Josh,
Glad to hear of your success. Not to burst your bubble but I believe we can get heli’s below 15 on the vibes. Your Vibes aren’t bad but could do better. Really good for a heli is below 5 but 5-15 is probably average. Looking at your mounting, it appears that you’ve tied all of the wires together going into the back of the pixhawk. It is possible that this is driving higher vibes. the stiffness of the wire bundle can transmit the vibrations into the pixhawk. Of course this could also be vibrations due to the rotor being transmitted through the frame. I will look at one of my heli’s when I get home that employs a pixhawk to see what my vibe levels are. It doesn’t look like you have much padding for vibration absorption. I use the thicker foam (1/4 inch) mounted in about the same location.
If you don’t mind, post your param file. I’d like to see how you tuned your rate PID’s. Glad to hear you are enjoying your venture into ardupilot!
no bubbles popped, this was a temp/trial that ended up working so well, I havent bothered to change it yet. I was NOT expecting this to work, or not work as well as it does. Originally, I just needed to ensure it would actually work before I spend anymore money on this thing, I have been through much moola with my 600 trying to isolate and fix the tail issues so it wasn’t intended to be this way for this long. The mounting was done to get the PIX installed as safely as possible so there was no risk of losing the copter (safety first). The mounting is isolated with foam for now, but this is version 1. The final product will be rubber mounted with the camera installed (this will only be my photography copter). In regards to vibes, I sure can get it lowered, BUT my comments were based on my drone (first attempts) which were almost doubled/trippled so I was really excited to see it behaving so nicely on my copter. Reading through the documentation showed it was safe enough to not worry about for my initial runs (but I do plan to fix it), that is a definite. I plan to isolate it further, remove the wire ties (again temp to hold it together for safety during my initial flights), I plan to finish the camera mounts and have it running through the PIXHAWK for control and shutter (but thats a day 2 project). I take everything you mentioned into account and plan to fix them all in time. My goal is for stable, smooth flights for camera surveying (friends/family/clients) and have achieved that. My TRex 600 was NEVER so smooth before, this thing flies so beautifully now that I am honestly, shocked. This thing has been a thorn in my side since day 1. The tail caused 1 true flight crash when I lost the original tail gear so I has no tail control and crashed her as gently as possible. Then I rebuilt it and it sat (damage wasnt really much as I controlled the crash as gently as possible but I couldnt auto it unfortunately). The tail was always an issue, no matter what servo/gyro combo I threw at her (and I spent some big coins on this thing), only the PIXHAWK seems to be the fix. IDK why, nor can I explain it, but it just works!
Here is my latest running config, note, I have my RPM set exactly how I like it (ramp up, RPM speed, ETC), I also have my collective curves and pitches exactly the way I need it for what I am doing with it so yes, they will look funky, but its intended:
Josh,
So the default parameters that is installed with the firmware for the Rate PID’s are very out of date. We have gone a long ways to knowing better defaults for the RATE PIDs. I would suggest that you load the defaults from the Config/tuning page and select Full Parameter List. On the right you will see the pull down for different default parameters lists (it is above the load presaved button). Choose TradHeli_Copter36_Setup-MP.param and then click load presaved. If you scroll down through the full parameter list, you will see many boxes that are green. Click “Write Parameters” box to send them to the flight controller.
This is a much better starting point for your helicopter. You can go to the traditional helicopter wiki and read through the tuning wiki to learn how to better tune your helicopter.
Thanks Bill, I found the file on github and reviewing it (TradHeli_Copter36_Setup-QGC.params).
Yup, I went through the PID tuning page a few times already, its saved and bookmarked for future quick reads.
-EDIT, I reviewed them from github and merged them into my config and will test. Here is the latest file (if you could check it out to make sure nothing was screwed up during the merge), I used QGC and the file for QGC:
Yes, that looks good. What flight mode are you flying in? The only other change that I would suggest is to raise the ATC_RAT_PIT_ILMI and ATC_RAT_RLL_ILMI to 0.08. This will help the controller hold the desired attitude better.
Thanks and cool, glad it worked, I will test flight as soon as the rain stops (been flying it all morning). I mainly fly in ACRO and STABLE, one question I had was the parameters to modify for the stable mode. I would like more angles (pitch/roll).
I know you like the way it feels with the default parameters but you really should go through tuning you aircraft according to the tuning guide. You can leave the tail params as they are but you will definitely need to tune pitch and roll if you plan on using any modes other than acro and stabilize.
@GROOVY1975 Also I realized that I was being a little insensitive. I apologize for putting you in that situation. These settings have been tested on many different heli’s and they haven’t had that adverse of an effect. I should have warned you that oscillations on any axis were possible. Did you get my PM?
Nah man, dont worry about it, we are solid as a rock! I appreciate EVERYTHING you tell me and help me with. Its all good! Didnt see PM, checking now but seriously, you were not a problem from my side! I have my bird back to almost normal (reset everything and went through the setup again), this time around I was able to get both compasses in the ‘green’ so I am happy, she flies perfectly again!
I would like to test some of the params in the file you pointed me to, but I want to pull out the tail portion (oscillation was scary bad) so any ideas on how to go about that? I am asking you here, verses PM so others can see the answer as I know I would be searching out this useful info. I find the more info I give, the more info I receive which in the end, benefits others in the same situation so I try to be as upfront and open as possible so EVERYONE gains the information. PLUS, without you and your help, 1) my CP drone will be dead in the water, 2) my TRex 600 would still be sitting in the corner gaining dust and not flying, NOW with YOUR help, BOTH are flying like birds in the sky, no issues! I am LOVING the PIXHAWK but I wouldn’t be where I am now without your help, I would have been stuck, dead in the water, looking for the answers in the docs (which sometimes are hit or miss) which probably would have ended up shefl’ing the projects so again, I thank you for EVERYTHING you do (including your help on all of the forums), I read everything you post!
I am a senior sys engineer, all I do is learn, redesign, tweak, rebuild, everything I can to learn how anything and everything works, SO this was a perfect learning example. I will learn what works, what doesnt, ETC., while tuning her better and better each time. Nothing lost is nothing gained.
Cool. I recommend changes a lot and forget to caveat them with warnings. I think what bit us in the butt on the tail was H_COLYAW which mixes collective to yaw. Your previous setup had no collective to yaw mixing and the default param file has it at 3.0. Also the P gain went up from 0.18 to 0.22. Most of the time when you see oscillations, it is due to either the P or D gain. Most of the other changes would not cause the problem you described.
You could download the file from github and then remove the parameters for yaw axis. Save the file and then use the load parameters button in the full parameter list page of Mission planner.
OR better yet. You could also use the Compare parameters button which will show you the parameters that were changed due to the new file. So download the default parameter file from github and then use the compare parameters button. then uncheck all of the yaw parameters you don’t want loaded. then hit continue. finally you have to click write parameters to load them on your flight controller.
Thanks man, yet again for the help I will do that, I will ‘compare’ them and then uncheck the yaw ones and follow-up. I am able to get the vibes even better than before (but not where it will ultimately be) once I receive my rubber mounts.
We are getting there though better and better with each tweak. I plan to continue tweaking until its as low as I can get it then as stable as I can get it. I will also incorporate the params from the tuning you mentioned (minus the yaw). I only care so much about the vibes because I plan to use this for camera only (no 3D), I save the 3D for my 700 which is balls to wall power.
Found the main cause of the vibes (still even without this they are under 20 for the majority of flight), it only touches 30’sih at the very beginning at spool-up when the blades are not straight. The dumbest thing too, my dang CANOPY isn’t the best at sitting still during flight. I first noticed the canopy wobbling ever so slightly, then I heard a “squeak” that bothered me (thinking it was my tail or belt as this is what caused the one and only minor crash when my tail gear stripped causing no yaw control) so I started to play with the canopy and noticed it was loose, causing the squeaks under collective lift (seemed to lift the canopy a bit then the air and vibrations was causing it to resonate downward). I removed it, and the vibes are almost gone for that entire flight (15-18). I will secure the canopy better from wiggling (but it would never come loose, it just doesnt snugly fit).
Josh,
Here are the Vibes from my 600 size heli with a Pixhawk 1 on foam mounts. Most of the spikes are because I was doing a tuning and making large stick inputs. during non maneuvering flight, you can see that they stay below 10 in all three axes.
That’s so awesome, thanks Bill! I believed you without the pics, but the graph pic helps my dyslexia/ADHD brain visualize it better than words so this was very helpful!
ALSO, GUESS WHAT I GOT WORKING?! POS-HOLD, I have been playing around with the parameters and flight modes, tuning it based on your previous post, and the GPS flight modes. At first, no GPS modes would work, but after I rebuilt it yesterday morning, I fixed the issues and now it locks in place, and holds the position. I have never had this before on any helis, I only use the PIXHAWK in my 600, my 700’s are tail-gyro only (no FLYBAR nor FBL gyros) so this is really cool and something new to me (again I have never had a GPS gyro before)! I didnt think it would work, but WOW, I couldn’t believe my eyes when I toggled POS-HOLD switch tied to channel 7 and sure enough, it just sat there and self-adjusted itself to remain in the same position as when I toggled the switch without my hands on the sticks! I couldn’t believe it, that was cool! Since this is primarily going to be aerial photography heli, I can simply hover over the location I wish to photograph, toggle POS-HOLD then my hands are free to snap the pics and move the gimbals to control the camera! WOW! I am so happy with this PIXHAWK that I plan to buy yet another one for my non-3D 700, I have been thinking about it since getting my 600 up in the air. I have two TRex 700’s, 1 strictly for inverted/3D, and the other is more tame, not as aggressive, both are 12S/HV so I will need to think the voltage but other than that, I plan to pair up my 700 with a new PIXHAWK!
I am having the time of my life flying this thing now, I seriously get in at least 3 flights a day now (yup every day) but usually more like 5 or 6 flights. NEVER before has my TRex 600 bird flown so perfectly, I am still dumbfounded how the FC fixed my tail issues, it makes no sense but I dont care, I am floored at how well it works!
FYI, just ordered a brand new 3DR PIXHAWK (brand new but the original 3DR versions), I found it pretty a decent price for it with all the goodies I need for my TRex 700 in the 3DR model (leftover stock). No way I am trusting anything but an official 3DR or HOLYBRO in my 700, that thing is way to expensive and dangerous to mess around with anything but an official build (3DR/HOLYBRO). I know even the official ones can still have issues but I figured its still safer than going with a 3rd party build (even though my RADIOLINK works fantastic and so does my HOLYBRO but I need a new one for my 700). My HOLYBRO version is in my CP UAV (drone you helped me sort out originally), and the radiolink in my 600, and even though I see absolutely NO differences in the hardware or performance, I dont mind paying a bit more for the official builds on my 700. I have WAY to much money into this bird to risk anything but the best. I cant wait to get my 700 running a PIXHAWK! Thats my Cadillac bird, my 700E DFC HV TRex uses all Savox HV servos, plus tons of upgrades and top of the line parts so I have to tread carefully with this build. I cant afford any issues or to have her down due to failure of the system.
Josh,
Is the 3DR pixhawk you bought a pixhawk 1 or pixhawk 2.1? I don’t think 3DR made pixhawk 2.1’s. I agree there are a lot of vendors of open source hardware and you have to be careful. If you want a Cadillac of controllers and are willing to spend the money, I would recommend CUAV pixhack v3x or v5. I have one of each. the benefit of these controllers over the pixhawk 1 is that they have internal vibration absorption for the IMUs. Even the HEX pixhawk 2.1 is a better choice than the 3DR Pixhawk 1 due to the vibration isolated IMU’s.
no bubbles popped, this was a temp/trial that ended up working so well, I havent bothered to change it yet. I was NOT expecting this to work, or not work as well as it does. Originally, I just needed to ensure it would actually work before I spend anymore money on this thing, I have been through much moola with my 600 trying to isolate and fix the tail issues so it wasn’t intended to be this way for this long. The mounting was done to get the PIX installed as safely as possible so there was no risk of losing the copter (safety first). The mounting is isolated with foam for now, but this is version 1. The final product will be rubber mounted with the camera installed (this will only be my photography copter). In regards to vibes, I sure can get it lowered, BUT my comments were based on my drone (first attempts) which were almost doubled/trippled so I was really excited to see it behaving so nicely on my copter. Reading through the documentation showed it was safe enough to not worry about for my initial runs (but I do plan to fix it), that is a definite. I plan to isolate it further, remove the wire ties (again temp to hold it together for safety during my initial flights), I plan to finish the camera mounts and have it running through the PIXHAWK for control and shutter (but thats a day 2 project). I take everything you mentioned into account and plan to fix them all in time. My goal is for stable, smooth flights for camera surveying (friends/family/clients) and have achieved that. My TRex 600 was NEVER so smooth before, this thing flies so beautifully now that I am honestly, shocked. This thing has been a thorn in my side since day 1. The tail caused 1 true flight crash when I lost the original tail gear so I has no tail control and crashed her as gently as possible. Then I rebuilt it and it sat (damage wasnt really much as I controlled the crash as gently as possible but I couldnt auto it unfortunately). The tail was always an issue, no matter what servo/gyro combo I threw at her (and I spent some big coins on this thing), only the PIXHAWK seems to be the fix. IDK why, nor can I explain it, but it just works!
