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Oct 7, 2013 (3 years and 11 months ago)

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‘AutoMaxi



AutoMaxi
’ stands for the

autonomous vehicular robots
. In this we
receive
proximity

data trough some
proximity sensors

and then
process the data
via some electro
nic circuitry or via
Microcontrollers on which
artificial

decision
s

are
taken with the
help of sophisticated algorithm and computing

to control the
deriving motors to guide vehicle in proper direction the follow the
instructions therein. This is application and example of real world in
electronic world

interfacing
. In this tutorial
the fundamental
building blocks are discussed to boost up the
strong foundation in
autonomous
-
field which helps you to design any autonomous
systems
.





+















Image Processing/ Compute
r interface Based

ROBOTS or
ROBOTIC SYSTEM

MANUAL

AUTONOMOUS

SEMIMANUAL or MIXED


Control by
Human Itself

Control by
circuits

or
microcontroller

Both type
of control

Wired

Wireless (Remote
controlled)

(Remote
controlled)

Circuit Based

Microcontroller/P
rocessor
Based

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T
his Study material is made for review of various components which meant for robot design. T
his list is
not exhausted, the components varies as per the design, working and control mechanism of subjected
robot.

1.

MOTOR

Motor which are used in robotics are commonly specified by three measures, (a) Supply voltage,
normally 6V, 12V, 24V DC (b) speed, n
ormally 10
-
100 rpm & (c) power rating, average 3
-
6 Watt
used in robot fabrication practices.

By motor we are generally concern with three things (a) required speed (b) torque needed, in
other word the load carrying capability & (c) available supply voltag
e. Problem of torque and
speed can be resolved by application of gear assembly as by transferring to low radius gear we
get more speed and less torque & vice
-
versa.


>>>>In general, for a motor:
Torque(load)*speed= Power

and for fixed power like 4 W we
can
find high toque on low speed and vice versa.

>>>> Another general property of DC motors:
speed


supply voltage



current drawn by motor


load carried

Note: as a controller we can only control the voltage that being supplied to the motor, current is
not in our hand it vari
es as the load varied on the motor. Normally current drawn in the range of
10 mA
-
1A by the said motors.


Note: Motor as an inductive entity produce very high reverse instantaneous EMF on supply off
which may circulate current of the order of 100 A which is

cause of electronic circuit burn if the
interfacing not done properly. (to overcome this problem normally H
-
bridge or Diode protection
or Power transistor is used).

2.

SENSOR

Sensor is used to measure some environmental parameters like temperature, light, di
stance from a
source or obstacles etc. which further provides to logic circuit or controller for controlling
purpose of robots. Mainly used sensors are LDR (Light Dependent Resistor, for detection of light
presence in its vicinity), RTD (Resistive Temperat
ure Detector, for measurement of temperature),
IR sensor like PT (photo
-
transistor), tough sensor, accelerometers, tilt sensor and many more. In
addition Sonar sensor and micro
-
mikes are used for sound based sensing applications

3.

Electronics components

In e
lectronics components normally three basic components i.e resistor, capacitor and inductor in
of main concern in which inductor are used rarely. In addition following are components may use



Transistors
:: QN2222 (normal transistor, low rating), MJC3055T (po
wer transistor, high
rating)



Motor derive
:: L293D (H
-
bridge motor derive), MJC3055T can also use as motor derive due
to its high ratings



IC (Integrated circuits
):: IC7404 (NOT GATE), IC7408, IC7416, IC7432, IC7486, IC741
(OP
-
AMP), NE555D (Timer circuit), I
C7474 (D flip
-
flop, can be used as 1 bit of memory)

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Diode
:: LED (IR, white, red, yellow, blue etc) in which IR & white may use in couple with
PT (photo
-
transistor) & LDR (light dependent resistor) as sensor couple, Zener Diode for
constant voltage drop acr
oss variable current carrying component like motor and for voltage
regulation, Normal diodes used for protection applications and many more



Voltage regulators
:: This is important to supply fixed voltage to certain component like TTL
logic family IC supply
. 7805, 7809, 7812 & 7815 are +ve voltage regulator of 5, 9, 12 & 15
Volts respectively. Similarly 7905, 7909, 7912 &7915 are

ve voltage regulators of 5, 9, 12
& 15 Volts respectively. In addition LM317 are used for variable power regulation.



Advanced Com
ponents
:: In this Microcontrollers, Microprocessors and other MSI (Medium
Scale Integrated), LSI (Large Scale Integrated) circuits are employed for more complex
applications.



Relay
:: This is used for current/ Voltage driven ON/OFF switch, Normally Relay w
ith 6V
and 12V are available in market for use.

4.

Power supply

Power management is very important area in robotics design after all it is the power who derive
your robot. For this Some adopter are use for motor supply (12V, DC) and most of the electronic
c
ircuit are derive by 5V for which you can use your
cell phone charger

which is normally of 6V
rating (
Never use cell phone charger for motor, since motor draws current of the order of
Amperes which may damage your charger, so limit its use only up to elect
ronics circuit
). DC
battery also available in market, in which
9V High Watt

battery is most famous due to its small
size, low cost, low weight & easy application. We can also use pencil battery of 1.5 V each along
with battery holder and connector to make
~5V onboard power supply.

5.

Circuit simulation tools

Before implementing any circuit on the desk we should simulate it so that any malfunction may
be resolved before its operation which will save lots of component from its burning & damage
which occurs freq
uently by new practitioner. Fro this purpose two circuit simulation tools are
very famous.
Microsim, P_Spice

&
Tina
-
Pro

. On these tools we can analyze any circuit on
various ways, like time domain analysis, frequency domain analysis and also able to decid
e the
values of basic components like resistances, capacitances etc for specific performance.

6.

Mechanical Components

These are various components which may helps you during your Robot design



Adhesive: Fevicol(SH), M
-
SEAL, Cello
-
Tape etcc



Switches: Toggle sw
itch is best for use



A very control efficient wheel called Caster wheel always better to use on the place of
supporting wheel for optimal control of our mobile robot.



Pulley, Gears, Springs , Gripper etc these are commonly used components for various
appli
cation.





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ision.com

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#
ROBOT PARTS

Manipulator:

Body structure of Robotic system

Power Supply Unit:

Different type of power sources and power management


Sensor:

Devices to sense Robot environment

Controller:

Circuit or Processing unit to take decision

Actua
tor:

Powerful Device to execute powerful work as per controller decision


MANIPULATOR (BODY) CONSTRUCTION:

Generally body of any robotic system designed as per the task requirement to be
performed by the Robots. Body design is very important which affect
s the dynamics and
controlling efficiency of the Robot. Usually following are the main techniques & tools
which used frequently.

A.
Body material:

Thermocol, Plywood, ceramic sheets or any other material having
good strength, low weight, easy for cutting,
electrically isolator (to avoid any short
circuit in case of autonomous and where lots of circuit present ) etc


B.
Joints:

(i)
Temporary joint:

It is done by Nut
-
Bolt, Screw system, Cello taping or
simply threading mechanism.

(ii)
Permanent joint:

p
ermanent joint usually done by Welding, Brazing etc

(iii)
Semi
-
permanent Joint:

It is usually done with the help of adhesive like
Fevicol SH, M
-
Seal, Feviquick and other glue capable to hold the joint load at
the time of operation

C.
Body construction tool
s:

This includes Hammer, Driller, Saw, File (to rub the
corners to shape up) etc

D.
Steering Mechanism for Robotic Car:

(i)
Differential speed Based:

Direction of movement control by creating
speed of left and right side motor (which is connected to derivi
ng wheel).

(ii)
Formal steering Based:

In this the direction of wheel itself changes but
the speed of both wheels always equal.


POWER SUPPLY

In this various type of power supply system are kept to derive the Robot. Generally two
type of power source used
, Electrical and Hydraulic

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#ELECTRICAL POWER SOURCE:

Either AC or DC, but DC supply used frequently. DC
supply can onboard (like small battery mounted on Robot structure itself) or off
-
board
(DC supply given through wires by the help of DC adopters or exte
rnal heavy battery)

NOTE:

for logic as well as electronic circuits where 5Volt requ
ired it is good practice to use
you
r

phone
charges to supply the DC power to circuit.


#HYDRAULIC POWER SOURCE:

This supply is given by pressurized cylinder trough pipes
and

tubes and used for very high load applications, like ROBOT FIGHT application.





COMPONENT DETAILS:

1.

DC Geared Motor:



Characteristics:

(i)

On changing the DC supply polarity direction of rotation will reverse

(ii)

n

V (up t
o certain limit)

(iii)

I ∝

τ

(up to a certain limit)

(iv)


(keeping I & V constant)


2.

Q2N2222 (General purpose transistor)


n= Speed of motor

τ
= Torque on motor

V= Supply voltage

I= current drawing


= Magnetic Flux

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Maximum Ratings:

(i)

V
CE

= 40 V(dc)

(ii)

V
CB
=75 V(dc)

(iii)

V
BE
= 6 V(dc)

(iv)

I
C

= 600 mA(dc)




3.

MJE3055T (Power transistor)


Maximu
m ratings:

(i)

V
CE
= 60 V(dc)

(ii)

V
CB
= 70 V(dc)

(iii)

V
BE
= 5 V(dc)

(iv)

I
C
= 10 Amp(dc)

(v)

I
B
= 6 Amp(dc)

4.

LDR (Light dependent resistor)

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Maximum ratings:

(i)

Maximum current = 20 mA (for typical LDR)

Resistance rating:


>In light = 2
-
4 KΩ



>In dark = 40
-
50 KΩ





5.

LED (light emitting diode)





Operating voltage normal LED is about 2
-
3 Volts



Operating voltage IR LED is about 4 Volts



IR LED emits light in the IR region (about 1x10
13

Hz)



Never operate > 4 Volts, it will burn

the LED

6.

NE555D (A timer device)

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Useful ratings:

(i)

Supply voltage (V
CC
)
ϵ

[4.5 V, 18 V], i.e 4.5 Volts < V
CC
< 18 Volts

(ii)

Maximum output Current, i.e current from terminal 3 as,

I
OUT
= 200mA @ V
CC
=+15V

I
OUT
= 100mA @ V
CC
=+5V

7.

KA7805 (+ve Voltage r
egulator
)



8.

DM7404 (NOT GATE, an inverter element)


Ratings:

(i)

V
INPUT

= 40 V(dc)

(ii)

I
O
= 1.5 Amp

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Maximum Ratings

(i)

Supply voltage 4.75 Volts < V
CC

< 5.25 Volts

(ii)

Maximum output Current = 16 mA

9.

IR Receiver/ Phototransistor



Maximum current trough the Phototransistor in the order of 20 mA






ASSEMBL
ING:

1.

Transistor as a Switch



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On Condition



Off Condition






2.

Use of IC
-
7404 as a Switch


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CI
CIR
CUIT DESIGN

1.

(LED+LDR)+X
sistor
-
Xsistor Circuit.



>>As LDR detects the light Xsistor
-
1 (Nearest to LDR) off, so Xsistor
-
2 on which causes for Xsistor
-
3
off and so Motor is off.

>> You can reduced no. of Xsistor by taking LDR on the upper side of voltage divider arm, but in this

case loading effect plays very significant role.



2.

(LED+LDR)+Xsistor
-
Relay circuit.

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>> Here ground of Motor segment and electronic circuit is different

>> Generally Relays comes in two operating range 6 V and 12 V.

>> General purpose

transistor sufficient to drive the Relay.

3.

(LED+LDR)+7404
-
Xsistor circuit.


>> Here r is the safety resistance for the Xsistor because output of NOT GATE corresponding to bit
‘1’ is 5 volts and we cant give this much amount to the base
-
emitter terminal.

>
> Here supply for electronic circuit is taken 5 volts because we are employing logic gate.

>> Transistor is power transistor to carry sufficient allowed Ic for Motor.

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4.

(LED+LDR)+7404
-
Relay circuit.


>>Relay working around 6V, If with 5v to electronic circu
it (left part) relay not work you can change
it to 6v.