Arduino Prototyping Inputs #31: Force Sensitive Resistor (FSR) 

Thanks! Hope it was helpful!

Thank you!

Thank you! There are 110 more videos to watch in my complete collection.

Thanks for the feedback. I really appreciate it.

Yes, of course. As long as you have a feee analog pins, you can keep adding more FSRs. (or digital, but that only give you an on/off and not ideal)

There is no easy way to calibrate it. You are most likely better off with a 9DOF sensor as the FSR is more fragile.

The concept is very similar but the code would need to be changed. Load sensors typically need a small daughterboard to amplify the signal they create. You would normally connect that amplifier circuit (an HX711 breakout board is an inexpensive and good choice) up to power, ground, and 2 of the analog pins. You can measure weight with an FSR, but it's not going to be accurate and also not as robust.

@@MarcdeVinck Thanks marc, can you contact me at: malikhussain97@hotmail.co.uk I have a few more questions and a private query to ask you. Hope to hear from you soon thanks

@@GloriousMaleck Please ask any questions here, that way the answers can help more than just 1 person. Thanks!

I don't have enough information about the circuit to give you a specific answer, (what is the circuit, what is a "bulb" an LED? What power, etc, etc) but here is some information that could help you. An FSR is just a variable resistor. Typically, the harder you press, the LESS resistance is in the circuit. Again, typically between ~100 Ohm - ~200 Ohm. If your circuit works with resistors in that range, then an FSR should work too. (generally speaking) There is a great guide on FSRs on Adafruit's Learning system. It uses an Arduino as an example, but it explains in detail how an FSR works. learn.adafruit.com/force-sensitive-resistor-fsr

Not sure. Please check the data sheet for the product you are sourcing. You can typically find them via a Google search.

It's just a range of pressure from 0 - 1023 which can be mapped to any range. No specific unit. For more calibrated measurements, look into load cells.

Yep! Use a load cell. They require a bit more electronics and are a little more complicated, but are also very accurate. It's what a scale would use.

@@MarcdeVinck Thanks! I'll give it a try

@@Thespiritofice Glad I could help. Good luck with your project!

Not to my knowledge, but the easy fix for that is protecting the FSR. Imagine wrapping it in a layer of rubber. It reduces the force and response rate. Just keep in mind if it's for repeated high forces, a non-mechanical, or non contact sensor might be best light an accelerometer. They are very reliable, have more lots of g-force ranges available, and can be incredibly small.

@@MarcdeVinck Thanks for the response, I;m not sure if the accelerometer will work for my project, I am trying to determine the forces inside a prosthetic socket. But the rubber wrap seems like a great idea, I guess it will take some trial and error to determine the correct amount of rubber.

Yes, use a load cell, not a piezo. Thats the best choice for better accuracy and less fluctuations.

@@MarcdeVinck yes ik but sir i have space constraints so i m going with fsr only , but one thing i got to know about fsr is that we can use smoothing and get very less fluctuations ,the results are amazing with that code ,also i used a 47 mf capacitor with it ( anybody interested for the project mail me at kb9829422@gmail.com) . Here is the link for smoothing www.arduino.cc/en/Tutorial/BuiltInExamples/Smoothing

@@BilalKhan-do9il Glad it worked out! Just keep in mind it is now much less accurate and slower. But it can be a good solution.

@@MarcdeVinck sure sir, thanks!

Miguel Angel Casado Unfortunately it is only a proportional amount of the minimum to maximum range. This can be helpful for some projects, but it isn’t going to work like a scale. For calibrated and precise measurements you need to look at a load sensor. A bit trickier to use, but they will give you precise results.

It depends on your circuit, etc. An FSR is a resistor. In the example the 10K is so the pin doesn't float (give back crazy signals). In general you want a 10k to stop random signals and tie the sensor to ground when not in use.

It might be, that's a tough one as the speed of the Arduino might be a limiting factor too. I would assume you could in a test setup. You might be able to get some idea with a piezo sensor mounted to a metal plate and measure the amount of electrical energy created. But that would only be relative to the BB and gun, not an actual fore measurement. I have a video on those -- ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-X3XXRZMBPO0.html

@@MarcdeVinck Thanks, yeah that could be enough. The goal is to just record that it has hit it, not how strongly so it should be enough. I will take a look at your other videos thanks! Subbed :)

@@fredd9740 Oh, then a piezo 100%. Will work perfectly. Easy too! Just adhere it to the back of the metal target plate. Thanks for the sub!

That is actually very easy! The nice thing about microcontrollers is you can easy reverse the #'s to decrease the LED strength (voltage to the pin) based on force. There are severals ways to accomplish that, but I recommend you look at the "map" function. For example: map(value, fromLow, fromHigh, toLow, toHigh) in practice would look like y = map(x, 0, 255, 255,0); That would inverse the range of numbers and you could apply that to the LED brightness. Hope that makes sense! Good luck! And thanks for the sub! Please share!

That is a very doable project. Unfortunately I can't help, but you can find a lot of information online.

You need a resistor to get the range and protect the input pin.

You can have multiple sensors. As many sensors as you have available pins, depending on the type of Arduino. You would read each pin and return the results.

Yes! A servo could easily be programmed to react based on the input from a force sensitive resistor.

Just use other pins. However, any vibration from one, can typically be picked up with additional FSRs, so isolation, etc, may be necessary.

@@MarcdeVinck would the code for the arduino still be the same? Do you have a video about it by any chance?

@@sjw0233 Any time you change a component, or add a component, the code is more than likely going to change. In this case you most likely could use the same lines of code and change the pins to read an FSR, but it really depends on what you are building.

@@MarcdeVinck is there a video or anything you know of that can help me more?

@@sjw0233 Sure, Google "arduino multiple FSR". Lots of results.

It depends on your estimated impact, which I assume is very high. Are you running, or jumping, how much does the user weigh, etc. Also where on the foot, as that can increase/decrease the impact by as much as 50%.

@@MarcdeVinck Thanks for your reply. I plan to put two in the middle of the pad and one in the heel position.

Yes! There are small pins on the sensor you can solder wires onto.

thanks for the quick reply appreciate it.

1N is ~ 6k Ohm depending on your sensor and hardware. You can google Simple conversion tables that will get you in the ballpark. Code is available too.

@@MarcdeVinck thank you. my fsr senses up to 5 kg (49.05N) so could i set it for every 6km ohm is a newton ?

@@MarcdeVinck also what would be the best terminology when googling this i find i often dont get the results i am looking for. thank you

@@rianmoore8693 Start here - learn.adafruit.com/force-sensitive-resistor-fsr/using-an-fsr

@@MarcdeVinck do you know if your able to solder these sensors to make the wire connection longer?

I think you'd be better off using conductive rubber and a strap around someones chest to measure breathing.

That is what this sensor does! If you need to be more precise you should look into load cells. That's what a bathroom scale would use.

@@MarcdeVinck iam using force sensor in my broject robotic can it load and catch things depending on weight of its .. and I need codes of the sensor pleas

Here you go! -- learn.adafruit.com/force-sensitive-resistor-fsr/using-an-fsr

@@MarcdeVinck thank you very much

It's not as accurate as a strain gauge, but yes you can. Just correlate the analog output as shown in the video to a known weight. Could use the map function too. But again, a strain gauge is much better suited for accurate weight measurements.

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You are measuring a resistance within the FSR. You can map that to a measurement of force, with some calibration, but just keep in mind it's not going to be very accurate and may not be linear.

@@MarcdeVinck Then what will be the use of this

@@alokkumarnyati There are lots of uses, in fact it’s one of the most popular sensors. Take a look online for projects that use FSRs and Arduino. You get a varied resistance. Use it to make music, sense when something is empty by weight, etc. that are lots of fun!

Watch the video for the code. And it can be found here -- learn.adafruit.com/force-sensitive-resistor-fsr/using-an-fsr

You get an analog voltage reading that you can convert to pressure. It's not as accurate as a load sensor, but it works in many applications.

By the slice!

It's in the video! And can be found here -- learn.adafruit.com/force-sensitive-resistor-fsr/using-an-fsr

Please watch the video I go over where to find the code and how to use it.

@ Marc de Vinck

Yes, but it's not accurate or calibrated. A load sensor would be a much better choice. That's what a digital scale would use. It involves a bit more components, but well worth the effort.