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Please help on Heliquad setup

(Robert) #1

Hi, I hope someone can give me a pointer or two for my collective pitch quadcopter. The settings are greyed out for most of the setup on mission planner. I have used servo settings to set -11, 0 and +11 on each rotor head. I have noticed in helicopter setup there are lots of col. min and max, and other settings. do these need to be set up? Also for altitude hold how does this work as center stick is zero pitch? Please help a noob! thanks!
Rob

(Chris Khosravi) #2

Do you need to fly upside down? The way we set up helicopters to hover at mid stick is to have a pitch curve around -3 to +11

(Chris Olson) #3

Unfortunately, we don’t have a lot of experience with the CP quadcopters. They got put into heli because they use the helicopter RSC for throttle control, but in reality they are the same as a regular quadcopter, short of using collective pitch instead of motor throttling for attitude control.

You do have to use the collective min/mid/max settings from heli to set the collective pitch range. Do not set it with the SERVO limits. I think the IM_STAB_COL settings work to set the mid-stick position for stabilize hover for them.

There is a tuning param file in the ArduPilot Tools for the WLToys model that might be useful.

(Robert) #4

Thanks for the reply! I’m way too scared to try upside down as it’s a 1750 and cost dear to build. I do like the idea of extremely fast descents. Is it possible to set the deadband on altitude hold to be wide enough that it could hover at 2/3 stick up and not misinterpret that as a command to ascend in altitude hold? Again thank you for any help!

(Robert) #5

Thank you I will plug in those values and see where we are!

(Chris Olson) #6

That parameter set should be available from Mission Planner’s drop down list in the frame params. It is for the WLToys V383. Since we don’t have much experience with these I can only suggest it may be a starting point for tuning.

There is no deadband for alt hold. You can only adjust the IM_STAB_COL’s for Stabilize mode to try to get the collective to line up at mid-control for switch to/from alt hold modes.

You can set your pitch range to whatever you like for Acro and limit it to what you want on the bottom end of Stabilize with the IM_STAB_COL_1 setting. So, like you have -11/+11, or 22 degrees of pitch range. So a setting of 500 for IM_STAB_COL_1 will set it at 50% of the pitch range, or 0 degrees with the stick at the bottom in Stabilize flight mode. Or a setting of say 400 will set it at 40% of the pitch range, or -2 deg with the stick at the bottom in Stabilize. And then set the STAB_COL’s 2&3 to get it to hover in the mid-stick position.

This is how you can retain your 22 degrees of collective travel for acro, but switching to Stabilize will change the pitch curve to something more manageable.

(Chris Khosravi) #7

I do believe that altitude hold modes will hold altitude if your throttle stick is between 40-60%.
That’s kinda like a deadband. Regardless, you should aim to have hover pitch around 50% stick using the method Chris Olson explained.

(Robert) #8

That’s perfect, thanks!

(Max Drougge) #9

Hello.

Do the IM_STAB_COL_1 carry over to other modes such as auto and poshold? That is, will the Stabilized hover throttle be the same in althold? Will the quad ever use a higher or lower collective than what is given by IM_STAB_COL_1 and IM_STAB_COL_4?

I’m a bit concered as my physically max/min values are quite small for my setup and thus I don’t want them to stall. Also if the STAB_COL_1 and STAB_COL_2&3 are set to 0 pitch, and hover, respectively. Will the poshold descend and ascend properly or are these changes only in stabilize mode?

(Chris Olson) #10

The IM_STAB_COL settings only set the pitch curve for stabilize flight mode and the minimum and maximum is limited by H_COL_MIN and MAX. All other modes use the full range that is set by H_COL_MIN and MAX. If STAB_COL 1 and 4 are set to 0 and 1000 respectively, the pitch range will be the same in all modes.

(Max Drougge) #11

Ok. Say that I find good values on IM_STAB_1, 2, 3, 4. How do I translate these to the H_COL_MIN and H_COL_MAX so that I get it for all modes?

(Chris Olson) #12

The H_COL_MIN and MAX is the absolute minimum and maximum pitch settings. The IM_STAB_COL’s are a subset of that. The H_COL’s must be set first, then you can fine tune it to what you want in stabilize with the IM_STAB_COL’s.

(Max Drougge) #13

I see. But I don’t quite understand how to set the H_COL’s. It says to select the PWM for the swash plate at MIN, MID and MAX, where MID is 0 pitch (no lift)? Where is the H_COL_ for hover? Which PWM should I look at? My servos has different PWM at the same throttle from the RC. Should I look at the RC input?

(Max Drougge) #14

I’ve got the same “problem” as the owner of the thread. My pitch has the possibility of becoming negative and I want to make sure that the system never uses the negative pitch. Is this done with H_COL, or IM_STAB?

(Chris Olson) #15

If you want no negative pitch, then set the H_COL_MID to zero pitch. Set H_COL_MIN to the same value as H_COL_MID. Set H_COL_MAX to the maximum pitch you want. Set IM_STAB_COL_1 to 0 and IM_STAB_COL_4 to 1000 and you will have the same pitch range in all flight modes, and no negative pitch in the setup.

(Max Drougge) #16

Thanks a lot. I think this is exactly what I needed to know.

(Max Drougge) #17

Hopefully my last question. I haven’t really noticed the dropdown menu for parameter lists. I’ve then used this one on all my frames: 3DR_Iris+_AC34.param

Which one should I be using on a heliquad? Can I use 3DR_Iris+_AC34.param but modify the parameters to fit the heliquad?

(Max Drougge) #18

I’m sorry for all the questions but this is extremely confusing for me. I’m trying to set up my H_COL_MIN, H_COL_MID and H_COL_MAX. It just doesn’t seem to work for me. I’m setting my Heliquad to 0 pitch at H_COL_MIN and H_COL_MID. However, trying to limit the H_COL_MAX only seem to increase my minimum pitch rather than the maximum (or both in some cases).

Am I missunderstanding something drastically?
UPDATE:
Here is my parameter file. The max/min of the collective seem to work but the biggest problem now is that I dont’ get any YAW authority at 50 % throttle… Under 40-50 % YAW works fine. Above 60 % YAW also works fine…

I can’t tell what’s wrong. Any ideas?

ParametersHeliQuad.param (14.2 KB)

(Chris Olson) #19

So when you set the H_COL_MID, for instance, are you setting that first setting H_SV_MAN to 3? Then set H_SV_MAN to 4 to set the H_COL_MAX?

What flight mode are you using to set it in and test it? What is the maximum pitch you are using in degrees?

I am not familiar with CP Quads but it is possible they don’t work without negative pitch. They rely on differential collective for yaw control, roll and pitch control.

These things are more related to a multicopter than they are a helicopter, the only reason they got into the heli category is because they use the helicopter’s throttle control system (make the distinction between what throttle is and what collective is in a helicopter). Collective and throttle are two different things. You are using MODE 1 throttle control, which is RC passthru. But at this point it is not clear how you are controlling the throttle or headspeed because your RC8 MIN is set to 1500 pwm and I don’t know how that possibly initializes the throttle.

Your RC7 min and max is 1500 and 1501 respectively. And you have that assigned to arm/disarm. I don’t understand how that can work either. It looks like the normal control channels want to calibrate from ~1000 to ~1995 or so. But RC3, which is the collective, is different and the max on that one is only 1906.

Did you calibrate all the channels on the RC? Or do you have some strange mixes in the RC?

I do like the fact that ArduPilot has RC Passthru throttle control in the first place. I would like to remove it. But you don’t have something strange going on in the RC like a mix between the collective and throttle, do you?

This might be an instance where seeing if you can make a video of the phenomenon and post it on YouTube or something might be helpful, so we can see what’s happening.

(Max Drougge) #20

Thank you for the support. I have not set H_SV_MAN to anything but the default.

I’m testing in stabilize currently. But with the new H_COL settings it doesn’t seem to work so I think I will change back to the standard for HELIQUAD and simply change the IM_STAB to get the correct mid throttle hover. It worked very well the other day. I just thought I would set the H_COL as well, but maybe the H_COL for heliquad is different from the traditional helicopter.

There is no mixing from the RC transmitter. The RC8 is connected directly to the throttle/headspeed motor which runs at 1800 PWM for correct rotor RPM.

The RC7 isn’t used any more. I use throttle/collective down and right to arm.
I did change the RC3 range from 1000 to 2000 with 1500 trim.

I think I will set it up as it was when it was flying well in all modes. I hope that leaving the H_COL settings as they are as standard causes no potential problems.