Telemetry data of hydraulic pressure

[Blender]

Been window shopping for a fresh radio and see Jeti has a ton of telemetry options. Battery voltage/current/capacity are straightforward as are motor RPM and temp since the airplane guys all use such data. They have air pressure for altitude, but it's not gonna work for hydraulic pressure.

It might be possible to acquire pump output pressure with a workaround. An industrial transducer can output 0-10V proportional to sensed value. Selecting a 1000psi sensor would output 4.50V at 450psi. As far as I can tell there is no way to apply the correction factor to the value in the radio, so it's probably best to stick to a base 10 multiplier. It gives up some accuracy since the sensor is capable of reading much higher pressure than we're actually using.

This 4.50V =450Psi value can be piped into the transmitter with a voltage reporting telemetry dongle like the S30 servo power meter. Biggest downside is the sensors are huge. Roughly 2in long. I do see mini and micro versions available with smaller 1/8 NPT or even M5 ports, but none are stocked/easy to get ahold of.

Is this a useable reading or just a novelty? In the past I've set pressure with an analog gauge then never looked at it again.

[trilliwilli]

Interesting that you want to use a Jeti radio. I have a DC16 and the possibilities are massive.

For your question about the sensor I don’t have a direct solution for Jeti, but for the Brixl radios you can buy a sensor directly at Brixl that works up to 35bar: https://bluecontrol.biz/index.php/pr...ie/drucksensor

Perhaps someone at the Jetiforum can help out with the signals, with a Arduino nano in between you should be able to get it to work.
On the Jetiforum you can ask in English as well: https://www.Jetiforum.de

[frizzen]

It's a really cool idea!
I'm not sure how useable it's actually going to be with the pressure swings at your pump head during use. Might also need to incorporate a damping circuit to slow the pressure changes. How often do you look down at TX display while running machine?

Can your radio set up to indicate it as like a gauge, or just sending raw numbers?

[trilliwilli]

With a LUA script you can display it as a giant meter if you want. Jeti is a premium radio that has a lot of functionality.

Monitoring the pressure, and temperature, can help to spot problems before you have boiling oil or a giant leak. You can give audio signals, or use the date for a logical switch to do something.
Jeti also makes a log of everything that you can read out in Jeti Studio, so you can look at the data to see how your mix for auto sensing is going, the more functions you use, the more rpm the pump motor has to make, the pressure should be the same at all time.

For a hydraulic setup you can best have three telemetry readouts: pressure, oil temperature and pump motor rpm. With these three you have very good control what’s happening when you use your excavator in a heavy situation.

[Blender]

@trilliwilli:

Thanks for the link to the Brixl sensor. Ofcourse the Germans already have such a thing! I dug through their transmitter manual and it states there are transmitter settings for different brands/ranges. From this I think it's safe to assume they are doing calculations inside the radio.

The freedom of Jeti is what drew me towards them. Our models are unusual so we need lots of flexibility. Paired with the radio's billet aluminum body I was enamored with the DS14/DS16. We do have US distribution now (but only one DC model) so they're a viable candidate in my eyes.

@frizzen:
I only have a vague idea of the capabilities of these radios since I'm a total novice. I've been too scared to press the order button. Trilliwilli detailed out the display and logging capabilities which helped me.



I'm thinking this might be worth experimenting with further. I'd like to avoid the Arduino interface for space savings. Maybe it's necessary as a "translator" to allow a smaller sensor.

[trilliwilli]

I see that Esprit Model only lists the DC24 as a traytransmitter. It is because the tray transmitters are a lot less popular in the US. The DS range is just as capable as the DC range, you only have two switches more on the DC, but I doubt if that is a problem, with flightfases you can assign the switches to different functions.

If you want to step in without breaking the bank, the DS12 is nice, you can buy optional expansions, and this radio can go up to 16 channels.

The 14 range is only interesting if you don’t need all the expansions, otherwise the price comes to close to the 16 which is fully loaded from the getgo.
You will not going to use all the functionality for construction models, because they are flyer oriented and a lot of functions are only usable for that.

I have, for that reason, bought a second hand DC16 first gen that was a lot more affordable.

The radios are build like a tank and they run on the latest firmware, so completely up to date. If you can find a second hand DS16 your the king, you have 24 channels on the 16 with FW4.0 or higher, so have I on my DC16.

I have build 3D sticks on mine, the stock sticks are so good, I only put the rotation nobs on top of the original sticks, it functions bautifully:





I am still working out the programming, I bought it recently. The old R-series receivers have got a recent update where they support S-bus, the REX-series already does that, so you can use this with a BeierElektronik module for communication.

A 6 channel receiver will do fine, the rest goes over the Beier, you can work with the electronics in a model compact this way.

I hope you can find something, the DS with a tray holder is very usefull, I wanted it in the first place because of the weight and screen on top, but the DC I have now was a great deal so I took it.

Be aware that a second hand unit is multimode, otherwise you don’t have self centering sticks on both sides, they came after 2016.
The serialnumber gives away the productiondate, first two numbers the year, the second pair of numbers the production week.

Good luck!

[Blender]

Your DC-16 is absolutely beautiful. The 3D sticks you've added look like a factory option. Very clean integration. Been casually looking for a used Jeti. They're pretty rare in the US and when they do show up the price is rather high. That's very helpful on the multimode, I think I had stumbled across an older radio at one point.

Currently leaning towards the DS-14. It technically does everything I need with only a couple firmware purchases. The plastic gimbals have good reviews. The -16 is a lot more radio for the money, but I'd rather save the cash. I'd spend the savings on accessories like telemetry devices and a tray harness.

Back on the pressure sensor: Spent some time looking for mV/V style output. Not sure what that type of output is called. Ratiometric maybe? Would allow me to use a higher voltage regulated supply to set the output voltage where I can interpret it easily. I was hopeful it would allow a smaller off the shelf sensor, but no such luck. The one in the original post is the best so far despite the large size.

[trilliwilli]

I think you need to look for something like this: https://nl.rs-online.com/web/p/hydra...ensors/7255954

They are in multiple options, but importent is the input voltage, these can be from 8V to 30V, which is usable with a 12V system. If they start at a higher voltage you need to have a buck/boost in your model, which seems complicated.

You can also choose the output, 0-5V seems okay, they also have a 0,5-4,5V option.

I really don’t know what to use, but the input voltage seems important to be in range of the model system voltage. I think the one you linked is also in more options available.
The interpretation of the signal should be programmed in a Arduino.
On the Jeti forum, and also the Dutch forum, a few guys also make their own GPS sensors for Jeti, it should be possible to do this also I guess.

Jeti has listed its EX protocol here: https://www.jetimodel.com/support/telemetry-protocol/
It is beyond my capabilities as a mechanical person, but perhaps someone else can help with that.

EDIT: I found this with a quick Google search: https://forum.arduino.cc/t/pressure-...er-code/362754
It is on the Arduino forum, a link to sensor on Ebay is in the thread. It also gives the programming code for the Arduino.
This will help I think.

[Blender]

The arduino method is looking appealing. Could also be used to adjust/calibrate the output if needed.

As far as boost converters, Dimension Engineering makes a small boost module. It maxes out at 14V which is the lower end of what the high voltage sensor requires.

Time to start tinkering.

[Blender]

Trilliwilli mentioned LUA in passing. Been reading up on it. It's a programming language some TX can run. Just a day ago I was dreading having to write my own app to do some simple math. As it turns out Dave McQueeney has already written a freeform algebraic LUA app called V-sensXF which has a walkthrough here. Exactly what I need to move the decimal and assign units. Could also be used to integrate a 0.5-4.5V output sensor and convert to psi with no external hardware aside from the jeti device to read the voltage.

[Blender]

Got the machine up and running to give this a proper test. Appears to work and is within 10% of an analog gauge. I still need to experiment with location to tap into the pressure side. Currently I'm on the far side of the valve block which is super easy, but I expect some pressure drop compared to right off the pump's output port. The MU3 voltage telemetry module only reads to 0.1V which corresponds to 10 PSI. This looks to help smooth the output some.




Uses a step upconverter to boost 3S lipo to a steady 14.0V

All the small pressure sensors are out of stock or made from exotic materials for aerospace applications. Too rich for my blood.