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In this case, an interrupt is programmed which tells the device to sample the input from the FSR and UGB network, convert it to digital, and update the LCD with the new information. This interrupt occurs one time per second. What this means is that the sensor is sampled and the LCD is updated only once per second. After the sampling, control is handed back to the loop until the next interrupt occurs.

The equation

Inside the microprocessor the instantaneous value of the analog signal is converted into a digital value and stored under a previously declared floating point variable. The following equation is used to calculate the actual weight in grams of the object on the sensor. The data is displayed on the LCD.



In the equation, “y” equals the weight in grams and “x” is the value stored under the floating point variable that is representative of the analog signal present on the microprocessor’s input pin. This equation was derived from the specifications sheet of the FSR when using a ten kilo-ohm resistor (See figure seven, use the purple plot). Using a different resistor might have allowed the use of a simpler equation. Bear in mind however that the rail voltage to the UGB was only 3.3 volts. This was necessary because 3.3 volts was the max allowable input to the microprocessor. The 10 kilo-ohm resistor yields a maximum output very close to 3.3 volts and was thus ideal.


Because the equation is cumbersome it takes the microprocessor some time to crunch the numbers. Mike Toth suspected that this is the cause of the flickering on the LCD. It turns out that the microprocessor we used is better suited for solving linear or quadratic equations in any efficient manner.

Accuracy of the device

What we have described is the inner workings of a device that can sense and output the magnitude of a force applied to its sensing element. The range of the device is between zero and 890 grams. Ideally the device should take measurements up to 1000 grams however the UGB becomes saturated before that is allowed to occur. The device is not terribly accurate but definitely can be used to get the sense that a force is being applied to the FSR. Some of the ways that accuracy can be improved are as follows. Firstly, we could invest in a more expensive sensor (we bought ours for $7.95). Secondly, we could do more testing to fine tune the equation used in the calculation. A piecewise continuous function might be more suitable. Finally, one of the main flaws in the device is the fact that pressure is not evenly applied across the entire sensing area. Some type of mechanism that evenly distributes the weight across the FSR is sure to boost the accuracy of the device (see figure 8).

Applications and conclusion

There are many different applications for force sensors that function in a manner similar to ours. The first one that comes to mind is the scale. The compact, rugged, and inexpensive nature of our sensor lends itself very well to those small digital scales used for weighing food portions. The only issue with the scale is that usually a high degree of accuracy is expected. Assuming we can correct that about our device a scale would be a perfect application for our creation. In all branches of engineering smart applications are the ways of the future. Force sensors can be a part of many different types of “smart” infrastructure. Roads and bridges are great places to incorporate force sensors. Transportation engineers could use them to gauge strain on roadways and electrical engineers could incorporate them into the design of the new red light camera systems that are coming our way soon. If they were only activated as car approaches their efficiency in terms of tickets per kilo-joule could be increased. In the near future force sensors may find their way into advanced applications such as robotics. Japan is the world leader in developing human like robots called androids. One of the more difficult tasks in mimicking human behavior is the act of walking. Most walking robots today have flat feet and lack the grace that humans have as they glide across a room. Instead they kind of lumber along. Force sensors could be a key element in developing a life-like walking android. Think about all of the nerve endings we have in our toes and feet that help us walk without any real effort. To conclude, this has been an excellent first opportunity to explore the possibilities that modern electronics has to offer. We look forward to taking it to the next level and one day implementing such technology in the field!

References

[1] (External Link)
[2] (External Link)
[3] (External Link)
[4] (External Link)

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
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
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
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?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
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
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 did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Eel3111 force sensor group july 2010. OpenStax CNX. Aug 23, 2010 Download for free at http://cnx.org/content/col11221/1.2
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