# 1.1 Dc motor control  (Page 2/3)

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## 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

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
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Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
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?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
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