Obstacle Recognition System For the Blind

PORTLAND STATE UNIVERSITY

Obstacle Recognition System For the Blind

Presented by Team 3

Prachi Pai Asnodkar, Padmashree Patil, Sarita L. Tellez Sanchez, Thuy Tran

December 13, 2014


ECE 411 Practicum Project 2

Overview• Problem and Need Statement• Value Proposition• Objective• Alternatives• Approach & Schedule• Requirements• Design• Implementation• Testing & Results• Contributions• Lessons Learned



Problem & Need Statement

• Problem Statement: Without vision it can be challenging for a visually impaired person to navigate through a room or a hallway without bumping into obstacles. Even with aid, such as walking stick, it can be sometimes inconvenient, uncomfortable, and perhaps inaccurate in avoiding obstacles.

• Need Statement: Develop a device that would assist visually impaired users to sense objects without touching the object or carrying a stick in their hand.



Value Proposition

• Significant number of visually impaired persons use long white cane or guide dog to identify the obstacles. Our project is aimed at reducing the dependency on white cane and guide dogs.

• Our solution is:– Cheap and affordable – Detects both static and moving obstacles– Saves the effort of carrying the white cane, saves on

the cost of maintaining a guide dog, and more.



Objective

• Objective: Design and build a working prototype of a system that will help visually impaired person to sense the obstacle in front of them by sending a vibration from the system.

• Motivation: Our team had an interest to create a device that could aid a visually impaired person as they need an aid that can help them avoid collision with obstacles. This system will help them detect obstacles by sending vibrations.



Alternatives• At present following are the primary methods used by

visually impaired person to identify and avoid an obstacle:– Long white cane: A long white cane is used to extend the users

range of touch sensation. It is usually swung in a low sweeping motion across the intended path of travel to detect obstacles.

– Dog guide: A small number of people employ guide dogs to assist in their mobility. These dogs are trained to navigate around various obstacles.

– Human guide: A person guides the visually impaired, but this makes them dependent on others assistance.



Approach• Step 1: Performed benchmarking to get ideas to help design our

project• Step 2: Define components and resources required• Step 3: Read & perform tutorials to gain knowledge for the required

components and resources, such as Atmel Studio and EagleCAD • Step 4: The project was divided based on each team members

strength• Step 5: Communications

– Timing and organization to complete tasks were formed based on homework deadlines

– Most of the tasks were completed in group and through proactive communication between the team members



Project Schedule



User Requirements

• Safe design• Accuracy in calculating distance from the

object• Differing intensities of vibration according to

proximity to an object• User friendly with ease to use• Cost effective• Reasonable size for comfort



Technical Requirements

• Sense objects within at least 1m of range• Vibrate when user is as far as 1 meter from an

obstacle• Have a vibration motor • Have an ultrasonic sensor to sense distance• Have a microcontroller• Fit on two layer PCB• Assembled by hand by each member of the group • Tested for acceptable working characteristics



Technical Requirements (Contd.)• Be designed in EagleCAD• Have an LCD that displays the distance values• Use a 9V battery as power supply and a voltage regulator

to output 5V for the components in the device• Operate within an enclosed packaging• Be manufactured on a PCB with dimensions of 10x7 cm• Have at least a 95% of accuracy in sensing the obstacle

at the farthest distance (1 meter)• Increase the intensity of the vibration based on the

proximity of an obstacle



Design



Top Level Circuit Block Diagram

There are four main components which provide a separate and distinctfunctionality towards the overall project, and other two are power supplies



Component 1: The Ultrasonic Sensor (HC-SR04)

Detects if the user is in the range of obstacle or not



Component 2: Atmeg-328P Microprocessor

The Atmeg-328P is the control unit of the entire device



Component 3: 310-101 Vibration Motor

Vibration motor is a button type motor that vibrates when sufficient power is given to it.



Component 4: LCD (Liquid Crystal Display)

Displays the distance value at which the user is within an obstacle.

The LCD is designed for testing purposes



Implementation



Schematic



DC Voltage Regulator



Connecting the AVR Programmer

The AVR programmer is connected to the microcontroller on the PCB via the ISP (In System Programming) connections



Ultrasonic Sensor

Connect the Trigger pin and Echo pin of the ultrasonic sensor to two I/O pin of microcontroller



Vibration Motor



LCD Display



Board LayoutTop View Bottom Layer



NY

Flow chart

Initialize

Obstacle within 1m?

Display distance

Display distanceEnable PWM

Turn on motor

Start



Design Code



TestingTest 1: Acceptance test for the obstacle recognition systemExplanation• The system unit must vibrate within 1 meter from an obstacleAction• Write program for a LCD to monitor the distance from an obstacle• Test the device by having a person wear the device and approach an

obstacleExpected Results• The LCD should give 90% accurate distance that it is from the user to

the obstacle• Vibration motor should start vibrating when the person is within 1

meter of an obstacle



TestingTest 2: Integration test case for the Ultrasonic module HC-SR04

with Atmega 328PExplanation• The ultrasonic sensor should have 95% accuracy in sensing

obstacles as far as 1 meterAction• Place an object within 1 meter of the sensor• Place an object further than 1 meter of the sensorExpected Results• Within 1 meter, LED should turn ON• Further than 1 meter, LED should turn OFF



Results

• Ultrasonic sensor worked accurately – Able to observe the behavior we expected when an

object was within the 100 cm range • Burnt at least 2-3 sensors in the debugging process but our

end result was better than expected

• LCD displayed accurate distance values• Methodology of PWM to increase and decrease

the voltage on the motor pin worked accurately from what we could observed on the multi-meter.



Results (Contd.)

• Challenges– The motor has a small operating voltage range– Soldering Surface Mount components– Inexperience with the software needed for project



Contributions

Sarita• Lead schematic development• Lead management of documentation and writing• Co-lead homework’s with Padma• Co-lead PCB setup with Thuy• Co-lead Wiki management with Prachi• System Testing and Validation Support• Project Idea development support• Consolidate final presentation

Thuy• Lead Board layout development• Lead System Testing and Validation• Co-lead PCB setup with Sarita• Co-Lead Code Testing with Prachi• Schematic development support • Homework support• Project Idea development support • Enclosure design

Prachi• Lead Code Development• Lead Project Idea development • Co-Lead Code Testing with Thuy• Co-lead Wiki management with Sarita• System Testing and Validation support• Homework support

Padma• Lead ordering, organization, and management

of major components• Lead Wiki Setup• Co-lead homework’s with Sarita• System Testing and Validation Support• PCB setup support• Project Idea development support • Co-lead management of documentation and

writing with Sarita

Our team divided the contributions by assigning leading or co-leading responsibilities along with support roles to each member for various tasks



Lessons Learnt• Time management and working with other team members to

split tasks and conquer are very important for success• Trust, mutual respect, team efforts is important to successfully

accomplish the tasks• Project management is as important as solving for the project

requirements– Project schedule and GNATT chart is a great tool to manage and track

work progress• Debugging takes a lot of time and requires relying on team

members for their expertise, which can result in positive outcomes

• Collaboration and coordination are key to success



Lessons Learnt (Contd.)

• Better understanding of synergies of tasks and due dates

• Better coordination amongst team members for ordering of parts

• Division of tasks could have been more balanced

• Need to highlight team expectations at the forming stage of the project



ReferenceUltrasonic sensor• https://docs.google.com/a/pdx.edu/document/d/1Y-yZnNhMYy7rwhAgyL_pfa39RsB-

x2qR4vP8saG73rE/edit• http://www.ezdenki.com/ultrasonic.php

Atmel• http://www.micahcarrick.com/tutorials/avr-microcontroller-tutorial/getting-started.html#section_4• http://www.atmel.com/microsite/atmel_studio6/

Eagle• http://tinkerlog.com/howto/mega328-header/• https://learn.sparkfun.com/tutorials/using-eagle-schematic/adding-parts-to-a-schematic

LCD• http://extremeelectronics.co.in/avr-tutorials/using-lcd-module-with-avrs/

Vibration motor• http://www.learningaboutelectronics.com/Datasheets/Precision-Microdrives-Vibration-Motor-Datasheet.pdf

http://www.ezdenki.com/ultrasonic.php



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