Go Down

Topic: Impact measurement sensor (Read 510 times) previous topic - next topic

adwsystems

Need one.

I'm looking for a sensor to measure the force of impact. Specifically the impact of a soccer ball on a solid target. It does not have to be accurate, it will not be calibrated or calibrate-able. Just needs return a value that increases with force.

Any ideas?

jremington


adwsystems

That may just work. Any breakout boards available?

pert

I've used a piezo disk for detecting impacts on a surface. Perhaps it's not the best sensor for that purpose, but it's certainly cheap and simple, and it worked perfectly for my application (which was detecting impact with much less force than yours). I got the idea from remembering the common "Knock Sensor" projects. You would need to make sure to set it up so that the voltages generated by the impacts were within the range of the ADC.

adwsystems

I saw the knock sensor projects as well, but wasn't sure if I could get a sample rate high enough to capture the peak magnitude of the impact. The accelerometer looks like it has an internal peak capture.

jremington

#5
Apr 06, 2019, 05:02 am Last Edit: Apr 06, 2019, 05:03 am by jremington
Quote
Any breakout boards available?
Yes, there are several. There are more for the ADXL377, which is analog, also 200g.

Both are designed to measure impact accelerations.

MarkT

#6
Apr 06, 2019, 03:21 pm Last Edit: Apr 06, 2019, 03:24 pm by MarkT
I saw the knock sensor projects as well, but wasn't sure if I could get a sample rate high enough to capture the peak magnitude of the impact. The accelerometer looks like it has an internal peak capture.
The Uno max analog sample rate (out of the box) of 9kSPS is going to be quite enough to capture a soccer ball
bounce, lets say it travels at 20m/s, thats about 2.2mm per sample!  A soccer ball is going to deform many
cm during the impact, it won't be hard to integrate the samples in question for a good measure of momentum
and the peak reading will be pretty accurately representative of the peak force.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

adwsystems

Doesn't the use of an accelerometer mean that whatever the sensor is mounted to has to accelerate, which means it needs to move and change speed?

If I mount the accelerometer to a wall, what would it read when the soccer ball hit? I would expect 0.

pert

The impact causes the wall to move a small amount, and the accelerometer along with it.

jremington

#9
Apr 20, 2019, 07:00 pm Last Edit: Apr 20, 2019, 07:00 pm by jremington
Quote
I'm looking for a sensor to measure the force of impact
Study hints:

The accelerometer measures acceleration.

Force is mass times acceleration.

Newton's Third Law: for every force, there is an equal and opposite reaction force.

adwsystems

The impact causes the wall to move a small amount, and the accelerometer along with it.
So the backstop does have to move in order for the accelerometer to read.

I'm trying to determine, with 200g of range and mounted to the center a piece of 4'x4'x1/2" piece of plywood hanging from the top edge (ie., hinged) impacted by a 16 ounce soccer ball, will the sensor read anything? What range of reading could be expected? How does the readings depend on the weight of the backstop?

jremington


adwsystems

#12
Apr 20, 2019, 07:03 pm Last Edit: Apr 20, 2019, 07:10 pm by adwsystems
Study hints:

The accelerometer measures acceleration.

Force is mass times acceleration.

Newton's Third Law: for every force, there is an equal and opposite reaction force.
No kidding, hence the thread. The ask was for an impact sensor, then direction has gone the way of using accelerometers. I'm trying to figure out how to make it work.

adwsystems

#13
Apr 20, 2019, 07:04 pm Last Edit: Apr 20, 2019, 07:05 pm by adwsystems
Try it and see.
Don't really want to spend $30 on a sensor that won't work. I'm trying to make sure I buy one with the correct range for the setup.

jremington

#14
Apr 20, 2019, 07:09 pm Last Edit: Apr 20, 2019, 07:12 pm by jremington
What is the informed basis for your decision to use a 200 g acceleration sensor?

If you are not capable of making a reasonable estimate of the acceleration experienced by a soccer ball when it impacts a surface, how do you plan to interpret any measurements you might make?

Start here: https://www.google.com/search?q=soccer+ball+impact+force

Go Up