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Haptic Device for Visually Impaired
(Comparison between 3 devices)

Abstract
In our project, we consider to design, manufacture and test haptic devices that will allow visually impaired
people to explore environments safely and independently
...
We have divided
our devices for three different levels
...

Similarly, Bag pack will be used for middle level and for high level we will use head band
...
It does not only navigate the path to the blind
one but also informs about his location to others, through a message on the mobile phone device
...
These wearable devices are physically
realized by interfacing different sensors and communication modules with Arduino
...

Our main objective is to have three haptic devices (Headband, Bag pack, and cane) that will detect obstacles
at different levels (high, medium and low)
...
Whereas, in the case of Bag pack we will
use IR sharp sensor and its output in the form of vibratory motor
...
Then, we will compare these devices that which device is
more suitable for the visually impaired people to detect hurdles
...
Using Global Positioning System (GPS) and Global System for Mobile Communication
(GSM) technology, one can have knowledge of presence of visually impaired people easily
...
Introduction:
1
...
It may be said that visual impairment is the functional limitation of the eye or
eyes or the vision system
...


1
...
According to the World Health Organization (WHO)
statistics, it is estimated that about 285 million people worldwide are vision-impaired, and
of that, 39 million are blind with 1
...
Recently,
WHO has estimated that approximately 1
...
If we look for distance vision, 188
...
Whereas, in the case of near vision, 826 million people are with a
near vision impairment
...

Within Pakistan, a nationally representative sample of 16,507 adults was examined in
2003
...
7% age- and gender-standardized prevalence of blindness
...


1
...
Financially savvy mediations
exist for real reasons for visual impedance and for visual deficiency
...
One way to improve this problem is by
giving awareness to the people, that how can they keep themselves away from this
disease
...
WHO has worked a lot
for this and is still working on it
...
Another way is to design
some devices which would be helpful for them
...
Our main goal is to design and build such haptic devices
that scan the environment accurately and helps the person to provide situational
awareness
...
)
in direction of the user
...


1
...
We came
up with the idea to use a series of rangefinders that would take input from sensors and output
feedback to pulse vibration motors placed on a person’s head
...
If a region was lacking feedback, then it would be safe to proceed in
that direction, but for some devices it is not possible to use vibratory sensor so we need to come
up with other idea that may be use of buzzer
...


1
...
First of all, we completed engineering research to determine the types of components
needed for a functional prototype
...


1
...
1 Engineering research
We conducted some experiments using different type of sensors with which obstacle can be
detected
...
We keep many points in
our mind to select the best sensor
...
These
sensors emits an ultrasonic wave and receive the wave reflected back from the obstacle
...
We find out that ultrasonic sensors send out high frequency
sound waves and receive the echo which bounces back from objects
...

We choose ultrasonic sensor due to following reasons
...




The resolution can be as low as 60 degrees
...
The emitted
light is a narrow beam
...
Laser sensors sends out (emits) electromagnetic radiation

through light to the surroundings
...

These sensors:




Have long range
Are not wide area can be used for indoor
For small object
...
It
electromagnetic waves to the surroundings
...
Not all signals are returned to the
device, whereas small number of the signals will be returned to the sensor and
these signals are usually very weak
...
As
the magnetic wave hits the obstacle, the signals are scattered in all
directions
...


Figure

1-3



IR Sharp Sensor:

Figure1-4

The GP2Y0A21 Sharp distance sensor is one of the best sensor to avoid obstacles
...
This IR sensor is more economical than
sonar rangefinders, whereas, it provides much better performance than other IR
alternatives
...
5 V to 5
...
5 g

Actually the signals we receive from object depends on different things such as
angle, reflectivity of the object, and the size of the object
...
The most significant forms, we found are in
the form of beep of buzzer or by vibratory motors
...
In our project we use buzzer as output
...
It is mini dc motor with nominal rated
voltage of 3V and motor size 6*12mm
...
5
...
It is also
important to understand where to place button, sensors, battery and processor
...
We interviewed various visually
impaired people to understand that how helpful would be this device for them
...


2
...
And at the end we will compare our devices with each other that
which device will be more suitable and helpful for the person using it
...


Yunqing Wang* and Katherine J
...
They used ultrasonic range sensors to find out distance
between the obstacle and device, and obtain their output in the form of vibrations
using eccentric mass motor
...
One
of the draw back
of their device is that it operate only for low level
...

Palleja et al
...
The location of obstacle is obtained by the user on
vibrotactile belt
...

Figure 2-1

Gallo et al
...
He uses haptic feedback system to make person know
about the obstacle at ground level
...

These devices help visually impaired people in many ways but most of the people
think about some
other devices used for different levels of hurdles for these people
...
Out of 307 visually
impaired or lawfully
dazzle people, 54% revealed having head-level mishaps once every year or all the more
regularly
...
In this case, two feedback haptic devices were
used; first one is
that the acceleration pedal is actuated to exert a force on the driver’s foot when
excessive collision
is detected
...

Morrell and Wasilewski [6] in 2010 generated a vibrotactile chair which inform
typically sighted
drivers
...

A paper distributed in the IEEE Transactions on Biomedical Engineering a year ago
depicted a technique for giving tactile criticism by methods for a couple vibrating
engines put on the lower arm and enabling the client to recognize vibration designs
by shifting the recurrence and example of engines enacted [7]
...
One plausibility is encode remove data
and hand-off it to the client utilizing the strategy in [7] to permit the oblivious to
detect both the nearness and the separation to forthcoming impediments more remote
than would be conceivable with a stick
...
Ultrasonic or infrared
rangefinders would be the doubtlessly sensor decision because of their ease and
scope of utilization, up to a few meters
...
Contingent upon time and assets, a beneficial expansion is fuse an
accelerometer chip to give haptic criticism to the client just when mentioned, for
example, by moving the sensor
...


[9] This paper considers issues significant for the plan and utilization of haptic
innovation for assistive gadgets for people who are visually impaired or outwardly
weakened in a portion of the real territories of significance: Braille perusing, material
illustrations, introduction and versatility
...
In
a couple of cases, ends from conduct tests have been legitimately connected to
structure with positive outcomes
...
Pragmatic confinements on gadget structure, for example,
execution constraints of the innovation and cost, bring up issues with respect to
which parts of these confinements are really essential to defeat to accomplish
superior
...

One of the most important aspects to appreciate in designing assistive technology
for individuals who are BVI is the diversity of the population in terms of medical
condition, experience, opinions, preferences and motivation
...

The pieces of the eye influenced may likewise change; in any case, this is for the
most part connected with low vision furthermore, of more significance while
thinking about visual improvement as opposed to haptic presentations
...
For
instance, hard of hearing visually impaired people may likewise differ in their level
of hearing, which may result in the requirement for a solely haptic (versus sound
haptic) arrangement [11]
...
These people may require an answer
that, in any event, requires the arrangement of haptic input nearer to the focal center
of the body (e
...
, wrist or middle)
...
Truth be told the awareness about and comprehension of the
haptic sense has changed ordinarily ever of
...
sight
2
...
smell
4
...
touch
By and by He bears witness to this sense a high significance concerning its
essentialness [13]:
The social estimation of the feeling of touch encountered every single
comprehensible stage
...
”
It was known as the feeling of abundance [15]
...

In western progress the congregation once disparaged this sense as prohibited due to
the joy which can be picked up by it
...
Without
this sensing organ we would be able to grasp our physical shape, whose perception the other
two first class senses (sight and hearing) have to be referred to, to generate some knowledge
from experience
...
It is
able to do showing the spatial impression of our condition
...
Albeit stereoscopic vision and hearing create early, the firstrun through understanding of what we see and hear, requires the association between the two
impressions saw freely and data about separations between articles
...
Such a sense is the feeling
of
touch
...


3
...
1 Main concept:

Figure 3-1

The main concept of our project is as above given flow chart
...
At the end, from
processor, haptic response will be produced, which will be sensed by the user
...
We have
choices of diffrerent sensors like ultrasonic, laser and radar sensors
...


Arduino
The Arduino is the brain of our system
...


Batteries:
Batteries are required for power consumption for the sensors, Arduino and buzzers
...

It is also required to have a long battery life, because it might be inconvenient for the
user to frequently change that
...
2 Design Details:
There are 3 design which we have to implement
...
We will make all these three devices and at the end we will
compare, which device is more suitable for the user
...


3
...
1 Cane:
Haptic or guide cane will help the visually impaired to detect the obstacle in the person’s path
...


3
...
1
...

The ultrasonic sensors are used to transmit sound waves and receive an echo that is reflected
back from an object
...
For this purpose, we use programming in Arduino, that allow
us to take the input from the sensor and use it to activate the motor at each particular location
...
A constant power is provided to the sensor from
processor
...


Ultrasonic Sensor:

Sensor Functionality:

The ultrasonic sensor, known as transceiver which “transmits “and “receives” signals from
each of its cylinders as shown in Fig
...
The time period of returning is called
the “echo
...


Sensor Description:
To detect the obstacles in the environment through sound waves, the Ping Ultrasonic Sensor is
used
...
Moreover, it is
compact and small in size and also requires 5 V power supply
...
If
the temperature (°C) is known, then to determine the speed of sound in air following formula
is sed:
Cair = 331
...
6× T) m/s
Sensor’s operating range of temperature is 0 to 70 ° C, while, the Ping Ultrasonic Sensor looses
accuracy of signal by approximately 10%
...


Buzzer:

Figure 3-3

Buzzer is used to provide feedback to the user so that he will be able to interpret and understand
the surrounding
...
We have not connected the buzzer directly to the
Arduino board since it requires a voltage that is lower than the 5 V provided by the Arduino board
...
As person get closer to the obstacle, buzzer beam starts increasing
...


Transistor:

Figure 3-4

The transistor is required to control the output in proportion to the input signal
...
The transistor is used to
amplify the current to allow the motor to function properly
...
We use water detector at the bottom of stick
to sense the presence of water or any moisture
...
It is a component that has a variable
resistance that changes with the light intensity that falls upon it
...
We make connections of LDR
with buzzer so that visually impaired person get to know about the darkness as well
...
The boards are
equipped with set of digital and analog (I/O) pins and other circuits
...
We perform coding in Arduino to
operate our project
...
2
...
this system
provide object detection along with real time global positioning system this system include
GPS GSM system ,IR sharp sensors and vibratory circuit
...
For our
project Bag-pack device scan the environment, process the information, provide a feedback to
the user and it can send the coordinate of the user to an other person
...
The location of the person is found
by using global system of mobile communication GSM and Global position system GPS
...
2
...
1 Components Required:
1
...
NEO-6M GPS module
3
...
vibratory motor /drone mini motor
5
...
LM259 dc to dc buck converter
7
...
LCD display
7
...
Regulator
9
...
It has
detection range of 10 cm to 80 cm
...
This sensor provides much better performance than other IR

alternatives and more economical than ultrasonic sensors
...
This sensor uses a 3-pin JST PH connector
...


Figure 3-7

GPS module:
GPS works with the help of radio signals sent by satellites in space and a ground stations on
Earth to accurately determine its position on Earth
...

This module contains an external antenna and input Power supply 3V to 5V ,the Default baud
rate is 9600 bps and Works with standard NMEA sentences



Figure 3-8

GPS receiver receives information signals from GPS satellites and calculates its distance from
satellites
Distance=speed *time

Speed =speed of the signal
Time=t2-t1
T1=transmit time of the signal from satellite
T2=receive time of the signal on GPS
If the receiver has the distance from 3 or more satellites and their location can be found
...

In 3D trilateration method for GPS we are dealing with spheres (Earth shaped)
...
If we have three radii in different location on earth but interesting each
other, then the point of intersection will be the location of the device
...

Therefore, through this method the location of an object can to be defined with reference to the
intersecting point of three spheres
...
Now
if a satellite B also inform the object at some distance apart says 150 km
...
If a third satellite inform the position, then the position of the object defined
from a third satellite C intersects this circle at just two points
...
GPS receivers uses
four or more satellites to improve accuracy and provide extra information like altitude,
longitude of the object
...



The location of a minimum of three or four satellites that lock in with the object to be
tracked or located
...


Figure3-9

GSM communication module/android:
GSM is standard communication system for the most of the world
...
it basically works on the principal of TDMA (time division
multiple access) TDMA allow different user to share the same station channel by dividing the
signal into different time slots, so multiple station can use same frequency by it only a part of
its capacity
...
SIM card is one of the GSM feature
...
They can even be used to pass
information between devices if a carrier allows it
...
In these days GSM is one of the mobile services we use and keep with
us contantly
...
3V MCU
...
It has a wide range of
applications
...
The reasons being:


LCDs are economical



easily programmable



have no limitation of displaying special character or event
...
In this LCD
character are displayed in 5x7 pixel matrix
...
it is mini dc motor with nominal rated
voltage of 3V and motor size 6*12mm

Figure 3-12

Lm2596 dc to dc buck converter:
DC-DC Buck Converter is a step-down switching regulator, capable of driving a 3-A load the
input voltage of buck converter can be 4
...
26V to 25V with maximum
rated current of 2A
...
Its application
involved
1
...
speed control of dc motor
3
...
light dimmer
5
...
it is based on the
ATmega328P (Arduino Nano 3
...
it works with a Mini-B USB cable instead of a standard one
...
A dc -dc buck converter is used to step down
the voltage from 12 v to - volts in order to provide it to GSM GPS module
...
From the main micro controller
which is Ardiuno Nano in our case, the 3
...
Voltage
regulator regulate the voltage from the source
...
LCD is used here to display if the coordinate is send to the
destination successfully or not
...


3
...
3 Head band (Overhead detection)
This device is used to detect the obstacle at upper level with the use of few inexpensive
component and sensors this device will allow the blind to navigate the surrounding and avoid
collision
...
it is yet simple but detect the
obstacle at a concentrated area
...


3
...
3
...
Arduino Nano
2
...
Vibratory motor/drone motor
4
...
3 Design Procedure:
3
...
1 Cane:
3
...
1
...

In this system the ultrasonic sensors are used to sense the obstacle (if there is any)
...
Obstacles found in different directions are indicated with different pattern beep and
speech (Top, Middle, Pit and Water) to identify them easily
...
The sound waves hits the obstacle and bounces back to detectors
...
After the collection of data the calculations are done
according to the formula : uS / 58 = centimeters or uS / 148 =inch
...
The signal is then send to
microcontroller to operate a buzzer
...
The buzzer beeps once for left side obstacle, twice for front obstacles and thrice for
right obstacles
...

The light sensor is gives a feedback about the environment
...
The moisture sensor is used to detect water
pits or any puddles if present
...
The main component of this system is
the Radio-Frequency module which is used to find the stick if it is misplaced around
...
These signals are received by the
receiver which then sends signals to the microcontroller which in turn causes the beeping of
the buzzer
...
3
...
2 Schematic diagram:

Figure 3-15

3
...
1
...
3
...
3
...
1 Working:
1- Connecting Power supply:
We have used 12 v power supply for whole device gps gsm module works on the voltages
ranging from 3 to 5V so we have used lm2596 module to step down the supply to desirable
value
...

The LM2596 is the most elementary forward−mode converter
...
The first one occurs when
the series switch is on and the second is when series switch switch is off
...
when the switch is off then the energy stored in the inductor
is now dissipated across the load R because now induction will reverse the voltage polarity
and the current will now flow through the diode
...

(𝑣𝑖𝑛 −𝑣𝑜𝑢𝑡 )×𝑡𝑜𝑛
𝑖𝑙𝑜𝑛 =
𝐿

𝑖 𝑙 𝑜𝑓𝑓 =

(𝑣𝑜𝑢𝑡 −𝑣𝑑 )×𝑡𝑜𝑓𝑓
𝐿

For the buck converter the duty cycle can also be described as

𝑣𝑜𝑢𝑡

D=

𝑣𝑖𝑛

Vin =12V
Vout =4
...
Step down buck
converter comes with a potentiometer to adjust the output voltage to the desired value
...
To test the buck converter we
attached a multi meter across the output pins of converter without any load and then feed the
circuit input pins with 12V voltage and then started tune the potentiometer till the voltage
readings on the output pins reach 3V
...

Voltage source can be connected directly to the voltage regulator but due to some factor like
frequent discharge of batter and reduction of battery voltage after a certain period it is not
recommended to use it directly so capacitor and diode is used to overcome this problem
capacitor also smoothened out the unregulated voltage
...

The detailed working of this unit is shown by the block diagram which is figure no- -- GPS
receiver uses a satellite or more than one satellite and ground stations to calculate accurate
location wherever it is located
...
1 to 1
...

GPS receiver receives information signals from GPS satellites and calculates its distance from
satellites as follow
Distance=speed × time
Speed =speed of the signal
Time=𝑡2 − 𝑡1
𝑡1 =transmit time of the signal from stalitte
𝑡2 =receive time of the signal on GPS

The GPS will send the data to the Arduino Nano Ardiuno will further process this information
according to the command and send the information to GSM will send the coordinate to the
cell phone or the device whose address is written in the command LCD will display if the
communication is successful
...
Another person with
the help of GPS visualizer or google map can find out the location of the visually challenged
person
...


Positioning of sensor:
For bag pack device we need to detect the obstacle at medium level so we used 2 sensors instead of one
and place them in an array IR sharp sensor is capable of sensing obstacle at the distance from 10cm to
80 cm
...
After
reflection from the object, the beam is directed through the second lens on a position-sensible photo
detector (PSD)
...
The output of distance sensor is inversely
proportional to the distance of object, which means when the distance grows the output decreases
...
Controller or ardiuno
process this information according to the command and send the signal to the pins of vibratory motor

...

The speed of the vibratory motor is inversely proportional to the distance of the object that is higher the
rotation speed if the distance become smaller
...
3
...
2

Figure 3-22

3
...
2
...
3
...
3
...
1 Working:
Ardiuno Nano is the main part or processor of this system, which is connected to the IR sharp
sensor IR sharp sensor detect the obstacle in the path and send signal to the Arduino Nano after
processing information the Arduino give command to the vibratory motor
...
The vibration of motor is sensed by the user since motor
is attached to a glove
...

Can be easily damaged






3
...
3
...
3
...
3 Hardware:

Figure 3-25

4
...
We make 3
devices which are haptic cane, bag pack and headband, which detects obstacles at 3
different levels
...
Whereas, headband is used to detect upper level obstacles
...
Following table shows
advantages and disadvantages of different sensors

Comparison between different proximate sensor:

SENSOR TECHNOLOGY
LASER sensor

ADVANTAGES
Low cost
Short time response

Ultrasonic sensor

Low cost
Wide angel of operation
Echo type
Does not affected by radio
signal or sun light
Very Costly
360° detection
Radio wave can easily
Dynamic
distorted the radar signal
Low cost
Infrared radiation
Long distance detection
High miss rate
Short
time
response
Reflectance Sensors type of
IR sensor
High accuracy rate
Very Costly
Not effected by extreme Laser beam can effect human
weather
eye
Less effective when in high
light

RADAR

IR sharp senor

LIDAR

DISADVANTAGES
Higher miss rate
Less effective when in high
light
Long response time
Medium range

Table 4-1

Comparison between the three device:

Level of detection
Sensors
*Overhead time
Voltage
consumption
Accuracy
Weight
Feed back
Indoor/outdoor
Life

**Real
detection

Bag pack
medium
2 IR sharp sensors

Head band
High
One IR sharp sensor

5-6 min
12V

2 sec
5V

Cane
Low
One
sensor
5-6 se
5V

high

Low

Good

Vibrotactile
both

Vibrotactile
Sound
indoor
Outdoor
Can be damaged
easily
due
to
component
are
exposed
to
environment
Low
Good

time good

Table 4-2

*Overhead time: overhead time is the time require for the whole device to start
...
e
...


Advantages and disadvantages of cane:
Advantages:










The system can be used both indoor and outdoor navigation
...

Low power consumption
Inexpensive
Suitable range to detect obstacle for the user
Low cost
Easy to move and handle
Long lasting
Components are not exposed to the environment so will not be damaged easily

Disadvantages / Limitations:
 The system developed here is a moderate budget navigational aid for visually impaired
people
...

 Not dynamic
 It is not environment friendly
 Produces noise due to buzzer
 Not hands free

Advantages and disadvantages of bag back:
Advantages:
 This system provides combination of various working units which makes a real-time
system that monitors position of the user
 It provides the feedback to the user at medium range
 No noise because feedback is provided by the vibratory motors
 Suitable range to detect the obstacle
 More space to add extra feature except gps gsm
 Hands free

Disadvantage:
 Components are exposed to the environment so will be damaged easily
...


 Infrared rays and radio waves can harm person
 Costly require GSM and GPS system to operate
 Not suitable during rain or snow

Advantages and Disadvantages of head band:
Advantages:







overhead detection
concentrated area detection
indoor purpose
can be used to detect small object
hands free
less overhead time approximately in seconds

Disadvantages:
 no under head obstacle detection
 exposed to the environment
...
It is not much expensive as all components we obtained are in
reasonable cost
...
Power consumption
of the device is low as it can operate at low voltage (5v-9v)
...
Our device is not hands free, we
have to hold it in our hands to use and have to move it by ourself
...
Overall cost of our cane is about
3000 – 4000/-
...
Similarly, Bag pack is also very
useful for visually impaired people, as it is hand free so, easy to handle and person get to know
about the hurdle by feeling vibrations through vibratory motors
...
Same is the case with head band, it detects overhead obstacles and person feel
output again in the form of vibrations
...
After presenting the brief

summary including advantage and disadvantages of the systems we concluded that although
these systems can perform fair independently but in some environment it is necessary to use
the combination of these devices due to the limitation of their services

References:
Virtual Sight: Haptic Device for Visually Impaired by Harry Cui, Rashmi Bhatt, Timothy Jin,
Yue Sun,
ME450 Department of Mechanical Engineering University of Michigan Ann Arbor, MI 48109
April 20, 2010
World Health Organization
...

Available:
http://www
...
int/blindness/ACTION_PLAN_WHA62- 1-English
...
Kuchenbecker§ Haptics Group, GRASP Laboratory
Departments of Bioengineering and Mechanical Engineering and Applied Mechanics,
University of Pennsylvania
...
Pallejà et al
...
11322-11339, Dec
...

[3] M
...
, “A Navigation Aid for Blind People,” J
...
Robotc Syst
...

[4] S
...
, “Augmented White Cane with Multimodal Haptic Feedback,” in Proc
...
Conf
...




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