MIME Senior Design Clinic
Fall 2007
September 13, 2007
Project Proposal:
Device to Assist in Buckling a Seatbelt
2007-04-10
Team Members
Keith Knippen – Group Leader
Chris Miller – Technical Liaison/Web Page Specialist
Michael Baiz – Purchasing Agent
Faculty Advisor
Dr. Efstratios Nikolaidis
Client Advisor
Ms. Jill Caruso, The Ability Center of Greater Toledo
Project Sponsors
The National Science Foundation
The Ability Center of Greater Toledo
2007-04-10 Device to Assist in Buckling a Seatbelt
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Device to Assist in Buckling a Seatbelt
Table of Contents
Section
Page
Executive Summary
3
Introduction and Project Description
3
Proposed Methodology
4
Work Plan and Project Deliverables
10
Budget
12
References
13
2007-04-10 Device to Assist in Buckling a Seatbelt
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Executive Summary
The objective of this project is to design, analyze, build and test a device that will
assist the client, who has cerebral palsy, in buckling his seatbelt. The client cannot easily
buckle he seatbelt because of two factors: He cannot reach the seatbelt tongue (male
connector) end and he has trouble lining the tongue with the buckle (female connector)
when latching them together. The proposed solution is to design a working system with
two main components. The first component is a grab handle attached to the seatbelt to
make it easier to pull forward the tongue end of the seatbelt. The second component will
possess a seatbelt extension containing a “funnel” to assist in lining up the tongue with
the buckle by putting it in a better position. This will not only make the process of
latching the seatbelt easier for the client but it is a simple design that can be easily
removed from the car in the case of a driver change.
Introduction and Product Description
The client, Tim, needs a device that would assist him in buckling his seatbelt. Tim
cannot buckle his seatbelt because he has cerebral palsy. The term cerebral palsy, better
known as CP, refers to any one of a number of neurological disorders that appear in
infancy or early childhood and permanently affect body movement and muscle
coordination but don’t worsen over time. Even though cerebral palsy affects muscle
movement, it isn’t caused by problems in the muscle or nerves. It is caused by
abnormalities in parts of the brain that control muscle movements. The most common are
a lack of muscle coordination when performing voluntary movements; stiff or tight
muscles and exaggerated reflexes; walking with one foot or leg dragging; walking on the
toes, a crouched gait, or a “scissor” gait; and muscle tone that is either too stiff or to
floppy. [1]
As noted earlier in the paper Tim cannot easily buckle he seatbelt because of two
main factors: He cannot reach the seatbelt tongue end located behind his left shoulder to
pull it around his body and he has trouble lining the tongue with the buckle when latching
them together. Because of these factors he does not wear his seatbelt at all. On the other
hand, Tim has no problems with the tension in the seatbelt while bringing the seatbelt
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around him. Tim has also made aware to the team that his right hand is his good hand and
he would like all interaction, if possible, with the system to be with that hand.
Personal safety is the biggest reason this project is being performed. Government
studies have shown that seat belts, when worn, reduce the risk of death by 45% and
serious injury to front seat occupants by 50%. [2] It is crucial that a design is made to
Tim’s preferences with overall safety in mind. Due to Tim’s work responsibilities he is
on the road almost every week on long trips not including personal trips. These trips are
all without a seatbelt because it is too difficult for him to buckle. This project is very
important to complete because it makes his life that much safer.
After looking at a variety of designs the best one was picked based on Tim’s
requirements using the house of quality found later in the paper. The main requirement
like most designs is that this device is safe because the seatbelts only function is for
personal safety. Tim also wants a design that is easy to use because there is a concern if it
is not easy to use that he might continue not using his safety belt. He wants a device
where are no permanent damages to his car current car, a 2000 Chrysler Concorde. He
does not plan on keeping his car forever so he wants a device that can be easily removed.
Once he sells his car he wants to be able to put it in his new vehicle, he wants something
that is universal.
Tim would also like something that isn’t really complicated and
something that is reliable.
Tim knows a lot of people that has his same issue in buckling his seatbelt that
could also benefit from this device. Learning through the client that this issue was present
with many people, research was conducted to see if there are any current products that
could be used. A comprehensive search over the internet for possible devices was done.
Some of the better design that would work with the application is included in the next
section.
Proposed Methodology
Vehicle dynamics, human safety, and environmental interaction all present
challenges in designing a device to assist an individual with buckling his seatbelt. The
interior of a vehicle is isolated from the road, yet it has been designed as a single system
to handle vehicle motion and vibration. Car manufacturers spend millions of dollars
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developing and testing safety belts specifically for each vehicle to maximize human
comfort and protection.
While the interior of a vehicle is normally a contained
environment, external forces resulting from collisions can cause problems inside the
vehicle.
While the process of buckling a seatbelt is a simple task to most users, people
with disabilities that limit muscle coordination and control find the task more challenging
and difficult. The design team wanted to approach the challenge from three completely
different views as to optimize the variation in idea development. The team looked at
mechanical systems, electric motors, new devices, manual operation, and several other
options that would be effective and safe in the environment. From the brainstorming, the
design team decided on three approaches:
1. Automatic Seatbelt
2. Seatbelt Retraction Device
3. Manual Two Piece System
1. Automatic Seatbelt
The design team’s first step was to investigate and evaluate current solutions on
the market and possible variations suitable for the application. The high complexity, low
interaction design involves an automatic seatbelt, similar to those found in vehicles in the
early 1990s.
This design was conceived to eliminate the human interaction in the
buckling process.
The intricate system would require adaptation to the Chrysler Concorde since it
did not originally have this design, where a rail and pulley process would be implemented
around the door frame. An electric motor would be built into the sidewall of the vehicle
or in the dash to control the movement of the buckle and latch.
2007-04-10 Device to Assist in Buckling a Seatbelt
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Figure 1: Automatic Seatbelt Placement
Figure 2 is an example of the latch and pulley system that would operate in the
built in track. Since the design has already been introduced as OEM product, the goal is
to develop a custom system for vehicles that do not currently have the feature. The
design scope could be expanded to include the lap belt with a second rail and latch, which
currently would require the user to manually operate this belt.
Figure 2: Automatic Rail System
The automatic seatbelt mechanism allows the design team the sturdiest, most rigid
design with no interaction for the shoulder belt. The automatic seatbelt in its current
design would still require the user to buckle the lap belt, a task the client would prefer not
to do. The system cannot be moved from vehicle to vehicle and would require extensive
modification of the doorframe and dashboard. Because of this electric motor, a controller
and power source would be needed to operate the motor, further extending the material
and development costs.
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2. Seatbelt Retraction Mechanism
The client preferred the system to be easy use and not require vehicle
modification, a peripheral device was devised to solve the issues regarding reaching the
buckle and finding the latch. Since the methods used to buckle a seatbelt can be complex
and especially difficult for individuals with disabilities. To simplify the entire process, a
seatbelt retraction mechanism permanently attached to the buckle could be employed.
Figure 3: Seatbelt Retraction Device
The user would only be required to grab the mechanism upon entering the vehicle,
and then the device would retract to the point where it can be attached to the buckle at the
base of the seat, depicted in Figure 3. The retraction can either be accomplished using an
electric motor as shown above or a loaded spring controlled by a release mechanism. The
retraction would occur to the location of the latch and draw the buckle to its destination,
allowing the user to lock it into place.
Figure 4: Retraction Device Seat Placement
The seatbelt retraction device is automatic once it is attached in place, which
allows the client buckle his safety belt with minimal interaction. The device is unlike any
available on the market, but is moderately difficult to function because it requires the user
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to introduce new steps when entering and leaving a vehicle. Since it is fully removable
and applicable to most vehicles, it meets his preferences of minimal installation. The
design team has decided that the device is somewhat cumbersome for the action that it
replaces, since it requires cables drawn across the user’s body while retracting the belt
buckle. It could become difficult to latch and unlatch the belt buckle due to the size of
the mechanism and its primary function. A mechanized system such as this would
require a battery power supply, further adding to the cost and compromising efficiency
and user functionality.
3. Two Piece System
The team’s next design was a departure from the previous attempts to accomplish
all of the client’s goals with one device. A two device system would allow utilization of
the individual’s strengths and develop a solution for the weaknesses. We would be easy
to find and pull the buckle by attaching a handle, depicted in Figure 5.
Figure 5: Grab Handle on Market [3]
The client wants to determine that this is sufficient for his needs. The team will
be working to modify the existing design or develop a different system depending on the
client’s preferences.
The design team has been working on designs for alternate
approaches depending on what works best for the client. The existing design requires
that the user switch hands to grab the buckle due to the design, something that the client
expressed concern with. An alternative approach would be to bring the buckle out from
the door frame into a position at which the user can grab the buckle, pull it across his or
her body, and buckle it with one complete motion.
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The next device in the system would include a seat belt extension consisting of an
existing buckling mechanism attached to a buckle machined to match the existing latch.
This will allow the extension to attach to the existing latch without modifications to the
vehicle and allow for quick removal when switching drivers or selling a vehicle. A
sketch of the extension, variable design ideas, and the funnel-type mechanism to assist
the user with finding the latch with the buckle are represented in Figure 6.
Figure 6: Latch Extension and Funnel
The funnel-type mechanism will direct the motion of the user with the buckle in
his or her hand to the latch. Because of the client’s disability and the design of the
seatbelt buckle, he has difficulty directing this motion which prevents him from safely
operating his vehicle.
The design team used the House of Quality to analyze the three designs developed
during brainstorming against the features that are most important to the client. The
results of the analysis can be compared in Figure 7. The House of Quality results have
shown that the third design, Two Piece System, is the best choice.
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Client
Importance
Rating (1-5)
DESIGN 1:
Automatic
Seatbelt Design
DESIGN 2:
Seatbelt
Retraction
Device
DESIGN 3: Two
Piece Design
Easy to use
5
4
3
4
Reliable
4
3
2
5
Safety
5
1
5
4
Universal
3
1
5
4
40
63
72
Client
Requirements
TOTAL
Figure 7: House of Quality
Work Plan and Project Deliverables:
To ensure that all stages of the senior design project are completed, the group has
developed a work plan and a timeline. The work plan outlines the duties of each member
of the group. The group leader for this project is Keith Knippen. His responsibilities
include scheduling and coordinating group meetings and making sure all deadlines are
met. He is the primary contact for the client and client advisor. He is also responsible for
submitting the weekly progress reports. The technical liaison and web designer is Chris
Miller. Chris, as the technical liaison is responsible for making sure all engineering
drawings and solid models are correct. He will also submit drawings to the machine shop
supervisor, John Jaegly, and maintain contact with him to assure the completion of
desired projects. Chris, also being the web designer has the responsibility of designing
the group’s web page with all relevant information and documents. Mike Baiz is the
purchasing agent. As the purchasing agent Mike will be responsible for keeping track of
the project budget, as well as keeping in contact with Ms. Carrie Schonter. When it
comes time to purchase material and equipment he will provide her with the necessary
purchase requisitions. Mike is also responsible for making sure all the material selected
are within the limits of the budget.
Due to the time constraints of this project a timeline has been created and must be
followed in order for completion of the project by the desired date. A detailed timeline
for completion of various tasks is shown in Figure 8.
The group anticipates meeting with the client and seeking input on a regular basis
throughout the design and build phases of the project. Weekly meetings with the group
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and faculty advisors have been set for Tuesday mornings from 10:00 a.m. to 11:00 a.m.
The client advisor, Jill Caruso will also be present at these meetings. These meetings
have been set to discuss the progress of the project. The faculty advisor will also assist in
engineering and design help.
Week of:
27-Aug
3-Sep
10-Sep
17-Sep
24-Sep
1-Oct
8-Oct
15-Oct
22-Oct
29-Oct
5-Nov
12-Nov
19-Nov
26-Nov
Meet Group & Assign Roles
Meet/Talk with Client
Project Research
Brainstorming
Proposal (Presentation & Report)
Design
Obtain/Order Equipment
Experiment/Implementation
Preliminary Design Presentation
Midterm (Presentation & Report)
Finalize Design Characteristics
Web Page Design
Final (Presentation & Report)
Design Expo
Figure 8: Timeline
Project Budget
A proposed budget has been put in place in order to give the group an idea of the
necessary funding for this project. The budget includes having the client experiment with
two existing grab handles that are on the market. If he does not like the design of these
more money is included in the budget for a new or modified design. For the extension
piece of the design material for the steel bracket and funnel is included. The cost of the
machining of these is donated by the University. Finally, the budget includes money to
purchase existing seatbelt, used ones from the junkyard are adequate, to modify and/or
experiment with. Table 1 shows the proposed budget with the estimated cost of each
item. The total estimation is $285 for the entire project.
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3-Dec
Ite m
Cos t
Existing Grab Handles
$40
Modif ication of Grab Handle
$90
Steel Bracket f or extension
$25
Material f or "Funnel"
$30
Seatbelts to modif y
$100
Total:
$285
Table 1: Proposed Budget
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References
[1] - Proposed Projects for MIME Senior Design Clinic Packet
[2] - http://www.safecommunities.org/articles/308/1/Alcohol-and-Seatbelt-Statistics
[3] - http://www.sammonspreston.com/Supply/Product.asp?Leaf_Id=555733
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