Making Fsr Panels (force Sensing Resister) To Register Hits

 
#1

this really deserved its own thread as it can be used for other applications than scoring for the air soft much warrior bots. I will include pictures , drawings and links.

This force-sensing resistor (FSR) from Interlink Electronics is a passive component that acts as a variable resistor, with resistance decreasing in response to increasing applied force, which makes it easy to add a touch interface to your project or create a robot with much more sophisticated tactile senses than are possible with simple lever switches. The polymer thick film (PFT) device is optimized for use in human touch control of electronic devices and can sense an applied force anywhere in the active area ranging from a few dozen grams to over 10 kg (22 lb).

In our tests, the resistance exceeded 1 M? with no applied pressure and dropped to a clearly detectable and very stable 50 k? with a 20 g weight placed on it. Pushing on the pad as hard as possible dropped the resistance to around 200 ?. This resistance range is well suited to work directly with the internal pull-ups of many microcontrollers such as AVRs and PICs. The FSR was responsive enough and sensitive enough to distinctly pick up light, rapid finger tap, and it was even able to pick up the vibrations of a small vibration motor placed on it on the motor's side.

#2

1.5 inch FSR $7.95 from pololu
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These are very thin and have an adhesive backing. In this thread I will show you how other robot owners are making their own fsr panels as cost effective as possible for the end product goal.

#3

THERE ARE GREAT FORCE SENSING DEVICIES, i have a few types and they come in many shapes and pressure amounts,and super easy to use ,only need resistor in a divider setup

They are easy to make using a prnted circuit board,only problem is not that accurate.its like trying to make a resistor ,dont have a machine to make them

Plus all other companies that sell them a little less,so its not really worth the time

BUT i guess is good project to play with

#4

I will first post how trossen much warrior competition assembled theirs. The pics and instructions are from their forums.

Full Size FSR Target Panels

1) Here are the parts for a Full Size Panel. learn them, love them. The black ABS is your back plate, the clear lexan is the front plate that protects the FSRs. FSRs go in between the black ABS and clear lexan plates. The PCB attachs to the back plate. But don't start building yet! Let's go over everything step by step.


2) Prepare the lexan plates by peeling off the plastic protective film. Set these lexans plates aside for later.


3) If you have back plates that have a textured side, the FSRs are mounted on the smooth side.


4) First we need to mount the FSRs to the black ABS back plates. Peel them ONE AT A TIME.


5) Very carefully align the first FSR. Use the edges of the back plate to line it up correctly. Please be very careful during this, you do not want to misalign the FSRs and have them hanging off the edge/too far in from the edge. Once you stick these on, they do NOT come off, so you only have one shot.


6) Your first FSR should look like this.


7) Peel & prepare the second FSR. Align this with the top edge (in this pic) of the back plate, and the center axis right up against the edge of the first (already mounted) FSR.


8) It should look like this if done correctly. If it doesn't look like this, cry. You've disappointed your ancestors.


9) Carefully align the 3rd FSR. Again, make sure its snug up against the adjacent FSR, and the bottom (in this pic) edge of the back plate.


10) Carefully align the 4th FSR. Make sure its snug up against the adjacent FSRs.


11) These be the parts for your FSR PCB. Word.


12) Install your components as shown. Note, resistors may be tan or blue, 4.7k-5.1k resistance. Solder the components.


13) Apply double sided sticky tape (not included, you cheap bastards). Make sure you use some high-strength stuff. DO NOT ATTACH THE PCB YET.


14) Without actually attaching the PCB, carefully insert all 4 FSR leads into the PCB as shown. Take your time with this, and be gentle.


15) Again, before attaching the PCB to the back plate, carefully solder the FSR leads to the PCB. Use low temperatures (375F) and do not hold the iron on any connection for more than 3 seconds. You will melt the FSR connections if you get too heavy handed.


16) Very carefully bend the connections flat. CAREFUL. Be a gentle lover.


17) Attach the PCB to the back plate with steady applied pressure.



18) Voila!


19) Line up the lexan plate.


20) Use tape (electrical is what I use) of your choice to attach the lexan plate, along the edge and around to the back plate.


21) Attach velcro to the PCB in preparation for mounting.


22) Look! Cable! Ready! I highly recommend putting a dab of glue on header/cable connection here to make sure it doesn't wiggle loose. You can remove the buckle from the cable if you like. The side that plugs into the transponder needs to be unbuckled.

Please note S, V, G.
S = Yellow/White, V = Red, G = Black.


Half Size (Split-Option) FSR Target Panels

NOTE: These instructions are for Half-Size FSR Target Panels that are used for the 'split option' on the FRONT of the mech only. This method utilizes a single PCB that is split in two, and a tether between the two half-size panels, which are then connected to the MWScore Transponder using a single cable.

Biped Side Panels: Half-Size FSR Target panels that are used for biped-only side panels are assembled slightly differently, in that they use 2 PCBS (split in two, you only use the side with the resistor, discard the other side) and they do not use a tether. Each half-size panel has its own cable that goes to the MWScore Transponder. These are assembled almost identically, please refer to the end of this section for the distinction.

If you are assembling a biped that uses a split-option front panel, you will need to build one set normally and one set using the variation explained at the end. If you have questions, ask. Again, read everything before proceeding, if you're building a biped make sure you understand the difference.

1) Here are the parts for a Half Size Panel. learn them, love them. The black ABS is your back plate, the clear lexan is the front plate that protects the FSRs. FSRs go in between the black ABS and clear lexan plates. The PCB attachs to the back plate. But don't start building yet! Let's go over everything step by step.


2) Use a ruler to score the PCB, several times. You don't need to press hard, just apply firm pressure and score it 5-6 times. You should be able to line it up to the edge of a table and snap it with your hands. I recommend sanding the scored edge so it doesn't get fiberglass fibers everywhere.


2) Prepare the lexan plates by peeling off the plastic protective film. Set these lexans plates aside for later.


3) If you have back plates that have a textured side, the FSRs are mounted on the smooth side.


4) First we need to mount the FSRs to the black ABS back plates. Peel them ONE AT A TIME.


5) Very carefully align the first FSR. Use the edges of the back plate to line it up correctly. Please be very careful during this, you do not want to misalign the FSRs and have them hanging off the edge/too far in from the edge. Once you stick these on, they do NOT come off, so you only have one shot.


6) Align and mount the 2nd FSR.


7) Place the components as follows.


8) Solder them.


9) Apply double sided sticky tape (not included, you cheap bastards). Make sure you use some high-strength stuff. DO NOT ATTACH THE PCB YET.


10) Without actually attaching the PCB, carefully insert 2 FSR leads into the PCB as shown. Take your time with this, and be gentle. Repeat for the other side.


11) Again, before attaching the PCB to the back plate, carefully solder the FSR leads to the PCB. Use low temperatures (375F) and do not hold the iron on any connection for more than 3 seconds. You will melt the FSR connections if you get too heavy handed.


12) Very carefully bend the connections flat. CAREFUL. Be a gentle lover.


13) Attach the PCB to the back plate with steady applied pressure.


14) Attach the lexan plate to the front using the same taping method described in the last section.


15) Velcro, do it.


16) This is how the cabling works for the split-option Half-Size FSR Target Panel set. You can shorten the tether cable between the two panels as much as you need. I highly recommend putting a dab of glue on header/cable connection here to make sure it doesn't wiggle loose. You can remove the buckle from the cable if you like. The side that plugs into the transponder needs to be unbuckled.

Please note S, V, G.
S = Yellow/White, V = Red, G = Black.


Half Size (Biped Side Panel) FSR Target Panels



Biped Side Panels: Half-Size FSR Target panels that are used for biped-only side panels are assembled slightly differently, in that they use 2 PCBS- split in two, you only use the side with the resistor and discard the other side. They do not use a tether. Each half-size panel has its own cable that goes to the MWScore Transponder.

Basically, you need to build two of these, minus the header that's used to tether two side panels together for the split option.


MWScore Transponder Pinout



We do not recommend powering these directly from an 11.1v (12.6v max) 3S Lipo. They can be powered directly off of a 5v pin from the arbotix without issue however.

Please note: If you ordered Xbees you will need to program them appropriately. Each one of you has a unique ID # (it's written on your MWScore transponder), this is important when setting up your Xbees.

Xbee info:

ATBD = 5 (38400bps)
ATID = 6200
MY = 6200 + TRANSPONDER_ID_NUMBER (written on the bottom of each transponder)
DL = 6201
CH = c

If you don't have a method of programming your Xbees, bring them to Robogames and we'll get you programmed before your qualification round. Make sure to get this done early, it's your responsibility.

#5

WOW a lot of work just to make a FSR,I seen that info on trossens alot,first not as good as a new one and to get very small,plus they wont last as long

But still good idea to learn how they are made

I like the very tiny ones you can put on end of a robot finger,also ,need to find the link to get them for about $4 each

i love XBEE i have 8 at home

You need to posts photo's JOSH for others

#6

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#7

ok great,i had about the same indea for my feet on my humanoid type of robot
biped type with 17 DOF and 17 servos ,i orders some parts alreal it will look kinda close to the johnny five robot only with legs and i boght already my FSR'S and my foot plates plus some sevo's and brackets

#8

These are for targets on robots. The basics to note are a plastic or abs backing , attach to FSR to the plastic and cover it with 1/8" plexi to protect the far sensors.

I imagine the front and rear of a robot would have a 4 sensor fsr panel and each side a half sized fsr panel.

That means for one robot we need 12 sensors. That's 88 dollars for a entire set. Hmm anyone know where we can get a good bulk deal on 1.5 inch fsr panels.

#9

Jameco.com will sell the force sensors for 6.99 in bulk order 10 or more but my uncle is a store manager at shields electronics and they have a jameco account. Maybe I can get another dollar or two off the price and a good shipping rate too.

@Bret what do you think? Like the FSR idea so the hits are electronically kept score by our ezb.

Nerf Darts - I had an idea that we could use darts with a Velcro tip and maybe Velcro covering the fsr target plate so Nerf darts that impact the fsr can be scored higher than a normal air soft strike. How's that idea?

#10

I like it.