Simulation Study On Active Ambulance Stretcher.
SIMULATION STUDY ON ACTIVE AMBULANCE STRETCHER
ADNAN BIN HASSAN
This report is presented in
Partial fulfillment of the requirements for the
Degree of Bachelor of Mechanical Engineering (Automotive)
Faculty of Mechanical Engineering Universiti Teknikal Malaysia Melaka
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I have read this thesis and from my opinion this thesis
is sufficient in aspects of scope and quality for awarding Bachelor of Mechanical Engineering (Automotive)
Signature : ……….
Name of Supervisor I : ……….
Date : ……….
Signature : ……….
Name of Supervisor II : ……….
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“I declare this report is on my own work except for summary and quotes that I have mentioned its sources”
Signature : Name of Author :
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ACKNOWLEDGEMENT
I am greatly to ALLAH SWT on His blessing for making this research successful.
I am sincerely appreciative to my lecturer, Mr. Mohd. Hanif Bin Harun for serving as my supervisor and for providing guidance while conducting the research and the writing of this Projek Sarjana Muda (PSM).
I would like to thank everyone who involved directly and indirectly in this project. The sacrifice and commitment given towards me earning my bachelor’s degree are indescribable and without them, this PSM thesis would have been impossible.
Finally, thank you my colleagues at the Faculty of Mechanical Engineering, UTeM for providing an enjoyable research environment.
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ABSTRACT
The aims of this research are to establish to non-linear mathematical model and active control technique of the hydraulically actuated active suspension system for a full stretcher ambulance ride model. It is characterized by a special-purpose 3-degree of freedom parallel structure. This compact mechanical architecture is able to compensate the shocks caused by road unevenness while performing pitch and roll rotations during accelerating, braking and curving phases. Stretcher loading and unloading operations have been considered. Direct and inverse kinematics and control strategy are discussed, and the system effectiveness is shown by simulation results. A simulation study is performed to proof the effectiveness and active control approach. The result thus compared with the passive suspension system. The simulation will be performed in MATLAB Simulink. The purpose of this research is not to create a better suspension, but to investigate how active control can improve ambulance stretcher ride and also to reduce this undesirable effect of the input vibration from road and driving behavior. A theoretical model of two-dimensional active control for ambulance stretcher suspension is proposed. Numerical calculations are carried out to examine the effectiveness of active control strategy, which is synthesized to minimize the mean square vertical and pitching response whilst considering the relative displacement of stretcher suspension. It shows that the active control with disturbance feed forwarded provides significant reduction of vertical and pitch angular acceleration of stretcher compared with the passive stretcher suspension. The relative displacement and resonance peak values of vibration components in the sensitive frequency range of human body are effectively suppressed in comparison with the passive stretcher.
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ABSTRAK
Kajian ini bertujuan mengetengahkan model matemetik tak linear dan teknik kawalan aktif dalam pemodelan dan kawalan ke atas gantungan aktif dengan dinamik hiraulik untuk model pengusung ambulan. Ianya berpandukan ciri-ciri yang digunakkan pada 3-darjah kebebasan rangka selari. Melalui senibina mekanikal kompleks, gegaran yang terhasil daripada ketidakrataan permukaan jalan raya ketika berlakunya situasi kecondongan, kegolekkan semasa memecut, membrek dan pada tahap kelengkungan. Proses menurunkan dan menaikkan beban pada usungan ambulan. Perulangbalikan kinematik dan strategi kawalan dibincangkan, dan sistem keberkesanan ditunjukkan dalam keputusan simulasi. Kajian simulasi dilakukan untuk membuktikan keberkesanan dan perkaitan sistem kawalan aktif. Hasil kajian kemudiannya dibandingkan dengan sistem kawalan pasif. Simulasi akan dijalankan mengunakan (Matlab Simulink). Tujuan kajian ini dijalankan bukannya untuk membina suatu sistem gantungan yang baik, tetapi menyiasat bagaimana kawalan aktif ini dapat meningkatkan pemanduan pada usungan ambulan serta mengurangkan kesan yang tidak diinginkan daripada gegaran dari keadaan jalan dan tingkah laku permanduan. Model teori dua-dimensi dicadangkan bagi sistem gantungan gantungan pada usungan ambulan. Pembentukan persamaan saringan berkadar dengan masa dikembangkan bagi melangkapkan anggaran kepada ganguan dinamik. Pekiranan nombor di bawa keluar untuk menyelidiki keberkesanan strategi kawalan akif, yang mana dapat mengurangkan purata seimbang pada keadaan lurus dan kecondongan semasa mempertimbangkan sesaran relatif penggantungan usungan. Ia menunjukkan yang kawalan aktif dengan suapan gangguan dihantar bagi menyediakan pengurangan signifikasi tegak dan pecutan sudut kecondongan usungan berbanding dengan usungan gantungan pasif. Sesaran relatif dan nilai-nilai puncak gema bahagian-bahagian getaran dalam julat frekuensi sensitif badan manusia adalah berkesan dalam perbandingan dengan usungan pasif.
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CONTENTS
CHAPTER TITLE PAGE NUMBER
CONFESSION ii
DECLARATION iii
DEDICATION iv
ACKNOWLEDGEMENT v
ABSTRACT vi
CONTENTS viii
LIST OF FIGURES xi
LIST OF TABLES xiii
LIST OF SYMBOLS xiv
CHAPTER I INTRODUCTION
1.1Background study 1
1.2Project Scope 2
1.3Researcher Objectives 2
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ix 1.5Structure and Layout of
Report 1.6Gantt Chart
3
4
CHAPTER II LITERATURE REVIEW
2.0 Introduction 6
2.1Suspension System 7
2.1.1 The passive
suspension system
8
2.1.2 Semi-Active
Suspension System
9
2.1.3 Active Suspension System
10
2.2 Pervious Study of Active Control System
12
2.3 Modeling with Simulink 18
2.4 PI Control 19
CHAPTER III METHODOLOGY
3.1 Introduction 20
3.2 Flow Chart 20
3.3 Equation of Motion
Modeling using MATLAB
23
3.3.1 Ambulance
Stretcher Ride Model
23
3.3.2 Theoretical Calculation
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x 3.3.3 Equation balance
unsprung mass
24
3.3.4 Full ride Model Integrated control (3 DOF)
26
3.3.5 Equation of Decoupling Transformation
28
3.3.6 Reference Data 29
3.4 Ambulance stretcher concept design
30
3.4.1 Controller Design 30 3.4.2 Ziegler-Nicholas
Method
35
3.5 Simulink Modeling 36
3.5.1 Design of Active suspension system
39
CHAPTER IV RESULTS & DISCUSSION 42
CHAPTER V CONCLUSION AND
SUGGESTION
53
REFERENCE 57
BIBLIOGRAPHY 60
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LIST OF FIGURES
No. TITLE PAGE
2.1 Ambulance stretcher 6
2.2 The passive suspension system 8
2.3 Semi-Active Suspension System 9
2.4 A Skyhook Damper 10
2.5 A low bandwidth or soft active suspension system 11 2.6 A high bandwidth or stiff active suspension system 11
2.7 Matlab Simulink 18
3.1 Project Process Flow Chart 22
3.2 Stretcher Ride Model for Passive System 23
3.3 Sprung Mass Free Body Diagram 24
3.4 Free body diagram of pitching 25
3.5 Free body diagram of rolling 25
3.6 Schematic diagrams for ride model active suspension system 26
3.7 Pitching of ambulance stretcher 27
3.8 Rolling of ambulance stretcher 27
3.9 Ambulance Stretcher 30
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No. TITLE PAGE
3.11 Side view of ambulance stretcher 31
3.12 Side front view of ambulance stretcher 31 3.13 Tray height of ambulance stretcher 32 3.14 Active control suspension ambulance stretchers 32 3.15 A block diagram of a PID controller 33
3.16 Ziegler–Nichols Tuning Rule 35
3.17 Example of trajectory compensation 36 3.18 Design of Simulink by using Matlab Simulink 37 3.19 Ride model schematic for passive stretcher system 38 3.20 Ride model schematic for Active stretcher system 39 3.21 Active Ambulance Stretcher Subsystem 40 4.1 The vertical body displacements of passive and active (case1) 43 4.2 The vertical body acceleration of passive and active (case1) 44 4.3 The pitching acceleration of passive and active (case1) 44 4.4 The vertical body displacements of passive and active (case 2) 46 4.5 The Body Acceleration of passive and active (case 2) 47 4.6 The Roll angle of passive and active ambulance stretcher (case2) 47 4.7 The vertical body displacements of passive and active (case 3) 47 4.8 The vertical body acceleration of passive and active (case 3) 50 4.9 The roll angle of passive and active (case 3) 50
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No. TITLE PAGE
4.10 The vertical displacements of passive and active (case 4) 52 4.11 The vertical displacements of passive and active (case 4) 53 4.12 The vertical displacements of passive and active (case 4) 53
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LIST OF TABLE
No. TITLE PAGE
1 List of parameters 30
2 Reduction in Peak Value in deferent parameters (case 1) 45 3 Reduction in Peak Value in deferent parameters (case 2) 48 4 Reduction in Peak Value in deferent parameters (case 3) 51 5 Reduction in Peak Value in deferent parameters (case 4) 54
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LIST OF SYMBOLS
a = Distance of sprung mass C.G. from front axle b = Distance of sprung mass C.G. from rear axle
= Front left suspension damping coefficient = Front right suspension damping coefficient = Rear left suspension damping coefficient = Rear right suspension damping coefficient = Front left suspension force
= Front right suspension force = Rear left suspension force = Rear right suspension force = Front left spring force = Front right spring force = Rear left spring force = Rear right spring force = Front left damper force = Front right damper force
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= Rear left damper force = Rear right damper force h = Height of vehicle C.G.
= Pitch moment of inertia = Roll moment of inertia
= Front left suspension stiffness = Front left suspension stiffness = Rear left suspension stiffness = Rear right suspension stiffness = Front left tire stiffness
= Front right tire stiffness = Rear left tire stiffness = Rear right tire stiffness
= Distance of vehicle C.G. from front axle = Distance of vehicle C.G. from rear axle
= Sprung mass
= Front left unsprung mass = Front right unsprung mass = Rear left unsprung mass = Rear right unsprung mass w = Track width
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= Front left road profile
= Front right road profile
= Rear left road profile
= Rear right road profile
= Sprung mass vertical acceleration at body C.G. = Front left sprung mass displacement
= Front left sprung mass velocity
= Front right sprung mass displacement = Front right sprung mass velocity
= Rear left sprung mass displacement = Rear left sprung mass velocity
= Rear right sprung mass displacement
= Rear right sprung mass velocity = Rear left sprung mass displacement
= Front left unsprung mass vertical displacement
= Front left unsprung mass vertical velocity
= Front left unsprung mass vertical acceleration
= Front right unsprung mass vertical displacement
= Front right unsprung mass vertical velocity
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= Rear left unsprung mass vertical displacement
= Rear left unsprung mass vertical velocity
= Rear left unsprung mass vertical acceleration
= Rear right unsprung mass vertical displacement
= Rear right unsprung mass vertical velocity
= Rear right unsprung mass vertical acceleration
= Pitch angle at the body C.G. = Pitch rate at the body C.G.
= Pitch acceleration at the body C.G. = Roll angle at the body C.G.
= Roll rate at the body C.G.
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CHAPTER I
INTRODUCTION
1.1 Project Background
For seriously injured patients the ambulance transport is often very dangerous. During about 10% of journeys some patient deterioration occurs. In order to avoid this risk, it’s often necessary to remarkably reduce the ambulance speed, but obviously this also may be dangerous. The most harmful vibrations to patients lying down are between about 2 and 8 Hz, close to the natural frequency of the human body. The vibrations caused by the road unevenness and transmitted through the vehicle suspensions are quite strong in this frequency range; the use of a device to isolate the patient can bring important benefits. Moreover, also the accelerations due to the ambulance trajectory (curves and speed variations) are harmful to patients (Source L.E. Bruzzone and R.M. Molfino, 2003).
For this project I am using Matlab SIMULINK to design mechanism of the active ambulance stretcher of ambulance for full car model. The block diagrams are drawn in Matlab Simulink based on the full car model according to the parameters. The block diagrams will drawn from the car model which was consider on body, damper, spring, actuator and wheel and describes of the Active Ambulance Stretcher, including
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2 control system design and performance evaluation. From the results of driving experiments and simulation, it shows that the Active Ambulance Stretcher is able to reduce the vibration acting on a patient.
1.2 Scope
The objective of this project is to propose control mechanism of the active ambulance stretcher for ambulance in Malaysia.
1.3 ResearchObjective
MATLAB Simulink Software will be chosen as a computer design tools used to simulate the dynamics behavior and evaluate the performance of the control structure. The research methodology implemented in this project takes the following steps of works: literature review on related fields, study some previous works and the latest development on active ambulance stretcher, development of equation of motion, simulation and comparison with the passive system.
The Active Suspension System is divided into three main categories: • Study about software called SIMULINK
• To study about passive suspension system in full stretcher ambulance ride model. • To study about active suspension system in full stretcher ambulance ride model. • To do the comparative study between passive suspension and active suspension. • To simulate the system using software called SIMULINK.
1.4 Problem Statement
An ambulance transfer service is required to take a patient to hospital as quickly and safely as possible. However, it is difficult to meet this requirement since there is
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3 essentially a trade-off between quickness and safety, quick transportation exposes a patient to large vibration acceleration or inertial acceleration, which causes strong pain, feeling of discomfort or sometimes critical damage for seriously injured persons. It is possible to reduce the acceleration by driving an ambulance carefully, but it usually results in a longer delay until hospital arrival.
Passive control method has a disadvantage of disturbance rejecting when used to control suspension system. Active control is believed can give a better control for active suspension system in term of maintaining a smooth drives for the drivers. The pneumatic tire is the first line of defenses and is the most important of all the suspension mediums.
1.5 Structure and Layout of Report
This project work towards developing active suspension and passive suspension for quarter car, using Matlab Simulink is presented in five chapters. As the development progress can be divided in to 5 main categories.
The first chapter introduces the active suspension system and details the problem statement and objective of this project.
The second chapter reports on the review of literature on passive and active suspension system that inspires the scope of the present report.
Chapter three proposes a method of design of the system in software by using Matlab Simulink software.
Chapter four, deals with result and discussion of active suspension system’s operation and design. Application of this suspension is also discussed. A compressive summary of the project efforts and the conclusions derived from this project work is presented in chapter five. Constraints and future research potential of the passive and active suspension system are also presented.
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4
Gantt chart for PSM I
NO. TASK
WEEK
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Confirming title 2 Literature review 3 Collect The Data
From Previous Study 4 Solving problems 7 Collecting raw data
from the actual ambulance stretcher 8 Preparation of
progress report
9
Develop mathematical equation 10 Ambulance
stretcher concept design
11 Preparation on technical report 12 Edit technical report 13 Submission of
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5
Gantt chart for PSM II
NO. TASK
WEEK
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 Survey form/questionnaire
2 Simulation passive and active suspension
3 Comparison results
4 Discussion of comparison results
5 Validation results
6 Preparation on technical repot
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6
CHAPTER II
LITERATURE REVIEW
2.0 Introduction
Basicaly the ambulance stretcher is very basic stracture to carry out the patient. It may be dangerous trauma to the patient with the accelerations due to a fast ambulance journey. A special active control system, interposed between the ambulance frame and the stretcher, and a possible control strategy have been designed in order to compensate the road profile and the accelerations due to the ambulance trajectory. In order to avoid this risk, it’s often necessary to remarkably reduce the ambulance speed, but obviously this also may be dangerous.
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CHAPTER I
INTRODUCTION
1.1 Project Background
For seriously injured patients the ambulance transport is often very dangerous. During about 10% of journeys some patient deterioration occurs. In order to avoid this risk, it’s often necessary to remarkably reduce the ambulance speed, but obviously this also may be dangerous. The most harmful vibrations to patients lying down are between about 2 and 8 Hz, close to the natural frequency of the human body. The vibrations caused by the road unevenness and transmitted through the vehicle suspensions are quite strong in this frequency range; the use of a device to isolate the patient can bring important benefits. Moreover, also the accelerations due to the ambulance trajectory (curves and speed variations) are harmful to patients (Source L.E. Bruzzone and R.M. Molfino, 2003).
For this project I am using Matlab SIMULINK to design mechanism of the active ambulance stretcher of ambulance for full car model. The block diagrams are drawn in Matlab Simulink based on the full car model according to the parameters. The block diagrams will drawn from the car model which was consider on body, damper, spring, actuator and wheel and describes of the Active Ambulance Stretcher, including
(2)
control system design and performance evaluation. From the results of driving experiments and simulation, it shows that the Active Ambulance Stretcher is able to reduce the vibration acting on a patient.
1.2 Scope
The objective of this project is to propose control mechanism of the active ambulance stretcher for ambulance in Malaysia.
1.3 ResearchObjective
MATLAB Simulink Software will be chosen as a computer design tools used to simulate the dynamics behavior and evaluate the performance of the control structure. The research methodology implemented in this project takes the following steps of works: literature review on related fields, study some previous works and the latest development on active ambulance stretcher, development of equation of motion, simulation and comparison with the passive system.
The Active Suspension System is divided into three main categories: • Study about software called SIMULINK
• To study about passive suspension system in full stretcher ambulance ride model. • To study about active suspension system in full stretcher ambulance ride model. • To do the comparative study between passive suspension and active suspension. • To simulate the system using software called SIMULINK.
1.4 Problem Statement
An ambulance transfer service is required to take a patient to hospital as quickly and safely as possible. However, it is difficult to meet this requirement since there is
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essentially a trade-off between quickness and safety, quick transportation exposes a patient to large vibration acceleration or inertial acceleration, which causes strong pain, feeling of discomfort or sometimes critical damage for seriously injured persons. It is possible to reduce the acceleration by driving an ambulance carefully, but it usually results in a longer delay until hospital arrival.
Passive control method has a disadvantage of disturbance rejecting when used to control suspension system. Active control is believed can give a better control for active suspension system in term of maintaining a smooth drives for the drivers. The pneumatic tire is the first line of defenses and is the most important of all the suspension mediums.
1.5 Structure and Layout of Report
This project work towards developing active suspension and passive suspension for quarter car, using Matlab Simulink is presented in five chapters. As the development progress can be divided in to 5 main categories.
The first chapter introduces the active suspension system and details the problem statement and objective of this project.
The second chapter reports on the review of literature on passive and active suspension system that inspires the scope of the present report.
Chapter three proposes a method of design of the system in software by using Matlab Simulink software.
Chapter four, deals with result and discussion of active suspension system’s operation and design. Application of this suspension is also discussed. A compressive summary of the project efforts and the conclusions derived from this project work is presented in chapter five. Constraints and future research potential of the passive and active suspension system are also presented.
(4)
Gantt chart for PSM I
NO. TASK
WEEK
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Confirming title 2 Literature review 3 Collect The Data
From Previous Study 4 Solving problems 7 Collecting raw data
from the actual ambulance stretcher 8 Preparation of
progress report
9
Develop mathematical equation 10 Ambulance
stretcher concept design
11 Preparation on technical report 12 Edit technical report 13 Submission of
(5)
Gantt chart for PSM II
NO. TASK
WEEK
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 Survey form/questionnaire
2 Simulation passive and active suspension
3 Comparison results
4 Discussion of comparison results
5 Validation results
6 Preparation on technical repot
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CHAPTER II
LITERATURE REVIEW
2.0 Introduction
Basicaly the ambulance stretcher is very basic stracture to carry out the patient. It
may be dangerous trauma to the patient with the accelerations due to a fast ambulance
journey. A special active control system, interposed between the ambulance frame and the stretcher, and a possible control strategy have been designed in order to compensate the
road profile and the accelerations due to the ambulance trajectory. In order to avoid this
risk, it’s often necessary to remarkably reduce the ambulance speed, but obviously this also may be dangerous.