Bangarang Musical
Engineering
University of Notre Dame
Department of Aerospace and Mechanical Engineering
Group Members: Roberto Ayala, Ryan Bradley, Pat Fox,
Matt Medlock, Mike Tieu
Outline of Presentation
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Project Overview and Objectives
Concept Selection
Identification of Technical Challenges and
Feasibility Issues
Prototype Creation
Feasibility Assessment
Conclusions
Project Objectives
Task: Develop an innovative musical instrument
Requirements:
-- Play in an automated and manual fashion
-- Utilize embedded intelligence
Concept Selection
Initial Concepts and Design Considerations
Air Guitar Concept
Fan Sound Generation
Key Design Considerations for Final Concept
-- Enable disabled people to play a new instrument
-- Generate mechanical sound
Concept Selection
Target Market Identification
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Initial Target Market: People suffering from motor-skill
disabilities
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Confirmed from meeting with physical therapist
-- “Call-and-response” method of rehabilitation
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Target market now includes neuro-rehabilitiation
capabilities
Concept Selection
Final Design Concept
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Group chose to pursue a mechanically operated drum set
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Features:
-- Two Drums Sticks
-- Two Actuators
Key Technical Challenges and Feasibility Issues
Drum stick actuating mechanism
-- Solenoid Selection
 Selection of pressure sensors
 Drum stick material selection
 Minimizing system response time
 Generating variable volume
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Key Technical Challenges and Feasibility Issues
Selection of Drum Stick Actuator
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Five actuating options considered:
-- solenoid, linear motor, rotary/servo motor, stepper
motor, pneumatic systems
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Merit based comparison:
-- cost, estimated response time, durability, variable
force control
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Selected a push solenoid as the actuating
mechanism
Key Technical Challenges and Feasibility Issues
Solenoid Selection
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Investigate stick tip velocity and actuation force through two trade
studies
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Requirements:
-- 65 dB of sound output
-- Stick tip velocity of 7 ft/s
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Selected a solenoid with a stroke length of 1.0 ” and 5 lbf of pushing
force
-- Attached a spring with constant 3.34 lb/in to recoil stick
Key Technical Challenges and Feasibility Issues
Pressure Sensors
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A trade study investigated the force exerted during
finger tapping
Average Tapping Force (lbs)
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Finger
Index
Middle
Ring
Pinky
Force (lbs)
0.299
0.363
0.310
0.260
Selected 0 to 1 lb pressure sensors
Key Technical Challenges and Feasibility Issues
Drum Stick Material Selection
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Study conducted in order
to determine the drum
stick tip material
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Selected wood as the material
-- Greatest slope
Velocity, Force, and Material Study
Material
Wood
¾” steel
¼” steel
Al
Plastic
Slope (dB-s/ft)
1.45
0.74
1.20
1.19
0.46
Key Technical Challenges and Feasibility Issues
Minimizing System Response Time
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Electrical response from sensors was negligible (5 µs)
Main contributor was mechanical response
-- Solenoid push
-- Stick recoil
Key Technical Challenges and Feasibility Issues
Generate variable volume
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Desired to create three different volumes
-- Pressure Sensor
-- Microcontroller
-- DC Solenoid
Utilized three
different
microcontroller
pins to output
variable
volume
commands
Prototype Creation
CAD Modeling
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CAD model created to visualize the prototype
Prototype Creation
Critical Functions
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Will prove concept feasibility in the following areas:
-- Generate variable volumes greater than 65 dB
-- Function both manually and autonomously
-- Operates at a minimum rate of 1 beat/s
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Additional goals:
-- Robust design
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Budget Requirements:
-- Maximum $500
-- Actual Cost - $432
Prototype Creation
Manufacturing
-- Striving towards a prototype
with complete adjustability
Frame
Mount
Clevis
Prototype Creation
Completed Prototype
Prototype Creation
Demonstration
Feasibility Assessment
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Prototype effectively demonstrated product feasibility
Scored 95/100 on team-developed performance requirements
Prototype Strengths:
-- Pressure sensor effectiveness
-- Minimum mechanical complexity
-- System response time
-- Packaging and presentation
-- Robust
Prototype Weaknesses:
-- Circuit assembly problems
-- Extra sound from solenoid actuation and contact with mount
-- Over weight limit
Conclusions
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Product has high market
potential
Group believes that product
will be successful
Prototype demonstrates
product feasibility
Final Product Changes:
-- Drum size
-- Circuit design
Questions????
Questions Asked:
Question: How important was it to return the stick to its original
position?
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The stick had to be returned to its initial position to be able to
change the volumes at which the drum played. If the drum stick did not
return to its initial position, the variable force firing of the solenoid would
have little to no effect on the stick tip velocity, thus making it impossible to
change the volume.
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Additionally, the stick had to return to its original position because
otherwise, it would not create sound. If the drum stick remained in contact
with the drum head, the firing of the solenoid would not generate sound.
The stick would be driven through the drum head.
 Question: How durable was the spring?
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The spring was effective for our use. The design team feels that
because of the spring constant, the durability of the spring would not be an
issue.
 Question: How easy would it be to add components?
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Adding components would be a significant challenge that would need
to be thought out. By adding more components, the weight of the design
would be significantly increased, which would cause the apparatus to be
difficult to move around. Additionally, to fit the design through a set of
doors, one could not extend the size of the frame to include more
components. This question requires much more thought, and would need
to be fully investigated if pursuing the product.
 Question: Have you performed a patent search?
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We have not performed a patent search. We are pursuing
undergraduate design competitions in an effort to get the design noticed.
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