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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!


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Questions & Answers

How is everyone doing
Lotegeluaki Reply
I didn't know it had this feature. Good, thanks for asking.
getting better thanks ... how are you ?
Oh hey
Doing well, thank you!
could someone talk about the 4th level of maslow's hierarchy of needs pyramid. thanks
@Neelkanth , The fourth level depicts self worth. It basically means pride enters one's life later on. Honestly, I don't confirm to the hierarchy much.
An example, this a drastic example, : Making an 11 year old kid that has gone through basic conditioning beg for his/her life may be easy when you put a gun to their head.
However, when you do so to a man in his late 30's to 40's who has also gone through the same conditioning in his childhood, it may be more difficult to make him beg. This is because he has earned a reputation. Went up the hierarchy
when young children speak in short phrases using verbs and nouns,what it is referred to
Simran Reply
how old? generally that's how kids talk isn't it?
especially shy ones
what are the social psychology concepts
their are about seven main theories... hope someone could help out with main one and their characteristic
the self concept, social cognition, attribution theory, social influence, group processes, prejudice and discrimination, interpersonal processes, aggression, attitudes and stereotypes.
what is different between psychoanalysis, psychopathology?
when do children form oppions
Tasha Reply
they sit in home and play home toys
How to know other person
what is the nature and scope of biopsychology?
Pratibha Reply
working along with neurologists and doctors closely on the field related to brain and nerves
How can one over come a sleep debt
Andy Reply
how does an algorithm save you time and energy when solving a problem
john Reply
by directing your attention or misdirecting your attention to a particular topic
can an obsession with blood and Gore be caused by psychological trauma
Dalton Reply
psychological trauma is a bit of a wild card in the case of long term effects. everyone has their own unique experience and I dont see why the example in your question couldn't be a possible manifestation.
it would be a bigger possibility of this resulting from trauma if this began after you witnessed a violent or gory event. however this often comes from the amount of violence and gore we are exposed to through social media, the news, and fictional material like books, movies and video games.
how can the bipolar and mood disorder can prevent?
Shana Reply
Control stress. Stress is a major bipolar trigger. ... If you would control stress you will simply feel good ....if you want to know more about this DM @shana mae
That brings us to the next question.. How do we actually control stress in an effective way?
well for me mindfulness meditation techniques are very much effective for coping with stress ....
please what are the major things I need to know now in psychology,because I'm a new student of psychology.
Godwin if it is your begining in this field you should first clear some concepts like what is psychology it's etymology , structuralism,functionalism , behaviourism and many other perspectives .....
first of all are you studying in psychology or working as a psychologist
studying Sir
Thank you Sir Khalid.
Muhammad Akram Both ☺️
Far too often, you can't control stress just like that on your own . And it will affect you On subconscious level . When it comes to meditation it's something to take seriously and best to be taught by professional.
I know there are many other ways but I found this one at my own Kira Emerala!
Hi friends
it can't be extracted I'll tell u that much
someone who study psychology here need help ? anyone ?
Can I ask for tips when you have no motivation and can't focus with your studies?
For Shana, I'm sorry, I can't answer your concern at the moment, because I'm still studying about the basics of psychology 😬
do meditation, start learning few pages initially n understand before moving to another topic
play a sport of your choice for half an hour or listen to your fav music, develop your positive outlook towards life
learn to balance work play study
n health
I'm struggling with BPD cptsd major anxiety disorders and going to college for a psychology degree. trying to maintain motivation is difficult. what can I do?
I already meditate take my meds use biofeedback and several other things
As a student, it is normal to lose motivation during college life but look at the long term goal. What do you want to achieve at the end? Divide it into small achieveable goals. Once you achieve it, focus on 2nd small goal. Last thing, it's okay to ask for help when needed. We are all in a journey.
what's your friend's circle
khawla saadouni yes how can I help you ?
Sarah you need CBT it will be effective on that what you are experiencing !!
implicit memory are those type of memories which can be written without any unconsciousness
Aayu Reply
m interested in this research...
me too plz I am suffering from depression so v forgetful which has ruined my life
yes plank youth
0rayers poracles a d majik
cuffed truthfullcreatibeclarity
sins saintly do you need any help regarding how to cope up ?
what do you mean by sensory memory
Aayu Reply
sensory memory simply is an automatic response, not under conscious control. It deals with the input from the senses. 
what is the name of a person who introduction the techniques of factors analysis in intelligence
JobJoy Reply
what is associated with the developmental
lifelong spiritual advice
Zach Reply
Can you define spiritual Zach?
Are teeth part of our minds?
who introduced the technique of factor analysis in intelligence
JobJoy Reply
Spearman's (1904)
apart from Spearmans 1904 who again
Howard Garner
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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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