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Topic: Looking for a way to measure the fuel level for an RC car tank ! help ! (Read 3533 times) previous topic - next topic

firashelou

Help us out a bit more on the project.
What is the purpose of having a fuel level reading?  What are you intending to do with that data?

Are you trying to determine if/when you need to pit to refuel?
Are you putting in telemetry so that you have access to this data in the pit?

Since there are many challenges with trying to get an accurate physical reading, I would consider approximating the fuel consumption.
Keep a running of of the throttle positions in small time slices. 
Assign a fuel used number for each throttle position, small amount at low throttle, large amount at fuel throttle.
Add those numbers.
Multiple by a factor to adjust for real word measurements.

Then adjust that multiplication factor over several runs, where you compare the estimated fuel used to the actual fuel used.

Possibly adjust the assignment of fuel used at various throttle positions.

The advantage of this is that there will be no physical change to the fuel system.


what I am trying to do is tracking fuel while running like a real F1 car

what do you mean exactly by your method ? I did not understand it :/

what do you mean by "The advantage of this is that there will be no physical change to the fuel system." ?
Aiming for the unreachable !

vinceherman

what I am trying to do is tracking fuel while running like a real F1 car
No, that does not answer my questions.  "Track Fuel" does not tell me what you are doing with the data.

Let's say that together, we all create a system that lets an on-board system determine that you have 47% fuel remaining.  What should that on-board system do with that data?

Is it going to remain on board for some decision making process?
Is it going to be transmitted to the pit?  If so, what is going to be done with the data in the pit?  Just displayed on some device for the driver to know?  How does this info help the driver?

Quote
what do you mean exactly by your method ? I did not understand it :/
I will be glad to give better detail but let's wait until you help us understand what you are trying to do.

Quote
what do you mean by "The advantage of this is that there will be no physical change to the fuel system." ?
Here too, let's wait until you help us understand your goals.


MarkDerbyshire

it's an F1 car of 1/4 scale using fuel engine, so what solution can be used for this ?
i found this fuel sensor which i have been told it uses capacitance to work, what do you think ?
http://www.goodluckbuy.com/telemetry-accessories-fuel-guage-sensor-fgs-01.html
Hitec use this type of sensor as well.  Only works with Glow fuel

firashelou

No, that does not answer my questions.  "Track Fuel" does not tell me what you are doing with the data.

Let's say that together, we all create a system that lets an on-board system determine that you have 47% fuel remaining.  What should that on-board system do with that data?

Is it going to remain on board for some decision making process?
Is it going to be transmitted to the pit?  If so, what is going to be done with the data in the pit?  Just displayed on some device for the driver to know?  How does this info help the driver?
I will be glad to give better detail but let's wait until you help us understand what you are trying to do.
Here too, let's wait until you help us understand your goals.


ah ok, well what i am trying to do is help the driver to know how much fuel is left so he knows when to pit and refuel
Aiming for the unreachable !

firashelou

Hitec use this type of sensor as well.  Only works with Glow fuel
glow fuel you mean the nitro, well I asked the engine seller about what type of fuel can I use and he said that I can use the Unleaded 95 which is used in normal cars
Aiming for the unreachable !

MarkDerbyshire

glow fuel you mean the nitro, well I asked the engine seller about what type of fuel can I use and he said that I can use the Unleaded 95 which is used in normal cars
The sensor won't work then.  What engine are you running in this car?

firashelou

Aiming for the unreachable !


firashelou

Nice.  It's not a small 1:24 scale then :D
no it is a 1/4 scale but even for a small scale that runs on fuel it would be a nice option to have
Aiming for the unreachable !

vinceherman

ah ok, well what i am trying to do is help the driver to know how much fuel is left so he knows when to pit and refuel
Awesome.
Reading through this thread, it is clear that it will be difficult to get an accurate physical reading.
Instead, I propose that you estimate the amount of fuel consumed.
I would think that a formula could be created that uses throttle position and engine RPM to estimate the fuel consumption.  
It might not be very accurate at first, but you can tweak it by running the estimate program while running the car.  After some number of laps, pit and measure the actual amount of fuel used. (fill the tank).  Then compare that to the estimated value.  Is the estimate too low?  Bump up the factor and try again.  Too high, bump down the factor and try again.

Something like this:
Code: [Select]
fuelConsumed += throttle * rpm * factor;

At some fixed time period, read the throttle and RPM.
Perform the calculation.
Transmit it to the pits.
Repeat.

firashelou

Awesome.
Reading through this thread, it is clear that it will be difficult to get an accurate physical reading.
Instead, I propose that you estimate the amount of fuel consumed.
I would think that a formula could be created that uses throttle position and engine RPM to estimate the fuel consumption. 
It might not be very accurate at first, but you can tweak it by running the estimate program while running the car.  After some number of laps, pit and measure the actual amount of fuel used. (fill the tank).  Then compare that to the estimated value.  Is the estimate too low?  Bump up the factor and try again.  Too high, bump down the factor and try again.

Something like this:
Code: [Select]
fuelConsumed += throttle * rpm * factor;

At some fixed time period, read the throttle and RPM.
Perform the calculation.
Transmit it to the pits.
Repeat.

i did not get this method  :smiley-confuse:  is there any way you can explain more what is happening here ?
Aiming for the unreachable !

vinceherman

Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.

  • Actual, physical measurements of your fuel level are hard.
  • I am suggesting that rather than a physical measurement, you programmatically estimate the amount of fuel being consumed.
  • The estimation process will use 2 inputs
    • Throttle
    • Engine RPM

  • You will need a sensor to read the engine RPM
  • You will need a method to read the throttle position
  • Throttle reading will be easy if you are using typical RC control - there are many tutorials on reading receiver output
  • Once you have the ability to read the throttle and RPM, you can compute an estimate of the fuel being used
  • The estimate will need to be tweaked to more closely match actual, physical fuel consumption measurements

Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.





MarkDerbyshire

Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.

  • Actual, physical measurements of your fuel level are hard.
  • I am suggesting that rather than a physical measurement, you programmatically estimate the amount of fuel being consumed.
  • The estimation process will use 2 inputs
    • Throttle
    • Engine RPM

  • You will need a sensor to read the engine RPM
  • You will need a method to read the throttle position
  • Throttle reading will be easy if you are using typical RC control - there are many tutorials on reading receiver output
  • Once you have the ability to read the throttle and RPM, you can compute an estimate of the fuel being used
  • The estimate will need to be tweaked to more closely match actual, physical fuel consumption measurements

Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.





Or put one of these in line with the fuel pipe and read the square wave output

Flow Sensor

Simples :)

JohnRob

I've done some work on automotive level sensing.  It is a PIA.   As said before at any given time you have no idea where in the tank the fuel is.  And a section of tank where fuel can run in and out slowly doesn't work either.

I think vinceherman had very good suggestion regarding trying to measure fuel consumption.

I have no expedience with RC engines, however if you could measure the inlet air flow you might get a better indication of fuel consumption.   If there is a inlet air filter or passage, perhaps the pressure drop across it could be useful.   And I'm not sure if it is practical but a hot wire anemometer might work as well.  Similar to the mass air flow sensors in some of the older vehicles.




Please do not PM me with thread based messages.  If your thoughts are worth responding,  the group should benefit from your insight.

firashelou

Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.

  • Actual, physical measurements of your fuel level are hard.
  • I am suggesting that rather than a physical measurement, you programmatically estimate the amount of fuel being consumed.
  • The estimation process will use 2 inputs
    • Throttle
    • Engine RPM

  • You will need a sensor to read the engine RPM
  • You will need a method to read the throttle position
  • Throttle reading will be easy if you are using typical RC control - there are many tutorials on reading receiver output
  • Once you have the ability to read the throttle and RPM, you can compute an estimate of the fuel being used
  • The estimate will need to be tweaked to more closely match actual, physical fuel consumption measurements

Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.

ok my system will have RPM reader by placing a wire around the spark plug and get the rpm from that, and will have a rotary switch to control the throttle pedal input, so what i did not understand is number 7 I how to get fuel info from throttle and rpm ?

what do you think about this method of making Liquid capacitive sensor?
Aiming for the unreachable !

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