final project review
DESCRIPTION
Final Project Review. Team Vibraid April 2014. Vibraid. Michael Balanov (Mike) EE. Spyridon Baltsavias (Spiros) EE. Reona Otsuka (Leo) EE . Andrew Woo (Andy) EE. Previous Block Diagram. 4. 4. 4. 4. 4. 4. variable resistance. variable resistance. s witch signal. - PowerPoint PPT PresentationTRANSCRIPT
Final Project Review
Team VibraidApril 2014
VibraidMichael Balanov(Mike) EE
Spyridon Baltsavias(Spiros) EE
Reona Otsuka(Leo) EE
Andrew Woo(Andy) EE
Previous Block Diagram
44
4 4 4 4
switch signal
variable resistance
variable resistance
• 5 different modules• Processing done in software, everything else in hardware
Current Block Diagram
• Processing block absorbs Filtering module• Filtering done digitally!
Reason behind Digital Filtering• Analog filters attenuated input signal• Extra amplification was required
• Physical space limitation• 3 filters per microphone = total of 12 filter circuits• Additional space for extra amplification/active filter
• Digital advantages• Ideal band cutoffs• No attenuation• Allows for easy combination of filters
Arduino Processing Changes• Optimized through low level coding to increase sampling rate• From 2.5kHz to around 14kHz rate for each microphone
• Implemented an optimized FFT to determine frequencies received by the microphones• If fundamental frequency is inside desired band, pass signal for
comparison• Block low-pass noise that was observed
• Due to limited analog inputs, the Motor strength knob has been changed to a Motor strength switch
Final Comparator Logic Design
• Decided to implement SPL (amplitude) comparison instead of Time Delay estimation• Time Delay could not be improved enough to meet the required
specs• SPL comparison met specs after purchasing better directional
microphones
FPR RequirementsSpecification Value Met?Max Detection radius for 70dB to 120dB within frequency range
>3m (10ft) Yes
Frequency Detection Range 100Hz – 10kHz Yes, in most cases
Belt Circumference 75cm – 105cm (small – large) Yes
Belt Width <10cm YesBelt Thickness <5cm YesProduct Weight <1kg YesDetection Directionality 4 Directions YesVibration Response Time <0.5s YesVibration Directionality Vibration to alert user in one
quadrantYes
Vibration to Corresponding Detection
99% of time Yes
Tunable Sensitivity Block all till Pass all YesTunable Frequency Detection 4 modes: full, low, mid, high Yes
Tunable Motor Strength No vibration to Max supply No (2 levels of intensity instead)
Battery Life >12h Yes
Demo Outline
• Frequency filtering demo• Wearing the device – 4 way directionality
Frequency Filtering
• 3 switches: High, Mid, Low (-pass)• Low band: 100Hz to ~300Hz• Mid band: ~300Hz to 600Hz• High band: ~600Hz to ~7000Hz
• Combination of bands possible
Q&A
Digital Filtering Disadvantages
• Sampling rate needs to be high enough (Nyquist rate)
• Adds to processing time