ECE 477 Final Presentation Group 9  Spring 2005 Nathan Smith, Omar Shaikh, Ryan Koors, Jeff Huston

Outline Project overviewProject overview Block diagramBlock diagram Professional componentsProfessional components Design componentsDesign components Success criteria demonstrationsSuccess criteria demonstrations Individual contributionsIndividual contributions Project summaryProject summary Questions / discussionQuestions / discussion

Project Overview: General Informative Medical Prosthetic Gait sensory feedback system for existing lower limb prosthetic devices.

Block Diagram MC9S12NE64 Amplifier Circuit Shielded cable LCD ATD PORT RESET Reset Button PORT RPG Ethernet device Network Applications (data upload) Power Supply: 7.2Vdc RC car battery DC Switching Regulator Power supply +/- 5Vdc reg.3.3 Vdc reg. BJT amps. Vibrating motors LEDs Pressure Sensors Clinometer Fused 7.2 supply

Professional Components Outline:Outline: –Constraint analysis and component selection rationale –Patent liability analysis –Reliability and safety analysis –Ethical and environmental impact analysis

Constraint Analysis Computational Requirements: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 RequirementsInterface Requirements –Provide PWM and ATD capabilities Power Supply ConstraintsPower Supply Constraints –Need to produce 5v,-5v,3.3v, 7.2v supplies, 1.5A max Packaging ConstraintsPackaging Constraints –Minimal packaging for prosthetic mounting Cost ConstraintsCost Constraints –Device prototype to be kept under $800

Component Selection Rationale FLEXIFORCE SENSORS: Clinometer: RationaleMain Components: Relatively inexpensive Flat and flexible Tried and true in previous senior design projects Easily-readable, non- discrete output Met durability requirements

Component Selection Continued… Vibrating motors: HC12 NE64 Variant Microcontroller: RationaleMain Components: Low current requirements Very inexpensive ($1.25 each) Flat shape for implementation Met I/O requirements (112) Integrated TCP/IP functionality 64K Flash memory

Component Selection Continued… DescriptionVendorPart NumberUnit Cost Quantity Total Cost FLEXIFORCE SENSORSTekscanA $13.754$55.00 SENSOR CLINOMETER HORIZONTL FLNGAccuStar $ VIBRATING MOTORS Sanko Electric1E120$1.2510$12.50 MC9S12NE64V1 freescale semiconductorMC9S12NE64CPV $0.001 Total (approximate): $600

Patent Liability Analysis Results of the patent search:Results of the patent search: –Existing Devices Similar to G.I.M.P. Peripherals: All patents between 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 Results of the patent search:Results of the patent search: –Existing Device Similar to Overall G.I.M.P. System: All patents between System and method for providing a sense of feel in a prosthetic or sensory impaired limb (US Patent #:6,500,210)

Patent Liability Analysis Results of the patent search: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”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 deviceIt is recommended that that “direct sensory” mode be eliminated from the device

Reliability/Safety Analysis Four Components AnalyzedFour Components Analyzed –Microcontroller MC9S12NE64CPV MTTF = 60.2 YearsMTTF = 60.2 Years –Voltage Regulator LTC1174HV-5 MTTF = 47.1 YearsMTTF = 47.1 Years –Transformer CTX100-4 MTTF = 19.8 YearsMTTF = 19.8 Years –NPN BJT 2N3704 MTTF = 6620 YearsMTTF = 6620 Years –Mechanical parts fail faster Foot assembly - TBDFoot assembly - TBD Motors – approx 5 yearsMotors – approx 5 years

Reliability/Safety Analysis Schematic Divided into Four SectionsSchematic Divided into Four Sections –Microcontroller Malfunction Causes Incorrect Motor Outputs - High CriticalityMalfunction Causes Incorrect Motor Outputs - High Criticality –Power Supply Regulator/Transformer Malfunction Damages Microcontroller - High CriticalityRegulator/Transformer Malfunction Damages Microcontroller - High Criticality –Pressure Sensor Amplifier/Filters Op Amp Malfunction Causes Incorrect Input to Micro – High CriticalityOp Amp Malfunction Causes Incorrect Input to Micro – High Criticality –Class D Motor Amplifiers Multiple BJTs Fail – High CriticalityMultiple BJTs Fail – High Criticality

Ethical/Environmental Analysis Ethical Impact AnalysisEthical Impact Analysis –Challenges Classification as a “medical device” by the FDAClassification as a “medical device” by the FDA Defining specific intended uses and related operating environments and conditionsDefining specific intended uses and related operating environments and conditions –Solutions Mandatory federal premarketing and postmarketing regulatory controlsMandatory federal premarketing and postmarketing regulatory controls Extensive usability testing to determine proper use and effective safety warnings and mechanismsExtensive usability testing to determine proper use and effective safety warnings and mechanisms

Ethical/Environmental Analysis Environmental Impact AnalysisEnvironmental Impact Analysis –Challenges Lead contents contained in the printed circuit board and waste created by the fabrication processLead contents contained in the printed circuit board and waste created by the fabrication process Proper recycling of the Ni-Cd rechargeable batteryProper recycling of the Ni-Cd rechargeable battery –Solutions Lead-free printed circuit board fabrication processesLead-free printed circuit board fabrication processes Incentives to recycle rechargeable batteries and dispose of the device properlyIncentives to recycle rechargeable batteries and dispose of the device properly

Design Components Outline: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.Minimize volume for compatibility with existing prosthetic legs. Final control module volume: 5”x7”x2.5”Final control module volume: 5”x7”x2.5” Design should be sturdyDesign should be sturdy

Schematic Design Considerations Separation of Digital and Analog ComponentsSeparation of Digital and Analog Components –Analog Circuits: 10 Class D, NPN amplifiers for vibrating motor strap10 Class D, NPN amplifiers for vibrating motor strap Power supply consisting of two switching regulators, supplying 5v,-5v,3.3v,7.2vPower supply consisting of two switching regulators, supplying 5v,-5v,3.3v,7.2v 4 ATD AC noise suppression amplifiers for pressures sensors in sandal4 ATD AC noise suppression amplifiers for pressures sensors in sandal –Digital Circuits: MicrocontrollerMicrocontroller Ethernet interfaceEthernet interface –Additional considerations: All peripheral devices and uCAll 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”PCB must occupy area no greater than 5”x7” Complete separation of all digital and analog componentsComplete separation of all digital and analog components Common ground between digital and analog componentsCommon ground between digital and analog components Headers for all peripheral circuits and Ethernet jack must be on perimeter of the boardHeaders for all peripheral circuits and Ethernet jack must be on perimeter of the board Trace length between sensorTrace length between sensor amplifiers and uC must be minimized.

PCB Layout Board designed to fit into 5”x7” container

Software Design StartupStartup Liquid Crystal Display (LCD)Liquid Crystal Display (LCD) Analog-to-Digital Sensor Inputs (ATD)Analog-to-Digital Sensor Inputs (ATD) Ethernet (HTTP, dynamic webpage)Ethernet (HTTP, dynamic webpage) Main Function Structure – Loop DrivenMain Function Structure – Loop Driven Rotary Pulse Generator (RPG)Rotary Pulse Generator (RPG) Sensor Data Management (SDM)Sensor Data Management (SDM) Pulse-Width Modulated Motor Outputs (PWM)Pulse-Width Modulated Motor Outputs (PWM) Power ConservationPower Conservation (ATD + Battery Monitor)

Software Design Training Direct Map Initialize Motor Duty Cycles to “0” Drive Motors if Corresponding Sensor Reading is Above Defined Threshold Send vibrating “instruction” signal Next Training Stage Wait for Sensor to Reach Expected Value Mode

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 Team Leader 1 – Jeff HustonTeam Leader 1 – Jeff Huston Team Leader 2 – Ryan KoorsTeam Leader 2 – Ryan Koors Team Leader 3 – Omar ShaikhTeam Leader 3 – Omar Shaikh Team Leader 4 – Nathan SmithTeam Leader 4 – Nathan Smith

Team Leader 1 – Jeff Huston Core Software Module DevelopmentCore Software Module Development –ATD Module –Sensor Data Management –PWM Motor Output –Idle Detection –Rotary Pulse Generator Integration Logic for Device ModesLogic for Device Modes –Direct Mapping Mode –Training Mode –Power Down Mode Safety and Reliability AnalysisSafety and Reliability Analysis “The Boston Elbow”

Team Leader 2 – Ryan Koors Design constraint analysisDesign constraint analysis Microcontroller interface schematicMicrocontroller interface schematic Circuit schematic and theory of operationCircuit schematic and theory of operation Parts organization and availabilityParts organization and availability PCB LayoutPCB Layout Physical constructionPhysical construction –Clinometer strap –Motor strap Video editing for final presentationVideo editing for final presentation “The Miser”

Team Leader 3 – Omar Shaikh “Shaikh Daddy” Packaging Specifications and DesignPackaging Specifications and Design Ethical/Environmental Impact AnalysisEthical/Environmental Impact Analysis Production of the motors/motor strapProduction of the motors/motor strap Pre-Module and Core-Module softwarePre-Module and Core-Module softwaredevelopment –Pulse-Width Modulation, Analog-to-Digital Converter –Liquid Crystal Display –Ethernet connectivity Hardware and Software debuggingHardware and Software debugging Website and lab notebook postingWebsite and lab notebook posting method development

Team Leader 4 – Nathan Smith Schematic design and bread-boardingSchematic design and bread-boarding Final Layout and Layout HomeworkFinal Layout and Layout Homework Patent Liability AnalysisPatent Liability Analysis PCB population – “solder guy”PCB population – “solder guy” Physical construction of hardware componentsPhysical construction of hardware components –Central Unit –Pressure sensors –Motor strap Hardware debugging during software developmentHardware debugging during software development Design review presentation PowerPointDesign review presentation PowerPointanimations “EEgon”

Project Summary: Lessons Learned Look for parts early—this really helped usLook for parts early—this really helped us Layout should be completed & bread-boarded almost immediatelyLayout should be completed & bread-boarded almost immediately Understand software environment almost immediatelyUnderstand software environment almost immediately Multiple revisions on PCBMultiple revisions on PCB Come to ECE477 with project ideasCome to ECE477 with project ideas –Choosing members by mutual interest –Brainstorming ahead of time Equal parts EE/CompEEqual parts EE/CompE Mutual responsibility-everyone must be a leaderMutual responsibility-everyone must be a leader “Grinder nights”“Grinder nights”

Project Summary : Version 2 Suggested Changes Smaller Design, actually integrated into an existing prosthetic legSmaller Design, actually integrated into an existing prosthetic leg No status LEDs needed—results in less power consumptionNo status LEDs needed—results in less power consumption Less “power hungry” LCDLess “power hungry” LCD More data management (additional forms)More data management (additional forms) Higher resolution for sensors and motorsHigher resolution for sensors and motors Sound feedbackSound feedback Use a more compact clinometerUse a more compact clinometer Wireless connectivityWireless connectivity

Questions / Discussion