Rotor speed control and (H_RSC_MODE set to XX ) behavior

ArduCopter Traditional Helicopter
1

Hi

after reading the WiKi I have a coule of questions for a FB heli.

If H_RSC_MODE is set to 2, the Pixhawk does everything and supplies through the PWM value that you have entered in the heli setup. The system arms like a quad, hold throttle low and to the right. how do you disarm the system after you land? if you hold low throttle (collective) and left rudder the heli is going to piroette because the throttle is still on the governor? or it will disarm itself in 10 to 15 seconds with collective low. so, how do I shut down the motor after I land in mode 2 ?

If H_RSC_MODE is set to 1, After the system is armed and spools up (ramped by Pixhawk or ESC), it pases through the PWM signal set by the reciever. It can be modifed and turned off after landing. but, if the system looses radio contact, (transmitter turned off or long distance waypoint flight) will the Pixhawk maintain the last PWM signal, or will the throttle go to zero and the heli crash? is it counting on the recievers failsafe for throttle PWM?

If H_RSC_mode is set to 0, complete bypass of Pixhawk controller with the exception of the need to arm for the collective to function. More for standard convential Heli flying and radio connection or radio failsafe setting is mandatory for ESC setpoint.

Also,

I read in another post that the flybar mode had a bug with the ACRO mode. Cyclic would not function in acro mode is this still the case?

Thanks again, getting close to that first flight, there is a lot of material to digest.

2

Hi Bobby:

So in both cases of RSC Mode 1 and 2, the systems is looking for a signal on Input Channel 8.

In Mode 1, after arming, Arducopter will pass-through the Ch8 signal to the RSC. I’m currently using this on all my ESC’s with YEP ESC’s (YGE clones). I allows me to have Ch8 on a knob so that I can vary the RPM in-flight. I also have a switch setup on my radio which operates like a Throttle Hold switch. When it is “down”, it cuts the Ch8 signal to minimum. When it is “up”, it sends a Ch8 signal according to my knob position.

So, the operation is simple. Arm the heli with the Throttle Hold switch “off”. Then flip the TH switch up, and the motor achieves the target speed using the governor mode. When I’m done flying, you simply flip the TH to off, and wait for the blades to wind down, then disarm.

Mode 2 is somewhat similar. The only differences is that it is only looking for Ch8 to be “on” or “off”. When it’s off, it sends a low signal out to the ESC. When it’s on, it sends the RSC Setpoint value to the ESC. Otherwise, operation is the same. Arm with TH on Ch8 off, then flip up the TH switch. After landing, flip off the TH switch, then disarm.

I originally played with not using Ch8, and instead, had it like for quads where, if the collective stick is all the way down, it kills the motors. But this led to two crashes for me, when I unintentionally shut the motor off inflight, and then they take too long to restart.

I also believe it is a safety issue that the pilot needs to be able to shut down the motor easily and quickly in any condition. So, we have to use a channel to accomplish this.

Cheers,
Rob

3

Thank you Rob,

Mode 1 sounds perfect.

I can put the throttle setting on the flight mode switch as usual, and map the throttle hold switch for autos.

and I completly agree, a fast way to remove the power is needed.

Best regards,

BV

4

Yep, that is certainly a very valid method of using Mode 1, with your idle-up mode switches as is commonly done now. You’ll probably want to set the ramp speed to something low (like 1 second) to take that out of the mix. The APM then is just a simple pass-through. The only real difference is that you get the additional protection of having to arm before the motor will engage, so it’s a bit safer. And I do recommend using the system this way, to avoid the problems others have had plugging the ESC direct into the Rx. That would allow you to take off in stabilize mode without having armed. But then if you switch to Alt Hold, Loiter, Auto or RTL, the swash will drop to the bottom because it’s not armed. Which does not end well unfortunately.

5

Like Rob I managed to loose two helis because I inadvertently move the throttle/pitch to full down for an instant and shut the ESC down and it takes too long to spool back up to recover.

Well I’m back in the air today after a long wait for a Pixhawk and all the necessary cables etc. and it’s flying great. But importantly I’ve got Ch 8 set up on a switch and a dial so that I can’t loosing my heli again.

I’ve set up a “hold” switch which sends a minimum signal to the ESC so that it remains shut down until I’m ready to fly. Once I switch this, I have a dial set up in “normal” mode and an idle-up 1 setting of 80% which is where I invariably will fly.

Pitch is set up on Ch 3. In Mission Planner, when you fly traditional helis, the radio calibration can be a bit confusing. “Throttle” really refers to “Pitch” and Ch 8 is used for “Throttle” only. Make sure you have your radio set up accordingly.

And happy flying.

6

I’d appreciate your comments on my parameter file attached. It’s for a 450 Mikado Logo.

7

@ozsteel,
You did not attach your parameter file. Please attach it or your post will be deleted.
Regards,
TCIII GM

8

[quote=“TCIII”]@ozsteel,
You did not attach your parameter file. Please attach it or your post will be deleted.
Regards,
TCIII GM[/quote]

Can’t seem to attach a file. Any tips?

OK, parameter file now attached.

9

[quote=“ozsteel”]Like Rob I managed to loose two helis because I inadvertently move the throttle/pitch to full down for an instant and shut the ESC down and it takes too long to spool back up to recover.

Well I’m back in the air today after a long wait for a Pixhawk and all the necessary cables etc. and it’s flying great. But importantly I’ve got Ch 8 set up on a switch and a dial so that I can’t loosing my heli again.

I’ve set up a “hold” switch which sends a minimum signal to the ESC so that it remains shut down until I’m ready to fly. Once I switch this, I have a dial set up in “normal” mode and an idle-up 1 setting of 80% which is where I invariably will fly.

Pitch is set up on Ch 3. In Mission Planner, when you fly traditional helis, the radio calibration can be a bit confusing. “Throttle” really refers to “Pitch” and Ch 8 is used for “Throttle” only. Make sure you have your radio set up accordingly.

And happy flying.[/quote]

Do I understand correctly that you are using Ch8 to control your ESC, but it’s not going [quote]through[/quote] the APM/Pixhawk?

If so, I very strongly recommend you route the Ch8 control through the Pixhawk, and then plug the ESC into Ch8 output of the Pixhawk. Then use RSC Mode 1. You’ll have almost the same control over the ESC, but it saves you the mistake of starting the motor and taking off in Stabilize mode without arming. If you fly without arming, then switch to AltHold, the collective will go full negative and you will crash.

With RSC Mode, you cannot arm without the motor stopped, and you cannot start the motor until you’re armed. And RSC Mode 1 simply passes through the signal from Ch8.

So I have it set up with a switch and knob. When the switch is down, it sets Ch8 low, so the motor stops. When I switch it up, it sends whatever I have on the dial, so I have complete control over rotor speed on the governed ESC.

10

Rob,

I have the ESC going through Ch 8 and have set it up just as you have. A switch to ensure the signal stays low and then a dial so I can set whatever rotor speed I want. I have always run the ESC through Ch 8 on the Pixhawk as you have suggested to avoid the possibility of flying while not armed. It’s working great for me.

The only thing I think needs adding to the manual is that Ch 3 should be used for “Collective” or “Pitch” and Ch 8 for “Throttle” or “Speed”. In previous versions I have plugged Ch 3 from the receiver into Ch 8 on the APM but now its better to separate collective on Ch 3 in your Tx from Throttle on Ch 8.

I’ve also attached a new parameter file with further updates particularly to Alt Hold parameters.

Thanks for the help as always

11

I have just read all the messages in this thread. In fact, I just solved the problem of calibrating the ESC and then have the APM armed while the ESC is connected to APM2.6 output #8.

Now I got another problem:–
With RSC set to mode 1 (CH 8 input) ,after I arm the APM, I switch the CH8 to high PWM and the motor ramps up.
After power down, I want to change the rotor speed, I go and change the high PWM to CH 8 to a lower value , the final speed of the rotor seems remain the same as before. Is this the correct way to change the rotor speed (same as all of you use a dial to change the speed during flight , in addition to a 2 position switch, as advised by Rob) ?

Frankie

12

When you say you changed the high PWM, what do you mean exactly? You changed the PWM level in your radio transmitter? Or you change RSC_Setpoint in the Arducopter parameters?

Mode 1 is Ch8 passthrough, so to change speed, you need to change the value coming out of your transmitter.

13

Thanks for yr reply Rob.

I changed the PWM value in the radio transmitter. When I had this problem (speed seemed remain the same even though I changed the PWM), I had CH 8 assigned to a toggle switch.

After I post the last message, I changed and assigned a knob to CH 8 and could change the speed after arming. The knob can even serve as an ON/OFF switch , as follows :–

I armed the APM with the knob at minimum (PWM 902). After arming, as I gradually turn the knob to 11 o’clock position, the motor started to ramp up. I could change the speed by adjusting the knob.

But another problem came up : In your thread titled " Rotor speed control and (H_RSC_Mode set to XX )", you mentioned about using a toggle switch, like a throttle hold switch for CH8, in addition to the knob for controlling the RPM in-flight.
How do you assign two different switches ( 1 switch, 1 knob) to the same channel (CH 8) ?
Channel 3 is for pitch in this case , and the Throttle Cut switch in my radio ( Spectrum DX7s) is linked to channel 3. When I activate the throttle cut, it cut the collective. Other guys in the thread could accomplish this. Pls advise.

14

Hi, as explained in the other thread, combining the Ch8 knob with a switch is an advanced setup and is radio specific, so I can’t really help you with that. Sorry. Best to read your transmitter owner’s manual.

15

Hey guys and sorry for grabbing this old thread,

I’m new to arducopter and still testing on the bench my trex 450. Came from beastx so far but changing to arducopter now for having all these auto modes. Really appreciating your work on this. Thank you!
I had a lot of issues with calibrating max/min travel of my tail servo cause I couldn’t find any parameters in full list/tree like for the swash plate but that’s off topic and calibrated magically on its own.
However my question related to this thread is about disarming in air which I’m a little afraid of.

What about flying upside down, putting throttle stick maximum down to bring the Heli into the clouds with yawing at maximum CCW? This procedure leads my pixhawk to disarm on the bench. I tested this behavior only on the bench with motor running at >=50% power in h_rsc_mode 1. Is there any difference in air? Hope so, otherwise this maneuver will not be flyable…
I’m really forward looking to 3.5 where you can arm/disarm via switch and hopefully don’t need to use throttle/yaw stick combo any longer. I’ve programmed a safety switch on my RX which disables the ESC and neutralizes all servos to prevent boom strikes etc. in an upcoming crash situation which I’m used to since I’m flying trad. helis.
Hope anyone of you can answer my question and dispel my doubts about accidentally disarming in air…
Thanks in advance
Eddy

16

So you are flying inverted. At maximum negative collective pitch. At full left rudder with a yaw rotation rate of probably ~700 degrees/sec? Just to make sure I have this right. So the helicopter will be completely out of sight within about 2 seconds. Wildly out of control. At that point, does it really matter whether the flight controller disarms, the EKF totally blows up, or the radio failsafe kicks in? Either way, it’s gonna crash.

Please refer to the above about why you’re used to crashing your helicopter. There’s a pretty common thing I hear from the 3D crowd as the pilot is gathering up all the pieces of his helicopter in a bag to carry it back to the flight line - “don’t do that”.

17

I have often wondered about just that… Say I want to catch some inverted, wildly yaw’ing video with my Canon 5D MKIII for that blur effect… My heli would then disarm and just ruin the shot. :wink:
In all seriousness though, I cant imagine many people decide to go with a Pixhawk for it’s 3D capabilities on a helicopter? Not that it isn’t a great flying controller, but I think it is designed under the guise that you are using it for more UAV style work where precision and stability & reliability trump being able to fly inverted piro-ing punch-outs.
And not all 3D pilots crash all the time. Lol :slight_smile: I cant tell you the last time I crashed a 3D heli… oh wait, that’s bad ju ju to say, the heli-gods will smite me. :confused:
Tim

18

master
noun
2. a skilled practitioner of a particular art or activity.
ex: “I’m a master of 3D helicopter flying. HeliMasters”

Notice how the big banner in the background that says, “BeastX - be Absolute Stable” gets nailed dead-on. Irony? Nope. Normal for these guys. You’d have to search for a really REALLY long time to find even a novice scale pilol that couldn’t fly around that parking lot without crashing into the BeastX banner.

19

:slight_smile: i knew id get a rise out of ya! I was just injecting some light hearted humor since I am aware of your view of 3D pilots. Hope you didn’t take offense.
Without getting too far off track I will say this. There are definitely some very talented pilots out there, from experience I know it takes an extreme amount of dedication to get to the level of some of these pilots but the truth is if you push your abilities to the limit along with pushing the frame beyond its designed specs its only a matter of time before something gives. Which you are right, usually ends in a pile of parts sprayed all over the field. :confused: I personally dont push that hard so my ratio is weighted in favor of bringing home an intact heli.
Back to UAS type flight, as I kind of injected in a humorous way above, in-line with what you had posted, the likelihood of disarming your heli mid-air is probably pretty nil unless your trying to use a Pixhawk as a 3D FBL at which point there are better options available. I personally have come to the conclusion that because the Pixhawk is using the EKF to ascertain a solution of the helicopters attitude it is not an apples to apples comparison or even fair to compare it to a typical 3D fbl that doesent have to worry about GPS, Barometer, Gyro, Accel and Magnetometer fusion to fly and because of that if you intend on flying hard 3D its not your best choice. As we have talked about before of there was the ability to just fly in rate mode without any other sensors being involved or the EKF it could be used for hard 3D or as a failsafe should EKF blow up.
I personally did not buy a Pixhawk 2.1 for flying 3D, I purchased it to make my platform a much more viable commercial UAS. The stability, GPS assisted modes and Autonomous flight modes are the primary reasons, which it is turning out to be great for! :slight_smile:
Tim

20

Correct. That’s why I said, “don’t do that”. The Pixhawk is an autopilot system for UAV’s. The EKF won’t handle it, so it’s really a moot point as to whether or not it disarms, or simply crashes anyway due to losing the attitude solution.

In theory you could do it yawing the other way, with full right rudder, and it won’t disarm. But the result is likely the same.

My dim view of the 3D scene is that it is what drives the RC helicopter market. And virtually every helicopter you can buy is designed and built for it, vs being a useful UAV platform. The RC helicopter marketing lost a whole bunch of pilots, and the market, to multi-rotors because they decided to focus on a minority market segment of the hobby.