When the RPM Signal is Lost

[Gyropilot]

Just out of curiosity, I pulled out the rpm signal lead from the Microbeast Plus Pro-Edition on my 450X while running on the bench using the Microbeast's governor mode. Nothing happened for about 2 seconds, then the Microbeast immediately sent a full throttle signal to the ESC and held it there.

That could be a bit scary if it were to happen in the air, but I guess it's better than completely shutting off the motor. Too bad the Microbeast doesn't simply hold the last throttle signal position until a low throttle signal is received from the Tx requesting a motor shut down.

[sutty]

I would have expected it to disable governor, and revert to throttle control, and you probably had a high straight line for throttle.

Repeat the experiment in normal mode and see if you have direct throttle control. That way you'll know for sure.

I've never run the MB governor, I'm just speculating from others I've seen and some logic.

Not saying it's right, but it might be.

[Gyropilot]

Originally Posted by sutty

Repeat the experiment in normal mode and see if you have direct throttle control. That way you'll know for sure.

Great idea!

I'll give that a try that today and report back.

[Gyropilot]

UPDATE:

The best I can tell after some additional testing, the Microbeast's electric governor IS driving the throttle signal full high whenever rpm input is lost AND the motor is already running... no matter what the Tx throttle signal is doing above 0%. I gotta tell you, it's sudden and it's scary... almost like there's no slow rpm change when this occurs, but it's hard to tell without blades installed due to low mass. Thankfully the Microbeast responds to a 0% throttle signal and shuts off the motor!

I also discovered that if the Tx's throttle either starts out at, or is brought back to 0%, the head speed won't advance above about 650-700 rpm without a valid rpm input to the Microbeast.

John

[sutty]

Interesting. Thanks for reporting back. I guess we need Stefan, or some other BeastX representative, to confirm exactly how it drops in and out of governed, in the absence of a valid sensor signal.

[Gyropilot]

There are a couple of additional things I'm not liking too much about the Microbeast Plus Pro-Edition electric motor governor...

One is the inability to specify an exact target head speed the way you can with the governor in a Castle ESC. Now granted the Microbeast governor makes it convenient to tweak head speeds on the fly by the Tx throttle curve without having to use a computer (or a field card) the way it has to be done with the Castle ESC. But finding a target head speed with the Microbeast governor has to be done by trial and error because the Tx throttle to head speed chart found in the 4.0 manual doesn't match the real world head speeds I'm seeing. Presumably this is due to altered Tx throttle end points??? Whatever the cause, it doesn't make dialing in a head speed very easy with the Microbeast governor. I've resorted to painstakingly mapping my Tx throttle settings to measured head speeds and putting them in a spreadsheet.

Second, several times during bench tests over the past couple of days I've observed the Microbeast governor simply fail to control head speed. It's happened both immediately after the first spool up and randomly in the middle of extended testing when I was switching flight modes to change head speed every few minutes. When this would happen the head speed wouldn't budge when I'd change the Tx throttle settings and it took completely returning the Tx throttle to 0% before the Microbeast governor would wake up and start responding correctly. Maybe this is just a software bug which need to be worked out.

[Frenchdress]

Hi,

- when the rpm signal fails in flight the system will fall back into manual throttle mode as I don't think it's so funny, when the throttle cuts completely just because the rpm signal is interupted. So it simply will send the actual transmitter throttle signal to the ESC. In flight you would easily see or feel that there is something wrong with the motor speed, i.e. rpm changes or drops heavily when giving pitch input.

- When there is not RPM input from the beginning the system will not be able to perform complete spool up. But at least it will start the first part of spool up sequence. In the beginning the governor starts blindly as simply in the beginning there is no RPM signal there and also because most sensors will not give a correct signal when the ESC initially sends pulses to start the motor. As soon as the rpm signal has stabilized it will start with the actual spool up sequence. But when there is no signal coming it'll not proceed with spool up but hang at a given throttle percentage.

- forget about bench testing. When there is no load on the motor the system sometimes behaves completely different. You can bench test if in general everything seems to work, but that's the most you can do.

- normaly the RPM chart is very exact. If you set 50% throttle you will have 2000rpm, increasing or decreasing by 5% will give +-200rpm. You can calculate and set the rpm you want very easily. If it doesn't work out for you, probably you are not using the throttle endpoints in the transmitter that you've set in the Microbeast governor menu at points B and C!? Of course, if the percentage in the transmitter will not fit to that, what you've teached to the Microbeast, the percentages might vary.
But 50% should always give 2000rpm as the center position is fixed as long as you don't use sub trim on the throttle channel! If even this is not the case then other possibility maybe that you've set the wrong gear ratio or motor pole count or that your gear ratio is something like 9,3257894 and you've set 9.30 or 9.35. Then there also might be some small deviation.
And lastly, third possibily might be that you've set manual gear ratio (i.e. to match above 9.32) with StudioX software but that this setting might not have been saved.

- I must admit there is some little bug in the electric governor function of V4.0.0. The rpm may hang if you decrease throttle very slowly and in very little steps. This issue will be solved with the next firmware. If you like you can PM me or send an Email to our support team, then you can have a beta firmware with modified electric governor.

[hilarious]

when i first set up the rpm function i had all sorts of problems and even crashed twice. from the very 1st successful flight i had with mbx governor, i knew i had an excellent governor imo. the rpm fluctuations i had in the beginning were due incorrect min. throttle set up. the manual won't tell you how to do it thoroughly and unfortunately i've lost the notes i saved. it seems i'm re-adjusting the tx throttle lower end points in the field if the esc won't arm correctly, if the heli lingers to spool up or if the hs is not stable during flight. imho you don't need to know which hs you are flying at. the way the heli responds depends on many things as pitch curve, motor power, blades and batteries so i prefer to fly at the rpm that ''feels'' better. i set a reference hs on the bench and simply increase or decrease the tc in the field until i find the "right spot", and i never look back to know what was the hs set in the end.