# 1.1 Dc motor control  (Page 2/3)

 Page 2 / 3

## I/f circuit

This circuit was designed as part of the demo that will be described in detail in chapter .

## Measurement equipment

1. Signal Generator
2. Voltmeter
3. Oscilloscope.
4. Stroboscope

## System identification

The transfer function of a DC motor can be approximated by a first order model with unknown constants. These constants can be identified experimentally.

The tachometer provides the feedback signal for speed control systems. A schematic diagram of the tachometer is given in Figure 6.

In this section we will identify the constants in the mathematical models of a DC motor and the tachometer experimentally. The process consists of consists of two parts:

1. Measurement of the tachometer coefficient and the motor constant
2. Measurement of the motor time constant.

## Measurement equipment

• Signal Generator
• Voltmeter
• Oscilloscope.
• Stroboscope

## Measurement of tachometer coefficient and motor constant

The tachometer coefficient and motor constant can be measured by generating a control voltage, using the PWM block of the DSP, and measuring:

1. The motor speed using a stroboscope
2. The tachometer output using a voltmeter

The setup is shown in Figure 7.

Figure 8 shows the model that will be used to generate the control voltage.

The PWM block will be configured to generate a PWM signal with a period of 4096 clock cycles of 75 MHz (please refer to Figure 9).

## Measurement procedure:

1. Connect the circuit shown in Figure 7.
2. Generate a 0 V input to the DC Motor Kit (Compile Build and Run the model with Duty Cycle=0)
3. Measure the motor speed using the stroboscope and the tachometer voltage using a voltmeter.
4. Repeat step 3 for input voltages in the range 0-15 V. Change the Duty Cycle from 0 to 100% in steps of 10 %.
5. Obtain a plot of tachometer voltage vs. servo amplifier input voltage.

The ADC input voltage of the DSP should be in the range 0-3V, the therefore the tachometer output voltage must be inverted and scaled down. This is done with the circuit shown in Figure 19. The gain of this circuit is G = - 100/270 = - 0.37, i.e., inverting and attenuating approximately 1/3. The results obtained are shown in Figure 10.

## Measurement of the motor time constant

The measurement of the time constant will be obtained by generating a square pulse and measuring the motor response to this stimulus. The principle of operation is shown in Figure 11; the experimental setup is shown in Figure 12.

The Function Generator generates pulses, as shown in Figure 13.

## Measurement procedure

1. Connect the circuit shown in Figure 12.
2. Generate the pulse shown in Figure 13.
3. Measure the rising and falling times of the motor response.

The DC motor was modeled as a first-order linear system where ${\tau }_{\text{rise}}={\tau }_{\text{fall}}$ ; however, the actual motor is not linear (due to friction, for example), therefore the measured values were:

#### Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

### Read also:

#### Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, From matlab and simulink to real-time with ti dsp's. OpenStax CNX. Jun 08, 2009 Download for free at http://cnx.org/content/col10713/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'From matlab and simulink to real-time with ti dsp's' conversation and receive update notifications?

 By Mistry Bhavesh