Rotor RPM Sensing

[ChrisOlson]

@Shotfire

Chris, I have have a Hal sensor for rotor RPM coming back through the RC telemetry link and I manually control turbine RPM.

Is this an older engine like a MW54 or a JetCat single stage?

It may be possible tridge has something like this working. If so I’m not aware of it. Rob may be referring to some basic governor code he did in AC3.4 that may or may not have been flown and tested, I’m not sure

GitHub - R-Lefebvre/ardupilot at Copter-3.4-Heli-Gov-3

[Shotfire (Doug)]

Chris, its a Jakadofsky Pro X

[Implicit (Jakob Schmidt)]

@ChrisOlson

As Bill mentioned, if someone would want to help by using the existing code to make a logging function (or feed it to a MavLink message to the GS), and test a suitable sensor that works, we would certainly help get it merged to master.

Unless I’m misunderstanding something, this already exists.??
Look at the RPM parameter in this log:
https://www.dropbox.com/s/a1m0mvhhmm48wi6/2018-01-14%2014-41-10.bin?dl=0

I’m using the hobbywing RPM sensor mentioned earlier.

[Shotfire (Doug)]

Jakob, The sensor your using pulls RPM from the brushless motor. What we’re talking about is a sensor that pulls actual rotor RPM directly from the main rotor gear and feeds that into the pixhawk and the associated code to take that RPM and control throttle and in the event of engine failure that RPM could also be used in-conjunction with collective pitch in order to preform a auto-rotation

[Implicit (Jakob Schmidt)]

Right!!

However, that should still work with the hall effect sensor? (I keep meaning to buy one of those Align ones)

[ChrisOlson]

OK, I had to get up-to-date on this. It appears the code reads pulses or PWM. If your hall effect sensor puts out a pulse per revolution, it should read it on pin 54 and set the RPM_TYPE to 2. 50Hz will show 3,000 rpm, so it appears the scaling would be 1.0 with a single magnet on the auto gear. Any hall effect sensor should work the way I read the code.

[Samuel_Tabor]

Hi Chris,

To combat the growth in number of parameters you might create a new group containing an ENABLE parameter with the AP_PARAM_FLAG_ENABLE flag. This way, the parameters in the group are only displayed to the user when the feature is enabled. https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_Soaring/AP_Soaring.cpp is the example I’m most familiar with.

Sam

[ChrisOlson]

@Samuel_Tabor

To combat the growth in number of parameters you might create a new group containing an ENABLE parameter with the AP_PARAM_FLAG_ENABLE flag. This way, the parameters in the group are only displayed to the user when the feature is enabled

Wow, thanks for that tip, Sam. I didn’t realize we could do that. That will certainly be helpful. Heli does not have a lot of params compared to some of the other things. But it is still good to try to keep the number of params that have to be downloaded to the GS at boot time to a minimum.