Hi. - Happy new year.

Im new to copters but have been using arduplane for a while.

 

I have been setting up a new quadcopter and following Dave Cs guide. Its flying very nicely in all modes and I have done a few auto missions around my field.

Before the problem flight I had done exactly the same Flight Plan (route and heights) except at speed 2m/s.

For the second flight I set 6m/s and a halfway waypoint with speed change to 10/m/s. On the way back there was another speed change down to 2 m/s.

Height keeping on this last flight was not great but on the way back it just went into full climb reaching 227m before I rescued it. The green height bar on the flight data display is defiantly below.

It is not an error in the flight plan and the alt-error feed shows an increasing error.

 

I just cant see why it did this.

Any help appreciated. Logs attached.

 

Vince

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Looking through the tlog, at 117sec the ‘throttle’ (graph this) seems stuck above 80 units. While the speed is high the height is not increasing much but after the slowdown to 2 m/s this excess throttle makes it climb.

Why is ‘throttle’ stuck above 80?

 

Hi Vince,

Looking at your tlog, it shows your distance to home at 250000 or something silly like that? suggesting the home point was not set correctly or there was an error with GPS?. You need to look at the dataflash files or post them here, to get a better idea of what happened..

Can you please share the link for Dave C's guide?

Thanks!

Thank you!

log file for that flight uploaded

I think the strange home dist is after the last W.P. when it goes into loiter. GPS must have been OK as route nav was ok.

Is there a guide to de-bugging with the log files? I can graph log data in the CLI but cant see much different from the tlogs.

Did a 60 waypoint grid flight this morning at constant height and speed - no probs. Not confident it wont go ballistic again though.

Vince.

 

 

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Doesn`t make any sense to me? maybe something to do with using sonar? I haven`t used it before as it isn`t really needed and seems to cause issues sometimes..

Another idea, what APM are you using?

Thanks for taking a look Dean. I have had quite a few flights today, getting ever more adventurous and the last one had a speed change 10m/s to 2 m/s like the problem flight but all seemed OK today. On occasions it did seem reluctant to descend though so I increased the IMAX alt hold from 3 to 4. (not really sure what Im doing but it seemed to improve things) As far as I can see there is no parameter for descent rate.

 

 

I dont really want to turn this issue into a general shout for copter help but, auto land sometimes doesn’t quite touchdown and then climbs to ‘home’ or descends too fast, sometimes with drift. Also ‘takeoff’ wont take off in auto unless I’m already hovering. Cant find any info on that.

 

By the way Dean, I dont have sonar, but was thinking it may help with the landing?

 Looks like you have a professional set-up?

 

I thought you had sonar as it was showing in the log file you posted? check it is turned off in hardware options... If you are using an open board i.e apm 1 or 2 make sure the air pressure sensor is covered with some cotton wool or something so that the wind or prop wash doesn`t affect the altitude. the altitude parameters and throttle will affect auto landing, You can get the machine to auto takeoff but it requires messing around or at least the last time I tries on arducopter 2.5 or 6 it did? it is possible though but requires making an error to take off and then the I term corrects the error in flight.. Probably sounds a bit confusing?

Auto Mode from Dean on Vimeo.

Now I run a business for aerial photography and cinematography although I dont use Arducopter for it as the kit costs around 10k a machine, so reliability and accuracy is very important, the APM will get there one day, and although it improves fairly quickly with time it isnt there yet, but a great tool for learning how these things work and how to fly.. The expesive stuff that I fly can get a little boring, so I get out a KK board or an APM to keep my hand in :) I plan to get another copter soon to put an APM on and get up to date with progress.

Data files of a recent upset - probably prop downwash. The copter was on the bench for ages so its a big file. Crash is at about 95%

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Opps, sorry you meant these ones.

I have looked at your logs and I have some feedback. This does look like the effect I was talking about but I suspect the real problem was your tuning of roll and pitch. This is the most aggressive tune I have seen so far.

Stab_P = 7.5 (This is massive, I would stick to 4.5 on all Stab P terms)

Rate_P = 0.17 (Large but might be ok)

Rate_I = 0.01 (too small, should be as large as Rate_P or bigger)

Rate_D = 0.004 (good number)

I think you have tuned this to a whisker away from stable and the copter started to oscillate as you descended. The roll and pitch input you gave in the last second seems to be the final straw and it let go.

I would suggest that you leave the Stab_P terms all the same at 4.5. I would also re tune the Rate P term with the Rate I term at 0.1. Then once you have finished tuning Rate P, I would make sure that Rate I is the same size or larger. You may also consider reducing the Rate P by 25% if you are tuning to near unstable.

After tuning I do a number of tests.

1. Full Roll input and let go of the sticks. (No motor oscillation should be heard)

2. Repeat 1 for Pitch and Yaw.

3. Repeat 1 and 2 in fast climb at 3/4 throttle.

4. Fast decent on near zero throttle for 5m followed by full throttle (all at about 30m+)

5. Fast forward flight followed by leveling and applying full yaw (all at about 30m+)

6. Fast shuttle runs with full Roll and Yaw input at each end. (all at.... you get it)

Warning: I break cheap Hobby King props on 6. (my tune lets me fly on half a prop)

During 4 and 5 I expect to get some wobble but nothing scary.

If you can do these things without any problems you probably have a very good tune. With large props you may still have a good tune but not have the power in the motors to cope with the more extreme maneuvers. The large prop problem should be seen in 6 as the copter falling out of turns and maybe bucking.

I am very sorry to see your crash. I hope this helps.

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