APM 450 Helicopter Help with Parameters

Randy told me I would be better off to post question here.
Thanks in advance
Newbie to APM helicopter and need some advice. I have used APM 2.6 and 2.8 board for a few years now on quads and tricopters. I have watched videos of APM helicopters flying waypoint missions with no input from the transmitter a they are smooth and steady, I cannot get mine to fly anything like that with me controlling the sticks? Actually heli with APM is only a small amount more stable than flybared? I am pretty much using stock parameters except in extended tuning Rate pitch P is 110 and Rate Roll P is 90 , if I try to raise P parameters to improve stability, I get oscillating right and left? I have read many pages in forums but cannot seem to improve stability, heli is drifting a lot like there should be more input from APM for self adjust? What am I missing?
Thanks again

APM 2.6 Ver3.2.1, 450 Trex clone (was flybared and flew pretty well) now tarot FBL head, Emax digital servos, (APM is mounted under belly of heli) flying in stabilize mode and right now no GPS or compass attached?

I would like to see your parameter file. Please upload it here. I want to get a better idea for all of your settings.

Thanks for reply, I am using telemetry and have a tlog, but not sure I know how to upload it to this site?2017-05-14 10-02-39.tlog (1.2 MB)

I haven’t worked with tlog all that much. If you can’t find your Param file, you can use Mission Planner and connect to your aircraft. Go to the config/tuning tab and on the left you should see full parameters. Click on full parameters and on the right you will see an option to save the file. Save the parameter file and upload to this discussion. If you don’t see full parameter as one of your selections to the left click on planner and under layout select advanced. Then you should see full parameter list on the left

Thanks again, I thought you wanted tlog. I will try to upload this parameter file?Apm Heli 5 21 17.param (5.4 KB)

So I have a few suggested changes to hopefully help with your tuning and the general feel of the aircraft.
First I would suggest a few changes that affect the control system.
This will change the response of the aircraft so I suggest to back off a little on the roll and pitch P gains and add FF gain so you have enough control.
You will have to do the tuning in pitch and roll but with the ATC_RATE_FF_ENAB set to one, the attitude controller will perform better. The ACCEL params limit the max acceleration. I didn’t have you change them but the ATC_RATE_x_MAX params limit the max rate. So if after you finish tuning you want a little faster response and rates then you can modify these. Lastly the RC_FEEL param is like a quickening effect. 50 is a better setting to start with. You probably put it to 100 because you didn’t have the FF_ENAB set to one.

Why are collective min and mid so close together. I don’t know enough about the collective setup in the code but I try to keep mid at the collective for hover like 4-5 deg. What is the significance of your H_COL_MID? Read the swashplate setup for this wiki to setup these params http://ardupilot.org/copter/docs/traditional-helicopter-configuration.html#traditional-helicopter-configuration

So lastly, any reason that you turned off the arming checks? I don’t recommend this.

So be sure you are comfortable with your swashplate behavior before you fly. The changes I’m suggesting are pretty big changes.

Thanks a lot for your advise.
Some of these parameters I have never heard of, and more than likely way over my head. but I will try the changes you recommend. I assume these parameters are under standard or advanced parameter list?
Arming checks where turned off when I had it on the bench testing controls (no blades).
I will try to get to changes in next few days, but it has been so windy in Illinois that flying is out for now?
Bill is there a way I can get in touch with you later on for more advise?
Thanks again, not much local advise available

I think I am answering your collective question, I am just learning with helicopter flying and did not want a lot of down pitch until I train my finger not to pull full back on the throttle when I panic?

William, I don’t think I would recommend that. A helicopter needs negative pitch because if it gets caught in the wind it can up and will not come down unless you use negative pitch.

I think something may be wrong with your collective pitch setup. You have a huge range from H_COL_MID to H_COL_MAX, which is not normal.

I recommend watching this video that explains how to set up the head with ArduCopter so you don’t get a crash

Now, keep in mind a lot of things have changed since 3.2.1, like the Stabilize collective curve only has a min and max in 3.2. But the video will help you understand how to set the collective pitch and what those parameter do. The other thing is, you mentioned using Mission Planner and the Extended Tuning page. You can’t use that with helicopter. Please only make your settings in the Full Parameter List for helicopter to prevent settings from being changed that you don’t want.

The helicopter settings in the Full Parameter List all start with H_. The ranges and scaling for the rate controller were also very different in 3.2. But after you get the pitch ranges properly set we can probably get you pretty close on the rate controller so it’s at least basically flyable so you can practice hovering with it. Since you are very new to helicopters, but have some experience with flybar, I would recommend getting it decent enough so you can practice with it. Fine tune the rate controller later when you feel you want to add a GPS and external compass and possibly progress to the more advanced flight modes.

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Thank you much for your input, I am open to any suggestions.
Is it not true that with a APM 2.6 board that Ver 3.2.1 is the newest firmware I can load? I will try to use your suggestions about only making changes in Full parameter list. When you say fine tune the rate controller later are you talking about the pitch, yaw and roll parameters P,I.Ds? If so do they have to be changed in Full parameter list also, and never use extended tuning?
I have read the Ardupilot traditional tuning for helicopter, question is that info up to date enough to use with Ver 3.2.1?
Thanks again

Yes, 3.2.1 is the latest version of the code that will run on the APM. And yes, when I mentioned the rate controller I was referring to the rate pitch, roll and yaw PID’s. And they must be set in the full parameter list because MP will complain about the “allowable” range and reset them for you with less than desirable results :slight_smile:

The trad heli tuning wiki should apply to 3.2.1 just fine. In fact it was more written for APM than Pixhawk. So the examples and scaling in the tuning instructions are correct for 3.2 and are way out of date for 3.4.

One thing you may have a problem with is having no external compass. Your APM 2.6 does not have an internal, so you may have to disable the compass to get it to arm. But it sound like you want to use the APM basically as a FBL unit to stabilize your FBL head, and it should work fine for that. Unlike the flybar which is basically rate control only, the APM will give you attitude control for your FBL. So it should be quite fun to fly once you get it working.

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Thanks again
I tried using Alt Hold once with very bad results, once I engaged the the switch the blades appeared to go full negative pitch and drove the copter into the ground, lot of repair (I was only 15 ft in the air).
Is there a trick to Alt hold with a helicopter, I know I have seen it done online?

The cause of that can be not having the collective pitch centered. In Altitude Hold there is a collective “dead zone” at mid-stick. So if you had your collective set so the heli would hover at a low stick position and switch to Alt Hold, it will slam the heli into the ground. If you had your collective set so it would hover at higher than mid-stick, the heli would soar into the air when you switch. This was also changed somewhat in the later firmware by adding in a four point Stabilize collective curve, where in 3.2.1 you just have H_STAB_COL_MAX and H_STAB_COL_MIN to set your Stabilize collective limits. With your current collective pitch range, I believe this to be the cause of your ground slam. You were hovering at too low of a collective (throttle in multi’s) stick position, and when you switched it commanded down pitch.

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The other thing, William, I don’t know if the current MP works for setting up heli with 3.2.1 anymore? It used to be that you captured the swash range and I think what I would do is manually set your H_COL_ min/mid/max params manually to prevent issues with MP maybe not working with the older firmware. Or if you have the old version of MP, use that instead of the current version.

If you can get H_COL_MID set to be about 5 degrees of collective pitch at close to mid-stick**, H_COL_MAX to give you 10 degrees positive, and H_COL_MIN to give you 8-10 degrees of negative, it should work. These must be set with H_SV_MAN set to the proper number for each setting, and they did not take effect unless you follow the instructions in the wiki on how to “cycle” H_SV_MAN to get it to take effect.

Then just set your H_STAB_COL_MAX and H_STAB_COL_MIN params to limit how much collective pitch you want in Stabilize flight mode. Do not limit the negative collective with the H_COL_MIN param.

I would recommend setting the H_STAB_COL_MIN to give you maybe -2 degrees, and H_STAB_COL_MAX to about 8 degrees, and this must be set in Stabilize flight mode by just moving the stick. And again, I don’t think they take effect without writing the params and rebooting the APM, or “cycling” the H_SV_MAN param.

I think once you get your collective pitch range sorted, you will have lots better luck with your collective control.

** The “trick” to getting this set in 3.2 is to adjust the swash linkages and HS_x_TRIM values to get that desired ~5 degrees of collective pitch at mid-stick in Stabilize flight mode. H_COL_MID should always be the zero pitch range. But you want ~5 degrees at mid-stick in Stabilize to get smooth transition to Alt Hold. So in the end actual zero collective pitch in Stabilize will be achieved at about 35-40% stick position :slight_smile:

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Thanks again for trying to help, really appreciated for your time and effort
I do not think I have a older Mission Planner, I am trying to absorb all that you are suggesting to help me, but one thing I cannot find much info on how to H_SV_MAN even on the Wiki page other than the values and meanings, I could not find (How to cycle H_SV_MAN to get it to take effect)? I hate to let you down but you are over my head and I cannot find more info on this? I may be better off to start over again with my setup, make changes in Full parameter menu only, try to H_STAB_COL_MAX and H_STAB_COL_MIN, and H_COL_MID
Thanks again

Sorry to be a pain
Any idea of what would be an example of a correct setup values with H_SV_MAN for a 450 heli?

Oh, Ok.
H_SV_MAN is normally 0
1 = manual servo control with the sticks without the PID controller running.

So you can set H_SV_MAN to each one of those to adjust your collective settings for each step to get the proper pitch, level the swashplate and set the servo trims. Like you would set H_SV_MAN to 3 and that places the swash at mid where the servo trims or linkages should be adjusted to level the swashplate, and H_COL_MID should be set to get zero pitch.

Then set it to 2 and that will make the swash got to top. Then you adjust H_COL_MAX to get 10 degrees of collective pitch.

Set it to 4 and the swash will go to bottom and set H_COL_MIN for 8-10 degrees negative pitch.

So when you change any of the swash params in 3.2 you must go to H_SV_MAN, set it to 1, then “write”, back to 0, then “write”. This resets the swash calculations so your new settings take effect. When you get done, make sure it’s set back to 0 for normal flight.

After making your settings you can put it in Stabilize flight mode and check the swash movement with your sticks to make sure it looks right. And you can also pick up the helicopter and roll it and pitch it by hand and observe the swash action. It should be trying to counter the roll and pitch and always keep it level.

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Hello gentlemen,

I was planning on using an old APM Mini 3.1 with an old 450 flybar heli - i understand this is almost never recommended to set up on old h/w and firmware, but i hope i can put this mini and heli to some use.

I have loaded the AC 3.2.1 on the mini, all ok. But i cannot seem to get to complete the servo/output setup. All the servo outputs seems to be disabled in MP. I checked the PARAM tree, i see HS1, HS2, HS3, HS4 but how to i enable them? and what about the throttle output channel? Any particular MP version i have to use?

I hope someone who’s been there can guide me.

Thanks in advance.