Pediatric Dynamometer ABSTRACT The Children’s Hospital of the University of Pennsylvania has long...
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Transcript of Pediatric Dynamometer ABSTRACT The Children’s Hospital of the University of Pennsylvania has long...
Pediatric DynamometerPediatric Dynamometer
ABSTRACTABSTRACTThe Children’s Hospital of the University of
Pennsylvania has long been involved with the study of the correlation between obesity or bone density and youth exercise. In 2004, the Pediatric Dynamometer was born as an engineering project in the Moore School of Electrical Engineering.
Current measurements of exercise are not capable of conveniently delivering the main metric by which correlation should be measured: exerted force. The Pediatric Dynamometer has been developed to provide a comfortable, durable modification to any youth’s shoes to allow for accurate measurement of force exerted by the foot over extended periods of time.
The full implementation of the design consists of an inside-shoe embedded system, which receives signals provided by a Piezoelectric sensor and processes them in an on-board microcontroller. The control system contains algorithms for uploading the data into a computer for processing and storage. The sensor and inside component are installed within the shoe in an unobtrusive fashion. A prototype of the shoe which is fully functional and possibly marketable for athletic shoe applications is ready for demonstration.
AUTHORSAUTHORSArmand O’Donnel
Kevin Ma
ADVISORSADVISORSJay Zemel
Professor Emeritus
University of Pennsylvania
Group #9Group #9
Department of Electrical Department of Electrical and Systems Engineeringand Systems Engineering
Top of PD CircuitTop of PD Circuit(Digital Layer)(Digital Layer)
Bottom of PD CircuitBottom of PD Circuit(Analog Layer)(Analog Layer)
Circuit and battery mounted on foam rubber. Sensors are Circuit and battery mounted on foam rubber. Sensors are mounted on spring steel and sealed with silicone.mounted on spring steel and sealed with silicone.
Cable connecting PD to a computer. USB Cable connecting PD to a computer. USB cable contains rs-232 converter. We added a cable contains rs-232 converter. We added a 3.3V regulator to power the PD in the event 3.3V regulator to power the PD in the event of battery expiration.of battery expiration.
BelowMinimum
Threshold?(2)
Update:Max ForceAvg. ForceTimestamp
Writeto FlashMemory
AboveMinimum
Threshold?(1)
ADC Data FromInstrumentationAmplifier, x[n]
NNOO
YESYES
YESYES
NONOIntegrate Signal
y[n] = y[n-1] + x[n]
ContinueIntegrating
Pack Data into 10-byte Packet
Progression of PD Circuitry over the years.Progression of PD Circuitry over the years.
Sensors used:2x polyvinylidene diflouride stripsPlacement Of Sensors:One under heel of foot One under ball of footComfort: Layers of foam rubber areinserted above and below circuit.Protection: Sensors and circuitare mounted using waterproof silicone
Shoe IntegrationShoe Integration
Uses simple methods to communicatethrough a chosen COM port to retrieveinformation from the chip and issuecommandsMethods:Record Data – Retrieve sampled dataBegin Sampling – Initialize force samplingClear Memory – Clear stored data on chipSave Data – Save data recorded from thechip in a text file for easy analysis withexcel
Graphical User InterfaceGraphical User Interface
Size: 1.4” W x 1.1” L x 0.3” H
Power Consumption: 450 microWattsPower Source:
3.3V, 540mAh Lithium BatteryBattery Size:
1” dia x 0.2” H
Hardware Hardware SpecificationsSpecifications
Force:
Algorithms: Digital integration: add each sample to accumulator Accumulator value is current force Intelligent algorithm clears accumulator if necessary Peak and average force, timestamp saved to flashThresholds:Algorithm uses min/max thresholds and hysterisis to prevent incorrect step detection, which would writespurious data to flash.
Sampling TheorySampling Theory
PIC16F690PIC16F690MicrocontrollerMicrocontroller
16Mbit16MbitFlash MemoryFlash Memory
DataDataArchiveArchive
PVDFPVDF SensorSensor
PVDFPVDF SensorSensor
InstrumentationInstrumentationAmplifiersAmplifiers
Inside ShoeInside Shoe
200 Samples200 SamplesPer secondPer second
3.3V Button3.3V ButtonCell BatteryCell Battery
32.768 Khz32.768 Khz
Watch Watch CrystalCrystal
GraphicalGraphicalUserUser
InterfaceInterface
Sleep ModeSleep Mode
USB toUSB toRS-232RS-232
ConverterConverter
PIC16F690PIC16F690MicrocontrollerMicrocontroller
16Mbit16MbitFlash MemoryFlash Memory
DataDataArchiveArchive
PVDFPVDFSensorSensor
PVDFPVDFSensorSensor
InstrumentationInstrumentationAmplifiersAmplifiers
Inside ShoeInside Shoe
200 Samples200 SamplesPer secondPer second
3.3V Button3.3V ButtonCell BatteryCell Battery
32.768 Khz32.768 Khz
Watch Watch CrystalCrystal
GraphicalGraphicalUserUser
InterfaceInterface
Sleep ModeSleep Mode
USB toUSB toRSRS--232232
ConverterConverter
PIC16F690PIC16F690MicrocontrollerMicrocontroller
16Mbit16MbitFlash MemoryFlash Memory
DataDataArchiveArchive
PVDFPVDFSensorSensor
PVDFPVDFSensorSensor
InstrumentationInstrumentationAmplifiersAmplifiers
Inside ShoeInside Shoe
200 Samples200 SamplesPer secondPer second
3.3V Button3.3V ButtonCell BatteryCell Battery
32.768 Khz32.768 Khz
Watch Watch CrystalCrystal
GraphicalGraphicalUserUser
InterfaceInterface
Sleep ModeSleep Mode
USB toUSB toRSRS--232232
ConverterConverter
BelowMinimum
Threshold?(2)
Update:Max ForceAvg. ForceTimestamp
Writeto FlashMemory
AboveMinimum
Threshold?(1)
ADC Data FromInstrumentationAmplifier, x[n]
NNOO
YESYES
YESYES
NONOIntegrate Signal
y[n] = y[n-1] + x[n]
ContinueIntegrating
Pack Data into10-byte Packet
BelowMinimum
Threshold?(2)
Update:Max ForceAvg. ForceTimestamp
Writeto FlashMemory
AboveMinimum
Threshold?(1)
ADC Data FromInstrumentationAmplifier, x[n]
NNOO
YESYES
YESYES
NONOIntegrate Signal
y[n] = y[n-1] + x[n]
ContinueIntegrating
Pack Data into10-byte Packet