Transcript ppt

ECE 477 Final Presentation
Group 9  Spring 2005
Nathan Smith, Omar Shaikh, Ryan Koors, Jeff Huston
Outline
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Project overview
Block diagram
Professional components
Design components
Success criteria demonstrations
Individual contributions
Project summary
Questions / discussion
Project Overview:
General Informative Medical Prosthetic
Gait sensory feedback
system for existing lower limb
prosthetic devices.
Vibrating
motors
Block Diagram
BJT
amps.
Network
Applications
(data upload)
LEDs
Reset
Button
Power Supply:
RPG
Ethernet
device
7.2Vdc RC
car battery
RESET PORT
PORT
MC9S12NE64
ATD
Clinometer
Shielded
cable
LCD
+/- 5Vdc reg. 3.3 Vdc reg.
Fused 7.2 supply
Amplifier
Circuit
Pressure
Sensors
DC Switching
Regulator
Power supply
Professional Components
• Outline:
– Constraint analysis and component selection
rationale
– Patent liability analysis
– Reliability and safety analysis
– Ethical and environmental impact analysis
Constraint Analysis
• Computational Requirements:
– Ability to resolve ATD conversions to 1V resolution
– Ability to compute average values (no floating pt.)
– Sufficient Flash to support Ethernet libraries
• Interface Requirements
– Provide PWM and ATD capabilities
• Power Supply Constraints
– Need to produce 5v,-5v,3.3v, 7.2v supplies, 1.5A max
• Packaging Constraints
– Minimal packaging for prosthetic mounting
• Cost Constraints
– Device prototype to be kept under $800
Component Selection Rationale
Main Components:
FLEXIFORCE SENSORS:
Rationale
•Relatively inexpensive
•Flat and flexible
•Tried and true in previous
senior design projects
Clinometer:
•Easily-readable, nondiscrete output
•Met durability
requirements
Component Selection Continued…
Main Components:
Vibrating motors:
Rationale
•Low current requirements
•Very inexpensive ($1.25
each)
•Flat shape for
implementation
HC12 NE64 Variant Microcontroller:
•Met I/O requirements (112)
•Integrated TCP/IP
functionality
•64K Flash
memory
Component Selection Continued…
Description
Vendor
Part Number
FLEXIFORCE
SENSORS
Tekscan
A201-100
SENSOR
CLINOMETER
HORIZONTL
FLNG
AccuStar
02110102-000
VIBRATING
MOTORS
Sanko
Electric
Unit Cost
Quantity
Total
Cost
$13.75
4
$55.00
$139.00
1
$139.00
1E120
$1.25
10
$12.50
MC9S12NE64CPV
$0.00
1
$0.00
freescale
MC9S12NE64V1
semiconductor
Total (approximate):
$600
Patent Liability Analysis
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Results of the patent search:
– Existing Devices Similar to G.I.M.P.
Peripherals: All patents between 2000-2002
System for continuously
measure forces applied
by the foot (US patent #
5,678,448)
Sensor device for monitoring
a prosthetic device (US
Patent #5,840,047)
Capacitive biofeedback
sensor with resilient
polyurethane dielectric for
rehabilitation (US Patent
#5,775,332)
Patent Liability Analysis
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Results of the patent search:
– Existing Device Similar to Overall G.I.M.P.
System: All patents between 2000-2002
System and method for
providing a sense of
feel in a prosthetic or
sensory impaired limb
(US Patent #:6,500,210)
Patent Liability Analysis
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Results of the patent search:
– Action Recommended
• Should be emphasized that the device
provides a unique function by acting as
an “addable system to existing
prosthetics”
• It is recommended that that “direct
sensory” mode be eliminated from the
device
Reliability/Safety Analysis
• Four Components Analyzed
– Microcontroller MC9S12NE64CPV
• MTTF = 60.2 Years
– Voltage Regulator LTC1174HV-5
• MTTF = 47.1 Years
– Transformer CTX100-4
• MTTF = 19.8 Years
– NPN BJT 2N3704
• MTTF = 6620 Years
– Mechanical parts fail faster
• Foot assembly - TBD
• Motors – approx 5 years
Reliability/Safety Analysis
• Schematic Divided into Four Sections
– Microcontroller
• Malfunction Causes Incorrect Motor Outputs - High Criticality
– Power Supply
• Regulator/Transformer Malfunction Damages Microcontroller
- High Criticality
– Pressure Sensor Amplifier/Filters
• Op Amp Malfunction Causes Incorrect Input to Micro – High
Criticality
– Class D Motor Amplifiers
• Multiple BJTs Fail – High Criticality
Ethical/Environmental Analysis
• Ethical Impact Analysis
– Challenges
• Classification as a “medical device” by the FDA
• Defining specific intended uses and related operating
environments and conditions
– Solutions
• Mandatory federal premarketing and postmarketing
regulatory controls
• Extensive usability testing to determine proper use and
effective safety warnings and mechanisms
Ethical/Environmental Analysis
• Environmental Impact Analysis
– Challenges
• Lead contents contained in the printed circuit board and
waste created by the fabrication process
• Proper recycling of the Ni-Cd rechargeable battery
– Solutions
• Lead-free printed circuit board fabrication processes
• Incentives to recycle rechargeable batteries and dispose of
the device properly
Design Components
• Outline:
– Packaging design considerations
– Schematic design considerations
– PCB layout design considerations
– Software design considerations
Packaging Design Constraints
• Minimize volume for compatibility with
existing prosthetic legs.
• Final control module volume: 5”x7”x2.5”
• Design should be sturdy
Schematic Design Considerations
• Separation of Digital and Analog Components
– Analog Circuits:
• 10 Class D, NPN amplifiers for vibrating motor
strap
• Power supply consisting of two switching
regulators, supplying 5v,-5v,3.3v,7.2v
• 4 ATD AC noise suppression amplifiers for
pressures sensors in sandal
– Digital Circuits:
• Microcontroller
• Ethernet interface
– Additional considerations:
• All peripheral devices and uC
require unique headers.
Final Schematic Class D Amplifiers:
Final Schematic Pressure Sensor Amplifiers:
Final Schematic Power Supply:
Final Schematic Microcontroller Module:
PCB Layout Design
• PCB must occupy area no greater than 5”x7”
• Complete separation of all digital and analog
components
• Common ground between digital and analog
components
• Headers for all peripheral circuits and Ethernet jack
must be on perimeter of the board
• Trace length between sensor
amplifiers and uC must be
minimized.
PCB Layout
Board
designed to
fit into 5”x7”
container
Software Design
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Startup
Liquid Crystal Display (LCD)
Analog-to-Digital Sensor Inputs (ATD)
Ethernet (HTTP, dynamic webpage)
Main Function Structure – Loop Driven
Rotary Pulse Generator (RPG)
Sensor Data Management (SDM)
Pulse-Width Modulated Motor Outputs (PWM)
Power Conservation
(ATD + Battery Monitor)
Software Design
Initialize Motor
Duty Cycles to “0”
Training
Mode
Send vibrating
“instruction” signal
Direct Map
Wait for Sensor to Reach
Expected Value
Drive Motors if
Corresponding
Sensor Reading is
Above Defined
Threshold
Next Training Stage
Success Criteria Demonstrations
Project-specific success criteria #1
Success Criteria Demonstrations
Project-specific success criteria #2
Success Criteria Demonstrations
Project-specific success criteria #3
Success Criteria Demonstrations
Project-specific success criteria #4
Success Criteria Demonstrations
Project-specific success criteria #5
Individual Contributions
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Team Leader 1 – Jeff Huston
Team Leader 2 – Ryan Koors
Team Leader 3 – Omar Shaikh
Team Leader 4 – Nathan Smith
Team Leader 1 – Jeff Huston
“The Boston Elbow”
• Core Software Module Development
– ATD Module
– Sensor Data Management
– PWM Motor Output
– Idle Detection
– Rotary Pulse Generator Integration
• Logic for Device Modes
– Direct Mapping Mode
– Training Mode
– Power Down Mode
• Safety and Reliability Analysis
Team Leader 2 – Ryan Koors
“The Miser”
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Design constraint analysis
Microcontroller interface schematic
Circuit schematic and theory of operation
Parts organization and availability
PCB Layout
Physical construction
– Clinometer strap
– Motor strap
• Video editing for final presentation
Team Leader 3 – Omar Shaikh
“Shaikh Daddy”
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Packaging Specifications and Design
Ethical/Environmental Impact Analysis
Production of the motors/motor strap
Pre-Module and Core-Module software
development
– Pulse-Width Modulation, Analog-to-Digital
Converter
– Liquid Crystal Display
– Ethernet connectivity
• Hardware and Software debugging
• Website and lab notebook posting
method development
Team Leader 4 – Nathan Smith
“EEgon”
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Schematic design and bread-boarding
Final Layout and Layout Homework
Patent Liability Analysis
PCB population – “solder guy”
Physical construction of hardware components
– Central Unit
– Pressure sensors
– Motor strap
• Hardware debugging during software development
• Design review presentation PowerPoint
animations
Project Summary: Lessons Learned
• Look for parts early—this really helped us
• Layout should be completed & bread-boarded
almost immediately
• Understand software environment almost
immediately
• Multiple revisions on PCB
• Come to ECE477 with project ideas
– Choosing members by mutual interest
– Brainstorming ahead of time
• Equal parts EE/CompE
• Mutual responsibility-everyone must be a leader
• “Grinder nights”
Project Summary: Version 2 Suggested Changes
• Smaller Design, actually integrated into an existing
prosthetic leg
• No status LEDs needed—results in less power
consumption
• Less “power hungry” LCD
• More data management (additional forms)
• Higher resolution for sensors and motors
• Sound feedback
• Use a more compact clinometer
• Wireless connectivity
Questions / Discussion