KATHMANDU UNIVERSITY
SCHOOL OF ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING
PROJECT PROPOSAL ON
DESIGN AND FABRICATION OF STAIR LIFT
Group Member
Roll. No
Supervised by:
Aavash Neupane
32091
Professor Dr. Bivek Baral
Suyog Poudel
32105
Ashesh Shrestha
32109
Prashant Bhattarai
32120
AUGUST 2023
Date: 25/08/2023
To
The Project Supervisor,
Department of Mechanical Engineering
Kathmandu University
SUBJECT: Cover Letter for proposal approval
Dear Sir,
Submitted for your review is our proposal entitled “DESIGN AND FABRICATION
OF STAIR LIFT” The report is submitted as requirement of course entitled
Engineering Project Work MEEG 312. Within this document you will find the basic
introductions, objectives, methodology and expected outcome from the proposed work
(Listed in detail in the table of content section).
We hope for your keen review and future assistance in this work along with the
approval.
Sincerely,
Aavash Neupane
Ashesh Shrestha
Prashant Bhattarai
Suyog Poudel
ii
Table of Contents
LIST OF FIGURES ...................................................................................................... IV
LIST OF TABLES ........................................................................................................ V
LIST OF ABBREVIATIONS ...................................................................................... VI
CHAPTER 1 INTRODUCTION .................................................................................... 1
1.1 Background........................................................................................................... 1
1.2 Objectives ............................................................................................................. 3
1.3 Significance .......................................................................................................... 3
1.4 Scope .................................................................................................................... 3
1.5 Limitations ............................................................................................................ 3
CHAPTER 2 METHODOLOGY ................................................................................... 4
2.1 Literature Review ................................................................................................. 4
2.2 Design Constraints................................................................................................ 7
2.3 Theoretical Framework ........................................................................................ 9
2.4 Component Survey ............................................................................................. 11
2.5 Study Design ...................................................................................................... 15
2.6 Gantt Chart ......................................................................................................... 17
CHAPTER 3 BUDGET ESTIMATION ...................................................................... 19
CHAPTER 4 EXPECTED OUTCOME ....................................................................... 20
REFERENCES ............................................................................................................. 21
iii
LIST OF FIGURES
Figure 1.1 Stair Lift ........................................................................................................ 1
Figure 1.2 Seated stair lift on a single rail ...................................................................... 2
Figure 2.1 Best Conceptual Design of Stairlift Development ........................................ 4
Figure 2.2 Schematic diagram of plant........................................................................... 5
Figure 2.3 Details of Design ......................................................................................... 10
Figure 2.4 DC Motor .................................................................................................... 11
Figure 2.5 Single Phase Induction Motor ..................................................................... 11
Figure 2.6 Proximity Sensor ......................................................................................... 12
Figure 2.7 Motor Driver ............................................................................................... 13
Figure 2.8 Flow Chart................................................................................................... 16
iv
LIST OF TABLES
Table 6.1 Component Survey ....................................................................................... 14
Table 6.2 Gantt Chart ................................................................................................... 17
Table 7.1 Budget Estimation ........................................................................................ 19
v
LIST OF ABBREVIATIONS
AC
Alternating Current
ASME
American Society of Mechanical Engineers
CAD
Computer Aided Design
DC
Direct Current
ESTRL
Energy Systems Technology and Research Laboratory
FSR
Force Sensing Resistor
HP
Horse Power
IDE
Integrated Development Environment
IOT
Internet of Things
IPL
Inclined Platform Lifts
KU
Kathmandu University
PID
Proportional Integral Derivative
VPL
Vertical Platform Lifts
IR
Infrared Sensor
IC
Integrated Circuit
vi
CHAPTER 1 INTRODUCTION
1.1 Background
The progress in technology has paved the way for disabled individuals to live
independently and contribute effectively to society. However, stairways in buildings
pose a challenge for people with mobility impairments, older adults. Various physical
obstacles or adverse conditions in private housing, general or public buildings not only
complicates the lives of the disabled/elderly people but also limits their participation in
social life. While there are existing home access solutions that enable entry and exit for
adults they do have limitations. This project aimed to create an inclusive university
access solution by combining a staircase and a lift, into one device [1].
Stairways into buildings have been reported amongst the most challenging
environmental barriers for users of wheeled mobility devices and those with mobility
limitations associated with aging. Although elevators are currently the efficient mode
of vertical transportation in terms of speed, capacity, rise and usability they do have
some drawbacks when it comes to accessibility mainly due to cost and space limitations.
There also exist scenarios where both elevators and escalators cannot be used due to
limitations in architecture. Traditional solutions to addressing home inaccessibility have
typically involved either moving to alternate housing or modifying the home to remove
accessibility barriers [2].
Figure 1.1 Stair Lift
1
On the other hand, lifts offer a more limited range of use, size, speed, capacity and rise.
There are three categories of lifts; vertical platform lifts (VPL), inclined platform lifts
(IPL) and stairway chairlifts (also known as "chairlifts"). A stairway chairlift (or "stair
lift") is a device designed for short range vertical transportation that allows seated
individuals with mobility impairments to travel on an inclined surface, like a staircase
[3].
The stairlift is transportation technology with electrical mechanical equipment to assist
vertical movements in buildings and it is used specifically and individually by the
elderly and people with disabilities. A person on the chair moves along the rail with the
help of motorized rail. A stairlift that uses a single rail as shown in Figure 1.2 Seated
stair lift on a single rail can reduce production costs as well as construction time. [4]
Figure 1.2 Seated stair lift on a single rail
2
1.2 Objectives
1.2.1 Primary Objective
•
To design a stairlift that would enable for safe travel on the stairs and railing that
were previously placed.
•
To fabricate and install the stair lift from KU ring road to the Mechanical
Engineering Department.
1.2.2 Secondary Objective
•
To demonstrate an alternative solution for old structures where a lift wasn't
feasible.
1.3 Significance
•
Stair lift is more profitable and cheaper than elevators or escalators.
•
Most effective for the disabled in homes, temples, old aged homes and many
other places.
•
Stair lifts do not require a large amount of space.
•
They can be installed on various types of stairs and easy to install.
1.4 Scope
•
Safety Features: The stair lift system would incorporate various safety features
to ensure the well-being of users.
•
For the safe design, a passenger weighing around 150 kg would be considered.
1.5 Limitations
•
Two-rail systems can be challenging to install.
•
The system may be designed primarily for straight stairs and not be suitable for
stairs with complex designs, bends or turns.
•
The seat of a stair lift wouldn't be intricately designed.
3
CHAPTER 2 METHODOLOGY
2.1 Literature Review
There are several designs and studies carried out on Stair Lift. The relevant documents
in the research of this project have been discussed below.
2.1.1 Smart Stair Lift for Disabled and Elderly
The International Journal of Pure and Applied Mathematics released an article titled
"Smart Stair Lift for Disabled and Elderly" on the creation of indoor and outdoor stair
lifts. Here, an IOT-based stairlift system was created to make it simple for elderly people
and people with physical disabilities to navigate stairs. This stair lift is powered by AC
or DC electricity and is made up of a motor, two tracks, and a sliding chair. The force
resistive sensor with the FSR406 specification is the sensor utilized in this system to
implement automation. It understands the aggregations of readings from all of the
individual force sensors after studying its behaviour. With only a little modification to
the usage of some ultrasonic sensors for obstacle detection, a more advanced system
might be put into operation [2].
2.1.2 A Novel Conceptual Design of a Stairlift for Elderly and Disabled People
Another journal article “A Novel Conceptual Design of a Stairlift for Elderly and
Disabled People” was published regarding design methods and optimization to be
followed. Among the design variants created, the result of a preliminary selection
process has been identified. The overall design process includes the problem definition,
the establishment of function structure and the assessment of design variants. A new
and innovative system has been pre-designed for the elderly/disabled to do the
comfortable transportation [5].
Figure 2.1 Best Conceptual Design of Stairlift Development
4
2.1.3 Development of an integrated staircase lift for home access
The goal of this study was to create a cutting-edge, open-access home accessibility
system that combines a stairlift and a lift into a single apparatus. A structured protocol
with stakeholder input at various phases of the design process, consistent with
rehabilitation engineering design approaches, was used to create an integrated staircase
lift. The integrated staircase lift has the following features: inclusivity, as demonstrated
by a design that offers the choice of using stairs or a lift; constant availability, as
demonstrated by a lift platform that is always available for use on either level; and
potential aesthetic benefits when the device is integrated into an existing home.
Additionally, self-powered versions and emergency descent during a power loss are
possibilities [1].
2.1.4 Attitude Control System Design of a Seated Stair Lift on a Single Rail by
Using Two-Degrees-of-Freedom Control
In this paper, a two-degrees-of-freedom control system operated by a sliding mode
controller is used to improve the overall control performance of the new stair lift. The
horizontal seating surface is controlled in real time by the use of an actuator. The sliding
mode controller achieved good ride quality in comparison with the PID controller
Figure 2.2 Schematic diagram of plant
5
because it maintained the seat surface in a horizontal position more precisely and there
was no persistent oscillation due to chattering [4].
2.1.5 Automatic sliding stair Lift for senior citizens/especially abled
Article “Automatic sliding stair Lift for senior citizens/especially abled” written in
International Advanced Research Journal in Science, Engineering and Technology
proposed a remote-controlled based system which provides an easy way for aged and
physically handicapped for mobility over stairs. The remote is already connected to the
system, easily using the remote, which is in your hand. one can ascend or descend over
the stairs. In the remote-controlled based system, smart positioning of the sensor enables
sliding over the stairs even easier with least efforts made by humans. This system can
be advanced to have a battery back in case of any power issues. This system can be
implemented on straight stairs only, and can be further modified for even turns [6].
2.1.6 Optimization of a stair lift design to realise a safe transportation system for
the elderly and the disabled when using stairs
The research article “Optimization of a stair lift design to realise a safe transportation
system for the elderly and the disabled when using stairs” was published to fulfil two
objectives:
•
To optimise the ability of the existing stairlift structure by developing lighter
stair lift designs and materials without reducing the capability of the stair lift,
•
To design a braking system on the stairlift.
The optimization of a stairlift structural design was to ensure that the strength of the
stair lift structure complies with the requirements of ASME standard 18.1. The
methodologies of this study are redesigning and conducting numerical simulations with
the finite element to get the optimum result. From the simulation results, the 6063 T5
aluminium profile can be used as a material substitution for guide rails. For A36 steel,
the weld connection between the guide rails and its support needs to be reinforced or
added with stiffener. The electric motor power needed to run the stairlift is 300 Watts
or 0.4 HP [7].
6
2.1.7 Design and Fabrication of Stair Lift
This study primarily focuses on the design and manufacture of the stair lift with the goal
of highlighting an option for old buildings. The staircases were fitted with rails. The
rope and pulley system were adopted. Motor was used to wind and unwind the rope,
with winding being used for the lift's ascent and unwinding used for the lift's descent. 1
hp 1400 rpm single phase motor worm and worm gear for gear reduction, Bluetooth
system for control and monitoring was used. Oldham coupling is coupled with the motor
and speed reduction was used which reduced 1400rpm into 72 rpm which was attached
with the bearing. The winding and unwinding of the rope were carried out by the help
of a wrench. 1000N of the load was considered from the cg for the full modelling and
safe design. The DC motor of the autorickshaw with the control box was used [8].
2.2 Design Constraints
Stairlift is a mechanical device that moves across an inclined plane to transport people
from one height to another. Before beginning the design process, a variety of aspects
need to be considered in order to create a safer and more user-friendly product. Below
is a list of some of the most important aspects to consider while designing a stair lift for
safe design.
2.2.1 Inclination
The slope of the railing is essential to the stairlifts safe design because the location
where the stair lift installation is to be built has a different slope. Therefore, inclination
consideration is essential for safe design.
2.2.2 Mass
The mass of an individual is a critical design constraint in the fabrication of stairlifts,
significantly influencing their structural integrity, efficiency, and safety. Stairlifts need
to be engineered to accommodate a range of user weights while ensuring optimal
performance. This factor affects material selection, mechanical component strength, and
motor power. Engineers must calculate weight-bearing capacity, seat durability, and
motor torque precision to guarantee secure vertical movement. Considering user mass
7
as a central design element enables the creation of reliable and safe stairlifts that enhance
accessibility for individuals with varying weights.
2.2.3 Drive track
Drive track is the term used to describe the path taken by a stair lift, which may involve
straight, curved, and severe curves. The route that a stair lift takes has a significant
impact on how safe the machine is designed. Only the straight and incline paths will be
considered in the design and fabrication; curves and bends will not be considered.
2.2.4 Rise height and tread depth
Rise height and tread depth refer to the height and area, respectively, of a single stair.
When going up and down stairs, a stairlift that had been designed to be installed should
not run against a ladder. For the purpose of the accident-free design It is essential to
consider rise high and tread depth.
8
2.3 Theoretical Framework
The term stair lift, stair gliders and chair lifts as well as other variations, are used
frequently. A stair lift is a mechanical device used to raise and lower steps for people,
usually those with difficulties. A rail is attached to the treads of stairs that are wide
enough. The rail is linked with a chair or lifting platform. The chair glides along the rail
as the user is lifted up or down the stairs after getting onto the chair or platform. For
persons with disabilities living in homes, hospitals, flats, temples, and many other
places, it offers a best solution where lift could not be installed.
The fundamental idea behind a stair lift is to convert the motor's rotational motion into
linear motion over an inclined plane while mounting a chair or platform whose motion
is also converted parallel to the track. Various ways were utilized to fabricate the stair
lift depending on the size, area available, ease of electricity, mass to be transported, and
path of the stair lift. The stair lift mechanism is same as one of the conveyor belt and
trolley. Rope and pulley, rack and pinion, and pulley mechanisms were used in the
framework.
Over the rope and pulley system the rope is attached to a motor, which creates winding
and unwinding, and this motor is paired with a coupling for gear reduction. A chain
mechanism is used to mount this sprocket, and a chain is installed that runs over the
motor that is mounted with the sprocket. However, regular maintenance is required.
Another basic and straightforward way is rack and pinion, in which the rack is fixed to
define the route and the pinion gear is moved by coupling with the gear reduction.
For converting rotating motion into linear motion along the track, rollers, ropes, and
pulleys could be used. One approach is to attach the pulley to the railing and convert the
direction of motion, while another is to attach the rack to the stair and roll the pinion
gear to convert the direction of motion. First drive mechanism must be determined,
which will transform rotational motion into linear motion along the inclined plane's
direction. To travel from the height to the base and from the base to the height, the lift
must be ascended and descended.
9
After this braking system must be developed to control the position of the stair lift where
the passenger wants to stop the lift system. For this proximity sensor, limit switch can
be used.
Then weight must be mounted over the system and weight must be balanced. This all
could be powered by the power source.
The major system required for the proper design and fabrication along with installation
are described below:
2.3.1 Drive system
The main function of the system is to drive the system and provide the necessary
electricity for the stair lift to function properly. Because the rpm of the motor is
frequently higher than the needed one, this connection is required for gear reduction.
2.3.2 Braking system
The lift must be designed with the user's control in mind. The elevator must be stopped
as necessary. Because of gravity and motor inertia, the lift should not slip. Different
braking systems, such as electromechanical, hydraulic drum, and mechanical drum,
could be utilized for this purpose. It can also be controlled by an electrical system, which
includes a limit switch, an emergency switch, and a proximity sensor.
Figure 2.3 Details of Design
10
2.4 Component Survey
Materials Required:
2.4.1 DC Motor
A DC motor is an electrical motor that uses direct current (DC) to produce mechanical
force. The most common types rely on magnetic forces produced by currents in the
coils. Nearly all types of DC motors have some internal mechanism, either
electromechanical or electronic, to periodically change the direction of current in part
of the motor [9]. Figure 2.4 DC Motor shows DC motor of Model PM8018-PL81181i.
2.4.2 Single Phase induction motor
Figure 2.4 DC Motor
A single-phase AC induction motor is a brushless motor designed with a single stator
coil that produces a pulsating magnetic field, reaching maximum intensity at 0° and
180° electrical. It does not produce a rotating magnetic field, but a pulsating field
reaching maximum intensity at 0° and 180° electrical [11].
Figure 2.5 Single Phase Induction Motor
11
2.4.3 Proximity Sensor
A proximity sensor is a non-contact sensor that detects the presence of an object (often
referred to as the “target”) when the target enters the sensor’s field. Depending on the
type of proximity sensor, sound, light, infrared radiation (IR), or electromagnetic fields
may be utilized by the sensor to detect a target. Types of proximity sensor:
•
Capacitive proximity sensor
•
inductive proximity sensor
•
magnetic proximity sensor
•
optical proximity sensor
•
ultrasonic proximity sensor [12]
Figure 2.6 Proximity Sensor
2.4.4 Toggle switch
A toggle switch is a type of electrical switch that is actuated by moving a lever back and
forth to open or close an electrical circuit. There are two basic types of toggle switches:
maintained contact and momentary. A maintained switch changes its position when
actuated and will remain in that position until actuated again, such as an ON/OFF
function. A momentary toggle switch is actuated only when someone is operating the
switch. We design and manufacture a wide range of toggle switches with several
mounting options. Our broad portfolio includes toggle switches with different actuator
styles and amperage ranging from 3 to 20 amps, as well as different load-carrying
capabilities and locking combinations [13].
12
2.4.5 Motor Driver
The motor driver IC is an integrated circuit chip used as a motor controlling device in
autonomous robots and embedded circuits. L293D and ULN2003 are the most
commonly used motor Driver IC that is used in simple robots and RC cars. A motor
driver is undoubtedly something that makes the motor move as per the given instructions
or the inputs (high and low). It listens to the low voltage from the controller/processor
and control an actual motor which needs high input voltage. In simple words, a motor
driver IC controls the direction of the motor based on the commands or instructions it
receives from the controller [14].
Figure 2.7 Motor Driver
2.4.6 Arduino
Arduino is an open-source platform used for building electronics projects. Arduino
consists of both a physical programmable circuit board (often referred to as a
microcontroller) and a piece of software, or IDE (Integrated Development Environment)
that runs on your computer, used to write and upload computer code to the physical
board. The Arduino platform has become quite popular with people just starting out
with electronics, and for good reason. Unlike most previous programmable circuit
boards, the Arduino does not need a separate piece of hardware (called a programmer)
in order to load new code onto the board [15].
2.4.7 Rack and Pinion
Rack and pinion is a type of linear actuator that comprises a circular gear (the pinion)
engaging a linear gear (the rack). Together, they convert rotational motion into linear
13
motion. Rotating the pinion causes the rack to be driven in a line. A rack and pinion
drive can use both straight and helical gears. Though some suggest helical gear are
quieter in operation, no hard evidence supports this theory. The maximum force that can
be transmitted in a rack and pinion mechanism is determined by the tooth pitch and the
size of the pinion as well as the gear ratio [16].
2.4.8 Rail
Rails are a steel frame structure that helps to support the weight of stairlift and helps for
guiding the path. There are two types of rails that can be used in stair lift.
•
Cylindrical Rail
•
Extrude Rail
Table 2.1 Component Survey
S.N.
Components
TYPE
1.
Seat
Full Seat
Half Seat
2.
Drive
Cable Drive
Chain Sprocket
3.
Track
Double
Single
4.
Rail
Cylindrical
Extrude
5.
Control
Push button
Joystick
6.
Seat Belt
7.
Brake
8.
Motor
Two-point seat
belt
Electro
mechanicals
DC
motor
Rack & Pinion
Automatic
Button
Five-point Seat belt
Hydraulic
shunt Single Phase Induction
Motor
14
Magnetic
9.
Sensor
Proximity
FSR406 sensor
Sensors
2.5 Study Design
The project got started when the group was chosen. The group members then began to
discuss potential project ideas. Individual suggestions were afterwards reviewed,
presented, and a decision was made about the design and fabrication of the stair lift.
Therefore, began to visit professors and other like-minded individuals for its
improvement. Writing a proposal and defending it are in progress. A thorough review
of the literature and amount of research will be done. The group will be conducting
research and working on choosing a preferred solution. The components will be
designed, calculations will be made, and then CAD modelling and simulations will be
done. After the project is finished, the team will work on fabrication, testing,
installation, and modification as needed under the supervision of the supervisor. The
project will later be presented to the department with the supervisor's oversight.
15
Figure 2.8 Flow Chart
16
2.6 Gantt Chart
The main objective of the project is to design a stair lift that will work in an old building without altering the steps that were already
there. Moreover, to construct and install the stairlift's functional prototype. The project's progress may be slowed down in the coming
months, but the group will continue to conduct research online. Here is a sketch of the work schedule that will be followed throughout
the project.
While working on the project, slight variations could happen throughout the project.
Table 2.2 Gantt Chart
SEMESTER 1
TASKS
2
SEMESTER 2
Month
1
3
4
Weeks
3 4 1 2 3 1 2 3 4 1 2 1 2 3 4 1 2 3 4 1 2 3 4 1 2
Project Selection
Literature Review
Proposal
Writing
Proposal Submission
Carry out Research
Calculations
Material analysis and selection
Working & Selection of Preferred
Solution
17
1
2
3
4
CAD Modelling
Simulation
Preparation of Working Drawings
Fabrication
Testing, Modification & Installation
Final Report
INDEX
Completed
Incomplete
18
CHAPTER 3 BUDGET ESTIMATION
The estimated cost involved in fabricating the stairlift is provided below. The necessary
budget may alter over time depending on the fabrication's feasibility. Depending on
where we manufacture, the cost may change. The parts would be selected with the least
amount of money feasible throughout the fabrication. The majority of the budget would
be provided by the ESTRL lab under the supervision of the supervisors.
Table 3.1 Budget Estimation
S.N.
List of Components
Quantity
Price Per Unit (NPR)
Total Price
1
DC Gear motor
1
16000
16000
2
Motor Driver
1
800
800
3
Toggle switch
1
200
200
4
Proximity Sensor
2
600
1200
5
Seat
1
1500
1500
7
Rail
-
-
-
8
Rack
-
1600
-
9
Arduino
1
1000
1000
10
Manufacturing Cost
-
5000
5000
11
Miscellaneous
-
2000
2000
Total
NRs. 27,700
19
CHAPTER 4 EXPECTED OUTCOME
By the end of the project, the stair lift's workable solution would have been researched,
which results in the formulation of the design and its fabrication.
The following are the expected outcomes throughout the completion of the project:
•
The stair lift would be fabricated according to the design that was developed.
•
Installation of the fabricated stair lift from the KU ring road to the Mechanical
Engineering Department.
•
On a straight and inclined track, the lift could carry a person safely and smoothly.
20
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[3]
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[4]
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22