[MinnowBoard] Automobile based on virtual path

[Mayank Davande]

*  Automobile based on virtual path*



*Abstract*— An automobile is based on virtual path algorithm has been
presented in this paper. The paper is useful in designing a vehicle which
moves from one point to another with minimum human intervention. To achieve
this, virtual path concept is used. To design a virtual path a set of
co-ordinates required to reach destination from origin is calculated. Based
on these co-ordinates the automobile takes its own decision to reach
destination. Meanwhile during its operation user can design next path and
calculate the co-ordinates for the same. Hence time required for execution
is saved.

*Keywords*—* Graphical User Interface (GUI), Global Positioning System
(GPS), Radio Frequency Identification (RFID). *

I.           Introduction

An autonomous technology is used here for minimizing the human labor
necessary to control the locomotion of a bot. GPS can be used to locate the
destination and find its path using its navigation system , but the system
has indelible error sources that have to been taken into account when the
receiver reads the GPS signal. Therefore an urged to better accuracy and
reliability is presented in this paper. *For generalizing the* *path, first
attempt was made to correspond it with Line follower which is an autonomous
robot* which pursued its path from a white area having black line or black
area having white line. The Line Follower Robot ought to encounter
appropriate line and preserve its succession. However it always needs a
physical path which is not versatile. In Autonomous Bot the path is virtual
and created by dynamic strings feed by the user. Complicated path are
difficult to implement physically in case of line follower bots, which is
overcome in this paper by giving predefined instructions. In case of RFID
based bots controlled motion is given by the individual RFID tags and need
to be given dynamically which is cumbersome. Hence in this paper a new
technique on bot navigation has been implemented. The radical idea behind
the project was to utilize software encoding to overcome the shortcomings
present in the referenced papers.

The operator creates a virtual path on the basis of sequence of
co-ordinates given to the bot initially. The co-ordinates are passed as a
string parameter in the program on a laptop. This is achieved by using GUI
technology. The co-ordinates instruct the bot to move along a direction for
certain distance as per requirement. Hence by giving appropriate
co-ordinates a complex virtual path can be created and that too of infinite
distance. However, the manual control of the bot is possible only within a
range of 2km. Currently, the three major kinds of machine locomotion are
present, i.e. line follower, line of sight bots and GPS controlled. However
these have certain shortcomings such as, Line follower has limitation of
physical implementation of line (path). GPS bots have less accuracy and
also it is not useful in a closed environment. The project motive was to
design a mechanism which combined best of all three above mentioned means
of locomotion into a single bot, by keeping following parameters in mind.

The features are,

1) Self-sufficient,

2) Beyond line of sight movement,

3) Mass producible and cost effective.

II.         Ease of Use A.    Working

Each coordinate in the string has two entities in it, first orientation of
the bot followed by magnitude. The orientation of the bot determines the
direction of travel followed by magnitude which determines the distance to
be travelled in that direction. Such sequence of co-ordinates can thus be
used to trace a complex path as per the operator’s requirement. The core
logic utilized here is the basic speed, distance, and time relationship to
create the virtual path for the bot.

Figure 1 Virtual path algorithm



Hence,

Speed=Distance/Time
                       (1)

Speed = Constant K
                        (2)

Distance = Time * Constant K
                       (3)

K = ideally surface dependent constant



The speed of the bot is kept constant, and each co-ordinate is an input to
software controlled down counter which determines the time for which the
two motor rotates. Thus with a known value of time the distance the bot
travels in a particular direction can be determined respectively. The bots
orientation is changed by either moving both motors in clockwise (rotate in
left) or motors in anticlockwise (rotate in right) direction. If one motor
is in clockwise and other in anticlockwise then bot move forward else
reverse for the other combination. The bot itself acts as the origin or
reference point, hence after every co-ordinate is executed the position of
the bot changes, and hence there is a shift in origin.



*B.    **Mathematical Concept*

Necessary condition for maintaining constant speed is as follows.

P=T*W
(4)

Where,

P=power delivered to the shaft,

T=Torque generated by the motor,

W= angular velocity of the motor.

Differentiating above equation by torque,

Hence,

dP/dT = T(dW/dT) +W
(5)

For constant speed of tire, rotational velocity i.e. angular velocity W is
to be kept constant.

Therefore,

dW/dT
=0
(6)

dP/dT =W=CONSTANT=P                                                  (7)



       P






                                                                       T



                      Figure 2 Graph of power versus torque

To navigate over a steep inclination the force required to rotate the
wheels increase i.e. higher torque is required. But speed is to be kept
constant. Hence, the angular velocity W of the wheels are to be kept
constant. Thus, an increased torque is required which is delivered from an
increase in power supplied to the motor. Ideally, a very large torque
should be produced at very low power consumption to achieve this
efficiently. Hence, ideally dP/dT =W=0 and practically the angular velocity
of rotating wheels should be slow as possible.
C.    Aloritham



1.       Pass the string of co-ordinates to the robot via laptop using
zigbee module.

2.       Each string parameter is used to calculate distance to be
travelled in a particular direction.

3.       The bots operation is read on laptop for real time monitoring
purpose.

4.       The direction of bot or its rotation is controlled by rotating the
two motors in the required direction.

5.       In case of an emergency the bot can be controlled using manually
using GUI interface.

TABLE I.             motor action

*VM1*

*VM2*

*            D1*

*          D2*

*DIRECTION*

*(BOT)*

-1

-1

Anticlockwise

Anticlockwise

         Right

-1

 1

Anticlockwise

Clockwise

      Forward

 1

-1

Clockwise

Anticlockwise

      Reverse

 1

1

Clockwise

Clockwise

          Left



Thus, the strings are given to a counter which rotates the motor for a
particular time hence a required distance.

The bot when in operations traces its path using the instructions fed to it
initially, hence self-sufficient. Also the concept of virtual path is the
key in making it move beyond line of sight. Sort of start and forget
system!! Here programming is the key behind the bots intelligence, and does
not make use of unwanted satellite navigation as such. This helped us to
cut down the cost of development and mass production of this bot in market
thus becomes realizable.




III.            AUTOMOBILE STRUCTURE

The automobile can be divided into several parts:



·         Microcontroller ATMEL89S52: A microcontroller is a computer
present in a single IC which is committed to perform one task and execute
one specific application.

The Atmel microcontroller is used in this project because it provides
adequate amount of ports for interfacing with the LCD and L293D. The
advantages of using the microcontroller are cost is less, Size is less,
Power consumption is less and speed is more

·         IR Sensor: *It is electronic equipment which is used to feel
certain attribute of its ambience by either emanating and/or recognize
infrared radiation. It is used as an obstacle avoider in this project*

·         NRF24L01 UART Module (ZIGBEE 2.4 GHz): It is a trans- receiver
module which provides foolproof RF communication at 2.4GHz.It is used at
the microcontroller side as the receiver and the other side as the
transmitter connected with the computer through Access Port and the MAX232
IC is adopted to adapt the TTL/CMOS logic levels to RS232 logic levels amid
serial communication of microcontrollers with PC.

·         L293D (Line Driver): It is a dual H-bridge motor driver
integrated circuit (IC). It is used to control the rotation of the motor
for its movement in forward, backward, left and right. Two L293D motor
driver ICs are used to drive the two rear motors of the bot, hence is a
rear wheel drive.

·         Voltage Regulater LM7805: It is a voltage regulator IC to keep
the consistent voltage.

IV.        technical specification

Microcontroller 89S51 is the brain of the bot, which stores the hex code
for the operation.

Two L293D motor driver ICs are used to drive the two rear motors of the
bot, hence is a rear wheel drive. Zigbee module transfers the instructions
wirelessly.

A ball bearing type of front wheel is used to obtain sharp 90 degree turns
for maximum precision.

V.         future recommendation A.    The autonomous concept applied here
can be utilized for autonomous aerial drones operating on 3-D space. B.    The
concept here is a template on which innumerable mountings as per
application requirement can be carried out. C.    More advanced coding for
variable speed locomotion can be implemented. D.    Mine diffuse is one of
the important application and modification recommended by us.
VI.        conclusion

The autonomous bot developed in this project was developed in order to
overcome the various constraints in locomotion in the existing bots. The
project is developed as a new concept and is purely logic based and not
application based. Hence the bot is basically a template representing new
technology in bot movements on which modifications as per users application
is always welcomed.


References



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