Dc Motor New

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HUMANROBOT COLLABORATION BASED ON MOTION INTENTION ESTIMATION

CHAPTER 3

SELECTION OF MOTOR

In the Market many different motors like servo motors, stepper motorcar synchronousmotors, dc motors with and without gears are available.

According to their applications and requirements these different motors are used for e.g.

We need to use servo motors if we want high torque and precise position. Stepper motors are

used if we want only position and high torques are not required .If we need high torque then

c geared motors are used . ! motors are used for only smooth motion . As though servo are

best suited for robotics it wasn"t economically viable , So we have used here stepper motor

.Stepper motors are of many types for e.g. #ariable reluctance motors, permanent magnet motorsand hybrid motors.

2.1) Introduction of D.C motor!

! motors plays a vital role in most of the industrial areas now a days , it can be seen in

most of the electronic devices. $or the mechanical movements of physical applications such as

rolling the bundle of sheets or ! drives, lifts etc we use mainly .! Motors.

In order to control the revolution of a motor many methods are evolved. We can control

! motors either by software or directly by hardware. Software controlling needs computers

which are bulky and common man cannot afford for it, so hardware controls are in use. %ven in

hardware if it is programmable device then it is preferred because it can be modeled according to

the requirements of the user.

Ad"#nt#$%& of u&in$ DC motor #r% $i"%n '%(o

1. SPEED& In 'I! I! the e(ecution of an instruction is very fast )in micro seconds* and can bechanged by changing the oscillator frequency. +ne instruction generally takes .- microseconds.

2. COMPACT& he 'I! I! will make the hardware circuitry compact.

3. RISC PROCESSOR& he instruction set consists only /0 instructions.

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*. EPROM PRO+RAM MEMOR,& 'rogram can be modified and rewritten very easily.

-. IN/ILT HARD0ARE S/PPORT& 1ere no e(tra hardware is needed since 'I! I! has

inbuilt programmable timers, ports and interrupts,.

. PO0ERF/L O/TP/T PIN CONTROL& 2sing a single instruction, output pins can be

driven to high state. he output pin can drive a load up to -0mA.

. IN/ILT IO PORTS E4PANSIONS& his reduces the e(tra I!"s which are needed for port

e(pansion and port can be e(panded very easily.

5. INTE+RATION OF OPERATIONAL FEAT/RES& 'ower on reset and brown3out

protection ensures that the chip operates only when the supply voltage is within specification. If

the chip ever malfunctions and deviates from its normal operation, a watchdog timer resets 'I!.

Con&truction of # DC Motor

he very basic construction of a dc motor contains a current carrying armature which is

connected to the supply end through commutator segments and brushes and placed within the

north south poles of a permanent or an electro4magnet as shown in the diagram below.

Fi$ur% -..1 !onstruction of ! Motor

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It is important that to have a clear understanding of $leming"s left hand rule to determine the

direction of force acting on the armature conductors of dc motor to go into the details of the

o6%r#tin$ 6rinci6(% of DC motor.

0OR7IN+ PRINCIPLE

$leming"s left hand rule says that if we e(tend the inde( finger, middle finger and thumb

of our left hand in such a way that the electric current carrying conductor is placed in a magnetic

field )represented by the inde( finger* is perpendicular to the direction of current )represented by

the middle finger*, then the conductor e(periences a force in the direction )represented by the

thumb* mutually perpendicular to both the direction of field and the current in the conductor.

Fi$ur% -..2 $leming"s 5eft 1and 6ule

Where 7 is the magnetic field in weber3m- .

I is the current in amperes and

5 is the length of the coil in meter.

he force, current and the magnetic field are all in different directions. If an %lectric

current flows through two copper wires that are between the poles of a magnet, an upward force

will move one wire up and a downward force will move the other wire down.

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$orce8 F 9 I Lnewton


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$or clear understanding the 6rinci6(% of DC motorwe have to determine the magnitude

of the force, by considering the diagram below.

We know that when an infinitely small charge dq is made to flow at a velocity 8v" under

the influence of an electric field %, and a magnetic field 7, then the 5orent9 $orce d$

e(perienced by the charge is given by&4

Fi$ur% -..3 Magnetic $lu( due to !urrent $low

$igure :& $orce in ! Motor $igure - & Magnetic $ield in ! Motor

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$i

gure / & orque in ! Motor $igure ; & !urrent $low in ! Motor

he loop can be made to spin by fi(ing a half circle of copper which is known as

commutator, to each end of the loop. !urrent is passed into and out of the loop by brushes that

press onto the strips. he brushes do not go round so the wire do not get twisted. his

arrangement also makes sure that the current always passes down on the right and back on the

left so that the rotation continues. his is how a simple %lectric motor is made.

3) C#(cu(#tion& For Tor:u%

Motor r#tin$&4 #+5A =.?A , =-@/.:;@/D =/.E rps

/* orque =.D@'3 B )because .D=motor efficiency* =:.;0 >m

7y using the formula =$@6 the load lifting capacity of our motor is ./-Dkg.

3) Contro( Of Motor

here are mainly three types of controls which are used&4

:* 'arallel ports of the '!

-* Micro controller I!

/* 'lc

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PLC

7ecause of certain advantages that many other controllers cannot give, '5! is widely

used controller in the market. Many companies like A7,SI%M%>S,+M6+> etc manufacture

plc"s, out of which A7 and siemens are widely used . Allen 7radley S5!0 '5! is used here.

'lc works on our logic. It takes the input"s from input devices like switches etc then

according to the given logic gives the output to the actuators.

In6ut&!-/ v Ac supply 0h9 frequency

Out6ut&4 -; v c supply

Pro$r#mmin$ d%"ic%&4 '! having 6ockwell software for programming

Modu(%& 4 Ac, c, Analog etc.

o control the manipulator we have used Allen 7radley 'lc here. We have used fi(ed

type of 'lc out of many types of plc available in the market like fi(ed, modular etc. !ompared to

microcontroller we have used plc as it is better in many ways like it is easier to program, more

i3ps and o3ps and many more.

0OR7IN+ THEOR, OF H!RID+E

he name 14bridge is derived from the actual shape of the switching circuit which

controls the motion of the motor. It is also known as F $ull 7ridgeG. 7asically in the 14bridge

there are four switching elements as shown in the figure below.

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here are four switching elements named as F1igh side leftG, Fhigh side rightG, Flow side leftG,

Flow side rightG as shown in the above figure. Motor changes its direction accordingly when

these switches are turned on in pairs. he motor rotates in forward direction if we switch on high

side left and low side right, as the current flows from 'Hpower supply through the motor coil goes

to the ground via switch low side right. his is the figure shown below.

Similarly the current flows in opposite direction and motor runs in forward direction, if we

switch on the low side left and high side right. his is the basic working of 147ridge Motor.

L2;3D Du#( H!rid$% Motor Dri"%r

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With one I! we can interface two ! motors which can be controlled in both clock wise and

anti clock wise directions when we have motor with fi(ed direction of motion since 5-E/ is a

dual 147ridge motor river. We can connect up to four ! motors by using all the four I3o"s.

1. L2;3D IC4

It is the quadruple high current half 1 driver. It is designed to drive inductive loads such

as relays solenoids d.c motors and to provide bidirectional currents from voltages ;.0 to /? volts.

All inputs are 5 compatible. %ach output is complete totem pole with darlington transistor

sink and a pseudo darlington source. It has two enables. When enables are high the driver

associated to it are high and vice versa.

$I


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1. 512 IC!

-. In order to protect the circuit in

situations of over current over voltage

conditions it converts :- to ; v in to :-

v. his is used for protection.

/.

;. $I


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:-.

:/. 5-E/ has an output current of ?mA and peak output current of :.-A per channel. +utput

diodes are included within the I! to protect the circuit from back %M$. he output supply

)#!!-* has a wide range from ;.0 # to /?#, which has made 5-E/ as the best choice for

! motor river.

:;.

:0. hree pins are needed for interfacing

! motor )A, 7, %nable* as shown in the circuit. If we want the output to be enabled

completely then we can connect the enable to #!! and only two pins needed from the micro

controller . It is fairly simple program to the micro controller as per the truth mentioned in

the above image. $rom the 7 circuit and 5-E/ it is clear that the programming will be

same for both of them, Just keep in mind of the allowed combinations of the A and 7.

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DC MOTOR 2

BASE

DC MOTOR 1DC MOTOR 2

BASE

DC MOTOR 1


16.

1. Fi$.H.rid$% on PC

15. Di&cu&&ion

:E. he above h4bridge thus can be used for moving motors, thus the 8ifferential Mechanism"

using two ! Motors is shown below.

2%&

21&

22&

23&

24&

2&

2!&

2"&

2#&

2$&

3%&

31&

32&

33&

34&

3&

3!&

3"&

3#&

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1. Motor Supply (+12V+24V)

2. Logic Supply (+5V)3. Clockwise (cti!

Low)

4. Cou"ter#Clockwise(cti!e Low)5. $rou"%6. &oi"ts to 'e sol%ere

wit C *otor. &ower ,r-"sistor. pto#Coupler e!ic

to pro!i%e isol-tio"

$igure : K $orward Motion


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DC


3$&

4%&

41&

42&

43&

44&

4&

4!&

4"&

4#&

4$&

%&

1&

0-. A simplified differential motor mechanism has been shown in the above figures.

he mechanism involved in $orward motion is shown in $igure :. In this both the shafts rotate in

the same direction )looking from the left, anti4clockwise*. he direction of both the shafts is

reversed )looking from the left, clockwise* and the rest remains same for backward motion.

3& he direction of rotation for the - motor shafts for taking a right turn is shown in

figure -. In this, the motor on the right moves such that it makes a backward rotation )clockwise,looking from left* while the motor on the left continues to rotate in the forward direction. his

makes the vehicle turn in the right. Although it is bit unreliable and backward rotation while the

right motor makes the forward rotation, similar effect can be achieved by stopping the right

motor.

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$igure - K 6ight Motion

Dc Motor New

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