This document outlines a proposed study to develop a tactile navigation system to assist visually and hearing impaired individuals. The system would use image processing, infrared sensors and ultrasonic sensors integrated with a smartphone to detect obstacles and navigate indoor and outdoor environments. It would calculate sensor thresholds, distance of obstacles and eliminate noise to guide users and provide hearing assistance. The proposed system architecture, software design including initialization, calibration, filtering and wayfinding logic, and hardware design including microcontrollers, motors and sensors are described. Expected results include faster obstacle detection, accuracy, user satisfaction, safety and flexibility.

1. Study of Tactile interactions for
visually disabled and hearing
impaired
Supervised by:
Prof. Dr. M.M.A. Hashem
Abu Saleh Md. Musa
Roll-0907013
Taslima Akter
Roll-0907046

2. Outline
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Introduction
Problem Statement
Specific objectives
Proposed System Architecture
Software Design
Hardware Design
Expected Results
Timeline
References

3. Introduction
• Over 21.2 million visually impaired in USA.
• Independent tactile interactions is becoming
a bigger challenge.
• Disablers are falling behind.
• Sometimes their lives at risk.
• device that aids disabled with Smartphones.

4. Problem Statement
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Difficult to develop a single device.
GPS not supporting in indoor
Objects are more congested in indoor
Possible Solution:
• Image Processing
• IR Sensors & Ultrasonic way finder
• New Google Phone(code name “Project Tango”)

5. Specific objectives
To assist physically disabled people.
To navigate for both indoor and outdoor environment.
To detect objects and obstacles in navigation path.
To calculate the threshold value of sensors.
To calculate distance of obstacles using Rangefinder sonar sensor.
To eliminate noises from the pulse information.
To make a system that employs total support for visually disabled
people.
• To perform assistance as hear aid for disabled.
• To analyze a system that employs navigational path using smartphones.
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6. Proposed System Architecture

7. Software Design
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Initialization and Calibration
Obtaining Range information from sensors
Median Filtering
Wayfinding Logic
Realtime scheduling

8. Initialization and Calibration
• ADC and TRT kernel
• determines threshold based on the height of
the user.
• Three calibration readings at 140ms apart
• chooses median value as calibrated value.
sensor threshold = sqrt(2) * calibrated value
• holding the tactile sensor at a 45 degree
angle

9. Obtaining range information from
sensors
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simultaneous use of sensor.
Semaphores are used to ensure that.
delay 50ms
require 49ms to obtain a range reading
8-bit from ADC is converted to distance.
Dis(m)=Vin*(512/5)(in/V)*0.0254(m/in)
=(5/256*ADC)*512/5*0.0254

10. Median Filtering
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Filter of size 3
effective
Two causes for Impulse noises
Sudden change in ranges
overestimating the distance of an object

11. Wayfinding logic
• Two real time tasks
• Navigation logic
• checks for the presence of obstacles in the fields
of view
• object in threshold of 2m, motor will buzz
• Tactile sensor logic
• checks for obstacles by calibration process
• scales intensity of the vibrations proportionately
with the proximity of the obstacles.

12. Wayfinding Logic
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Pulse duration=1/range*multiplier
For Navigation Logic,
Multiplier=30
& for Tactile Logic
Multiplier=20

13. Real-time scheduling
• sensors are working independently and
simultaneously.
• tactile sensor logic task and ranging tasks
have priority over navigation logic.
• navigation logic frequency =300ms
• 250ms for all the other tasks.

14. Software Design

15. Hardware Design
• Microcontroller
• Motor
• Ultrasonic RangeFinder
• Power
• Smartphone

16. External Design for Hearing
impaired
• Amplified Sound and vibration will indicate
command generated by smartphones.
• amplifier circuit will be embedded.
• Mini motor vibrator will be used.
• Vibration indicates navigational way.

17. Expected Results
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Faster Detection of Obstacles
Accuracy
User Satisfaction
Safety
User flexibility
Environment independent

18. Timeline

19. References
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An acoustic wayfinding device with haptic feedback for the visually
impaired, http://
people.ece.cornell.edu/land/courses/ece4760/FinalProjects/f2013/xs46_ebl43
Real-time Mobile-Cloud Computing for Context-Aware Blind Navigation,
http://goo.gl/1vI5Ao
FootPath: Accurate Map-based Indoor Navigation Using Smartphones,
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6071934
Ultrasonic range-finder with haptic feedback, http://
people.ece.cornell.edu/land/courses/ece4760/FinalProjects/f2013/jjb284_cc69
Ultrasonic Pathfinder,
http://people.ece.cornell.edu/land/courses/ece4760/FinalProjects/f2013/
js2587_mg792/js2587_mg792/js2587_mg792/finalProject.html
Pedestrian Smartphone-Based Indoor Navigation Using Ultra Portable
Sensory Equipment, http://ieeexplore.ieee.org/xpl/articleDetails.jsp?
arnumber=5646697