SDP Presentation1 STEVI: Sensory Technology Enhancement for the Visually Impaired 10/20/2009 Comprehensive Design Review Alex StarosielskiUltrasonic SensingWeb-Developer Brendan GavinLaser SensingTreasurer Charbel KobrianosLaser SensingTeam Administrator Yi LinUltrasonic SensingSlide Developments Team Vouvakis Electrical and Computer Engineering

SDP Presentation2 Electrical and Computer Engineering The Problem The visually impaired can not navigate without assistance. Cane People The Guide Dog

Solution - STEVI 3 Electrical and Computer Engineering SDP Presentation

4 Electrical and Computer Engineering CDR Deliverables Demonstration of Ultrasonic Detection Range and Direction up to 4m (Non-Stationary) Vibrating motors with microcontroller Demonstration of Laser Detection Laser and Camera Microcontroller Processing Vibrating Motors with microcontroller

SDP Presentation5 Electrical and Computer Engineering Previously Proposed FDR - Block Diagram

SDP Presentation6 Electrical and Computer Engineering FDR Proposed Deliverables – Block Diagram

SDP Presentation7 Electrical and Computer Engineering UDS Design Modifications from MDR MDR Design: 4x Maxbotix UT CDR Design: 2x Maxbotix LV-EZ4 Transducers Reason for Change: Previously 4 used (2 Transmit, 2 Receive) Currently pre-assembled transducers on chip can both transmit and receive. On chip microcontrollers compute distance for individual transducers.

SDP Presentation8 Electrical and Computer Engineering Microcontroller Operation Synchronizes transducer operation. Receives distance from transducers & LDS. Controls Feedback operation. Switched between LDS & UDS mode. FPR Goals: Directionality in UDS module. Range of UDS & LDS simultaneously.

SDP Presentation9 Electrical and Computer Engineering User Feedback System (Vibrating Motors) Tactile feedback controlled by dsPIC. Decreasing distance to obstacle increases frequency of vibrating pulses (2/sec at max range, 20/sec at min range. FPR Goal: Allow for feedback of direction to obstacle.

SDP Presentation10 Electrical and Computer Engineering UDS Test & Analysis: Range Error Goal: 15cm – 4m range Achieved: 15cm – 4m range Limitation: Range error significant for longer distances Solution: Modify programming to account for error at long ranges

SDP Presentation11 Electrical and Computer Engineering UDS Test & Analysis: Lateral Detection Error Goal: Detect obstacles within 20º of direction of travel (5cm wide pole used for tests) Achieved: 26º beam angle at 50cm, 17º beam angle at 100cm, 10º beam angle at 200cm, 8º beam angle at 300cm, 5º beam angle at 400cm Limitation: Small obstacles difficult to detect at long ranges

SDP Presentation12 Electrical and Computer Engineering UDS Test & Analysis: Obstacle Size Limitation Goal: Detect object with 25cm 2 CSA at all ranges up to 400cm Achieved: 9cm 2 object up to 200cm 16cm 2 object up to 340cm 25cm 2 object at all ranges CSA (cm 2 )Max Range (cm) CSA: Obstacle Cross Sectional Area

SDP Presentation13 Electrical and Computer Engineering LDS Algorithm Algorithm same as from MDR: Find brightest pixel in camera’s vision Use y-coordinate of pixel to calculate distance

SDP Presentation14 Electrical and Computer Engineering LDS Design Modifications from MDR Reason for Change: USB camera excessively difficult to integrate with electronics. New camera small enough for device housing. Camera MDR Design: Logitech USB 2.0 MP Camera CDR Design: Camera Mod C3188A-6018

SDP Presentation15 Electrical and Computer Engineering LDS Design Modifications from MDR (Cont.) Reason for Choice: CPLD can easily take data synchronously from camera MDR Design: Matlab CDR Design: CPLD Camera Data Processing

SDP Presentation16 Electrical and Computer Engineering LDS Design Modifications from MDR (Cont.) Reason for Choice: Ease of use for floating point calculations and data transmission MDR Design: Matlab CDR Design: ATMEGA32 16PU Processing Unit

LDS Test & Analysis: Experimental Data Goal: Detect distance to obstacles up to 3 meters Achieved: Detection of light-colored obstacles between 0.6 and 2.1 meters

LDS Test & Analysis: Quantization Error Goal: Reduce Quantization error Solution: Increase laser-camera separation distance (w) Limitations: Increases smallest detection distance

SDP Presentation19 Electrical and Computer Engineering Laser Safety Safety issue: device pointed parallel with ground poses laser hazard Plan to use three tilt sensors to account for multiple possible orientations of device Currently working on circuit to prevent tilt sensor activation due to shock or suddent movement

SDP Presentation20 Electrical and Computer Engineering Updated Power Consumption ItemVoltage (V)Current (I)P (watts) camera laser cpld AVR uC dsPIC uC motor motor transducer transducer Total: W Estimated power consumption reduced, but close to original calculation of 0.8 W.

SDP Presentation21 Electrical and Computer Engineering Weight Estimate Component# of componentsWeight (g) Misc Camera115.2 Battery1110 Housing160 Optical Filter15.1 Laser Diode17.3 Total Weight STEVI will weigh less than 2 Blackberrys =

SDP Presentation22 Electrical and Computer Engineering Current Budget Update DateItemQTYUnit PriceTotal Price 10/27/2009ATMEGA88PA-PU-ND microcontroller Ultrasonic Transducer - Maxbotix UT Vibration Motor ROB megapixel webcam17.95 laser diode /12/09laser diode /13/2009Ultrasonic Transducer - Maxbotix UT /17/2009bandpass filter /25/2010serial cmos camera /18/2010laser diode dsPIC30F E/P tilt ball switch Budget: Expenditure to date: Remaining Funds:

SDP Presentation23 Electrical and Computer Engineering Summary and Look Ahead Summary: Better ultrasonic sensor detection Successful breadboard integration of STEVI prototype FPR Deliverables: Final STEVI prototype Sensor fusion algorithm (s) (Implemented in dsPIC) PCB + housing + sensors + power system RangeAccuracy UDS4 m< 11% LDS2 m< 5%

SDP Presentation24 Electrical and Computer Engineering Updated Gantt Chart

SDP Presentation25 Electrical and Computer Engineering

SDP Presentation26 Electrical and Computer Engineering UDS Prototype Control Circuitry Detection/Feedback System

SDP Presentation27 Electrical and Computer Engineering LDS Camera-Laser Separation Testing