Vibrations control test with Simulink

Using Arduino Project Guidance
1

Hello forum,
I realized my thesis about vibrations control made with Simulink and virtually it works in this way (real time processing and correction):
the structure is excited by two shakers, then the response is measured with two accelerometers. If the output overpass a certain limit, the input (excitation) is modified in a proper way.

I would apply this Simulink algorithm to a real structure in a real test: I have two shakers and two accelerometers, so 4 BNC plugs.

In order to proceed with this project, I would ask:

  • is it possible to connect this 4 BNC plugs to Arduino Uno?
  • is it possible to drive the shaker with Simulink (passing for Arduino that will generates a certain variable voltage)?
  • do you have suggestions in order to help me in this project?

Thanks in advance!

2

You've left out so much detail that there's little hope anyone can help much. Remember, we haven't been there with you. What you might think of as common knowledge isn't common to everyone.

d4rkn3bul4:
Hello forum,
I realized my thesis about vibrations control made with Simulink and virtually it works in this way (real time processing and correction):
the structure

What structure?

d4rkn3bul4:
is excited by two shakers,

What shakers?

d4rkn3bul4:
then the response is measured with two accelerometers.

What accelerometers?

d4rkn3bul4:
If the output overpass a certain limit, the input (excitation) is modified in a proper way.

A "proper way"? Proper for what? What does this mean? How is it modified? What are you talking about?

d4rkn3bul4:
I would apply this Simulink algorithm to a real structure in a real test: I have two shakers and two accelerometers, so 4 BNC plugs.

Accelerometers don't normally have BNC plugs. They're just chips. So you need to bring some details here.

d4rkn3bul4:
In order to proceed with this project, I would ask:

  • is it possible to connect this 4 BNC plugs to Arduino Uno?

The Arduino doesn't have BNC plugs on it. You should be able to see that.

d4rkn3bul4:

  • is it possible to drive the shaker with Simulink (passing for Arduino that will generates a certain variable voltage)?

What shaker? How is it driven? What voltages?

d4rkn3bul4:

  • do you have suggestions in order to help me in this project?

Maybe if you can describe it where other can understand what the heck you are talking about.

3

Delta_G:
You've left out so much detail that there's little hope anyone can help much. Remember, we haven't been there with you. What you might think of as common knowledge isn't common to everyone.

Sorry for this. I will reply with more details

Delta_G:
What structure?

It is a beam, but a different structure will not affect my algorithm results

Delta_G:
What shakers?

They are electrodynamic shaker, model 2004E

Delta_G:
What accelerometers?

I have a lot. Generally single axis or triaxial (models 356B20/NC, just to name one)

Delta_G:
A "proper way"? Proper for what? What does this mean? How is it modified? What are you talking about?

It means that, if the output of the system (the response measured by an accelerometer) overpass a certain level, there is the correction (weaker input). How is it modified? It is a proportional correction (proportional to the error)

Delta_G:
Accelerometers don't normally have BNC plugs. They're just chips. So you need to bring some details here.

Yes, sorry. The output of each accelerometer should be acquired and processed on a computer. In order to do this, it is necessary to link the accelerometer to the computer, via BNC cable

I can give you several informations, if needed. Thank you very much

4

I have a lot. Generally single axis or triaxial (models 356B20/NC, just to name one)

Please step back and ask yourself if microscopic tidbits of information like this could actually lead to useful, practical advice.

Google "arduino accelerometer" for hundreds of thousands of entries on how to connect and use accelerometers with Arduino.

5

It is a beam, but a different structure will not affect my algorithm results

Like a laser beam? OK, I'm be fascetious but see what i mean? Is this a big beam? A small beam? A metal beam? A wooden beam?

They are electrodynamic shaker, model 2004E

got link?

I have a lot. Generally single axis or triaxial (models 356B20/NC, just to name one)

Got link? Which one are you wanting to use?

It means that, if the output of the system (the response measured by an accelerometer) overpass a certain level, there is the correction (weaker input). How is it modified? It is a proportional correction (proportional to the error)

That still doesn't tell me anything. All I know is that some math is happening somewhere, but nothing about what the hell it is supposed to accomplish or how it is calculated or anything. Just that some math is happening somewhere.

it is necessary to link the accelerometer to the computer, via BNC cable

Then you're hosed. The Arduino doesn't have any BNC connectors. So you'll either have to get some connectors and add them to the Arduino, or cut the connectors off and wire it up some other way.

Maybe if you told us what the heck this thing is it would help. Like back up and give us the 10,000 foot view. What is it? IS it an Earthquake predictor? Is it a part for a rocket to measure vibration? What the hell is it?

6

Delta_G:
Like a laser beam? OK, I'm be fascetious but see what i mean? Is this a big beam? A small beam? A metal beam? A wooden beam?

It is a metal beam, but as I said, you can imagine a wooden beam, a rocket or a pencil, it will not affect the algorithm (if I understood what are you trying to suggest me)

Delta_G:
got link?

Yes, this is the link of the shaker: Mini Electrodynamic Shaker 7 lbf

Delta_G:
Got link? Which one are you wanting to use?

Yes, this is what I would use: Triaxial ICP Accelerometers

Delta_G:
That still doesn't tell me anything. All I know is that some math is happening somewhere, but nothing about what the hell it is supposed to accomplish or how it is calculated or anything. Just that some math is happening somewhere.

I will try to explain it with a practical example: Arduino drives the shaker with a variable voltage, let say 0.1V, 0.2V, 0.1V, 0.2V, and so on (the time step can be X seconds). The structure (metal beam) will start vibrating and so the accelerometer will read a certain signal. This signal is sent to Arduino and it is compared with a reference signal. If there is an error, so the input voltages are modified ad hoc (let say 0.05V, 0.1V, 0.05V and so on).

Delta_G:
Then you're hosed. The Arduino doesn't have any BNC connectors. So you'll either have to get some connectors and add them to the Arduino, or cut the connectors off and wire it up some other way.

This is exactly what I was asking, because I don't know if it is possible the connection

Delta_G:
Maybe if you told us what the heck this thing is it would help. Like back up and give us the 10,000 foot view. What is it? IS it an Earthquake predictor? Is it a part for a rocket to measure vibration? What the hell is it?

During environmental testing, generally can be required that the specimen (metal beam, in this case) will behave in a proper way (when excited). So what is the right excitation, in order to obtain that "proper response" of the structure?

Thank you for your suggestions! I just believed all these details could be "boring", sorry.

7

If there is an error, so the input voltages are modified ad hoc (let say 0.05V, 0.1V, 0.05V and so on).

To what end? What is an error? What does this correction accomplish? Are you trying to vibrate something else along with it or something? You really need to think about the people who can't see this thing.

This is exactly what I was asking, because I don't know if it is possible the connection

Well you could just look at the board and see that there are no BNC connectors on it.

During environmental testing, generally can be required that the specimen (metal beam, in this case) will behave in a proper way (when excited). So what is the right excitation, in order to obtain that "proper response" of the structure?

Again, I'm betting that this means something to you. You need to make it mean something to other people if you want help doing anything with it. We haven't been in class with you. We aren't studying with you. You need to explain it like you are talking to a 5 year old. What is this behavior you are measuring? What is "proper"? What is the goal of this?

I just believed all these details could be "boring", sorry.

I write code. I can handle boring. What I can't do is give you suggestions about something if I have no idea what that something is.

8

BNC connectors indicate analog signals (voltage). Make a patch board with BNC connectors, all grounds connected to Arduino Gnd, and the signals connected to analog inputs and outputs. Many Arduinos don't have a DAC, then you'll have to add your own. ADC input depends on a (usually settable) reference voltage, between 1.1V and 5V for full range.

Are your waves (frequencies) really in the seconds range? Both excitation and response?

9

Analog accelerometers are likely to have millivolt outputs. You need an amplifier and signal conditioning before presenting that to the Arduino analog inputs.

The shakers will also require amplification to get (I'm guessing) a few watts of power and few Arduinos have a direct DAC suitable to feed to an analog amplifier.

Both of the above amplifiers can be bought from the same place you got the other hardware.

The 16MHz Arduinos have a limited speed of analog readings. 10kHz is possible but at that speed you have no processor leftover to do anything useful with that data. What sample rate do you require for how many accelerometers?

10

DrDiettrich:
BNC connectors indicate analog signals (voltage). Make a patch board with BNC connectors, all grounds connected to Arduino Gnd, and the signals connected to analog inputs and outputs. Many Arduinos don't have a DAC, then you'll have to add your own. ADC input depends on a (usually settable) reference voltage, between 1.1V and 5V for full range.

Are your waves (frequencies) really in the seconds range? Both excitation and response?

They are in the first range (both excitation and response)

MorganS:
Analog accelerometers are likely to have millivolt outputs. You need an amplifier and signal conditioning before presenting that to the Arduino analog inputs.

The shakers will also require amplification to get (I'm guessing) a few watts of power and few Arduinos have a direct DAC suitable to feed to an analog amplifier.

Both of the above amplifiers can be bought from the same place you got the other hardware.

The 16MHz Arduinos have a limited speed of analog readings. 10kHz is possible but at that speed you have no processor leftover to do anything useful with that data. What sample rate do you require for how many accelerometers?

The sample rate is 6.4 kHz, for two accelerometers

11

d4rkn3bul4:
The sample rate is 6.4 kHz, for two accelerometers

That is going to be difficult or impossible to achieve with a 16MHz Arduino.

Have you looked at the Teensy or Due?

12

d4rkn3bul4:

  • is it possible to connect this 4 BNC plugs to Arduino Uno?

If this is taken literally..... then the question is..... have you seen an Uno before?

If you have seen one.... you will then quickly know the answer to your question.

But if you actually implied interfacing bnc to arduino..... then sure.... you can have wires coming out from the arduino, where bnc sockets can be soldered. These sockets can then connect to the bnc 'plugs'.