# Measure high amounts of force ! Need advice !

I’m working on a project where I want to try and measure that impact force of a punch. Initially I thought this would be doable with an FSR but then I realised how little force they could actually measure. Does anyone have any suggestions on how this could be done ? It should be able to measure between 500 and 1000lbs of force.

You need a mechanical arrangement, say springs, that converts the force into a very small movement. Then you measure that movement.
One way would be to use a flex sensor.
How accurate do you want it and are you going to calibrate it?

I think you could get a parallel beam load cell with a large enough max load to handle your situation. You will need an amplifier before the signal could be measured with the Arduino. The impulse delivered by the punch is going to be applied over a short period of time and the analog to digital convertor IADC) on the Arduino may not be fast enough to give you the temporal resolution needed.

Once you have the amplifier set up I would capture the signal off the load cell from a punch on an oscilloscope, then you would know how fast the ADC on the Arduino will have to be. Take the load cell setup to a friend that has an oscilloscope if you don't have one as I think understanding the timing of the event is important.

Don't get caught in the common trap that some do and think since the processor runs at 16 MHz it will perform 16 million ADC's every second. You can measure the time it takes for an ADC to complete with your Arduino or search the forum for that.

Hope this helps,

No you don't continuously take A/D readings. What you do is to set up the comparator to give you a trigger when the analog input reaches a certain level and then you take the analogue readings. Otherwise you have a simple peak detector and then you have all day to make a reading.

I am willing to be corrected on this but does that really need an arduino ?

A load cell will give force , measurement of peak force depends on when the sample is taken.

An analogue circuit could be used to generate a sample signal I suppose when the peak force decays.
if its a punch however it likely to be much slower than an arduino is capable of responding to.

edit
mike beat me to it
by an hour if I believe the timestamp

if it is a handpunch with a sprin you can measure with a sliding potmeter the distance.
when using a long lever the force is lower.

another way is with strain gauge howver this will need an amplifier

a simple weighing scale and leveris simpler.