Welcome student’s to my 20th lecture in the
series of this NPTEL course on Farm Machinery. Well ah this is entitled as Embedded GPS integrated
Variable Rate Fertilizer Applicator. Well before I say um get into details of this I
must tell you that we had also discussed of the GPS DGPS integrated Variable Rate Fertilizer
Applicator. Where in actually we wanted to tell you as to how we should be in a position
to identify what is the amount of nitrogen which is already present in the soil at any
particular point of time. It could be because of the previous crop there
could be nitrogen fixation because of the previous crop. If it is in leguminous crop
all because of the residual amount which has been ah applied in the previous year or years
like that. So, we wanted to have a um precise amount of ah this fertilizer particularly
urea ah particularly this we wanted to give with respect to nitrogen application.
So, we wanted to check how much is there in the uh plot in the given plot and what should
be applied now this will be also varying from location to location in a plot and that is
why we had discussed in my previous lecture that we would like to follow ah ah procedure
of finding out what is the amount which is already present now there are two ways I had
told earlier one is a sensor based approach direct online, the other is map based approach.
So, we discussed about to map based approach because sensor based approach so far we have
not been in a position to to uh design that or developed that.
All though people in other locations are trying we are also trying, but we have not yet as
successful. So, we are not in a position to talk about that, but definitely this map based
approach we say which people have tried at different locations. We have tried at iit
Kharagpur also and we have been ah grated amount of success in this. . So, in the map
based approach we said that we would like to have an information about the the condition
of the soil of a particular uh field where in we want to apply the amount of nitrogen
through urea. So, we had uh as discussed earlier we had
taken samples soil samples, real soil, soil samples, from the field ah large number of
samples then we identify the various constituents of this NPK. We mostly talked of n, but we
definitely found out also P and K of the location and then we you might have ah if you see my
previous lecture you will also see that I can graded that in each of the grids.
What was the uh amount of nitrogen present at those locations and corresponding how much
of urea was present over there. So, in the embedded and their we got a certain um type
of machine wherein we had ah the GPS which was ah rover GPS which were there on the ah
tractor itself. There was another which was there at the base and the system which was
there which was connecting the um fertilizer application system.
Now since the cost involved in all these was quite high ah we wanted to think of ah further,
um innovation in this and with the help of our friends and with help of our knowledge
we um rate ah more about electronics and we thought of having introduction of embedded
systems and then we have modified the same units. So, I would today I will discuss about
that where is the modification and how far this modification has been in a position to
give you a cheaper unit. Because, ultimately we must produce units
which are cheaper and which we are in position to produce at our location or in our country.
So, that we do not have to ah barrow from ah anywhere else and we should be in a position
to produce large number too, in fact ah export and give it to other people. So, in this context
this lecture has been prepared. So, let us go one by one; well what is this embedded
system you would ah you would ask me. Now, look as an elect electronics engineer
many things are needed, but um as an agricultural engineer I went it I went into finding out
what are the things which are the basic importance to an agricultural engineer to understand.
we may not be in a position to know the um ah much details of the electronic hardware
etcetera, but definitely will have some idea about what it is and what is its job. So,
embedded system is a computer system with a dedicated function within the larger mechanical
or electrical system often with real time computing constraints.
Now, it it is all the detail now why we are hav[ing]- I am saying also and I have written
here. So, that when you see the lecture at any point of time; you can come back and have
this definitions known, but then I have written here for your benefit. So, that ah you we
can follow and have a dialog here for this lecture today
embedded is is complete device often including hardware and mechanical parts as a part as
a part of a complete device what are the components of this uh embedded system well what are the
hardware well you might have heard of these it is at our level it is very essential to
know this part we have um we should have our ah um other colleagues who could help us in
ah finding out the details of electronics per it.
But then definitely we must have some idea when we are thinking of designing such a system
ah when we are thinking of agro electronics and when we are thinking of ah internet of
things into agricultural application definitely we will have to have some idea about this
. So, the hardware consist the processor, the timer, port, memories, input-output devices,
sensors. Main application software we do need to you will have to have the software created
for the job that you want ah to be done by this ah it could be to form the series of
task or multiple tasks depending upon what you want.
So, this um com the component of application software real time operating system now this
real time operating system defines the way the system works and supervise the system
software it will supervise the system that whether everything is going on in proper way
or not. Now if you see the ah figure which I have
um given on this site ah the whole details are given over here. Now, you can see the
software is the base which will. In fact, do the job the work the single task or multitask
that you want it will do the job. So, um it is there in the centre the embedded computer
that we are calling off hardware and link to other systems we will definitely link to
other systems which will ah ask it to do the job, but then there are certain inputs.
So, we will have certain input variables to the system and there will be definitely certain
output variables which will come out of this and hence there will be user interface this
user interface will help us that what sort of data, what sort of uh ah parameters, which
need to be embedded into this apart from the input variables how do you get.
So, this is what we talk about the embedded system as such if you want to know more and
more details of this when you can open any electronics book and you can have about these
details, but what is important from ah an agricultural engineer’s point of view is to
understand the application part of it. We are more concern about application their better
um hardware engineers. But then what we are concerned is how that
knowledge can be introduced into our application which will give us a precise application of
this precise application of the um item which I want to do precise time and the operation
at which I want to do. Application of ah embedded system in agriculture
well this is a worth giving you because then as an agricultural engineer as a or a designer
you, you may not be a formation engineer you could be dealing with my be soil water you
may be dealing with some other machines and things like that. So, the um the um the use
of this all the applications uh this system is enormous ah just jotted down into ah these
details, but then details if you go into details of each and every aspect you will find that
it application is enormous. The water management, yes we would like to
manage water we know that water is a scarce commodity day by day we are losing water.
So, how best we can ah manage water? How you can utilise embedded system to manage um water
at location? What is the available water at that location? What is the ah uh uh amount
of water available at certain ah depth of the aquifer? And what is the catchment area?
How do you manage? What sort of GPS location we have? How do you manage that?
So, you require application of this embedded system there as well. Then soil monitoring,
soil monitoring sensors we need to know about the soil moisture content we would like to
know, they contain nutrients contains of the soil these are important we ah things which
we will have to have and for that because this soil is there at various locations.
And then ah from satellite we have information about every ah field at various locations.
We would like to know what is the soil type? What is constituents? What are the other details
of this, so that we will know what is sort of um crop can be grown, what will happen
if the moisture is high? What will happen if the moisture is less? What sort of equipment
can be ah employed onto operation for doing particular field operation? Things like that
these are essential. The drones for field monitoring, now embedded
system can also be there on that because when we have a drone ah need not to say that drone
is now um everybody knows for the various applications of taking photographs and then
finding out the diseases we are also working on various aspects of utilisation of drones
ah identifying things now I saw in um ah one ah whatsapp videos that people are also using
this for ah uh transporting or supplying food materials or the um food Tiffin etcetera several
aspects of this. So, here also you can utilise this embedded
system you can write a software which talk of what to do and where to do accordingly
this drone which is nothing, but also a uh robot ah form of a robot which will do and
do their job. Then machines for rooting operations um what are the various machines the infrastructure
requirement the road making or the earth moving machinery etcetera.
You can have the embedded system which will minimise the cost of various other appli[cation]-
other items or components which will be there in the whole gemmate of the system. That is
why we say that embedded system if help is taken then it will be cheaper system as compared
to any another system. So, I wanted to show you that what are the various major ah applications
of embedded system if you go into details of each one of them you will find ah much
more details. Well it is it is important because I said
in the beginning that we had discussed about the ah the differential GPS based uh um variable
rate fertilizer applicator application system earlier ah um you may mark that this is system
which is an IPR and it is developed at IIT Kharagpur. So, um ah the this is important
here; now this system has been developed we wanted as you um as I discussed initially
that we wanted to um make unity will cheaper because ultimately our aim is to make it simpler
cheaper machines ah compatible and then this can be used by the farmers can be purchased
by the farmers and hence we want we went into the the embedded system.
So, when we have an embedded system what are the things that we we we get what are the
things we add what are the things we delete from the total components. Let me go to the
um next um slide first then I will come back to this slide yes.
Now, um if you see ah this particular slide here the with the uh ah VRFA system earlier
system here is the earlier system. This this is a earlier system here, where we had the
satellite information from here this is the rover GPS, then this is the base GPS, at the
um base of the ah location where we are doing this and this is the system which is there
this system is there connected with the fertilizer applicator system.
You can see here the furrows and all that is connected to three point linkage here of
the tractor. Now you see this was the system and I I um I would like to draw your attention
towards what was there in that system, well um um just see on the other side here that
GPS rover, then GPS base which are these two here.
Then the computer which was there yes this is the computer which is there. So, you have
certain cost for the computer, then microcontroller, then the DC um DC actuator motor because this
DC actuator motor will now then do the job of changing the location um location and the
exposure of the fluted role ah in into this system, the rake and pinion arrangement; well
the rake and pinio, feed shaft um with fluted roller.
Now here when we talk of this we must see the ground wheel because we have taken um
ah power from the ground wheel. So, when we take power from the grounds seed fertilizer
chain revenue unit will talk of the details of this power transmission at later stage,
but then I am talking of those details. Here then it goes to the feed shaft (Referral-Time:
14:48) mechanism. Now here this DC motor will do the job here and then the variable rate
application will be applied or the ah the amount of um fertilizers to be applied will
be activated by end of this. And power for the transmission is taken here.
So, ultimately from the um in location of the GPS rover and compare with the GPS we
will have an accurate information has to where ah um ah we have reached with when the tractor
is going into the field and then the microcontroller will talk of the um conditions and find out
and then we will have this software that software will identify the grid etcetera and then the
dc motor will be asked to do the job and then it will ultimately through the power transmission
unit it will indicate the feed shaft with the fluted roller change the position of the
fluted roller and then the variable application will be ah available to us.
Now this is that part of it now in the next system that we had called as a embedded system
what did we do. So, I will ah um show you what we did now here you can see here that
we do not have this part, we do not have this part, we do not have this part now you can
see that so many things has have been minimised. These are virtually eliminated by the system
this system which I want we wanted to indicate this is um ah you can say a higher version
of the earlier unit where we had the GPS based the GPS based system.
Now here we have a GPS module ah system variable rate system here the micro if we see the working
micro procedure procedure see microprocessor, microcontroller unit, the relay is their,
DC motor is there, fluted roll and potentiometers. So, this all will do the same thing, display
will indicate certain aspects display will tell where where you have reached and what
is the available an nitrogen at that place and hence the urea and how much urea you should
apply? So that the exact amount which is required at that position will be applied. So, the
same thing which was done earlier here will be done by this system.
But then ah with lesser number of components and many of the components have been embedded
into one. So, if we go back to the previous slide then will be in a better position to
compare those systems at this point of time. Yes, now you can see we have discussed this
part now what we can get here is; that if this is the balance here now you can you can
check in this in LCD touch screen display of 2 of 2000 and Ublox GPS module is rounded
off 2 2 ah ah ah 2000 rupees, then Raspberry PI 2 model B has a rounded of price of 3000
k and arduino price is 1.5 k. Now and what is here DGPS which has a price
of a about 4.5 because you need one at the base one at the lower there, then laptop which
is about something of the all of this. So, you can see that how much is the um difference
between this, this is 2000, this is 2000, 4000 and this is 3000 about 7000 and this
is 8500 roughly, say um location of about for 4000 ah 48,000 to 45,000 here and 3000.
So, we are getting ah ah ah a larger reduction in this and that is why this is shown that
this is in this way. Here you are using more money or you are in requiring more money for
the same job, here you are requiring sorry here you are requiring less money I am sorry
here you are requiring less money and here you are requiring high money when you have
DGPS like this. Now, with these are the systems which way
when we compare with the previous one. Ok let us now proceed because we have now compared
what is the DGPS which was the earlier and what is the embedded system which we have,
what are the things we do not need etcetera. Of course soil analysis the methodology here
also ah it is needless to tell you that ah the moment we want to utilise this system
what it does. In fact, it cuts the drone those items which we do not have, but the basic
system remains; that you need to measure the amount of soil which is there, ah the um in
the grid the nitrogen which is there and amount of information that you need from a particular
field about the soil that details are required anyway. So, the soil analysis is required
at Kharagpur since we did the work at Kharagpur. We had made we had made 32 grids of this size
5 po[int]- 5 meter into 4 meter side and this is a grid one grid is this another grid is
this. Now wh[at]- um where are the locations where you can takes soils samples. Now this
you um there are lot of debate in the previous one people have taken samples at the corners
here, here, here and one from the ah centre. Now in this we decided that know this may
not be representing that. So, we wanted to have a larger zone of idea
ah uh um soil which which is covered by the samples when we take diagonally. So, we thought
that if this is the say for example, if I talk of this, then the there will be zone
which it covered this, it covers this zone, this covers this zone, this covers here, this
covers here. So, more or less we will be this, what we think and possibly we got also the
information. In fact, we compare that when we have these ah four locations or the four
corners and one at the centre and take an average of that.
And with this we found that there is better accuracy of the data information that we got
here as compared to that one. So, um the that is why we decided this ah to be the ah grid
and this is to be the process of collecting the soil samples, those samples have to be
taken to the laboratory for finding out this. Now is a different question that ah how much
sample you will do this and ah um if this system has to be operated the machine has
to be operated ah how how much time, when? And all this this information has to be hired
has to be taken before and given those are at different aspect we will not talk of that
at present, but what will say that in case you have gone found out the information then
you can use this machine and get the benefit of that. So, we will ah with this promise
we are going ahead. Well this stocks of this stocks of the information
actually what is the information with respect to the grids as I said that we made 32 grids.
So, you can see here that 32 grids from grid 1 to 32 grids here and at each grid we had
found out what is the amount of nitrogen which was available through this you can see this.
So, we know that about ah in urea 46 percent nitrogen is present.
So, with this when we we know how much of urea is there in a particular at a particular
grid say at grid 1 this is the amount of urea which is which which is already there this
90 at this this is this. So, we had decided our design was such that we can give up to
400 kg per hectare of the uh ah urea to the system. This is what we had decided because
of the limitations of the size of the uh fluted roles and the size of the machine which which
we are taking. So, we had said that a minimum of 5kg to a
maximum of 400 kg or so you will ah you will recall that in my previous um talk also I
talked of this and here also I am saying that up to maximum of 400. So, with that base of
400, we had written the software the user interface which will tell us that if you go
to the grid if you reach to a particular grid what is the amount which is available there
and how much is to be given. So, auto automatically this system will do and will show you how
it does. So, uh uh the data points these are the data
points urea you can see in this one that each data point there are various data points here
at each point here we are in a position the available once or given with this um known
ah this colour and the urea to be applied is given in this and I have talked of these
samples etcetera. So, this ah um data tells us what we got at IIT Kharagpur.
You will have to if you want to do this experiment you repeat the experiment or to verify the
experiment you will have to follow it at your location as well in order that check what
it happens at your locations. Embedded electronic control unit well some
details of this actually as I told you that we ah as an agricultural engineer you must
have idea what is happening inside, what are there the constituent of this embedded system,
what does it do? and um. So, that we know that a these are the information’s coming
because it has these inputs. So, if you see the microprocessor GPS module has certain
things, see this GPS module now this has the microprocessor system on chip and then the
uh NM the parse the NMEA uh sentence there will be a um string in which they details
of the information which will be um available ah to convert the latitude longitude to um
LTP which is local tangent plane. Because um um local tangent plane of that
area in the field which we are talking off. Then calculate the shortest distance of the
current position for the field boundary, it will talk of always the shortest distance
because when parsing of data will be required by the software it will tell us to what is
the shortest distance and accordingly it will find out the coordinates of that point. So,
ah that is very important we must know the coordinate of that point when ah parsing of
data is taking place by the system. So, that remained the grid so what will happened
so we need to determine the grid and location all right. So, where there it will display
user input here. In fact, this is going here. So, it will display the user input it will
display the information and then say what is the amount of user input which is to be
given. Then match the grid with the fertilizer requirement. Then this has to be um match
with the fertilizer requirement how much is the requirement require ok.
So, then it will go to the come microcontroller now, this microcontroller well which will
have direction of single ah direction direction signal to the motor via relay feedback from
the potentiometer interrupt back to processor and then e um information between mechanical
fertilizer and the applicator potentiometer applicator and the potentiometer.
The job will be taken up and a whole thing will be done we will show you how these are
being done actually. So, the embedded electronic control unit we have since this is uh done
at our place and we have the IPR issues. So, we are not telling you all the details of
the circuit as such, but we are definitely telling you what we are doing, how we are
trying to do this thing. Now, this slide shows some of the locations
of what it is in the field. Because we wanted to do in the field we have
done this ah test in the field. Now figure A figure A here this shows the setup or the
machine system in the field there you can see here that we have talked of the lever
this is the lever here. Now this is the lever which um actually will move and change the
exposure of the ah um the fluted roller while we want to have a change and now this will
be um done ah on the advice of the um ah DC motor which is there.
That motor has been accordingly this um uh has been fixed at 120 rpm this ah fixed because
we want certain amount of information certain amount of ah ah chemical sorry the ah fertilizers
to be applied. So, we have set all this things then we have the relay system which will tell
us as to um how much is the gap and what is the um ah I mean what are the ah systems which
are working with respect to the others. Then the um do 2 is the um 3 is the 4 is microcontroller,
where this is the microcontroller system over here. Now there is a TFT LCD display, this
LCD display over here which will tell us what is the amount of ah information which is display
in this TFT ah display ah this is about thin film transistor ah LCD display.
Now figure B shows the fertilizer collected zippers see what happens we when we are testing
in the field we do not want that this should be lost. So, um we have um the zippers here
you can see that zipper bags we have kept to each one of this and then we have collected
while we are testing. So, that we can test unnecessary waste because once it goes to
the soil ah you will appreciate that we will lose that. So, we do not want to do that.
So, we wanted to have those things figure c shows the lever which marks the movement
of the fluted roller. So, this is the this is that lever I have
shown you the lever in the previous uh um figure also, but this is the lever. So, this
lever we will move when we show video you will see how it moves . So, we will move to
the next and have a look at field testing. Well field testing of the unit, now we have
discussed a lot about this unit now and all the um the locations and the ah systems which
are there are indicated here. I can show you again the electronic controller is here, the
embedded GPS module is here, then the DC motor is here, there is a battery which is running
giving the power to the whole system, and then a machine is working in the field. So,
we will show you the ah um video of how it works in a field.
How it changes the ah location of the ah exposure of the ah um fluted roller. Well you can see
there this this ah particular location it has move .
This lever has moved here change their you might have seen that this speeds are there
lower speed higher speed you have seen this speed and then this lever moves you can again
see that the lever is moving. If you watch properly you can see that this lever moves
and these are the advice of the motor which is there.
Well comparison of data three different speeds as I said that.
We have tested in the field condition and we tried at two um three speeds in the field
at 2 kilometre per hour, 3 kilometre per hour and 4 kilometre per hour and then this is
a uh detailed information about that I have we have given we have shared with you. So,
that you can have a look at it and understand the level of accuracy or the level of effort
that we have made in actually field testing of the system.
Well if you compare this the actual amount dropped and the required urea you will find
that R square is coming about 0.9528 and hence you will appreciate the our effort that yes
this system is working all right, but then there are certain hiccups because when we
compare the when we compare the errors with respect to at different display at 2 kilometre
we will find that the error is um very less about 2 percent error what is the fertilizer
actually dropped and the fertilizer to um to happened dropped this.
Then in 3 kilometre with this is to be happened dropped, but this much has been dropped then
at um 4 kilometre this is to be dropped this has been dropped. Now that means, there is
a speed the there is some mismatch between this period which we are moving. So, we are
further working on to this and trying to see that um either it should not be dependent
on the speed ah possibly we have to do some more manipulation of the speed forward speed
and the movement of the exposer etcetera. So, you can find that this value is very high.
So, as such a we find that 2 kilometre if you move which is generally we are 2 to 3
kilometre per speed ah per hour is the speed at which we appeared these uh um ah these
equipment or these um ah machines you will get a reasonably ah accurate ah um ah delivery
or accurate application of the fertilizer. Thank you very much.