discovered prosthetic was an

artificial leg from Capua.

Around the same time, François de la Noue is also reported to have had an iron hand, as is, in the

17th Century, René-Robert Cavalier de La Salle. During the Middle Ages, prosthetic remained

quite basic in form. Debilitated knights would be fitted with prosthetics so they could hold up a

shield, grasp a lance or a sword, or stabilise a mounted warrior. Only the wealthy could afford

anything that would assist in daily life. During the Renaissance, prosthetics developed with the use

of iron, steel, copper, and wood. Functional prosthetics began to make an appearance in the 1500s.

The first skeletal prosthesis attachment unit for application in humans was developed and tested

in three patients—above-knee and above-elbow.amputees—at Rancho Los Amigos Hospital

(RLAH, Downey, CA). The device had a stainless steel shaft for intramedullary implantation and

a subcutaneous collar made of unpolished carbon. The implant was cemented with

methylmethacrylate to the intramedullary canal of the bone in the amputee’s stump and then passed

through the skin. Suspension of the prosthesis was made possible with a quick disconnect device

that locks into the shaft of the implant. It was reported that all implants had to be removed within

6 months postimplantation due to chronic infection aggravated by mechanical irritation. A main

catalyst of infection was assumed to be the relative motion between the skin and the device.

1.3 Polio:

Poliomyelitis is a viral disease that often affects nerves. It can produce either a partial or complete

inability to move (paralysis). The virus that causes the disease can be spread through person-to-

person contact as well as through contact with infected bodily substances. The polio vaccine is a

way to prevent poliomyelitis.

https://en.wikipedia.org/wiki/Roman_Capua_Leg

https://en.wikipedia.org/wiki/Fran%C3%A7ois_de_la_Noue

https://en.wikipedia.org/wiki/Cavalier_de_la_Salle



Symptoms vary from mild, flu-like symptoms to life-threatening paralysis. In one to two per cent

of cases, polio affects the nerves, resulting in paralysis of the arms, legs or the diaphragm (that

controls breathing). Between two and five percent of people who develop paralytic polio will die.

Half of those who survive will have permanent paralysis.



Chapter 2

LITERATURE SURVEY

2.1 History of Lower extremity:

Socket technology for lower extremity limbs saw a revolution during the 1980s when John

Sabolich C.P.O., invented the Contoured Adducted Trochanteric-Controlled Alignment Method

(CATCAM) socket, later to evolve into the Sabolich Socket. He followed the direction of Ivan

Long and Ossur Christensen as they developed alternatives to the quadrilateral socket, which in

turn followed the open ended plug socket, created from wood. The advancement was due to the

difference in the socket to patient contact model. Prior to this, sockets were made in the shape of

a square shape with no specialised containment for a muscular tissue. New designs thus help to

lock in the bony anatomy, locking it into place and distributing the weight evenly over the existing

limb as well as the musculature of the patient. Ischial containment is well known and used today

by many prosthetists to help in patient care. Variations of the ischial containment socket thus exist

and each socket is tailored to the specific needs of the patient. Others who contributed to socket

development and changes over the years include Tim Staats, Chris Hoyt, and Frank Gottschalk.

Gottschalk disputed the efficacy of the CAT-CAM socket- insisting the surgical procedure done

by the amputation surgeon was most important to prepare the amputee for good use of a prosthesis

of any type socket design.

Fig 2.1: Egyptian toes likely to be the world’s oldest prosthetics



Fig 2.2: Ancient Prosthetics

The first microprocessor-controlled prosthetic knees became available in the early 1990s. The

Intelligent Prosthesis was the first commercially available microprocessor-controlled prosthetic

knee. It was released by Chas. A. Blatchford & Sons, Ltd., of Great Britain, in 1993 and made

walking with the prosthesis feel and look more natural. An improved version was released in 1995

by the name Intelligent Prosthesis Plus. Blatchford released another prosthesis, the Adaptive

Prosthesis, in 1998. The Adaptive Prosthesis utilised hydraulic controls, pneumatic controls, and

a microprocessor to provide the amputee with a gait that was more responsive to changes in

walking speed. Cost analysis reveals that a sophisticated above-knee prosthesis will be about $1

million in 45 years, given the only annual cost of living adjustments.



2.2 Advancements:

Over the years, there have been advancements in artificial limbs. New plastics and other materials,

such as carbon fibre, have allowed artificial limbs to be stronger and lighter, limiting the amount

of extra energy necessary to operate the limb. In addition to new materials, the use of electronics

has become very common in artificial limbs.

Fig 2.3: Evolution Of Prosthetics

2.2.1 Myoelectric prosthesis:

The myoelectric technology uses sensitive electrodes to read activity in specific muscle groups

and send signals to processing units that employ a specific function in electric motors in the

prostheses. Once it is attached, the prosthetic uses electronic sensors to detect minute muscle,

nerve, and EMG activity. It then translates this muscle activity into information that its electric

motors used to control the artificial limbs movements.

2.2.2 Direct Skeletal Attachment:

In direct skeletal attachment (DSA) of limb prostheses, a construct is implanted into an amputee’s

residuum bone and protrudes out of the residuum’s skin. This technology represents an alternative

to traditional suspension of prostheses via various socket systems, with clear indications when the

sockets cannot be properly fitted.



2.2.3 Stump and Socket method:

Most modern artificial limbs are attached to the stump of the amputee by belts and cuffs or

by suction. The stump either directly fits into a socket on the prosthetic, a liner is used that then is

fixed to the socket either by vacuum or a pin lock. The socket is custom made to fit the residual

limb and to distribute the forces of the artificial limb across the area of the stump, which helps

reduce wear on the stump. The custom socket is created by taking a plaster cast of the stump or,

more commonly today, of the liner worn over the stump, and then making a mould from the plaster

cast.

2.2.4 Microprocessor control:

To mimic the knee's functionality during gait, microprocessor-controlled knee joints have been

developed that control the flexion of the knee. A microprocessor is used to interpret and analyse

signals from knee-angle sensors and moment sensors. The microprocessor receives signals from

its sensors to determine the type of motion being employed by the amputee. Most microprocessor

controlled knee-joints are powered by a battery housed inside the prosthesis.

The sensory signals computed by the microprocessor are used to control the resistance generated

by hydraulic cylinders in the knee-joint. Small valves control the amount of hydraulic fluid that

can pass into and out of the cylinder, thus regulating the extension and compression of a piston

connected to the upper section of the knee.

2.3 Polio:

Polio (also known as poliomyelitis) is a highly contagious disease caused by a virus that attacks

the nervous system. Children younger than 5 years old are more likely to contract the virus than

any other group.

According to World Health Organization (WHO), one in two hundred polio infections will result

in permanent paralysis. However, due to the global polio eradication initiative in 1988, the

following regions are now certified polio-free:

Americas

https://en.wikipedia.org/wiki/Hydraulic_cylinders

https://en.wikipedia.org/wiki/Hydraulic_fluid



Europe

Western Pacific

Southeast Asia

The polio vaccine was developed in 1953 and made available in 1957. In 1978, the Government

of India began a vaccination program to eradicate poliomyelitis (polio), in the country, by

vaccinating all children under the age of five years against the polio virus. By 1984, it was

successful in covering around 40% of all infants in the country.

Fig 2.4 Poliovirus cases: 1995-2012

Fig 2.5 Polio Cases In India



2.4 Current Situation:

Once the polio patients are affected, they remain paralysed throughout their life. Disability due to

polio may be either partial disability or complete disability. Patients with a partial disability, such

as immobility of tibia, use walking aids for commuting. Not all patients opt for prosthesis due to

various reasons. These patients choose conventional aids such as wheelchairs or crutches. The use

of these aids requires a more of upper-body strength commuting. The effort that has to be applied

by the users, to walk, is severe. This causes both lower and upper body muscular discomfort.

Fig 2.6 Alternatives



Chapter 3

CONCEPTS

3.1 Concept Generation:

There is a need to develop a prosthetic which is a crossover between a typical prosthetic add-on

and an advanced bionic leg.

Concept generation is the main step in the course of bottoming the product. The main perspectives

of perseverance of this particular need statement are multitasking cost effectiveness ergonomics

of the prosthetic user. With respect to all the above considerations, there has been the development

of multiple generations of concepts with permutations and combinations of all possibilities of the

prosthetic designs. During the course of obtaining the strong concept customizations and trails of

material combinations are been executed as explained below. The following parameters are

considered for the process of concept generation:

1) Power Consumption 5) Complexity

2) Ergonomics 6) Compactness

3) Kerb Weight 7) Adaptability

4) Reliability 8) Cost



3.1.1 Concept 1:

Fig 3.1



Fig 3.2 Fig 3.3

In this concept, the prosthetic is controlled by the patient by the push of a button.The shaft is

eccentric to the gear axis where , the gear is driven by DC motor, the step angle achieved is very

less , the time taken to walk is more.



3.1.2 Concept 2:

Fig 3.4 Fig 3.5

The stepper motor is mounted on the patient waist, the shaft of the stepper motor is fastened to

socket and solenoid switch is placed between the socket and pylon which act as a locking

mechanism. Prolonged activation of solenoid switch increases the temperature of the switch and

battery consumed by this setup is more.



3.1.3 Concept 3:

Fig 3.6

Fig 3.7



Fig 3.8

In this concept two stepper motor is used to ease the motion of the leg, one of the motors is placed

on the waist and the second motor is placed next to patella.The alignment of the motor should be

more precise and also it should be well balanced, motor one drivers the femur and pylon are driven

by the other motor.



3.1.4 Concept 4:

Fig 3.9



Fig 3.10

The main aim of this concept is to reduce the weight and increase the holding torque of the motor.

Elimination of the motor on waist makes the setup more compact and simple to strap on to the

patient.



3.1.5 Concept 5:

Fig 3.11



Fig 3.12



Fig 3.13

By replacing stepper motor by a linear actuator, the complexity of alignment is reduced. Also, the

setup is well balanced. Unlike stepper motor, holding torque is achieved when there is no power

supply.



3.1.6 Concept 6:

Fig 3.14



Fig 3.15



Fig 3.16

The motto of this concept is to reduce the battery consumption, making the prosthetic highly

compact and more reliable.By eliminating the linear actuator which is placed on the waist reduces

the risk of back pain. Hence, the setup is actuated easily by placing the sensor on the paralysed

limb.



3.2 Concept Screening and Scoring:

SL No SELECTION

CRITERIA

CONCEPTS

01 02 03 04 05 06

1 Power

consumption

- - - 0 - +

2

Ergonomics -

- - - - 0

3 Kerb weight - 0 - 0 - -

4 Reliability - - - - 0 0

5 Complexity - - - 0 0 +

6 compactness 0 0 - + - 0

7 Adaptability - - - - - 0

8 cost - - - 0 0 +

9 +’S 0 0 0 1 0 3

10 -‘S 7 6 8 3 5 1

11 0’S 1 2 0 4 3 4

12 NET -7 -6 -8 -2 -5 2

13 RANK’S 5th 4th 6th 2nd 3rd 1st

Table 3.1: Concepts and their Ranks

NOTE: +’S for better, 0’s for moderate and –‘s for worse in respective selection criterions.

Based on the concepts, concept 6 and 4 are ranked first and second, and concept 1,2,3,4,5,6 ranked

as 5th, 4th,6th,2nd,3rd,1st rank. So concept 6 and 4 is selected for further review, improvement

and design purpose. Concept screening is used for further elimination and selection process of

concepts,

Concept 6 ranks 1st among all other concepts generated.



Chapter 4

METHODOLOGY

This is a case study and customised design in the development of economic automated prosthetic

add on whose application is real time.

The principle of operation of the prosthetic is that when the tibia of the user is tightly secured to

the fixed cup of the prosthetic, a linear actuator connecting the cup and the pylon can be actuated

by sensing the movement of the anterior of the femur thereby, by actuation the linear actuator

induces motion to the pylon. Thus, replicating the action of walking.

Prosthetics consists of a cup having the contour of the user, pylon with a joint mechanism and a

linear actuator.

The electronics consists of two 5A relays, microcontroller and two MOSFET’s.

The cup and the pylon are separated by an obtuse angle and the actuator connected to the cup and

the pylon, diagonally.

The motion of the femur is sensed by a flex sensor, placed at the pelvic joint. The resistance of the

flex sensor changes with the angle bent by the femur. The flex sensor resistance increases with

increase in the bending angle thereby decreasing the output voltage. The change in the output

voltage of the flex sensor is detected by the microcontroller.

The DC motor of the linear actuator is controlled by the microcontroller through a pair relays based

on the voltage output of the flex sensor.

When the voltage ranges from 0 to 1.85V, the microcontroller clockwise the direction of the motor

thereby retracting the arm of the actuator. If the voltage is above 1.85V, the direction of the motion

is reversed thereby extending the actuator arm. Hence, the pylon moves in relation to the femur.



4.1 Components involved:

4.1.1 RELAY:-

A relay is an electrically operated switch. Relays are used where it is necessary to control a

circuit by a separate low-power signal, or where several circuits must be controlled by one signal.

Power Supply Direct Current

Current Rating 5A

Max. switching Voltage 24V to 30V

Coil resistance 1440 ohm

Table 4.1 Specifications of relay:

4.1.2 MOSFET (Metal Oxide Semiconductor field effect transistor):

The metal oxide semiconductor field effect transistor is a type of field-effect transistor (FET).

It has an insulated gate, whose voltage determines the conductivity of the device. This ability to

change conductivity with the amount of applied voltage can be used for amplifying or switching

electronic signals.

4.1.3 Flex Sensor:

A flex sensor or bend sensor is a sensor that measures the amount of deflection or bending.

Usually, the sensor is stuck to the surface, and resistance of sensor element is varied by bending

the surface. Since the resistance is directly proportional to the amount of bend it is used as a

goniometer, and often called flexible potentiometer.



4.1.4 Linear Actuator:

A linear actuator is an actuator that creates motion in a straight line, in contrast to the circular

motion of a conventional electric motor.

Max. Load 500N

Speed 55 mm per second

Current at full Load 6A

Rated Voltage 24V

Stroke Length 100mm

Operating temperature 0 to 40 degree C

Table 4.2 Specification of Linear Actuator

Linear actuators are used in machine tools and industrial machinery, in computer peripherals such

as disk drives and printers, in valves and dampers, and in many other places where linear motion

is required.

4.1.5 Lithium Polymer Battery:

A lithium polymer battery, or more correctly lithium ion polymer battery, is a rechargeable

battery of lithium-ion technology using a polymer electrolyte instead of the more common liquid

electrolyte. High conductivity semisolid (gel) polymers form the electrolyte for LiPo cells that are

being used in tablet computers and many cellular telephone handsets.

Rated Voltage 12V

Current Rating 2200mAh

Discharge rate at max. load 25C

Table 4.3 Specification of Lithium Polymer Battery



4.1.6 Pylon:

A pylon is a member which provides the connection between the residual limb (leg stump) and the

prosthetic foot.

4.1.7 Socket:

The socket is used to contain the residual limb (amputated limb) and transfer the weight of the

body to the rest of the prosthesis, this may also contain liners to act as padding and provide

suspension.

4.2 Software:

Embedded C is a set of language extensions to the C programming language by the C Standards

Committee to address commonality issues that exist between C extensions for different embedded

systems. Historically, embedded C programming requires nonstandard extensions to the C

language in order to support exotic features such as fixed-point arithmetic, multiple

distinct memory banks, and basic I/O operations.



Chapter 5

MECHANICAL COMPONENTS

5.1 SOCKET:



suspension.

The original below-knee patellar-tendon-bearing sockets were made of plaster of paris applied

directly to the stump over a five-ply stump sock. This procedure was change& and the socket is

now made of plastic laminate shaped over a modified plaster mould. Plaster sockets were more

difficult to fit the stump of the below-knee amputee than the above-knee patient. A hard socket,

patellar-tendon-bearing prosthesis without socket insert has been satisfactory for the geriatric

amputee as well as the younger patients, as the stump sock is all that is needed to protect the bony

prominences, provided that a satisfactory total-contact fit has been obtained. It was planned

initially to add knee joints and thigh laces but these have been rarely necessary for the geriatric

patients. Most commonly, they were added for adolescent boys who required additional stability

during competitive athletics or in any patient with a very short stump.

Fig. 5.1 Socket



The plastic socket is moulded by any of the available casting methods such as hand moulding,

Northwestern Ring Suspension, or VAPC moulding plates. Specific directions are given in order

to modify the positive mould depending on which technique is followed. When the soft insert is

eliminated, the patellar tendon bar must be more prominent, and all reliefs must be feathered into

the mould to produce a smooth transition between pressure bearing and pressure relief points. The

socket is attached to a reusable below-knee adjustable aluminium.A pylon shin with a laminated

SACH foot attached. Before the temporary prosthesis is finished, a weight-bearing X-ray of the

stump in the prosthesis is made to determine the accuracy of fit. The X-ray of the leg socket unit

should show even contact between the socket and the stump

5.2 PROSTHETIC FOOT:

Another aspect of the prosthetic prescription that strongly influences comfort and function is the

stiffness of the foot-ankle system. Selection of an appropriate stiffness is primarily based on a

patient’s body weight, choice of activities, and the intensity level of those activities, but other

factors such as residual limb length, residual-limb pain, and patient sense of stability may also be

considered. Nearly all manufacturers allow the physician to choose the desired stiffness from a

variety of available components. For example, the Seattle Foot (Seattle Orthopedics Group,

Poulsbo, WA) is available in seven different keel stiffness’s, and the Flex-Foot has nine categories

of stiffness. The physician must weigh the various factors and choose a single stiffness to serve all

conditions a patient might experience.



Fig 5.2 Prosthetic Foot

An inappropriate choice of stiffness may lead to increased metabolic costs, abnormal muscle

activation patterns, and decreased gait symmetry, tissue damage associated with abnormal

residual-limb and intact-limb loading, and pain. Each of these studies describes the biological

response to prosthetic limbs with different stiffness profiles and establishes an empirical link

between a particular commercial product with an inherent but often unknown stiffness and the

observed effects on metabolic cost, muscle activation patterns, gait symmetry, and limb loading.

5.3 SLEEVE:

The liner is a protective cover made of a flexible, cushioning material. Worn over your residual

limb, it reduces movement and chafing between the skin and the socket. Liners are designed with

specific characteristics to work with different suspension systems.

Selecting the right liner helps ensure that your prosthesis fits well and is comfortable to

wear. A silicone liner provides high stability and good adhesion if your limb has a lot of soft-

tissue. It performs best with shuttle lock suspension. (“Shuttle lock suspension” means there is a

pin attached to the end of the liner which inserts into a locking mechanism in the bottom of the

socket. The lock connects your socket to your prosthesis.) Soft but resistant to pressure, silicone

is durable and easy to clean.



Fig 5.3 Sleeve

Polyurethane has a unique ability to flow away from high pressure. That means the pressure in

your socket is well distributed. A polyurethane (sometimes abbreviated as PUR) liner offers a

precise, intimate and comfortable fit for all types of residual limbs. These “flow characteristics”

and damping of pressure on your limb make it a good choice for sensitive, bony or scarred residual

limbs. Polyurethane performs best with vacuum suspension or suction suspension.

5.4 Pylon:

Pylon assembly for a leg prosthesis including an upper pylon, a lower pylon and a spring. A portion

of both the upper pylon and the lower pylon are tubular. The spring is disposed between the upper

pylon and the lower pylon inside the tubular portions. Upon assembly, the tubular portion of the

lower pylon extends at least partially inside the tubular portion of the upper pylon with the spring

extending from a plug inserted into the tubular portion of the lower pylon to a plug inserted into

the tubular portion of the upper pylon. The spring biases the lower pylon away from the upper

pylon. Compression and extension of the spring allow the lower pylon to reciprocate within the

tubular portion of the upper pylon. This reciprocation allows the leg prosthesis to simulate the

stride and cadence of a natural leg. In addition, a key may be inserted through the tubular portion

of the upper pylon and extending into a key channel cut in the external circumference of the lower

pylon. Prosthetic legs typically include what is referred to as a pylon between a prosthetic foot and

either the calf of the wearer or a prosthetic calf. The pylon is typically a metal or carbon fibre tube

that attaches to the calf and the foot. The pylon is cut to size so that it provides the proper length



between the calf and the foot. This process is time-consuming and limited in accuracy because it

requires a practitioner to manually cut the shaft to length. An additional problem with using a

single tube is that there are no means to adjust the length between the calf and the foot by the

practitioner or user is a situation arises that requires a different length. Examples are the use of

different type of shoe, use of a different prosthetic foot and physical body changes in the user.

What is needed is an adjustable pylon, which allows a faster and more accurate length adjustment

by a practitioner and could enable the practitioner or user to change the length of the pylon when

required. An adjustable pylon to be used with a prosthetic limb. The adjustable pylon including a

fixed tube having an attachment end to attach to the prosthetic limb, a receiving end, and a retainer

bulkhead with a hole. The adjustable pylon including an adjustable tube having an attachment end

to attach to the prosthetic limb, an insert end sized to fit inside the fixed tube, a threaded bulkhead

with a threaded hole inside the adjustable tube. The adjustable pylon including a length adjustment

screw including a threaded body and a centring post.

Fig. 5.4 Pylon



The width of the key channel being greater than the width of the key to allow the lower pylon to

rotate within the upper pylon. A plurality of key channels may be cut around the circumference of

the lower pylon (or interchangeable keys) each with a different width to allow variable amounts

of rotation. This variable rotation allows proper rotation for a chosen activity but restricts

undesirable excessive rotation of the lower pylon in relation to the upper pylon in order to simulate

the lateral flexibility or rotation of a natural leg.



Chapter 6

HARDWARE AND ALGORITHM

6.1 HARDWARE:

6.1.1 Flex Sensor:

This flex sensor is a variable resistor, the resistance of the flex sensor increases as the body of the

component bends. Sensors like these were used in the Nintendo Power Glove. They can also be

used as door sensors, robot whisker sensors, or a primary component in creating sentient stuffed

animals.

Flex sensor used is 4.5" (11.43cm) in length, Left flat, these sensors will look like a 10kΩ resistor.

As it bends, the resistance between the two terminals will increase to as much as 27kΩ at a 90°

angle.

By combining the flex sensor with a static resistor to create a voltage divider, you can produce a

variable voltage that can be read by a microcontroller’s analog-to-digital converter

Fig 6.1a Flex Sensor Fig 6.1b Resistance change with bending



Types of flex sensors being Conductive ink based flex sensor, fibre optic flex sensor,

Capacitive flex sensor.

Mechanical Specifications:-

Life Cycle: >1 million

Height: 4.2 inch

Temperature Range: -35°C to +80°C

Electrical Specifications:-

Flat Resistance: 25K Ohms

Resistance Tolerance: ±30%

Bend Resistance Range: 10K to 27K Ohms (at 90 degrees)

Power Rating: 0.50 Watts continuous. 1 Watt Peak

Working:

The changing length of the flex sensor results in the change in the resistance offered by the sensor

to the flow of voltage. This is due to the increasing separation between the conducting particle

which results in an increase in resistance.

Flex sensor can be tested using the following methods:

Adjustable Buffer

A potentiometer can be added to the circuit to adjust the sensitivity range.

Variable Deflection Threshold Switch

an op amp is used and outputs either high or low depending on the voltage of the inverting input.

In this way, you can use the flex sensor as a switch without going through a microcontroller.



Resistance to Voltage Converter

uses the sensor as the input of a resistance to voltage converter using a dual sided supply op-amp.

A negative reference voltage will give a positive output. Should be used in situations when you

want to output at a low degree of bending.

6.1.2 RELAYS:

Relays are switching devices used to switch higher currents and voltages. The first relays were

used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one

circuit and re-transmitted it on another circuit. Relays were used extensively in telephone

exchanges and early computers to perform logical operations.

Specifications:

Coil voltage: 12VSwitching

Voltage: 24V to 125V DC

Current: 5A max.

Operating Temperature: -10 to 50 degree C

Working:

A type of relay that can handle the high power required to directly control an electric motor or

other loads is called a contactor. Solid-state relays control power circuits with no moving parts,

instead of using a semiconductor device to perform switching. Relays with calibrated operating

characteristics and sometimes multiple operating coils are used to protect electrical circuits from

overload or faults; in modern electric power systems, these functions are performed by digital

instruments still called protective relays. A simple electromagnetic relay consists of a coil of wire

wrapped around a soft iron core, an iron yoke which provides a low reluctance path for magnetic

flux, a movable iron armature, and one or more sets of contacts (there are two contacts in the relay

pictured). The armature is hinged to the yoke and mechanically linked to one or more sets of

moving contacts. The armature is held in place by a spring so that when the relay is de-energized



there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the

relay pictured is closed, and the other set is open. Other relays may have more or fewer sets of

contacts depending on their function. The relay in the picture also has a wire connecting the

armature to the yoke.

Fig.6.2 Relay

This ensures continuity of the circuit between the moving contacts on the armature, and the circuit

track on the printed circuit board (PCB) via the yoke, which is soldered to the PCB. When

an electric current is passed through the coil it generates a magnetic field that activates the

armature, and the consequent movement of the movable contact(s) either makes or breaks

(depending upon construction) a connection with a fixed contact. If the set of contacts was closed

when the relay was de-energized, then the movement opens the contacts and breaks the connection,

and vice versa if the contacts were open. When the current to the coil is switched off, the armature

is returned by a force, approximately half as strong as the magnetic force, to its relaxed position.



6.1.3 LINEAR ACTUATOR:


motion of a conventional electric motor. Linear actuators are used in machine tools and industrial

machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and

in many other places where linear motion is required. Many other mechanisms are used to generate

linear motion from a rotating motor. Linear actuators are used in a variety of applications across

numerous industries, including medical equipment, agriculture machinery, high-voltage switch

gears, train and bus doors, and factory processes and assembly machinery. Typical end uses

include medical beds, patient lifters, wheelchairs, adjustable tables and workstations, diagnostics,

to name a few. Each linear actuator application has unique requirements.

Fig. 6.3a Linear Actuator

There are many manufacturers throughout the world that offer innumerable models of linear

actuators in a wide variety of stroke sizes, speeds, voltage and types. With the availability of so

many manufacturers, models and options, selecting the right linear actuator for your application

can be a daunting task. When a system is tailored for an application, the specific requirements will

influence both the design and the manufacturing processes. Regardless of end use, an actuation

system is designed by first identifying basic needs, then evaluating certain key parameters that

ultimately affect the overall system operation.



Specifications:

Fig 6.3b Graphs

Max. Load: 500N

Speed: 55 mm per second

Stroke: 100mm

Current at Max. Load: 6A

Duty Cycle: 2 min ‘ON’ 18 min ‘OFF’ or 20%

Operating Temperature: 0 to 40 degree C

Duty Cycle:

A duty cycle is the fraction of one period in which a signal or system is active. Duty cycle is

commonly expressed as a percentage or a ratio. The duty cycle indicates both how often an actuator

will operate and how much time there is between operations. Because the power lost to inefficiency

dissipates as heat, the actuator component with the lowest allowable temperature (usually this is

the motor) establishes the duty-cycle limit for the complete linear actuator system. Please note:

There are some heat losses from friction in a gearbox, and via ball-screw and acme-screw drive

systems. To demonstrate how the duty cycle is calculated, assume an actuator runs for 10 seconds

cumulative, up and down, and then doesn't run for another 40 seconds. The duty cycle is 10/

(40+10), or 20%. If the duty cycle is increased, either load or speed must be reduced. Conversely,

if either load or speed decreases, the duty cycle can increase. The duty cycle is relatively easy to

determine if a linear actuator is used on a machine or production device. In other, less predictable

applications or those where the linear actuator will be used infrequently, it's advisable to estimate

the worst-case scenario in order to assign a meaningful duty cycle calculation. It is not advisable



to operate on the edge of the manufacturer's power curves because this might cause the linear

actuator and other components to run too hot. However, in some applications where the duty cycle

is 10% or less, the actuator can run to the limit of its power curves.

6.1.4 MOSFET

The metal–oxide–semiconductor field-effect transistor (MOSFET) is a type of field effect

transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device.

This ability to change conductivity with the amount of applied voltage can be used for amplifying

or switching electronic signals.

The main advantage of a MOSFET is that it requires almost no input current to control the load

current when compared with bipolar transistors. In an "enhancement mode" MOSFET, the voltage

applied to the gate terminal increases the conductivity of the device. In "depletion mode"

transistors, the voltage applied to the gate reduces the conductivity.

Fig 6.4 MOSFET

The metal in the name MOSFET is now often a misnomer because the gate material is often a layer

of polysilicon (polycrystalline silicon). "Oxide" in the name can also be a misnomer, as different

dielectric materials are used with the aim of obtaining strong channels with smaller applied

voltages. A metal-insulator-semiconductor field effect transistor or MISFET is a term almost

synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect-transistor.

The MOSFET is by far the most common transistor in digital circuits, as hundreds of thousands or

millions of them may be included in a memory chip or microprocessor. Since MOSFETs can be



made with either p-type or n-type semiconductor, complementary pairs of MOS transistors can be

used to make switching circuits with very low power consumption, in the form of CMOS logic

6.1.5 Lithium Polymer Battery:

Fig 6.5 LiPo Battery

LiPos work on the principle of intercalation and de-intercalation of lithium ions from a positive

electrode material and a negative electrode material, with the liquid electrolyte providing a

conductive medium. To prevent the electrodes from touching each other directly, a microporous

separator is in between which allows only the ions and not the electrode particles to migrate from

one side to the other. The voltage of a LiPo cell depends on its chemistry and varies from about

2.7-3.0 V (discharged) to about 4.20 V (fully charged), for cells based on lithium-metal-oxides

(such as LiCoO2), and around 1.8-2.0 V (discharged) to 3.6-3.8 V (charged) for those based on

lithium-iron-phosphate (LiFePO4).

The exact voltage ratings should be specified in product data sheets, with the understanding that

the cells should be protected by an electronic circuit that won't allow them to overcharge nor over-

discharge under use.



For LiPo battery pack with cells connected in series, a specialised charger may monitor the charge

on a per-cell basis so that all cells are brought to the same state of charge (SOC).

Safety:

LiPo cells are affected by the same problems as other lithium-ion cells. This means that

overcharge, over-discharge, over temperature, short circuit, crush and nail penetration may all

result in a catastrophic failure, including the pouch rupturing, the electrolyte leaking, and fire.

All Li-ion cells expand at high levels of state of charge (SOC) or over-charge, due to slight

vaporisation of the electrolyte. This may result in delamination, and thus bad contact of the internal

layers of the cell, which in turn brings diminished reliability and overall cycle life of the cell. This

is very noticeable for LiPo’s, which can visibly inflate due to lack of a hard case to contain their

expansion.

6.2 Circuit Diagram:

Fig 6.6 Circuit



6.3 Algorithm:

What is an Algorithm?

An algorithm is an effective method that can be expressed in a finite amount of space and time and

in a well-defined formal language for calculating a function. Starting from an initial state and initial

input (perhaps empty), the instructions describe a computation that, when executed, proceeds

through a finite number of well-defined successive states, eventually producing output and

terminating at a final ending state. The transition from one state to the next is not

necessarily deterministic; some algorithms, known as randomised algorithms, incorporate random

input.

Program Algorithm:

Step 1: START

Step 2: Initializing variable ‘b’ as an integer

[Global declaration, declares a variable named b as an integer and assigns the value to zero]

Step 3: Write the speed of the motor

[The speed of the motor is set, speed of the motor being controlled by using PWM with the help

of MOSFET]

Step 4: Analog read input from the sensor through pin A0

[The value obtained from the analog input is stored in variable ‘b’]

Step 5: converting analog value to digital with help of an ADC

[Analog value is converted to digital varying from 0 to1023)

Step 6: if (b >1.85)

Activate relay 1



Else

Activate relay 2

[Relay being used for direction reversal of the DC motor]

Step 7:Goto step 4

[Loops from step 4 to step 7]



Chapter 7

CONSTRUCTION

7.1 PYLON ROD:

Pylon assembly for a leg prosthesis including an upper pylon, a lower pylon and a spring. A portion

of both the upper pylon and the lower pylon are tubular. The spring is disposed between the upper

pylon and the lower pylon inside the tubular portions.

Figure 7.1 Pylon Rod

Upon assembly, the tubular portion of the lower pylon extends at least partially inside the tubular

portion of the upper pylon with the spring extending from a plug inserted into the tubular portion

of the lower pylon to a plug inserted into the tubular portion of the upper pylon. The spring biases

the lower pylon away from the upper pylon. Compression and extension of the spring allows the

lower pylon to reciprocate within the tubular portion of the upper pylon



7.2 Tibia to Knee Connector:

The Tibia to Knee connector is used to connect the tibia and the knee of the prosthetic. The one-

half connector is a threaded shaft which is used to mate the connector and the pylon.

It acts a support for the links which are bolted to the connector. The links form the basis of the

rotation of the joint.

Figure 7.2 knee connector

Thus, the connector is the main joint between the upper and the lower pylon. The connector is

usually made from nylon. Modern day connector is made of lightweight composites to reduce the

weight of the prosthetic.



7.3 Hexagonal Nut

A hexagonal nut is a type of fastener with a threaded hole. Nuts are almost always used in

conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together

by a combination of their threads' friction (with slight elastic deformation), a slight stretching of

the bolt, and compression of the parts to be held together.

Figure 7.3: Hexagonal nut

7.4 Cup Catcher

Cup catcher is an internally threaded flat disc-like member which is used to secure the cup to the

pylon of the prosthetic. The cup of the prosthetic has a circular slot into which the cup catcher is

tightly secured.



Figure 7.4: Cup catcher

7.5 Cup Support

The cup support is placed below the cup. The threaded extension from the knuckle joint runs

through the centre of the cup support. The cup support provides a larger surface area of contact to

the cup thereby providing stability to the cup.

Figure 7.5: Cup Support



7.6 Link:

The link connects knee joint to the connector. Two out of the three links are connected with bolts

while the other link is connected by a double ended screw. The two pairs rotate about the bolt and

the other link rotates about the double ended screw.

Figure 7.6: Link



7.7 Bolt:

A bolt is a form of threaded fastener with an external male thread. Bolts are often used to make

a bolted joint. This is a combination of the nut applying an axial clamping force and also the shank

of the bolt acting as a dowel, pinning the joint against sideways shear forces. For this reason, many

bolts have a plain unthreaded shank (called the grip length) as this makes for a better, stronger

dowel. The bolts are used to hinge the links. Also, connecting the links to the knee joint.

Figure 7.7: Bolt



7.8: Double ended screw:

Double ended screw is used to connect the link to the knee joint and the connector.The link joining

knee joint and the connector rotates about the Double ended screw.

Figure 7.8: Double ended screw

7.9 Knee Joint:

The knee joint is the movable joint which is connected to the connector by three links. One end of

the knee joint is connected to the connected and the other end hinged to the links.

Figure 7.9: Knee joint



7.10 Socket:



suspension.

Figure 7.10: Socket

7.11 Foot:

Another aspect of the prosthetic prescription that strongly influences comfort and function is the

stiffness of the foot-ankle system. Selection of an appropriate stiffness is primarily based on a

patient’s body weight, choice of activities, and the intensity level of those activities, but other

factors such as residual limb length, residual-limb pain, and patient sense of stability may also be

considered. Nearly all manufacturers allow the physician to choose the desired stiffness from a

variety of available components.



Figure 7.11: Foot

7.12 Linear Actuator:


motion of a conventional electric motor. Linear actuators are used in machine tools and industrial

machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and

in many other places where linear motion is required. Many other mechanisms are used to generate

linear motion from a rotating motor.

Fig 7.12



7.13 CAD Model views:

Figure 7.13: Main Assembly Isometric view Figure 7.14: Main Assembly Back view

Figure 7.15: Main Assembly rear isometric view Figure 7.16: Main assembly side view



Figure 7.17: Main Assembly front view Figure 7.18: Exploded view



Chapter 8

ASSEMBLY PROCESS

Step 1: Connector being threaded to the pylon.

Step 2: links fastened to the connector using a nut and bolt



Step 3: Securing the remaining links to the connector using double ended screw

Step 4: Securing the upper half of the knee joint using nut and bolt



Step 5: Socket support aligned to the knee joint

Step 6: socket being held between the socket catcher and the socket support



Step 7: Foot assembled to the pylon and the linear actuator mounted diagonally between the socket

and pylon



Chapter 9

TESTING

Table 9.1 Cup angle and linear actuator position

The position of linear actuator and cup angle plays an important role , help in achieving maximum

displacement and improve in ergonomics of the prosthetic.The optimum angle and maximum

displacement achieved is tabulated and graph been plotted

SI no Angle (degrees) ‘ X’ coordinate ‘Y’ coordinate Displacement

(degrees)

1 90 25 -20 30

2 20 25 -20 18

3 30 25 -20 25

4 40 25 -20 20

5 50 25 -20 20

6 90 20 -25 18

7 20 20 -25 20

8 30 20 -25 18

9 40 20 -25 17

10 50 20 -25 15



9.1 CAD Analysis:

Impact Analysis:

Impact analysis is basically analysing the impact of the changes in the deployed application or

product. It tells us about the parts of the system that may be unintentionally affected because of

the change in the application and therefore need careful regression testing.

9.2 Results:

9.2.1 Displacement:

A displacement of 0.077mm was obtained when a load of 50 kg is applied to the pylon.

Fig 9.1 Displacement Analysis



9.2.2 Strain:

Maximum strain of 0.0017 is induced at 50 kg Load

Fig 9.2 Strain analysis

9.2.3 Reaction Forces:

Reaction Force attains a maximum value of 53.63N

Fig 9.3 Reaction Analysis



9.2.4 Von Mises Stresses:

Maximum stress generated for a load of 50 kg is 226.1MPa

Fig 9.4 Von Mises Stress



Chapter 10

ADVANTAGES AND DISADVANTAGES

10.1 ADVANTAGES:

The automated prosthetic is an affordable cross-over between pylon prosthetic and an

advanced bionic leg which makes it appeal to large masses.

The use of upper body strength is eliminated and hence walking is not as much tiring as

when crutches are used.

Power consumed for walking is considerably low as only a few power consuming

components are used.

The cup of the prosthetic add-on is custom made for every user and is lined with paddings

to support the limb. This results in comfort while walking.

The prosthetic is compact and is simple in construction.

The users can quickly adapt to walking with the prosthetic.

Elimination of amputation of the limb saves the patients from trauma and phantom pain.

This also boosts their confidence while using the device.

10.2 Disadvantages:

The weight of the device is slightly high. This causes discomfort to its users at the initial

stages.

The steps taken during walking are small due to which the time is taken to travel in slightly increased.

Cannot be used for very long distances due to the short working duration of the actuators.



Chapter 11

RESULTS AND DISCUSSIONS

Considering the polio patient, the comparison between pylon prosthetic ,automated prosthetic and

bionic prosthetic based on incurred cost.

Pylon

prosthetic

Automated

prosthetic

Bionic

prosthetic

Cost 2000rs 8000rs 50000rs>

Adaptability Yes yes no

Durable no yes yes

Table 11.1 Cost Analysis

Automated prosthetic and pylon prosthetic can be equipped to the patient .the cost , adaptability

and durability involved in this are optimum , but the pylon prosthetic lack in durability , bionic

prosthetic are expensive and are not adaptable.



Chapter 12

CONCLUSIONS

Automated prosthetic has a greater advantage over other prosthetic.Automated prosthetic lies

between low end and high end prosthetic. Manufacturing of automated prosthetic is easier,

assembly of this prosthetic can be done in a warehouse.The only specialised equipment required

is a linear actuator.By using this prosthetic ,adaptability, reduction in complexity is achieved.Thus,

the following conclusions can be drawn.

Patient need not be amputated to wear automated prosthetic

Automation of this prosthetic can be achieved without tapping neural signal

Automated prosthetic is more cost efficient



Chapter 13

SCOPE OF FUTURE WORK

The existing prosthetic can be improved by working on some parameters which are discussed

Duty cycle: Duty cycle of the linear actuator need the increased which enables the actuator to

operate for a longer period thereby helping the patient to walk for a longer time.

Battery: The battery should be more durable, by equipping the prosthetic with higher voltage

battery higher speed can be obtained, use of different type of batteries which are lighter enables

reduction in weight and net power consumption

Adaptability: The prosthetic can be made adaptable by having variable cup angle and by providing

variable length pylon, by doing so, the requirements of different cases are satisfied.

Stair climbing and sitting condition: The step angle needs to be increased and with the suitable

addition of electronics stair climbing and sitting process can be achieved.

Sensor: The delay in the response can reduce by introducing new sensor like myoware, Gyroscope

etc. A myoware sensor which is sensitive compared to other sensor and is more reliable.



Chapter 14

REFRENCES

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limbs

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Prosthetics.aspx

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http://www.hangerclinic.com/limb-loss/adult-lower-extremity/Pages/Below-knee-Prosthetics.aspx


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734678/

http://www.hindustantimes.com/health-and-fitness/india-completes-5-polio-free-years-last-case-reported-on-jan-2011/story-ZjeItJz3aea7ImdnVfCOeJ.html

http://www.hindustantimes.com/health-and-fitness/india-completes-5-polio-free-years-last-case-reported-on-jan-2011/story-ZjeItJz3aea7ImdnVfCOeJ.html

https://www.health.ny.gov/diseases/communicable/poliomyelitis/fact_sheet.htm

https://en.wikipedia.org/wiki/Actuator

http://www.thomasnet.com/articles/pumps-valves-accessories/types-of-actuators

https://en.wikipedia.org/wiki/Microprocessor

http://whatis.techtarget.com/definition/microprocessor-logic-chip

http://www.pvc.org/en/p/what-is-pvc

http://www.greenprosthetics.com/areas-of-care/prosthetics-care-for-life/lower-extremities/

http://www.greenprosthetics.com/areas-of-care/prosthetics-care-for-life/lower-extremities/

https://rogershobbycenter.com/lipoguide/

http://www.encyclopedia.com/science-and-technology/computers-and-electrical-engineering/computers-and-computing/microprocessor

http://www.encyclopedia.com/science-and-technology/computers-and-electrical-engineering/computers-and-computing/microprocessor

https://www.tutorialspoint.com/microprocessor/index.htm

https://www.elprocus.com/microprocessor-history-and-brief-information-about-its-generations/

https://www.elprocus.com/microprocessor-history-and-brief-information-about-its-generations/

http://www.androidauthority.com/lithium-ion-vs-lithium-polymer-whats-the-difference-27608/

http://www.androidauthority.com/lithium-ion-vs-lithium-polymer-whats-the-difference-27608/

https://scottiestech.info/2015/06/21/lithium-polymer-vs-lithium-ion-batteries-whats-the-deal/




https://www.sparkfun.com/datasheets/Sensors/Flex/FlexSensor.pdf

https://www.sparkfun.com/datasheets/Sensors/Flex/flex22.pdf



https://electronics.stackexchange.com/questions/207029/how-does-a-flex-sensor-

workhttp://www.rhydolabz.com/sensors-flex-force-c-137_143/flex-sensor-22-p-887.html

https://www.robomart.com/flex-and-forc

https://simple.wikipedia.org/wiki/Nylon

http://www.encyclopedia.com/sports-and-everyday-life/fashion-and-clothing/textiles-

and-weaving/nylon

http://www.oandplibrary.org/al/1969_02_043.asp

http://www.hangerclinic.com/limb-loss/adult-lower-extremity/Pages/Below-knee-

Prosthetics.aspx

Muzumdar, Ashok (2004). Powered Upper Limb Prostheses: Control, Implementation

and Clinical Application.

https://www.creativemechanisms.com/blog/3d-printing-injection-molding-cnc-nylon-

plastic-pa

https://electronics.stackexchange.com/questions/207029/how-does-a-flex-sensor-workhttp:/www.rhydolabz.com/sensors-flex-force-c-137_143/flex-sensor-22-p-887.html

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https://www.robomart.com/flex-and-forc

https://simple.wikipedia.org/wiki/Nylon

http://www.encyclopedia.com/sports-and-everyday-life/fashion-and-clothing/textiles-and-weaving/nylon

http://www.encyclopedia.com/sports-and-everyday-life/fashion-and-clothing/textiles-and-weaving/nylon

http://www.oandplibrary.org/al/1969_02_043.asp



https://www.creativemechanisms.com/blog/3d-printing-injection-molding-cnc-nylon-plastic-pa

https://www.creativemechanisms.com/blog/3d-printing-injection-molding-cnc-nylon-plastic-pa



Chapter 15

CASE STUDY

Mr Shivram, aged 35 is a resident of Mysore. He was attacked by the polio virus at the age of three

and has been partially paralysed since then. The tibia of his right leg is dysfunctional while the

femur movement can be controlled by him. Mr Shivram is currently using crutches to walk.



This project is dedicated to Mr.Shivram. Due to the use of crutches to walk he has to exert a lot of

effort while walking and requires upper body strength. Since the dysfunctional tibia of his right

leg remains bent when he walks, it has to be supported. Considering our project, his knee is made

to rest on the rigid cup and the tibia is supported on the extension of the cup. The pylon and foot

assembly helps him rest the leg on the ground. While he lifts his femur, the actuation occurs

helping him to move forward.

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