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Calibrating your Current Sensor in INAV
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- Опубликовано: 4 авг 2024
- In this video we look at how to calibrate the current sensor in INAV.
There are a couple of ways to do this. A popular method is to use a charger and compare the mAh put back in to the pack with the OSD reading of the mAh used. However, this method is not very accurate, for a couple of reasons. Using a charger, you not only have to consider the accuracy of the current sensor in the charger. But, also the cut off point is an unknown. If you take the mAh reading as the balance charging commences, the chances are the reading will be too low. If you take it when balance charging completes, it will be too high; as balance charging charges the pack, then drains the cells with the most charge. This method also only alters the current scale. It does not take the offset in to consideration, meaning unless the offset is zero (highly unlikely), the scale will be wrong.
The method shown in this tutorial is more accurate, as the only device that we need to worry about the accuracy of, is a device that has been specifically built to read power and current. The big drawback of this method, is that we need to power up the motor indoors.
My online calculator www.mrd-rc.com/tutorials-tool...
DISCLAIMER:
I point out in this video that doing this procedure can be dangerous. If you don't take proper safety precautions, you could end up hurting yourself. Please take every precaution possible when doing this. If you don't feel that you have assessed all risks and done everything possible to do this safely, don't do it. I will not be held responsible, liable, or in any way to blame for any injuries that occur following this tutorial. You do this at your own risk.
Contents
00:00 Introduction
01:11 Equipment needed
02:45 Disclaimer
03:49 Accessing the Current tool online
04:36 Getting INAV and the calculator ready
06:04 The line of best fit explained
07:11 Why use this method to set the current sensor?
12:49 What we will do in INAV configurator
13:27 Plugging in the power meter
14:12 Putting the model in manual, to stop the servos moving
15:17 Taking the current readings
18:05 Calculating and setting the new current sensor values
19:35 Conclusion
If you found the video useful, I'd appreciate a thumbs up. If you would like to get more videos when they become available, please subscribe and click the notifications bell icon.
There are more tutorials on my web site at www.MrD-RC.com. You can also join like-minded people at the Fixed Wing RC Rebels group on Facebook. Also, if you found my videos useful, and would like to leave me a little tip, you could always buy me a Coffee at www.mrd-rc.com/go/ko-fi/
Thank you for your time, and don't forget to fly it like you stole it!
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this guy is my god, from rc user point of view , of course
this is a great tool, I started using this to setup all my FPV planes and when I recheck via my OSD the readings are the same as the watt meter across the throttle range. thanks mate
Awesome. Its always great to hear feedback like this. It’s worked well for me on my builds too 👍🏻 Thank you.
This is great, much better than that charger method. I'd like to suggest a simple sanity check in case someone enters a wrong value by checking if the R-squared is above 0.99. Since both current meters are linear, the scatter plot point should all lie on a straight line. Any point that are significantly far away from this line must be the result of measurement error or a typo.
Thanks Alexander. That’s a great tip too. The plots usually are pretty linear, with only a little deviation. I’ll see if I can get some sanity checking added.
Been running my current build to 1000mAh drawn on OSD and then charging like 8 times now trying to get it calibrated. Will be using this method now!
This should be much more accurate. And you can do it on the bench 🙂
Really informative thank you
Thanks for watching Samantha 🙂
Great instructions here, Darren. I was needing this. Thanks. BTW, last thursday in got my first 10km with a Mini Drake. Good adrenaline.
Awesome Silvio. The Mini Drak is a fantastic plane. Hope you have loads more fun with it.
Something went wrong. After calibration I have noticed a dolphin effect when she was on Cruise Mode.
That’s strange Silvio. The current sensor calibration will have no effect on how the plane files. It only alters how the value from the current sensor is interpreted.
Dolphining could be too high rates on the pitch axis. Also check that your control surfaces aren’t binding, move smoothly, and centre correctly.
@@MrD Thanks, Darren. Also I will try auto tune and see what happens. ✌️✌️✌️
I've found the Matek figures to be fairly accurate, under the wiring guide and mixer tab of the product page.
For the f411 wing
Voltage scale = 1100
Amps scale = 423
Matek are definitely one of the better providers, with pretty good base scales. However, my F411-WING has a scale of 445 plus an offset. So there is still room for improvement.
Nice one Darren, I take it this will also work with a quad, just need to put a brick on top of it lol
🤣 or tie a brick underneath it. Yes, it should be no different. Its just current draw at different throttle levels. The calculator will even give betaflight values 👍🏻
@@MrD Very useful, thanks very much!
No worried Greig 👍🏻
i used a dc clamp meter that can go up to 100 amps, as far as the props yes cannot agree more, i actually taped mine down between the washing machine and drier so if anything it hits those and not my fingers :D
Totally. Anything that can be done to minimise the chance of a prop strike is a good thing.
Awesome - as always a great and informative video! 😊
But one question remains for me, because I would rather calculate offline: how do you determine the offset? When I do this with Excel, I get a different offset displayed in the formula of the scatter plot (the rest fits perfect)...
Sorry for the delay in getting back to you. I had to revisit it myself. All the data is in Excel, but needs some changing to get the correct values for the flight controller.
You'll need the slope, offset and new sensor scale. The easiest way to get that is by turning on "Display Equation on chart" trendline option. You will get something like y = 1.0044x + 0.276. The 1.0044 is the slope, and the 0.276 is the offset.
If you want to use this with a mA based offset, you can just multiply the offset by 1000. For example 276mA. That would work fine with BetaFlight. However, iNav uses mV for the offset, so we need to do a little processing. We need to use the offset, slope, and new current sensor scale.
To get the new current sensor scale, you need the last scale and the slope:
newScale = round(oldScale * slope)
newScale = round(443 * 1.0044)
newScale = 445
To get the offset for iNav, you need to do the following:
iNavOffset = chartOffset / (10 / newScale)
iNavOffset = 0.276 / (10 / 445)
iNavOffset = 0.276 / 0.02247
iNavOffset = 12.3 mV
I've created an article on this, for anyone else who would like all the details. www.mrd-rc.com/tutorials-tools-and-testing/inav-flight/current-sensor-scale-and-offset-calculation-how-it-works/
Hello Mr. D, greetings from California! I have a question, I’m in the middle of a new build, I’m using the F411WSE by MATEK and even with the factory current scale value recommended by MATEK and the voltage offset set to 0. When conducting the calibration INAV shows current draw of 22A while my amp meter shows only about 5A @50% throttle. With power applied to the model and no motor running INAV trades and amp dray of 8.7A. This is with INAV 4.0 Could I have a bad flight controller?
I think I saw your post in either the INAV or INAV Fixed Wing Group on Facebook. Something doesn't seem right there. I did check the F411-WSE in my Dart 250G yesterday. That's not far off the recommended scale. It could be faulty. Have you tried running the calibration? Maybe a wrong component has been fitted which has adjusted the scale. 5A @ 50% throttle sounds about right on the ground. In the air, my Dart was pulling around 4.1 - 4.2A at 50% throttle.
I used your website tool to calibrate my matek boards, thanks.
Any chance I could get a copy of the spreadsheet with the formulas too please? I actually only used 2 throttle level values, and I like the look of the graph.
The spreadsheet doesn't actually have any formulas. It is just used as an example. I literally just added the flight controller and power meter readings to cells, then created an X Y scatter graph from those readings. The line of best fit is a trend line option you can select, as is to display the equation. The y= value, up to the x, is what you multiply your scale by to get the new scale (I added that in a cell labelled slope). All the real calculations are done on the web page. I was looking in to adding a graph on the page, but so far, couldn't find a solution that works with a line of best fit. But I will keep looking if people find the graph useful.
I'd highly recommend doing more readings. At least 4 or 5. If you just take 2 readings, you are just drawing a line between those points. With more readings, the errors are averaged out, which will give a more accurate scale and offset.
Hi. Thank you for this video and the article on your website. Could you tell us if we should do this with or wihout VTX and servos powered during the calibration? If we add offset calculation, is the value drop to zero amps even if we power the VTX and ESC or the value would be greater than zero? Thank you.
Have everything connected 👍🏻
I did the calibration with my OSD goggles and everything connected, drone armed. Perfect for me. Thank you!
Hello Daren,
Would you suggest soldering the XT60 or the XT90?
Anyway i will not be passing the 45 A with my plane.
Thanks
I went for XT90’s as this can handle a fair amount of current. I also use XT90 to XT60 adapters and XT60 to XT30 adapters, so it will work on any setup I want to use it with.
@@MrD thx Darren.
Gonna use it with lion 4s2p 8000mah.
I m gonna end up doing the same as you, xt90 :)
Im setting my curr right now. I goto motor tab because when i adjusted ADC scale i noticed its sitting on desk at 3.5a. But when i spin the motors the amps go down 😳 lol
Yeah, I think that needed calibrating 🤣
@@MrD I put a negative number in.. and will go test today.. but evewrytime i change the negative number i have to adjust offset. what a headache
if you follow the same steps with the props off will it be too far off of the real numbers ?
With props off, you won’t get the current draw you would with props on. It may be thag full throttle isn’t near your cruise throttle. The amps going through the sensor will be the same measurement. But you won’t get the range of current draw that you do with props on. Still, try it with props off if you feel safer that way.
@@MrDgot it , thank you
Hi Mr d. I have a problem with current meter - maybe you know the answer?
My equipment is a stac (Holybro Kakute F7, ESC Tekko32 4in1 45A and VTX Atlatl HV V2)
There is no way to calibrate the current measurement because the readings are very strange, for example:
I connect the Lipo battery to the ESC with the connected flight controller (no other devices) and, for example, inav displays the current consumption value of 0.5A to me - it is logical that after connecting a device, the power consumption should increase. For me it is the other way around. For example, I connect the receiver and the value in inav changes to 0.4A I connect another device (e.g. more power-hungry) VTX, the value in inav drops again to 0.0A
Turning on the engines also does not increase the value of current consumption, well, maybe slightly ...
I wouldn't worry too much about current readings under 1A. Some flight controllers use a flat reading below 1A, due to it not being accurate. Others can just have strange readings. The best thing to do is calibrate the current sensor from 1A and up. If when the motors are on and at a decent throttle level, and you're not seeing a change. There is something wrong.
Hi there, I have callobrated my esc in inav 3.0 and when I power on it cuts out on anything above 20% 1.3amps . At 20% the voltage drops off to 10 volts in seconds. When I check this on my meter there is no voltage loss. What am I doing wrong ? At first i thought it was a duff motor not sure now .TA
Do you have a smoke stopper connected? I’ve done this a couple of times and wondered why the motor keeps stopping. Then I usually slap myself 🤣
@@MrD omg no .How on earth. I have kicked the shit out of mysef . Many thanks . This hobby sometimes .....
As soon as u said smoke stopper my head fell into my hands.Cheers again it works.
No problem Traci. Better that than the smoke stopper being needed and not connected. BTW, it’ll happen again 🤣 It’s just one of those things. I know I’ll do it again at some point and wonder what’s going on.
So having current sensors problem. Maybe u can share some of your magic maytek h743v1 inav 5.0 at an idle current sensor reads 30 amps maytek say to use current scale 250. I’ve tried all kind of different scales and nothing works. I did find some cli commands to use but not sure if they r correct.
Hi Aaron. That does sound pretty strange. What happens with the current when you increase the power? Does it go up still or just stay around 30A?
For me, all I do is set the voltage using a reasonably decent multimeter. Then calibrate the current sensor using my tool www.mrd-rc.com/tutorials-tools-and-testing/flight-controller-therapy/setting-the-current-sensor-in-inav/. I don't change anything in CLI.
@@MrD it goes up but not right away I am using maytek pdb hex the high dollar one but only running v batt through it no signal just power I also have cap on pdb and fc both r 470 uf I wouldn’t think that would cause any problems. I’ve tried multiple current scales amps nothing seems to fix it. Battery voltage is spot on. To me it has to be the pdb causing the problem
I really love this plane rmrc anaconda supper slow flyer when flaps r down very sturdy plane. I’m about to add a foxeer 30x zoom cam and a hevey duty pan and tilt mount. Haven’t really thought about this yet but I need a way to have full speed on pan when cam is zoomed out and then slow pan down when zoomed in I think I could do it I may just find a happy medium that would be easy.
Back to current censor at idle it jumps around a bit 30 40 in flight be up around 120 the plane only draws 25 amps at full throttle on my meter I run lion bats so it’s kinda important to know amp draw
It could be down to the PDB. Which model flight controller and PDB exactly? Also, how is the power connected. Battery to FC, FC to PDB?
can you use clamp meter with no wires?
No, but you can’t connect a battery without wires either 😉
why did you put manual mode if you are not using tx?
Because if you are not using a TX it defaults to ACRO mode. Which means the servos will be trying to correct while you are performing the test.
Mr.D - Falling, with style ok
Thank you my Friend
I had to put 470 capacitor to esc as amps were going crazy in osd
This can happen. More on smaller ESCs with less draw too. I hope you managed to get a good reading after.
Mr.D - Falling, with style if esc has capacitor built in then no need to put additional one?
So were's the video shown TAR
Sorry Bob, I don't follow?
your site not working?
Thanks Chris. It decided to break when I went on holiday. It's back up and running now.