H_PIT_MAX and H_ROL_MAX values

ArduCopter Traditional Helicopter
1

Okay, so after reading through the heli PID tuning page and getting familiar with the idea and the process of PID tuning a traditional heli, I set up the heli as per the recommended start values in the wiki with channel 6 set for tuning RATE_PIT_P and RATE_RLL_P with minimum and maximum values 0.01 and 0.075 with all working and responding well. I spooled it up for a tentative attempt.

I set the collective range as per the recommendations, with +/- 10° pitch maximum range and then setting the stab collective to 30% and 90% min and max respectively.

I did not check the degrees of pitch for cyclic inputs.

Heeding the warnings i was very cautious and expecting the worst, but i was pleasantly surprised, the heli just sat there very solid with a drift to the left which I assume was because of the tail rotor. It was starting to oscillate in the tail before it lifted off but i could stop it by tweaking the rudder slightly. it took a lot of stick to resemble some sort of control over the bird with it being very reluctant to respond and even though i gradually increased the tuning knob i could not observe any oscillations or anything close to it.

I also noticed that there was very little response from the swash when holding the heli armed and tipping the heli or from cyclic inputs.

After re checking my settings and reading through the page again i re read the section stating the main influencing factors on the final PID values.

I knew the mechanical set up is fine because the bird has flown fine as it is currently set up, which left only the H_PIT_MAX and H_ROL_MAX values.

these were both at 2500 i think, in the full Parameter list by default. I noticed the further I increased them the more response I got from my cyclic and from tipping the Heli. (wonders never cease, who would have thought right?)

So my question is this.

How do I set the cyclic travel? In what mode do I need to be in and with what rate values. I was initially thinking of setting the tuning knob on channel 6 to the maximum (within the maximum recommended values) and then adjusting the H_PIT_MAX and H_ROL_MAX values to achieve a max cyclic pitch of about 7° which is what I normally set my cyclic to with a normal flybarless controller, then turning the tuning back down again and proceeding with the testing as outlined in the wiki. Or, have I missed something somewhere and is there some other way?

Normally I can hunt down the answers to these sorts of questions myself but as was mentioned in another post somewhere quad copters seem to be what the cool kids are doing these days and as such the forums and information are geared towards them. As well being brand new to PID tuning and on something as unpredictable as a heli I thought it would be best to consult the Oracle that is the forum. It can be hard to find answers through other peoples experiences and problems for helicopters. As the issues seem to be varied and no two people seem to have the same issue twice.

Many thanks for reading and for your help in advance.

2

I had another go at setting up the initial tuning for the PIDs in stabilise mode. I set the H_PIT_MAX and H_ROL_MAX values to allow a maximum swash movement that equated to 7° pitch. I then went through and carried on tuning as per the instructions on the wiki. I found the point of oscillation for the P values and backed it off and then carried on with the I and FF values. I ended up with a heli which was manageable by all means (until it did something I’m still trying to figure out and flew into a rugby post and completely destroyed itself) but still far from what Id expect a heli to fly in stab mode. The Issues I encountered were.

  1. I had a substantial drift to the left i have read of this being a known problem before but I am still unsure of how to fix this

  2. on spool up the tail went through a substantial wag it seems like its transitional though and eventually settles down, I have a feeling it could be due to a frequency of vibration the heli goes through on spool up. or am I able to tune this out using the yaw parameters?

  3. The motor sounded like its running at maximum revs and the Govenor is being bypassed somehow. I am using a YEP which I’ve never had issues with the governor before, I calibrated it to the endpoints of the radio on a separate receiver as it is a fickle and fussy little bugger to get to behave but once its working normally its fine. I was wondering if the throttle Accel had something to do with this? (could someone please explains to me what throttle Accel actually is? and if it is relevant with an external governor?)

  4. In tuning the I parameters for pitch and roll I was struggling to see or understand what I was actually supposed to be tuning out, what characteristics am I looking for and trying to fix in a heli which at that point is very difficult to control and fly and is unpredictable. With the P term it is straight forward enough, wind it up slowly until it oscillates then back it off till it just stops and then a little more so as to allow for wind or a skid bump or some other external force. The explanation is not so clear for adjustment of I term. It was mentioned that if the I term was too high there might be a bounce experienced.

I had the heli hovering relatively nicely and it seemed to be okay so I tried a tentative circuit, Just before it got gobbled by the rugby post and blew into a million pieces, i was completing a turn and from what i can remember of it (it happened very fast) it seemed to jerk, I was wondering if it reached a maximum allowable roll angle or something and it kicked back upright? It then seemed to be jerky in its movements, that combined with the compensation i was manually adding on the stick to allow for that drift to the left, the brown pants factor of a fast running out of control situation and she was nose in which normally is fine if i didn’t have a rush of sh** to the head, all contributed to make her fair game for the post and she was ruthlessly gunned down. A genuine write off.

RIP.

If anyone could please take the time to shed some light on the above issues or even a give me a direction to point in or clarify some of the questions I have about some of the parameters i would be eternally grateful.

Many thanks.

3

I am very sorry to hear about your crash :astonished:
I had read your first post and I am in the same boat are far as the setup phase goes, I screwed everything up so bad yesterday in the settings I had to start from scratch and I’m back at it today…
This is my first heli build (I have some smaller ones) but I’m mainly a multi rotor guy, this is my 2nd pixhawk (1st is in a QAV 400 Quad ).
The Pixhawk is a solid controller that out preforms my other Naza’s (3 of them) hands down no competition !
There is a lot more to setting up the pixhawk and can be a hair puller but I know It can be done, I am by no means a rocket scientist when it comes to setting up the pixhawk I’m just saying hang in there :slight_smile:
My build is a Blade 600X the Tx is a DX8 with a AR8000 Rx and 3dr ppm encoder, I have been reading many posts of peoples issues and how they were resolved so that hopefully I can better understand the setup and settings (so far that’s workin for me). :bulb:
I was just going to reply to your first post this morning on the values thing and was very shocked to see this new post, I hope that you will be able to find it in yourself to rebuild your heli and make it fly with the pixhawk.
I will push on with my setup and hope to soon be able to do a maiden.

Best of luck to you!
Mark

4

Mark,

Thankyou for your kind words. I was actually surprised to jump back on and see a reply, Ive since done a lot more reading through the wiki and found a lot of the answers to the questions I have. Im still not clear if the way i set up the H_PIT_MAX and H_ROL_MAX values was the correct way to go about it but it seemed to work (bar the part where the rugby post jumped out and blew the heli into a zillion pieces, i can say now though,that it was awesome to watch) how did you set yours up?

I’d be interested in following your build and it’d be great to hear of your breakthroughs to the problems you have had and if you are stuck on something i can have a look and see if i can help. it may have even been something I’ve worked through myself.

I have a Trex 500l Dominator due to turn up in the next week or so. I have read about a lot of people who arnt that impressed with the new design of it but I think for what I’m wanting to do it will be okay and it probably won’t much resemble the original heli by the time I’m done with it anyway :slight_smile: . Im by no means a 3D master and I’m not that interested in it. Ill get it set up to fly, maiden it with my old FBL controller and then look at putting the hawk on it. I want to also set up a mount to carry a Tarot T2D go pro gimbal off the nose as well with a video switcher which I will be able to change view between that and a fixed flight cam for FPV. Eventually i want to use it for things like Real estate photography, fire scene investigation for the fire service and the like. So at this stage starting everything from scratch I might start a blog somewhere else logging my progress and the build. I don’t know how much Ill get done before I have to head back to sea for six weeks but there is a lot ill be able to do on the ship with all the goodies in the workshop on board. :slight_smile:

Thanks again for your reply mate.

Laurence

5

I sent you a pm a bit ago did you get it?? :slight_smile:

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Hi Mark, sorry for the late reply mate, just flicked ya a big message back, did you figure it out in the end?