An-najah National University Engineering Collage

Electrical Department

Supervisor: Dr. Ra'ed Jaber

Prepared By: Sa'ed Qariab Mos'ab Naffa

SEMINAR 1 SMART SHOE

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Table Of CONTENTS

Table of contents ................................................................................................................................................................ 1

List of Figures ........................................................................................................................................................................... 3

List of Tables ............................................................................................................................................................................. 4

List of Nomenclatures ......................................................................................................................................................... 5

Acknowledgement ................................................................................................................................................................. 6

Abstract ....................................................................................................................................................................................... 7

Chapter 1: Introduction ..................................................................................................................................................... 9

1.1 : Statement of problem ................................................................................................................................................................9

1.2 : Purpose ............................................................................................................................................................................................9

1.3 : Objectives ....................................................................................................................................................................................... 10

1.4 : Scope of work ............................................................................................................................................................................ 11

Chapter 2:Constraints and earlier work ................................................................................................................ 12

2.1 : Constraints ................................................................................................................................................................................ 12

2.2 : earlier coursework ................................................................................................................................................................. 12

Chapter 3: Literature review ....................................................................................................................................... 13

3.1 : Citation relevant work and results ..................................................................................................................................... 13

3.2 : Theoretical background ......................................................................................................................................................... 13

Chapter 4: Methodology: ............................................................................................................................................... 14

4.1 Block Diagram: ............................................................................................................................................................................... 14

4.2 Block Diagram Description: ...................................................................................................................................................... 15

4.2.1 Google Mapping Database: ..................................................................................................................................................... 15

4.2.2 Android Application Unit: ........................................................................................................................................................ 15

4.2.2.1 Accessibility Service : .......................................................................................................................................................... 15

4.2.2.2 Android Application: .............................................................................................................................................................. 15

4.2.3 Bluetooth Unit: .............................................................................................................................................................................. 16

4.2.4 Microcontroller Unit: ................................................................................................................................................................ 16

4.2.5 Vibration Motor Unit: ............................................................................................................................................................... 17

4.2.5.1 Coin Vibration Motor : ........................................................................................................................................................... 17

4.2.5.2 N-Channel MOSFET: ............................................................................................................................................................. 18

4.2.5.3 Pull-Down Resistor : ............................................................................................................................................................... 18

4.2.6 Pressure Sensing Unit: ............................................................................................................................................................. 18

4.2.6.1 FSR (Force Sensor): ................................................................................................................................................................ 18

4.2.6.2 27K Resistor: ..................................................................................................................................................................... 19

4.2.7 Power Unit : .................................................................................................................................................................................... 19

4.2.7.1 Lithium Polymer (LiPO) Battery: ..................................................................................................................................... 19

4.2.7.2 Step-Up/Step-Down DC-DC Converter : ....................................................................................................................... 20

4.2.7.3 Charging Circuit: ...................................................................................................................................................................... 20

4.2.7.4 Charging Port: ............................................................................................................................................................................ 21

4.2.7.5 USB Charging Cable: .............................................................................................................................................................. 21

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4.2.7.6 Switches: .................................................................................................................................................................................... 21

4.2.8 Shoe: .............................................................................................................................................................................................. 21

4.3 Design: ................................................................................................................................................................................................ 22

4.3.1 Google Mapping Database: ................................................................................................................................................... 22

4.3.2 Android Application Unit: ..................................................................................................................................................... 22

4.3.3 Bluetooth Unit: .......................................................................................................................................................................... 24

4.3.4 Microcontroller Unit : .............................................................................................................................................................. 25

4.3.5 Vibration Motor Unit: ............................................................................................................................................................ 26

4.3.6 Pressure Sensing Unit : ......................................................................................................................................................... 28

4.3.7 Power Unit: ................................................................................................................................................................................ 29

4.4 Shoe Layout : .................................................................................................................................................................................. 30

4.4.1 Mounting Vibration Motors : ............................................................................................................................................... 31

4.4.2 Mounting FSRs: ....................................................................................................................................................................... 32

4.4.3 Mounting Charging Socket : ................................................................................................................................................. 33

Chapter 5: Results And Analysis ................................................................................................................................. 34

5.1 Elements Pins and Power : ......................................................................................................................................................... 34

5.1.1 HC-06 Bluetooth: ........................................................................................................................................................................ 34

5.1.2: Vibration Motors : ...................................................................................................................................................................... 35

5.1.3 Pressure Sensing Units : ............................................................................................................................................................ 35

5.1.4 Arduino Pro Mini : ...................................................................................................................................................................... 36

5.1.5 Power Unit : ..................................................................................................................................................................................... 37

5.2 Power Budget : ................................................................................................................................................................................. 38

Chapter 6: Conclusion ................................................................................................................................................... 40

6.1 Accomplishments: ........................................................................................................................................................................ 40

6.2 Uncertainties : ................................................................................................................................................................................. 40

6.3 Ethical Consideration : ................................................................................................................................................................. 41

6.4 Project Feasibility : ......................................................................................................................................................................... 42

6.5 Future Work : .................................................................................................................................................................................. 43

References ............................................................................................................................................................................ 44

Appendences ........................................................................................................................................................................ 45

Schematic Circuit Diagram: ............................................................................................................................................................... 45

Arduino Circuit (pins): ........................................................................................................................................................................ 46

Bluetooth circuit (pins): ...................................................................................................................................................................... 47

Attachment(A) ................................................................................................................................................................... 48

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Table of Figures:

Figure 1: General Block Diagram ........................................................................................................................ 14

Figure 2: HC-06 Bluetooth ...................................................................................................................................... 16

Figure 4: Coin Vibration Motor ............................................................................................................................. 17

Figure 3: Arduino Pro Mini ..................................................................................................................................... 17

Figure 5: FSR ................................................................................................................................................................. 18

Figure 6: LiOP Battery .............................................................................................................................................. 19

Figure 7:MAX 710 ....................................................................................................................................................... 20

Figure 8: Charging Circuit ...................................................................................................................................... 20

Figure 9: Overall Control Flow for Android Application .......................................................................... 23

Figure 10: Arduino Pro Mini and HC-06 Schematic ..................................................................................... 24

Figure 11:Contents of Bluetooth Message ........................................................................................................ 25

Figure 12:Vibration Motor Schematic ............................................................................................................... 27

Figure 13: Pressure Sensor Schematic ............................................................................................................... 28

Figure 14: Power Unit ............................................................................................................................................... 29

Figure 15: Layout of Vibration Motors inside the shoe .............................................................................. 31

Figure 16:Layout of Pressure Sensors inside the shoe ................................................................................ 32

Figure 17: USB Charging Cable and Charging Socket ................................................................................ 33

Figure 18: Schematic Circuit Diagram .............................................................................................................. 45

Figure 19 :Arduino Pro Mini Circuit .................................................................................................................. 46

Figure 20:Bluetooth Circuit ................................................................................................................................... 47

file:///C:/Users/S.Q/Desktop/Graduation/ours/22222.doc%23_Toc405241789

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List of Tables:

Table 1: HC-06 Bluetooth power .......................................................................................................................... 34

Table 2: Vibration Motors Power ......................................................................................................................... 35

Table 3: FSR Power .................................................................................................................................................... 35

Table 4: Arduino pro Mimi power........................................................................................................................ 36

Table 5: Power Unit ................................................................................................................................................... 37

Table 6: Poewr Budget ............................................................................................................................................. 38

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List of Nomenclatures :

*Mobile App: programmable application for smart phones(Android and iOS).

*Android/iOS: programming languages and launchers for smart phones.

*BLE: Bluetooth low power consumption

* LiPO : Lithium Polymer Battery

*FSR : Force Sensing Resister

*VM: Vibration Motor

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Acknowledgement

We take this opportunity to express our profound gratitude and

deep regards to our guide Dr. Ra'ed Jaber for his exemplary

guidance, monitoring, continued support and constant

encouragement throughout the course of this project.

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Abstract

The world is getting bigger and bigger, and the technology is invading the

globe to comfort the human being, and technology still seeking new products

to make life much and much easier, and we as engineers this is one of our

tasks.

Every day we hear the word 'smart' in everything that the technology has

produced such like Smart phone, Smart car and Smart TV, so why not a Smart

shoe ? Okay, we are going to make a Smart shoe ! Yes it's that simple, a smart

shoe that would lead you to any place you want to go, of course by using help

from the Smart phones.

Our project would revolve about coming with a prototype for a smart shoe

that could pair with Smart phones by using Bluetooth, to reach the

navigational information through a mobile app to get these information and

instruction from Google map's database.

In a matter of fact, this smart shoe could give indications for the user of this

shoe when and where to take a turn and also the type of the turn. All these

indications would be relayed by six vibrating units (motors) placed inside the

shoe in the six directions up,down,left,right,front and back ,these units would

take the instruction through a microcontroller located inside the shoe, that

already would be paired with a smart phone by Bluetooth.

So we designed the whole project block diagram and the circuits for each

section of the diagram as a complete system. Thus, the data for navigation will

be taken from the Google's map database and processed by the mobile App

and transmitted through the Bluetooth to the microcontroller to give

instructions for the vibration units to guide the user for the desired route.

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We made some calculation for the power consumption and for the sizes for

the components. The results were satisfying, where we can use the shoe up to

one day ,and the components can fit in the shoe as we aiming to build a

prototype with regular items.

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1. Introduction

We successfully designed the circuits and the layout for Smart

Shoe. Smart Shoe provides a reliable and unique way for indoor and outdoor

navigation relying on the idea of haptic feedback. Our design also integrates

detailed pressure sensing to give accurate information about a persons feet

movements and feet pressure distribution while walking, jogging or running.

With support for USB charging, this product represents a complete and

marketable final product. We believe that our product will cater to the vast

number of people who use their Smartphones for navigation, athletes and the

common masses.

1.1 Statement of problem

Smartphones have been an excellent asset for navigation in the past couple of years and companies such as Google have come up with some really impressive navigation solutions. Although, these Smartphones assist us with both outdoor and indoor navigation, they still impose a restriction which is the necessity of holding them/looking at their screens or listening to them to get directions, also there's a lot of people don't know how to use the navigation system in the smart phone and sometimes they get confused which way is the left or the right. Moreover, deaf people can't hear the instructions from their phones.

1.2 Purpose

We seek to overcome this challenge by proposing a novel way of how these navigation directions are relayed to us from Smartphones using an underappreciated wearable: the shoe. Our project would revolve around coming up with a smart shoe prototype that could pair with Smartphones using Bluetooth and help provide navigational information through vibration units placed all around the shoe. In essence, these shoes could give indications about when to take a turn, where to take a turn and the type of turn to take to the person wearing these smart shoes. All this information would be

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relayed through 6 vibration units located in the bottom, top, front, and back, left and right segments of the shoe representing the 6 directions that one could go in. There would be a microcontroller connected to a Bluetooth trans-receiver that would send signals to the vibration units based on information received. This new and distraction-free way of navigation will certainly help in

providing directions using something that we all definitely use especially if

were navigating. Using Googles navigation database, we can not only provide

information for outdoor but also indoor navigation. Imagine the convenience

of walking to your departure gate at the airport without having to use your

Smartphone or any other directions at all.

Also imagine the convenience of being directed to the nearest Starbucks in

the terminal when youre feeling hungry without looking around at all!

Sometime in the future, when indoor mapping becomes more widespread,

imagine walking straight to the Apples section in a supermarket from your

hotel in a foreign country without looking around or peeking into your

Smartphone screen! All of this and a lot more is possible with the help of

Smart shoe.

1.3 Objectives

Goals and Functions : Our project goal is to develop a prototype that uses vibration motors to relay

navigation instructions obtained via Bluetooth from a Smartphone. We seek to

develop a mobile app that leverages navigational information from Googles

indoor and outdoor mapping database and sends this information via

Bluetooth to a micro-controller. Our project would also involve programming

a microcontroller to connect with a Bluetooth Chip via the serial cable to

receive messages and control the vibration motors accordingly. Based on the

instructions received, the microcontroller would create different vibration

patterns to guide the user to his/her destination. A significant part of this

project would also be focused on developing the circuitry required to provide

different components with the right voltage, power for the required amount of

time.

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Features

Android Application/Accessibility Service to retrieve Navigational instructions

Support for both Outdoor and Indoor Navigation

Bluetooth Low Energy Chip to send/receive directional information

Control of 6 Vibration Motors

Vibration Intensity Control

Benefits

Navigational Assistance while travelling

Distraction-free travel

Automatic rerouting and alerts

Various User-controlled Vibration patterns

Precisely Calculates pressure distribution on different areas of your feet.

1.4 Scope of the work

In this project ,our work will be concentrated on making a complete design

for the prototype for the shoe with all the components inside it, and to be

perfectly distributed in the shoe without affecting the feet.

On the other side, we have a serious challenge which is to make the circuit

small and to choose the smallest components as possible as we can to fit in

the shoe as a primitive prototype design made by our hands, and in the long

term to be abroad manufactured.

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2.Constraints and Earlier coursework

In this chapter we will go through some constraints and obstacles that we

have faced through studying and analyzing this project. Besides, the

international codes we used and any earlier work for this project.

2.1 Constraints

As any project or work you do in your life, you should face some obstacles

while doing it. At first, we encountered the problem of limited elements we

need for the project, but we have got over it by finding a shop that has what

the project requires from the unique components.

2.2 Earlier coursework

We took a course called (Microprocessors and controllers ) which is a 3 credit

hours, we learned how to program the controller .We also made a project to

detect the distance by using the Microcontroller and Ultrasonic sensor. In

addition to the Electronics 1,2,3 and electronics lab ,where we made a circuit

to amplify the sound wave by using many techniques.

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3. Literature review

3.1 Citation relevant work and results

Our project is kind of unique, and its idea has no one ever done it completely. We did a search for any earlier match work or the same, we found that Apple company by cooperating with Nike company has a similar idea, but it's not exactly the same as ours . Apple's idea is a small device that you put in some specific kinds of shoes that made especially by Nike for this device, this device only calculate the distance that you run and how much Calories that you have lost through pairing with your iPhone.

We also found that some students in India are trying to make something that looks almost as our project, and they are trying to produce it by factories, but they have not done completely.

3.2 Theoretical background

From the expertise that have been gained through past courses, it was easier to deal with the project. Our project almost depends on the controllers and electronic elements, and they already have been mentioned in different courses such as Microcontrollers and processers, Electronic circuits.

Many other courses helped us in performing this project such as Control systems and electronics lab.

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4. Methodology

This chapter will show the General Block Diagram for the project, and the design we made including the layout of the shoe.

4.1 Block Diagram

Figure 1: General Block Diagram

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4.2 Block Diagram Description:

4.2.1 Google Mapping Database

Google has an extensive mapping database for both outdoor and indoor

purposes. This information will be leveraged by the android application to

calculate control signals for the vibration motors. Navigation Notifications

from the Google Mapping Database will be sent over to the Android

Application depending on user location.

4.2.2 Android Application Unit

The Android application consists of two components: Accessibility Service and

Android Application. This unit is responsible for handling Bluetooth

Communication with the microcontroller, sending motor control signals and

receiving pressure sensing information. And finally sending signals for

comforting the user as an extra feature such like a massage for the user's feet.

4.2.2.1 Accessibility Service

The Accessibility Service runs in the background and syncs with the Bluetooth

unit whenever in close proximity. It receives navigation notifications from

Google Maps application and calculates control signals of the 6 vibration units

which are then sent over to the microcontroller. It also retrieves live and

aggregated pressure sensing information from the microcontroller and stores

it locally on the Smartphone.

4.2.2.2 Android Application

The Android Application displays current and aggregated feet pressure

distribution received from the microcontroller and calculates various walking

attributes such as steps walked, distance travelled and speed.

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4.2.3 Bluetooth Unit

The Bluetooth Unit was changed from TI-CC2541 BLE chip to HC-06 Bluetooth

Module to ensure compatibility with all Bluetooth supported Smartphones.

With support for Bluetooth 2.0, this module helps in sending and receiving

messages from android application to microcontroller and vice-versa. The

Bluetooth Unit requires 3.0 6V for optimal performance and it syncs with a

Bluetooth device within a distance of 5 ft. According to Datasheet [8], this

Bluetooth module encompasses all the aforementioned features.

Figure 2: HC-06 Bluetooth

4.2.4 Microcontroller Unit

The Microcontroller Unit consists of an Arduino Pro Mini 5V/16Mhz. A

decision was made to go for the Arduino Pro Microcontroller to provide for a

distributed arrangement of components for improving ergonomics in the final

product.

The Microcontroller receives control signals from the Android Application

through the Bluetooth Unit and sends control PWM signals to the different

vibration motors. It also measures voltage across the three Force Sensitive

Resistors (FSR) and calculates current and aggregated feet pressure

distribution on the arches and heel. All this information is relayed back to the

Android application through Bluetooth. The Arduino Pro Mini requires an

operating voltage of 2.7 5.5V to function correctly. Analog Input from the

Pressure Sensing Units should be measured by the microcontroller with 0.01V

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accuracy. According to Datasheet [9], the Arduino Pro Mini is able to provide

this accuracy.

4.2.5 Vibration Motor Unit

The Vibration Motors Unit consists of 6 vibration motors placed around the

shoe that provides haptic feedback to guide the user in different directions

based on PWM input signals from the microcontroller.

4.2.5.1 Coin Vibration Motor

Our Design contains six Coin Vibration Motors placed at the top, bottom, left,

right, front and back of the shoe in order to provide corresponding directional

output vibration impulses. Since, these motors have to be placed inside the

shoe it is very important that they are lightweight, compact and consume

minimal energy while still being able to provide sufficient vibration output.

We used 310-313 Pico Drive Vibration Motors for this purpose. According to

Datasheet [2], these Vibration Motors provide for the aforementioned

features.

Figure 4: Coin Vibration Motor

Figure 3: Arduino Pro Mini

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4.2.5.2 N-Channel MOSFET

Our design uses six N-Channel MOSFETs that control the six motors through

the PWM output coming out from the Microcontroller. It takes in 3.3V drain

voltage from the power supply and PWM outputs serve as Gate Voltage. We

chose N-Channel MOSFETs over P-Channel MOSFETs since it is more cost

effective and more efficient when operating in the saturation region. We used

NDS331N to make it compatible with our compact design and consume less

power. Datasheet [10] details more information about NDS331N in this

regard.

4.2.5.3 Pull-Down Resistor

Our design uses six pull down resistors each of R= 50k which reduces the

quiescent current.

4.2.6 Pressure Sensing Unit

The Pressure Sensing Unit is responsible for taking in pressure inputs from

the feet and relaying them to the microcontroller.

4.2.6.1 FSR (Force Sensor)

Our design contains three Force Sensitive Resistors laid out so as to measure

foot pressure distribution for the arches and heels. We chose FSR 400 for our

design. We wanted the FSRs to have direct contact with the foot and

adequately cover the respective pressure points for accurate pressure

measurement without discomforting the user. According to Datasheet [3], FSR

400 met these specifications.

Figure 5: FSR

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4.2.6.2 27K Resistor

Our design contains three 27 K Resistors each of which are placed in series

with the FSRs. 27 K Resistors provide a voltage sweep from 0V to 5V across

the FSRs when the resistance varies between 0 100k.

4.2.7 Power Unit

The power unit is responsible for providing regulated 3.3V to the Bluetooth Chip and Vibration Motor Unit and 5V to the Pressure Sensing Unit and Microcontroller. It is also essential that it provides adequate power to all the components for at least 24 hours when fully charged. We also added support for USB Charging. 4.2.7.1 Lithium Polymer (LiPO) Battery We changed our initial battery design from a parallel combination of three LIR 2450 button cells to a 3.7V 850mAh LiPO battery in order to make all the components run for a longer time. The small size of the battery helped in making the design more compact. According to datasheet [4]

Figure 6: LiOP Battery

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4.2.7.2 Step-Up/Step-Down DC-DC Converter We replaced the initially chosen MAX779CSA step-up DC-DC converter with the MAX 710 Step-Up/Step-Down DC-DC converter for the 5V power supply and added another MAX710 Step-Up/Step-Down DC-DC converter for providing regulated 3.3V power supply. The MAX779CSA step-up DC-DC converter required at least a 50mA current draw which was above our maximum current draw for the 5V power supply. We used Step-Up/Step-Down topology because our battery voltage varied between 3.2V and 4.2V and a step-down converter by itself could not suffice the 3.3V power supply requirement. According to datasheet [5]

Figure 7:MAX 710

4.2.7.3 Charging Circuit The Charging Circuit is responsible for providing fast and easy USB charging for the LiPO battery. It consists of a LTC1734L DC charging chip. The LTC1743L DC Charging chip takes in regulated 5V power supply from a USB Charging Cable and charges the battery until it reaches its maximum power capacity. According to datasheet [6]

Figure 8: Charging Circuit

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4.2.7.4 Charging Port A Charging Port located on the side of the shoe provides for an easy plug for the USB charging cable. 4.2.7.5 USB Charging Cable A Special USB Charging Cable with two pins that can go into the Charging Port provide easy USB charging. 4.2.7.6 Switche The product features a switch for turning on/off the device.

4.2.8 Shoe All our components are embedded inside a large size pair of shoes. The large

size of the shoe, its wide girth and its low cost made it really viable for our

purpose.

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4.3 Design

4.3.1 Google Mapping Database

Google has an extensive mapping database for both outdoor and indoor

purposes. This information is leveraged by the android application to

calculate control signals for the vibration motors. Navigation Notifications

from the Google Mapping Database will be sent over to the Android

Application depending on user location. The reason why Google Mapping

Database was chosen over other options such as Nokia HERE maps or Apple

Maps was because of the ease of integration of various navigational

capabilities into an Android Application. Google Mapping database also has

comparatively far broader and detailed coverage for both outdoor and indoor

maps. Another important reason why Google Mapping Database was used was

because of its usage of various experimental features such as Wi-Fi-GPS in

indoor navigation which deal with GPS inaccuracy problem indoors.

4.3.2 Android Application Unit

The project involved using a Smartphone application based on the Android environment to communicate with the microcontroller using Bluetooth. Other alternatives include iOS or Windows Phone Smartphone applications. An Android Application was chosen over its other alternatives because of its extensive and detailed support for various Google Maps navigation features. The ease of application development arising out of the familiarity with the Android development environments was another key reason why it was used for this project.

Figure (9) shows the overall flow of control between different subcomponents

of the Android Application Unit. The accessibility service takes in notifications

generated from the Google Maps application, processes them and generates

the control signals which are then sent over Bluetooth to the microcontroller.

The Accessibility service is also responsible for managing Bluetooth

connectivity with the Bluetooth module. It automatically connects to it

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whenever its in range. After pairing is complete, pressure sensing information

from the microcontroller is relayed over Bluetooth to the accessibility service

which then logs all the information for further use by the Android Application.

The android Application displays current and aggregated pressure sensing

information.

Figure 9: Overall Control Flow

for Android Application

We decided to go for stages in vibration alert system for notifying the user of

an impending turn. The motors are vibrated for a period of 1 sec, 3 sec and 5

sec at a distance of 10m, 20m and 30m from the turn. A destination arrival

vibration comprised of simultaneous vibration of all motors. Notifications

were also sent out in cases of Loss of GPS accuracy and Rerouting.

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4.3.3 Bluetooth Unit

Our Bluetooth unit comprises of an HC-06 Bluetooth module (shown in Figure

2) which communicates over serial connection with the Arduino Pro Mini.

The detailed pin-level connections between the Arduino and the HC-06

Bluetooth module are (shown in Figure 10) The HC-06 Bluetooth Module is

powered by regulated 3.3V power supply from the power unit. Figure (11)

shows the format of the Bluetooth Message sent out from the Accessibility

Service to the Microcontroller. The contents of the Bluetooth Message packet

are minimized to ensure that Bluetooth power consumption is kept to a

minimum. Offering support for Bluetooth v2.0, the HC-06 Bluetooth module

ensures compatibility with most Smartphones out in the market today.

Figure 10: Arduino Pro Mini and HC-06 Schematic

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Figure 11:Contents of Bluetooth Message

4.3.4 Microcontroller Unit

The Microcontroller Unit comprises of the Arduino Pro Mini 5V/16Mhz (shown in Figure 3). It supports 6 PWM outputs, UART and I2C communication interfaces and up to 6 analog inputs. This makes the Arduino Pro Mini well suited for the requirements of the device. The small size of the Arduino Pro Mini suits our compact distributed design. Running at a clock cycle of 16MHz, this microcontroller receives instructions from the Bluetooth chip through UART and controls each of the motors for the required amount of time. In essence, the microcontroller relays navigational directions to different motors based on the vibration pattern customized by the users. Messages received from the Bluetooth Unit are processed by the Arduino using the Arduino Software Serial Library. Figure (11) describes the message format received from the Android Application. The message is decoded and various Vibration Intensities are converted to their respective PWM control signals for the 6 vibration motors .

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4.3.5 Vibration Motor Unit

The 6 vibration motors in this unit are controlled by PWM signals from the microcontroller. The coin vibration motor 310-330 PICO DRIVE (shown in Figure 4) were easy to layout around the shoe without taking up too much space or significantly increasing the weight of the shoe. Figure (12) shows the schematic for driving a single vibration motor unit. According to Datasheet [2], the Arduino Pro Mini has peak current capacity of 50mA. One vibration motor requires 60mA to be driven at peak intensity. Consequently, the total current draw for this unit is 360mA when all motors are vibrating at peak intensity which is beyond the maximum current draw for the Arduino Pro Mini. To overcome this shortcoming, we had to use an N-MOSFET to drive the vibration motor. The purpose of the N-Channel MOSFETs is to act as switch. N-Channel

MOSFET act as switch when operating in the saturation region. The saturation

region for the N-Channel MOSFET is governed by the conditions: V (GS) > V

(TH) and V (DS) > V (GS) - V (TH). The gate is connected to the PWM output of

the microcontroller, the drain is connected to the motor and the source is

grounded. In our design, V (DS) = 3.3V provided by the power unit. Therefore,

when PWM output of the microcontroller is greater than Vth transistor is

switched on and current is able to flow through the motor.

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We can vary the current flowing through the motor, and therefore the voltage

drop across it, by varying the PWM output voltage of the microcontroller. This

feature allows us to provide vibration impulses of different magnitudes based

on PWM control. Figure (12) shows the schematic for driving one vibration

motor.

Figure 12:Vibration Motor Schematic

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4.3.6 Pressure Sensing Unit

The Pressure Sensing Unit is responsible for taking in pressure inputs from

the foot and relaying them to the microcontroller. As shown in Figure 5, we

use FSR 400 to sense foot pressure. As pressure is applied on the FSR the

resistance of the FSR and the voltage drop across it decreases. Our design has

three FSRs which are laid out so as to measure foot pressure distribution for

the arches and heels.

Figure (13) shows the schematic for measuring the output from one FSR. The

5V (Vcc) is provided by the power supply. The FSR is placed in series with a

27k resistor and the voltage drop across the Force Sensitive Resistor is

measured by connecting it to the analog I/O port of the Microcontroller. 27 K

Resistors provide a voltage sweep from 0V to 5V across the Force Sensitive

Resistor when the resistance varies between 0 100k.We included 27 K

resistor in our design to reduce current draw and power consumption making

sure that the microcontroller could measure the voltage across the FSR. The

maximum power consumption of each FSR was brought down to 0.926mW.

Figure 13: Pressure Sensor Schematic

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4.3.7 Power Unit

The power unit is responsible for providing regulated 3.3V + 5% and 5V + 5%power supply to other components of the circuit. We also added the circuit to support charging via a USB cable to provide a convenient way of charging our battery without having to remove the battery. The maximum current draw from our circuit is 400mA when all the six motors

are running. Even though, this current draw lasts for only a few seconds when

a person is close to the destination or is being rerouted, we wanted to make

sure that our battery was capable of handling such a load. As shown in Figure

15, we use 3.7V/850 mAh Lithium-Ion Polymer (LiPO) battery in our design.

Under average load conditions, the battery should last for 24 hours once

completely charged.

In order to provide regulated 3.3V + 5% and 5V + 5%, we used two MAX710 Step up/down DC-DC converters. Figure (14) shows the schematic for a MAX710 chip. Both the converters get power supply directly from the battery.

Figure 14: Power Unit

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The 5V + 5% output from one converter is used to provide power to the

Arduino Pro mini and the Pressure Sensing unit. The 3.3V + 5% output from

one converter is used to provide power to the Bluetooth Unit and the

Vibration Motor Unit. We used MAX710 because it had preset 3.3V and 5V

output, so we didnt have to add additional circuitry to obtain the desired

output voltage. In addition, its low power consumption and packaging made it

appropriate for our compact design.

We also designed a USB charging circuit using a LTC1734L Lithium Ion Linear

Battery Charger. Figure(14) shows the schematic for LTC1734L. According to

Datasheet [6], the maximum charging current for the charger is 180mA. Even

though we could have chosen battery chargers with higher charging current

capabilities, we chose this as a safety measure to ensure that the battery did

not get over-heated while charging.

4.4 Shoe Layout

All components of our project were placed inside the right shoe of a pair of

large Size Shoes. Several modifications were made to the shoe to embed all the

components inside the shoes sides and sole. Figure (15) shows our final

product with all the components placed inside the shoe.

The Battery, Arduino Pro Mini, the HC-06 Bluetooth module will be

embedded under the fabric lining the interior sides of the shoe. The fabric

lining the sides was sliced up and the components were laid out in space

between the leather sides and fabric. To ensure a robust design, we will tap

down all the components and connecting wires and uniformly add padding to

reinforce the comfort level for the shoe. The fabric covering will be glued

down to increase the aesthetic appeal of the shoe.

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4.4.1 Mounting Vibration Motors

The six vibration motors were placed at the front, back, left, right, up and

down sides of the shoe as shown in Figure (15) representing the six basic

cardinal directions.

Figure 15: Layout of Vibration Motors inside the shoe

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4.4.2 Mounting FSRs

Three slits were made through the insole at the two arches and heel. FSRs

were slid through the slit to ensure that only the head was visible and was in

direct contact with the foot as seen in Figure (16).

Figure 16:Layout of Pressure Sensors inside the shoe

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4.4.3 Mounting Charging Socket

5V input power supply to the charger is provided by a USB cable through a

two-pin charging socket that is placed on the side of the shoe as shown in

Figure (17). This will be made by drilling a small hole onto the side of the

shoe. The USB cable will also be specially designed to ensure stable and easy

connection with the charging socket.

Figure 17: USB Charging Cable and Charging Socket

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5. Results And Analysis

In this chapter we will show the results that we have obtained through

preparing the project, the complete schematic circuit and the pins that used

for the project to be done, and also the most important part the power budget

for the project.

5.1 Elements pins and power

5.1.1 HC-06 Bluetooth This Low Energy Bluetooth supports Bluetooth 4.0 standards and pairs with a Smartphone to receive encrypted message packets. The same information is

relayed to the microcontroller using serial connectors TX and Rx. The

decoding of messages is done by the Microcontroller using the Arduino

Software Serial library. This BLE chip has an extremely small power

consumption and high reliability for Bluetooth communication. Data from the

Android application is sent over to the Bluetooth chip only when necessary to

remove any unnecessary consumption.

Table 1: HC-06 Bluetooth power

Inputs Outputs From Power Unit

3.3V power ( PIN 12 ) GND ( PIN 13 )

To Microcontroller Unit: Serial Data COM RF_N ( PIN 2 ) D0 Serial Data COM RF_P ( PIN 3 ) D1

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5.1.2 Vibration Motors

This unit contains 6 vibration motors distributed in 6 locations inside the shoe

to represent the 6 navigation directions to be followed: move forward, move

backward, move up, move down, move right, move left. These motors are

controlled the microcontroller depending on the distance from a turn and the

direction of the turn to take.

Table 2: Vibration Motors Power

Inputs Outputs From Power Unit

3.3V power GND

N/A

From Microcontroller Unit FRONT VM BACK VM UP VM DOWN VM LEFT VM RIGHT VM

5.1.3 Pressure Sensing Units

The Pressure Sensing Unit is responsible for taking in pressure inputs from the foot and relaying them to the microcontroller. The Force Sensing Unit consumes max power when the resistance of the Force Sensitive Resistor is almost 0.Therefore, max power per Force Sensitive Resistor = V2/ R = 25 / 27K = 0.926 mW.

Table 3: FSR Power

Inputs Outputs

From Power Unit 5V power GND

To Microcontroller Unit FRONT FSR (PIN 23) BACK FSR (PIN 24) Middle FSR (PIN 25)

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5.1.4 Arduino Pro Mini

The Microcontroller supports 6 PWM outputs, UART and I2C communication

interfaces. Running at a clock cycle of 16MHz, this microcontroller receives

instructions from the Bluetooth chip using either UART or the I2C interfaces

and controls each of the motors for the required amount of time. In essence,

the microcontroller relays navigational directions to different motors based

on the vibration pattern customized by the users.

Table 4: Arduino pro Mimi power

Inputs Outputs

From Power Unit: 5V power ( PIN 7 ) GND ( PIN 8 )

To Vibration Motor Unit: FRONT VM : PWM (PIN 5) BACK VM : PWM (PIN 11) UP VM : PWM (PIN 12 ) DOWN VM : PWM (PIN 15) LEFT VM : PWM (PIN 16 ) RIGHT VM : PWM (PIN 17)

From Bluetooth Chip: Serial Data COM RXD ( PIN 2 ) Serial Data COM TXD ( PIN 3 )

From Pressure Sensing Unit: FRONT FSR : Analog I/O PIN 23 BACK FSR : Analog I/O PIN 24 Middle FSR : Analog I/O PIN 25

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5.1.5 Power Unit

The power unit is responsible for providing adequate voltage supply, 3.3V and

5V, to power Vibration Motor Unit, Pressure Sensing Unit, BLE Chip and

Microcontroller. It is also essential that it lasts for at least 24 hours and up,

and it has a capacity rating capable of handling the current requirements.

Table 5: Power Unit

Inputs Outputs To Microcontroller

5V Power Supply GND

To Pressure Sensing Unit

5V Power Supply GND

To Vibration Motor Unit 3.3V Power Supply GND

To BLE chip

3.3V Power Supply GND

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5.2 Power Budget

Table 6: Poewr Budget

Vibration Motor:

160mW when running

0mW when stopped

Average Power Consumption : 1) Assuming the motor vibrates for (3-5) second every 20 seconds. 2) For 1 minute it will vibrate 3 times for 15 sec. 3)For 1 hour 900 vib*hour 4)power for the VM mW/h: P=160/(60*60)=0.04 mW/h Average power consumption =900 * 0.04= 36 mW

Microcontroller:

5mW when on

Average Power Consumption : 5mW (Assuming microcontroller is on all the time)

BLU Chip:

86.4mW when sending/receiving messages

3.24W when in sleep mode

Average Power Consumption : 17.28mW (Assuming Messages are sent/received once every 5 sec).

Pressure Sensor:

2.775mW at maximum feet pressure

0.24mW at minimum feet pressure

Average power consumption : 1.38mW (Assuming a person lifts his feet uniformly)

Total Power: 72.73mW

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Total energy stored in the battery : 850mAh = 3.7*850 = 3145 mWh

Average Battery life=

Total energy stored in battery/Total average power consumption = 3145/72.73 = 43.24212

1 day 19 hours 24 minutes and 20 seconds

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6. Conclusion

6.1 Accomplishments

We had several accomplishments throughout the semester. After getting our project idea approved, we started working on getting a proof of concept (POC) for our navigational guidance capability. We created a design for each circuit in the project .In addition to make each circuit work perfectly we read every component datasheet so we can make them work in optimum operation as much as we can. Our biggest achievement for this project was how to get everything assembled

inside a shoe. We spent a lot of time trying to add user comfort and how to

make the product look nice. We added in charging socket on the side so that

the product looked more complete and finished. We also added in a special

USB Charging Cable to add to the ease of charging for our finished product.

6.2 Uncertainties

Although our design is extremely light weight and compact, we are not sure if

the users will become used to the added weight if these components are

added to the shoe. We did several tests with the shoe which we added a

weight exactly the same of our circuit's weight. We found out that, initially, the

added weight is very evident but after some time the user tends to forget

about it and become accustomed to it. However, these results could be

different for different people and we will have to perform further tests to

ensure the device is not causing any distraction or discomfort.

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6.3 Ethical Consideration

For this project, we will follow the IEEE code of Ethics along with our own

moral standards. Our project process and our final product will adhere to the

following relevant IEEE Code of Ethics.

Our project, Smart Shoe, is potentially enjoyed by people of all ages and many different locations. Therefore, our product must consider the safety, health and welfare of the public; in order to protect the users of our product. To accept responsibility in making decisions consistent with the safety, health, and welfare of the public and to disclose promptly factors that might endanger the public or the environment;

We will accept and seek honest criticism of our technical work in order to improve out project, and giving credit to whoever contributed to our project. To seek, accept, and offer honest criticism of technical work, to acknowledge and correct errors, and to credit properly the contributions of others;

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6.4 Project Feasibility

Part Description Quantity Cost($)/Unit Total Cost($) 310-313 Pico Drive

Vibration Motors 6 2.00 12.00

NDS331N N-Channel MOSFET

6 0.105 0.63

50k Resistor Resistor 6 0.13 0.78

4.7k Resistor Resistor 1 0.09 0.09

27k Resistor Resistor 3 0.15 0.45

PRT-00341 LiPO Rechargeable Battery

1 7.95 7.95

0.1F Capacitor Capacitor 2 0.10 0.20

1F Capacitor Capacitor 1 0.10 0.10

4.7 F Capacitor Capacitor 2 0.20 0.40

10F Capacitor Capacitor 1 0.20 0.20

100 F Capacitor Electrolytic Capacitor

4 0.30 1.20

22H Inductor Inductor 2 0.15 0.30

MAX710 Step up/down DC-DC Converter

2 1.10 2.20

FSR 400 Force Sensitive Resistor

3 6.95 20.85

Arduino Pro Mini Microcontroller 1 12.50 12.50

HC-06 Bluetooth Module

1 10.99 10.99

LTC1734L LiPO Battery Charging Chip

1 0.50 0.50

UMT4403 BJT Transistor 1 0.50 0.50

66-1801 SPST Toggle Switch 1 0.60 0.60

A to A USB 2.0 Cable

USB Cable 1 3.14 3.14

Shoes Shoes 1 15.00 15.00

Total 90.59 $

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6.5 Future Work

Our biggest challenge will be to make the design more modular so that it can be placed inside any shoe. Also, implement this project into reality by

making a prototype for the shoe with all the components inside it ,and

work perfectly.

We also intend to make the design more compact and light weight, so that it causes minimal distraction to the user.

Wireless Induction Charging could be added to provide a convenient way of charging the device without having to hook up any wires to it.

Adding an IMU (Inertial Measurement Unit ) chip to our design could allow useful features in the domain of sports and fitness. The data from

the IMU chip could also be integrated with the data from pressure sensing

unit to provide more accurate pressure measurement. In addition, the

magnetic compass of the IMU chip could help in navigation by helping us

determine the direction that the user is facing.

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References

[1] Institute of Electrical and Electronics Engineers, Inc. IEEE Code of Ethics, ieee.org [Access date: 5/10/2014] Available: http://www.ieee.org/about/corporate/governance/p7- 8.html [2 ] Precision Microdrives,10mm Shaftless Vibration Motor 3,4mm Button Type,310-101 Available: https://www.sparkfun.com/datasheets/Robotics/310-101_datasheet.pdf [Access date: 15/10/2014] [3] Interlink Electronics, FSR 400 Series Round Sensing Resistor,FSR 400 Available: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/ForceFlex/2010-10-26-DataSheet-FSR400-Layout2.pdf [Access date: 5/10/2014] [4] Polymer Lithium Ion Battery - 850mAh Available : https://www.sparkfun.com/products/341 [Access date: 1/11/2014] [5] Maxim Integrated Products, Low Voltage-Input/3.3V/5V/Adjustable-output, Step-Up DC-DC Converter, MAX710 Available: http://datasheets.maximintegrated.com/en/ds/MAX710-MAX711.pdf [Access date: 23/10/2014] [6] Charging Circuit 80mA Li-Ion Battery Charger Available: http://cds.linear.com/docs/en/datasheet/1734lf.pdf [Access date: 28/9/2014] [7] Texas Instruments, 2.4-GHz Bluetooth low energy System-on-Chip, CC2541F256RHAR Available: http://www.ti.com/lit/ds/symlink/cc2540. [Access date: 3/11/2014] [8] HC Serial Bluetooth Products, HC Serial Bluetooth Products User Instruction Manual, HC-06 Available: http://www.exp-tech.de/service/datasheet/HC-Serial-Bluetooth-Products.pdf [Access date: 12/11/2014] [9] Arduino, Arduino Pro Mini, Arduino Pro Mini Available: http://arduino.cc/en/Main/ArduinoBoardProMini [10], NDS331N N-Channel Logic Level Enhancement Mode Field Effect Transistor,: http://www.xilinx.com/products/boards/ml505/datasheets/NDS331N.pdf [Access date: 10/11/2014]

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Appendices

Schematic Circuit Diagram

Figure 18: Schematic Circuit Diagram

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Arduino Pro Mini Circuit

Figure 19 :Arduino Pro Mini Circuit

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Bluetooth Circuit

Figure 20:Bluetooth Circuit

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Attachment (A)

DISCLAIMER

This report was written by student(s) at the ( Electrical ) Engineering

Department, Faculty of Engineering, An-Najah National University. It

has not been altered or corrected, other than editorial corrections, as a

result of assessment and it may contain language as well as content

errors. The views expressed in it together with any outcomes and

recommendations are solely those of the student(s). An-Najah National

University accepts no responsibility or liability for the consequences of

this report being used for a purpose other than the purpose for which it

was commissioned.