I did do it on the bench when it was first noted. This goes back to March and thru summer when Alan first got this thing together to get his feet wet with helicopters. While I can’t find the email right now, he sent me a video of (I’m pretty sure) that 1 servo jittering like it had gone wild right on the bench.
At the time, the telemetry radio did not cross my mind because I found some other settings that were messed up. But like I say, most of those radios are 0.1 watt. This one is a 0.5 watt. And I’ve seen the 100mW ones cause servos to jump before with every packet.
Here is original video. I started with. Tried firing it and got scared and tried several times. Was even doing this on the bench without blades. Swash was dancing. Up until we dropped rat xxx rates. But radio has always been hooked up.
Yep. Load the flight plan, shut the system down. Unplug the telemetry radio. Just use your RC. You got the telemetry on the RC anyway and you’ll be able to tell right away if it’s working right based on the visual of where the helicopter is and what waypoint is announced by the girl in the RC.
DO NOT fly it at 50kts. Set the speed at like 20kts (about 10 m/s or 22 mph) and try that. That should be pretty safe.Your I-gain in the rate controller is pretty low to go much faster than that right now. And I suspect you have the VFF over-tuned. I have never yet seen a 700 or 800 that takes over 0.15 VFF if the main rotor is turning at a reasonable speed.
No, those limit the maximum frame rotation rate in deg/sec. Turn those off when you tune the VFF because you have to use full-cyclic deflection inputs to properly tune the VFF. All those rate limiters will do is limit the rate, which will cause you to over-tune the VFF. After you get it set, then if you want to limit the frame rotation rate you can set those. The yaw one will probably be the most important for UAV. Most of these things will spin at 720+ deg/sec with full yaw. That’s way too fast for UAV. I like around 180 deg/sec so it takes two seconds to make a full spin with a full yaw input. But you can tune that to your liking after you get the rest of it set.
Yeah. The thing is, the default parameters that I developed and that are in the Tools/Frame_params should fly that thing out of the box. They were developed on a machine that size, tested in many including 600 and 500 size. Other than the unknown on the tail because so there’s so many different tail servos, I haven’t seen one yet that those params don’t work for a starting point.
So IMO the root of the problem has not been gotten to (yet). Your jello plate mount is not the greatest. But I did fly nitro with a Pixhawk 1 with one of those plates back in the day, because it’s all there was for Pixhawk 1’s and APM’s. While those old helicopters didn’t handle the greatest I never seen where that jello plate caused the sort of thing you got going.
Eliminate the radio first. That’s easy to test. If it’s not the radio, it’s not. Then take a hard look at that controller mount. But that very strange looking output on servo1 is not right. The mixer in the code has no reason to oscillate that servo like that without doing the same thing on servo2 because the mixer outputs are just pitch, roll and collective. So if the system wants a roll the mixer is going to make servo1 go one way, and servo2 the other. But it’s only bouncing servo1 which causes a combination pitch/roll input to the swashplate. Doesn’t make sense.
I also use the Pixhack v3 and did not use that blue jello plate mount what comes with the FC. I do not believe that the manufacturer has ever tested that plate on a Heli. Maybe it is good with a drone?
That is some impressive footage. Really smooth. Was that the auto mode of loiter circle. Looked like the heli was flying sideways. Or was the camera below the landing gear?
Thanks I fell progress has been made. Me trying for a year to diagnosis this thing has been heart breaking. Iv worked as a mechanic all my life. On a everything. Walking in the dark with all these params that 1 change can effect other params. We knew something was wrong and not just over tuned with factory params or Chris params. The rat xxx being set low must have been the bandaid we needed to get it to function.
Iv considered mailing it of to an expert to get it repaired. Many many times. I’d cool off a few weeks do more reading catch some advice on the form and try again. Learning what to look at in the logs has and will help me in the future figure this thing out. With your guys help of course. The logs are still some of a mystery to me until I learn all the acronym.
@Alan.h I think @ChrisOlson is on to something with respect to fixing your issue with the low P and D gains that are not typical to what we normally see in helicopters. I really think the mount is your problem but it sounds like you have a plan to determine what the cause might be.
Chris and I don’t agree on how to tune and it sounds like he wants to take over. I’m confident that he can get you flying. Good luck!
Thanks bill. I am gonna try it all. But one at a time. I apparently need to do a lot of learning what the code does with all those params. I hope it is caused by the radio and mount. To be determined yet. The goal is flight. To start surveying.
I don’t want to “take over”. I’ve been emailing with Alan on an off since last March when he first got interested in trying a helicopter. I didn’t have time to properly answer all his questions at the time, so told him to use the community forum for support.
After all this time I’m convinced there’s something wrong mechanically or electronics that is causing the extreme instability in his machine and trying to fix it with “tuning” is only putting a band-aid on the underlying problem. The type of helicopter he has is normally very responsive because they are a popular 3D helicopter and they are factory balanced to be quite fast on handling. But other people have flown them successfully for UAV without the extreme problems Alan has experienced. Even with the current “tune” being de-tuned from what is normally used, not being able to get beyond 5 or 6 kts on an Auto flight because the the helicopter is pitching, rolling and yawing indicates a serious problem that has not been found (yet).
The extreme delay in the RC telemetry alone, when I use that same telemetry system and it works flawless, raises an alarm that something is wrong in the electronics.
I would agree that it does appear that his aircraft is overly sensitive to P and D gains. However there are other 700 size tunes that I’ve seen that have P and D gains less than what you consider normal. And they perform well in all flight modes. I have not seen any data from your 700 size aircraft to provide me a baseline. I’ve seen other tunes where users thought they have backed off on the gains enough where they didn’t have feedback instabilities but when you looked at the data there were some still present. The feedback instabilities, if not seen, could create problems with the VELXY_D term and could explain users experiencing oscillations when using that parameter. I’ve been able to use VELXY_D in my 626 and Josh was able to use it in his 700 size. So that is one parameter I wanted Alan to explore to remove the lag between the desired and actual velocities.
I think the things you’ve brought up regarding the RFI and flight controller mount are great feedback. And could help explain this 1 hz oscillation that I’m seeing in the rebuild but didn’t see in the previous one.
I agree these issues with auto are peculiar but like I pointed out, from the attitude controller point of view, it appears to be providing the attitudes requested.
I want to get Alan flying auto missions but what I don’t want to do is get into arguments with you on the direction of how to tune the attitude controller. Whether the VFF is too high or low doesn’t impact how high the P and D gains can go. That is just one example.
I greatly appreciate your insight on what could be causing the odd behavior but I am going to stay out of it. We don’t think alike in how to tune the attitude controller.
I’m looking forward to hearing about the test with the telemetry radio unplugged. Even during the auto flight it appears to track on attitude, short of the weird weaving back and forth and failure to follow the GPS track. There is some GPS anomalies, “bad GPS signal health” reported about 85% of the way thru the flight. The telemetry on the FrSky passthru is lagging seriously behind. CPU load looks ok, free memory looks ok, but even when RTL is executed it follows a weaving flight path, wildly deviating side to side. While the position controller position targets are way off on the y-axis, the target and actual acceleration and velocity request don’t look too bad in the PSC, trying it get it back on target.
I’m wondering about the wind conditions on this flight. Alan is in Kansas where the standard wind speed indicator is a length of log chain nailed to the top of a wood fence post. If the chain is 45 degrees out from the post it indicates a light spring breeze. If it’s standing straight out from the post it means the wind might pick up later. Fighting strong wind would maybe cause the deviations from the desired flight path. But it doesn’t explain the lagging RC telemetry. And I’m not seeing high bank angles indicative of a strong crosswind.
The flight controller mount can cause some deviations from desired attitude. Or at the right harmonic where the frame is going one way while the controller mass is going the other it can cause oscillations. But it’s not going to cause those wild deviations from the desired flight path in auto, and those are really wild deviations - I’ve never seen that before.
I don’t think the huge delays in RC, the GPS anomalies, or the wild weaving in auto has anything to do with the attitude controller. If we can’t get to the bottom of what’s causing all that I’ll have Alan pull the tail boom and blades, pack the helicopter and RC radio in a box and send it up to me so I can find the problem and fix it for him. He wants to use this machine for commercial purposes, and that’s what I do.
Haha my tummy hurts after the Kansas wind description. I live in a bad windy Kansas zone. But that say of flights was a light 5 to 8 mph breeze from west to east. Path was north and south.
The radio lag in the telemetry side for battery voltage is what caused my crash and being a noob. Once I seen it was coming down with little to no warning I kept off the road had it to 1 ft and did a flare but thanks to a breeze and my poor judgment of where to stand on a bright sunny day with the laptop under a bush to see the screen. I lost sight if the heli and instead of a pro pilot pulling collective down to drop only 2 ft. I leaned cyclic and went into a 40 ft pine tree at 2 ft high. Blades were mostly stopped but does not do a heli good. On stabilize or loit the battery telem works fine. I even set up yaapu warnings but don’t work in auto. That’s the need for a ground link to the computer. Unless the ground link is causing the lag. Hope it cures all.
There is some issues with bandwidth for the packets for the passthru telemetry. I’m not sure what the solution is for that, Alex had a possible solution for it in some modifications to the passthru code I think. He’s got a big thread in the blog section on the FrSky telemetry you can check in on and read up about it.
What’s more concerning is the lag in the waypoint announcements. I haven’t seen that and we’ve flown that system on flights up to 250 waypoints without an issue. So I’m wondering if that (relatively) quite powerful telemetry radio might be causing interference for the RC?
Just because it’s a different frequency doesn’t mean it can’t cause interference if that telemetry radio has quite dirty output with spurious emissions. The quality of those cheap radios is not that good. And they are not legal in the US in the first place because they don’t meet the FCC 47CFR Part 15 standards for causing interference to licensed radios. 33 centimeter band belongs to ham radio in the US, but radios that use frequency hopping can be operated by non-licensed people in the band as long as it has the FCC Part 15 compliance testing done on it. While it’s not likely to happen, getting a ham radio operator bent because you caused interference to his/her station with an unlicensed radio putting out spurs will bring the FCC down on you. Hams are federally licensed operators and they got a direct line to the FCC, and the FCC uses them for enforcement to police their own bands. So I’m always leery of those cheap radios because I’ve had some of them on the scope that are pretty bad (and yes, I’m a licensed ham, Extra Class, call sign AC9KH).
Bill, I totally agree with you regarding PSC_VELXY_D to have that not at 0.
I use on my 700 =0.28 and on my 600 =0.25.
Now both are doing a perfect Loiter what both did not do with the value 0.
ok the verdict is … maybe. So i took my zip tie that was holding the v3x to the jello plate off and put it around the entire jello plate. so that removes that from the equation. I took my pitch gauge leveled the main shaft. the checked the blades. i rotated them as i was checking the servo to swash level. both blades are the same pitch all the way around. maybe .1 pitch variation total. i lost light to do a hover to check tracking. still had minor vibration on spool up. I noticed the radio say sensor lost when spooling up. i dont know if that was bad timing or the vibe caused a problem. the radio says that from time to time. i have read other peoples have the same issue. The flight took of fine. looked like it could have been going 22 mph thats where i had it set at .the flight was mostly smooth not drunken like before. on second pass back the it looked like it slowed down. i set all spline waypoints. it was done with the flight when it finally said 3 across the radio. so still a lag from something. when i armed the heli the yaapu said 25.1 volts after take off and switching into auto the radio said 23.3 volts and never changed during the flight. i took out of auto to loiter and flew it a 100 feet. it shook on forward flight for a moment. then it smoothed out. when i landed it in stabilize batterys were below 23 volt radio still said 23.3 volt. only after i disarmed did the radio correct the voltage. I had the ground control radio unhooked after setting the flight path.
No Wind to speak of mabey a breeze tail and head wind at 70 ft.
With no ground control i have no tlog
Other changes i raised the yaw input from 15 to 40. and the rate stops i zeroed out.
I did a full calibration of gps and accelerometer and level horizion.
could these old servos on the swash cause some of this if they are not responding like they should or if a vibration is causing them to react wrong. when i was adjusting servo 2 the servo did not respond one time i touched it and it worked fine after. ???
My radio ground control was purchased from these guys. In Texas. Hope that helps.
Looks like servo 1 was still dancing. Now servo 1 is a different servo from the other 2. We burnt a servo we placed blame on the blade holder being on when the heli got plugged in but that was servo 3 so we took servo 1 and put it in 3. Then I found the specs speed and pressure and found a servo that was as just as fast but stronger. That one went in servo 1. The signal from rc out is from the v3x right or does it have to get some info from the servo. I am under the understanding the v3x sends signal down the line. That happens few months ago.
Also I see it went into failsafe landing when I was in loiter. Radio did not say a thing. Good thing I was already in the process of landing it.