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Learn Robotics(2) - Modules of a robot.

Question asked by silverscorpion in #Robotics on Apr 7, 2009
silverscorpion
silverscorpion · Apr 7, 2009
Rank A3 - PRO
We’ll see a bit about the basic strucutre of a robot today. There are
certain basic componentrs or modules, which together make a robot.
There are many of them. Some are,

1)Sensor (Transducer)
2)Processor
3)Actuator (Motors and the like)

Well, these are the most basic modules of a robot. Before going into
each one, let me make it clear that,


1)Every robot need not have all of these modules.
2)But every robot will have at least one or some of these modules.

Moving on to the basic definitions,

SENSOR :
A sensor is the thing which senses and provides information about the
environment. We can make some decisions based on the information it
gives. You would have come across the term Transducer. A sensor is
also an electrical transducer.


Technically, a sensor is anything which converts some quantity to be
measured into electricity. For example, there are pressure sensors and
temperature sensors. As you can infer, they convert change in pressure
and temperature into a voltage or current. Using that voltage or current,
we may take some action, may be move a motor or something.


ACTUATOR :
An actuator is anything used to respond to the information from the
sensor. The most widely used actuator is the motor. You can think of the
actuator as the thing used to move the robot, or move some parts in the
robot. (Simply, it’s used to actuate the bot. Know the meaning of
‘Actuate’).


PROCESSOR :
A processor is the interface between the sensor and actuator.
It gets the signal from the sensor, does some processing and commands
the actuator to do something. So, the inputs to the processor are signals
from the sensor. Outputs are the signals for the actuators.


A processor can be a micro controller, a micro processor, a DSP
processor or even a computer. And in some special cases, it can also ba
a human being.



SENSOR ------> PROCESSOR ------> ACTUATOR



That’s enough for an introduction for now. We’ll see each one of these in
detail in the following days.



So, now that you’re familiar with the frame work of a robot, we’ll see
where these modules are used.


Let’s say you make an autonomous line follower robot (A line follower is a
robot which folows a line in the ground. The line should be a dark line
against light background or vice versa. More on this later...) How do you
go about making one? What modules do you need?


To answer that, think how you can sense how the line is moving. You can
sense the colour, because, there’s a colour contrast between the line and
background. So, you need a sensor which differentiates the light and dark
colours. One solution is to use LDR (Light Dependent Resistor). It’s
simply a resistor whose value changes based on the light falling on it. So,
when the resistance value changes, the voltage also changes. So, you
sense that the line is changing track.


A more easy and accurate approach is to use Infra Red sensors. It’s
useful to know that dark colours (say black) absorb IR rays, and light
colors (Say white) reflect it. So, if you place an IR sensor on white color, it
gives a high voltage. On black color, it gives something near zero. This
can be used to identify which color the line is currently.


Next, you need a processor, say a microcontroller to decide what to do
with the sensor signal. The controller may, for example, move the motor
right if white color occurs, and move them left if black occurs. This is a
very crude algorithm, but this’ll suffice for now. So, you need a processor
to process the sensor info.


Finally, you need actuators to carry out the commands given by the
processors. You need some two or four motors to move the robot over the
line.


So, for a line follower, you need all three modules.

Next case, take a manual robot which you’ll use to pick objects from the
floor and place it somewhere in the shelf. You obviously dont need a
sensor to find where the object is. Also, you dont need a processor to
process the sensor information. You just need a remote control module to
issue commands to the robot, and some motors to actually lift the objects
and place them in the shelf. Here, the human operation the robot is
obviously the processor. So, you need only actuators for such a robot.


PS (Well, you may need a sensor after all, but that’s a special case. Take
for instance you are building a bot to be used by a blind person. Then you
need sensor to find where the object is.)


The point of the above discussion is simply that, what modules are
required for a robot cannot be determined a priori. You need to think and
decide for yourself what components the robot is gonna need.
So, now you know what is what of any basic robot. We'll go into the
details of each one.

Hope you liked this. Be interested, and ask questions.
Cheers!!😁😁
Posted in: #Robotics
ms_cs
ms_cs · Apr 7, 2009
Rank B1 - LEADER
Wow...Good Intro...😀
ms_cs
ms_cs · Apr 7, 2009
Rank B1 - LEADER
I think line follower robot will be like this...
@Scorpion: While learning the things regarding to robot,,whether we are going to design the line follower robot?
[​IMG]
silverscorpion
silverscorpion · Apr 7, 2009
Rank A3 - PRO
Yea, that one is a line follower robot.
And mind you, there's nothing limiting the size or shape of a robot. If it's a line follower, there's no rule that it should be in a particular shape and size only. No. The look and feel of your robot is decided purely by your imagination.


And yes, I plan to start with line follower only.
ms_cs
ms_cs · Apr 7, 2009
Rank B1 - LEADER
Ok,,After the Line Follower Is it possible to add some of the extra features like,,"Maybe I want to store my mails in my robot and it should alert me whenever I am receiving the new mails",,
Whether it is possible to change the sensor ,,as per my needs after the line follower design,,without affecting the functionality of the robot?
Whether it is possible to design the robot as a Human but in a very small size?
shalini_goel14
shalini_goel14 · Apr 8, 2009
Rank A3 - PRO
Hey Scorpion ! Good one , how does a robot make a grip for object? Any kind of module for it also? 😕

Are there different kind of sensors also or just kind of which can only detect light, temperature and pressure, hmm?

Thanks !
raj87verma88
raj87verma88 · Apr 8, 2009
Rank A3 - PRO
Sensor is anything that measures a physical quantity and i.e. takes an input and gives an output which is in a form readable via a proper intrument.
There are different kinds of sensors

Some Types of Sensors
1 Acoustic eg microphone, seismometer etc
2 Chemical eg the breath analyzer that the police uses to test whether you are drunk. etc
3 Electric Current Sensor eg ohmmeter, voltmeter etc
4 Sensors that sense change in the Environment eg Gas Detector, Smoke sensors, Rain Gauge etc
5 Navigation and Direction Control instruments eg Gyroscope, altimeter, flux gate indicator etc
6 Optical Sensors
7 Temperature Sensors
8 Pressure sensors
9 Radiation Sensor
10 Sensors used in Aotumotive application
11 Flow sensor
etc

Gripping
Different types of grips can be used. The simplest being like forceps to more complicated one.
These are usually controlled using Servo motors which in turn are programmed by a mC or mP.
The whole design depends upon the type of job the robot is being designed for and different types of arms are used accordingly. These will come later on and am sure Silver will be covering them.
Don't rush. These are later topics. Silver has started with the basics first and will eventually reach the arms, their equations, trajectory planning, vision, control etc.
Ashraf HZ
Ashraf HZ · Apr 8, 2009
Rank A2 - PRO
Great initiative guys 😀

We got some additional information at the CE Bot site regarding the materials and other miscellaneous stuff you can use:
CE Bot ‎(CE Lab Projects)‎

If you guys plan to do a line follower with a PIC 16F877a, I provided a basic guide here:
https://www.crazyengineers.com/forum...etition-i-dont-know-how-start-2.html#post8240

SS, you can go ahead an simplify it more to make it easier for others to understand, if you want 😀

Hopefully once we complete the CE Bot, we can provide all the documentation. xhx has nearly completed a sensor analysis report that will be really useful. We can also document all the tutorials SS or anyone does regarding robotics into a complete CE documentation 😀
silverscorpion
silverscorpion · Apr 8, 2009
Rank A3 - PRO
ms_cs
Ok,,After the Line Follower Is it possible to add some of the extra features like,,"Maybe I want to store my mails in my robot and it should alert me whenever I am receiving the new mails",,
Whether it is possible to change the sensor ,,as per my needs after the line follower design,,without affecting the functionality of the robot?
Whether it is possible to design the robot as a Human but in a very small size?

it's always possible to add extra features to your robot if you make it in a modular way.

ie, if you make a separate pcb for the sensor circuit, another separate one for the motor control part, and a third one for the interface part (ie, the microcontroller circuit), we can always change the sensors and actuators.

ie, if you wanna change the sensor, do only the new sensor circuit and hook it up to the bot. If you wanna change the motor, from DC to stepper or something, you only want to change the motor control circuit. And dont worry, these things come later. I'll explain them to you.

But, you can also do the whole circuit in a single pcb. That way, you'll have only one pcb for your robot. But you cant change functionalities easily. It'll become difficult to change, add or remove components because you've desolder, place the new components and resolder, and all.
silverscorpion
silverscorpion · Apr 8, 2009
Rank A3 - PRO
And as for your Java related thing, which notifies us of incoming mails, I think it's asking for too much.
I dont say that it cant be done. It's just more difficult. You have to be constantly connected to the internet. For that, you need wireless protocols like wifi or ethernet enabled in the robot. You need to do some additional circuitry...

One thing I's tell is, robotics is predominantly based on electronics and mechanical things. Programming is there. But that too is hardware oriented. For example, most of the programs you'll be writing for a robot will go about setting or resetting a pin in the microcontroller based on some conditions. So, the maximum you'll be using will be loops. No OOPS concepts, no networking or other advanced features are needed here.

So, if you plan to combine robotics and networking concepts, it becomes difficult.
silverscorpion
silverscorpion · Apr 8, 2009
Rank A3 - PRO
And as for the human being robot, it's not only possible, but already being done.
It's called a humanoid robot. It can also be called a biped, because it has two legs.

Heard of Honda's Asimo?? It's an excellent humanoid which is only about 2 feet tall. It's being used as a receptionist in Japan and Korea. It canbe trained to understand many japaese words and even reply to some.

it might seem very complex, and complex it is. But a very basic biped with two legs and a manually controlled motion isn't very difficult to do. You just have to be careful about the balancing.
Harshad Italiya
Harshad Italiya · Apr 8, 2009
Rank A1 - PRO
Good Going scorpian
deeps31
deeps31 · Apr 9, 2009
Rank D3 - MASTER
Is it possible to learn MATLAB by self?
ms_cs
ms_cs · Apr 9, 2009
Rank B1 - LEADER
Ok...My doubts are cleared...Scorpion:Our robot should have that modularity ..in such a way that we have to design(which enables us to add extra features)
silverscorpion
silverscorpion · Apr 9, 2009
Rank A3 - PRO
deeps31
Is it possible to learn MATLAB by self?
Yes Deeps.
Matlab is very simple. You can learn it all by yourself.
If you have prior experience in any other programming language like C or C++, then it becomes even more easier.
And the best resources to use would be MATLAB documentation itself. It comes with the installation itself, and is quite comprehensive.
You can also use the Mathworks website's matlab tutorials. They are fine too.
ms_cs
ms_cs · Apr 9, 2009
Rank B1 - LEADER
Waiting for the next tutorial,,,SilverScorpion
sarveshgupta
sarveshgupta · Apr 9, 2009
Rank B1 - LEADER
great SS.. your thread is really shaping up nicely..all the best
sarveshgupta
sarveshgupta · Apr 9, 2009
Rank B1 - LEADER
hey SS
can we attach a small lcd display to our robot and check for - stats of the sensors, memory used(if applicable), RAM used, voltage value etc..?
silverscorpion
silverscorpion · Apr 9, 2009
Rank A3 - PRO
Yes. That's a good and efficient debugging procedure and this comes after you've designed your circuit and you want to test it for errors in it.

But i'd prefer LED's because, for one thing, interfacing LCD is in itself a big process and we dont want to do it unless absolutely necessary.
We may as well use simple LED's in place of LCD's. For ex, if you wanna test if a certain node (say sensor output) in a ckt is high or low, place a led there. If it glows, then that is high. If not, that node is low. So easy..
sarveshgupta
sarveshgupta · Apr 10, 2009
Rank B1 - LEADER
thanks SS..
but if possible in future please teach lcd interfacing too
silverscorpion
silverscorpion · Apr 10, 2009
Rank A3 - PRO
Sure, I'll try to.
Thing is, I haven't successfully done LCD interfacing, myself. I've tried, but it didnt succeed. But I know how to do it, and may be I can share it here.
shalini_goel14
shalini_goel14 · May 5, 2009
Rank A3 - PRO
Guys ! Don't make such nice threads dead. 😀
Ashraf HZ
Ashraf HZ · May 5, 2009
Rank A2 - PRO
shalini_goel14
Guys ! Don't make such nice threads dead. 😀
You're right. SS, where art thou?
shahrul
shahrul · May 6, 2009
Rank C3 - EXPERT
ms_cs
I think line follower robot will be like this...
[​IMG]
This is another design for line follower. Using a servo to turn left/right. Using IR sensor to detect the black line.
[​IMG]
Rohan_sK
Rohan_sK · May 7, 2009
Rank C2 - EXPERT
Interesting thread indeed. Nice initiative taken silverscorpion. Hope you come up with some more details like this for novices in Robotics.
Anyway can you suggest some basic books or e-learning ie some good websites for beginners who dont have an electronics background, but wanna learn more about robotics. Just getting the basics properly. Do suggest something, it will help us a lot!
silverscorpion
silverscorpion · May 10, 2009
Rank A3 - PRO
I'm back..
Sorry dudes. I was a little busy with my exams and stuff. Now everything is over and I'll get back to this thread full time.

Will put up the third part very soon..
Harshad Italiya
Harshad Italiya · May 10, 2009
Rank A1 - PRO
i got one micro Line Follower Robot...can i post it here?
shahrul
shahrul · May 10, 2009
Rank C3 - EXPERT
godfather
i got one micro Line Follower Robot...can i post it here?
Why not. Maybe we can see many design here..
silverscorpion
silverscorpion · May 10, 2009
Rank A3 - PRO
godfather
i got one micro Line Follower Robot...can i post it here?
Sure. But I'll give the third part of this tutorial very soon. If you put it in that thread, it'll be more apt.
Please wait for one more day.
Is it ok??
Harshad Italiya
Harshad Italiya · May 11, 2009
Rank A1 - PRO
as you wish SS.
oaskanta
oaskanta · Aug 13, 2009
Rank D2 - MASTER
i needed to know..... how do we start making a robot at home after we have sufficient info about its parts and processes...... i mean how do we start "making it"......
msmuthu3
msmuthu3 · Jan 20, 2010
Rank E1 - BEGINNER
suggestion for suitable microcontroller for robot arm project..

hi engineers..am doin ma final year project on robot arm.am using stepper motor as actuator.this involves five degree of freedom.can anyone suggest me suitable microcontroller for this project?..thank you.

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