Gun Trigger Force Logger

This is a project which aims to create a DIY solution to fight bad aim due to uneven pressure on the trigger by smartphone logging over BT.

Similar projects worth following
This project started of as an idea of [Anna Dedova], who is a succesful rimfire pistol shooter. The initial question was whether a force sensor thin as tinfoil exists - a quick google answered affirmatively. So far we decided to use AVR (which I have some experience with), a flexible force sensor with the apropriate force range and the CC2540 BT 4.0 module from TI (well, the copy of it, we are high school students, not millionaires). We might as well add an IMU to monitor the caused movement. At best we will develop a script for logging the force (and delta movement) and displaying a graph, possibly an algorithm for finding peaks to cut the graph into small pieces for each pew and computing the deviation from the ideal linear function. Triggerwiggle, try saying that ten times really fast. Heh.

Well the description says it all so far...

  • 1 × Force-Sensing Resistor: 0.25″-Diameter Circle, Short Tail
  • 1 × Probably Homemade Barebones 'Duino
  • 1 × BT 4.0 Module TI CC2540
  • 1 × IMU module? not yet sure whether or not to use this

  • Finally a board

    Emil J10/05/2014 at 19:08 0 comments

    So the piece of scrap copper clad board I drew traces on didn't turn out good at all - when I started scrubbing it with the chloride, the traces smudged away! I relally didn't know that scrubbing it off makes it easier only for toner transfer made PCBs. Nevermind, grabbed myself a protoboard and soldered a few wires to the module I sticked to the border with some tape. Also I made a basic voltage regulator with three 10k resistors so the CC2540 does not get fried from the RX again. Heh. Fried T-Rex.

  • So we got another BT module!

    Emil J10/02/2014 at 18:45 0 comments

    Yay for that! It's CC2540 based as well, but the unpopulated board pins are so tiny! I tried making an adapter board for it with the classic - laser printer, magazine paper, iron it on, peel off, dissolve excess copper. Since the spaces between individual pins are only 0,47 mm wide so that was quite unsuccesful - they sort of merged. Laser toner is just plastic you melt on the copper so no wonder. Order a good prototyping PCB? Not my thing. I have drawn the traces to pins we need (GND, VCC, TX, RX, RST) by hand with aan alcohol based pen. Aw yeah, old school. I shall etch and solder and be back with an update with pictures , hopefully we finally get to actually test it all with the arduino mini and the briliant code to build on from this series:

    Thanks [WaiHoYan]!
    In the future I'm thinking once we have a proper working board to parse data to android, we could design a holder under the pistol barrel and 3d-print it in the nearest hackerspace Balance is vital. Give this a skull or follow for more updates!

  • Guess who messed up?

    Emil J09/19/2014 at 12:56 0 comments

    So yeah, I connected the 3.3V Rx on the BT module to the Arduino's 5V Tx. Well, another one coming in a few days.

  • Deadline stuff:

    Emil J08/20/2014 at 22:31 0 comments

    I'm going to tell you a story of procrastination and bad timing. When [Anna Dedova] had the idea of building this device, I was on a German language course. Then I was with my family in Switzerland. Then for a week at my ouncle's house, doing DIY stuff, learning C and whatnot. Then is now - I had about four days to start writing stuff up and, being a procrastinator, am writing this just a few hours before the deadline. Also, the under 18 form is a bit stupid - you have to scan it again? It has the same legal potential as having people write down their names in an online form and would have the same probability of someone faking it. Supplyframe's lawyers kill trees. But the trees are slowly getting vengefull... just saying.

  • Sensoric Test of Force Sensor

    Emil J08/20/2014 at 22:23 0 comments

    Yeah, that means my kitten tried to eat it. What a cute little murderous bastard.

  • Whelp, four project logs? Okay, what's now:

    Emil J08/20/2014 at 22:21 0 comments

    So according to the official rules, you must have at least four project logs. Huh. Okay: we have the sensor! I'm going to be having fun with it to test out how the area of finger affects the resistance and stuff. I order a Arduino Nano clone and an 9DOF IMU so in a few days we should be able to have some results!

  • First Thoughts

    Emil J08/19/2014 at 20:17 0 comments

    In the beginning, we thought that sticking a USB cable in a notebook and having an Arduino on the other end would be enough. Well, nope! The cable would be freaking annoying when trying to get the ultimate shot. Bluetooth slipped into mind almost immediately as a pretty universal solution. BLE was chosen for the low energy consumption - we want to keep the weigh including the batteries low so the feel of the gun isn't heavily affected. After a while of googling a 0,25" force sensor was chosen due to the size of the trigger. The real challenge is mounting the sensor on the trigger, we might need to modify the trigger itself - or even opt out for a different solution. We'll see about that later, when we actually have the necessary supplies to get the thing going.

View all 7 project logs

Enjoy this project?



Xavier wrote 08/26/2014 at 12:58 point
I'm starting the same project but for biathlon shooting and googleing i discovered yours. Did you test the sensor? Is it accurate enough to record intervals of about 5/10 grams?

  Are you sure? yes | no

Anna Dědová wrote 09/27/2014 at 19:46 point
Hi, I am pistol shooter and we have 500 or 1000 grams on a trigger so we choosed sensor with greater range, but I think I saw there more accurate sensors too, even in smaller sizes

  Are you sure? yes | no

robhumb wrote 08/19/2014 at 20:31 point
Lower number of fliers on the target the better. Very good project idea.

  Are you sure? yes | no

Emil J wrote 08/19/2014 at 21:10 point
Not mine, I'm a mere realisator!

  Are you sure? yes | no

jlbrian7 wrote 08/01/2014 at 19:57 point
I have never used an accelerometer in anything before, but this might be a good application.

  Are you sure? yes | no

Emil J wrote 08/19/2014 at 17:32 point
Oh yeah! Thanks, we could try mapping the movement of the gun vector in 3D. That did just add some challenge to it!

  Are you sure? yes | no

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates