Need help to find suitable sensors

Hi Everyone,

I need some suggestion with selecting suitable sensors for a project in college, please help. The project is to find out the velocity of a wooden block when it leaves a pressurized tube along with the maximum pressure developed in the tube. I have attached a picture of the experiment for better understanding (Please have a look at it :slight_smile: ). My main aim is to find P and V (refer to the picture in attachment).

Please recommend suitable sensors to be installed in the wooden block to facilitate this.

  1. I am trying to use an accelerometer and an industrial grade pressure sensor to be installed in the wooden block. But many of the posts here say that the accelerometer will give a lot of errors if we use it to calculate velocity. Is there any other sensor to use here or if possible is it feasible with accelerometer?

  2. The only restriction is not to fit anything in the barrel and all the equipment is to be fitted in the wooden block only. Is it possible with this condition?

  3. If not what other arrangements can be done on the barrel to achieve this?

Some kind of break-the-beam muzzle brake on the end of the tube?

vrpraveen:
Please recommend suitable sensors to be installed in the wooden block to facilitate this.

It is a college project. You should know how to select a sensor!

So, when you find a job, are you going to do the same thing?
Have someone else do your job? ? ?

Jobs going to Asia and south Asia and to people who need Western know-how to even do a college project!
Ridiculous!

.

ieee488:
It is a college project. You should know how to select a sensor!

I have already selected the sensors, I just wanted to know if its feasible or not? and I am sorry if you felt that ridiculous. This is one of the ways to select, by asking some experienced people. If you know any feasible solution with an accelerometer I would be happy to know.

TolpuddleSartre:
Some kind of break-the-beam muzzle brake on the end of the tube?

But that would lead to adding some attachment to the tube. Is it possible without that, using an accelerometer?

Thanks in advance :slight_smile:

Ignore the pedantry and sharp remarks on here, it's rife, just let it sail past you.

In terms of what you are truing to achieve, I don't have any experience with using accelerometer for this application. Presumably, all sensors and the arduino need to be mounted on the wooden block?

What are you doing to keep the wooden block from tumbling?

You could use a small sonar emitter on the front of the block, and a receiver monted in front, and the doppler shift caused by the movement? That would mean that you don't need your board on the block. But it wouldn't be so accurate without being able to correct for trajectory etc.

fall-apart-dave:
Ignore the pedantry and sharp remarks on here, it’s rife, just let it sail past you.

What are you doing to keep the wooden block from tumbling?

Thanks Dave, I am sorry i didnt explain the experiment completely i dont have any problem if the wooden block is tumbling, when inside the tube the block has guide studs to stop it from rolling if thats what you asked, when outside its free and falls onto the ground, the aim is to propel the block in such a way that it lands between two marked points on the ground. We need to find different velocity and pressure profiles for it. A receiver mounted in the front as you told would require again modification to the tube which I am trying to avoid. Is there any workaround for this?

Ah, so you only need to know the velocity of the block inside the tube, not once it is out?

Pressure inside the tube is easy - I take it you have that sorted.

For velocity of the block inside the tube, to be clear:

You cannot modify the tube
Sensors must be mounted on the block

Correct?

To use the sonar idea, you would not need a receiver anywhere near the tube, you just put it in front of the tube, maybe on a wall, on a stand, anything so long as it is directly in front.

fall-apart-dave:
For velocity of the block inside the tube, to be clear:

You cannot modify the tube
Sensors must be mounted on the block

Correct?

To use the sonar idea, you would not need a receiver anywhere near the tube, you just put it in front of the tube, maybe on a wall, on a stand, anything so long as it is directly in front.

Yes basically I need to find the maximum velocity it has achieved in the tube, you may call it muzzle velocity. And mounting a reciever outside the tube may not be possible near the tube as the wooden block may hit the reciever and placing near a wall or stand is not possible with the experient :frowning: . Would like to know any other method you have in mind thanks in advance :slight_smile: .

How about a cheap Doppler radar module?

So.

No modifications to the tube.

No external sensors.

Any and all sensors must be mounted on the wooden block?

Ah! Wood.
Not good for radar, sorry.

TolpuddleSartre:
How about a cheap Doppler radar module?

Doppler radar module would need a surface opposite to it but there outiside of tube is open air and nothing else so it may not work :frowning:

fall-apart-dave:
So.

No modifications to the tube.

No external sensors.

Any and all sensors must be mounted on the wooden block?

Exactly

So why not put a sonar on the back of the wooden block, facing the back of the tube? Doppler shift works both ways. You don't have to have a receiver at the back of the tube, the sonar can send and receive.

fall-apart-dave:
So why not put a sonar on the back of the wooden block, facing the back of the tube?

This could actually work will try for that thanks :slight_smile: .

Will you have to compensate speed of sound for the higher pressure?
Will ordinary sonar be able to make enough measurements in the time available?

Air pressure will have no discernible effect (read up on how SONAR works)

I can tell you with absolute certainty that you will have more than enough time to make measurements, unless you are firing the wood at mach1 or above, but in that scenario I'd be less worried about measuring the speed and more worried about the wall at the end of your lab...

What pressure are you firing with?

fall-apart-dave:
Air pressure will have no discernible effect (read up on how SONAR works)

I can tell you with absolute certainty that you will have more than enough time to make measurements, unless you are firing the wood at mach1 or above, but in that scenario I’d be less worried about measuring the speed and more worried about the wall at the end of your lab…

What pressure are you firing with?

Ha ha thats true and infact the firing pressure is around 20 bar not more than that and the wood velocity would not cross 50 kmph.

If that were the case you were firing at extreme speeds, light could also be used and look for redshift (though now I'm being silly).

using sonar, you have doppler, distance, time... You could add an accelerometer and include data about the accuracy of that too.

How long is the tube?
What size is the wood? What shape? And what weight?

it's unusual to put sensors on a projectile, I'd be worried about damage.

fall-apart-dave:
How long is the tube?
What size is the wood? What shape? And what weight?

it's unusual to put sensors on a projectile, I'd be worried about damage.

The tube is around 5m and the block is 4m tubular shaped weight I am not sure will measure and tell. My plan is to drill a hole in the block and mould the circuit complex in that shape and fix it to be able to remove the whole complex to retrieve data after firing. So, damage won't be a problem.

fall-apart-dave:
Air pressure will have no discernible effect (read up on how SONAR works)

And the expansion of the air will be adiabatic?