Erratic autonomous flight with BIG drops in altitude

Hi Ardu-people!

This is my first post on the forums, I have usually fixed previous problems with my build by searching on here or google search. Yesterday I took my quadrotor out to fly a pre-programmed autonomous flight, the intention was to check the video afterwards to see how much vibration and wobbles were present in the video. I was using a simple python script with waypoints which I have done many times before without any problems. This time my quad behaved erratically. It looked and sounded like the motors cut out briefly, big drop in altitude then big throttle which fortunately saved it from bouncing or crashing into the ground. This continued until it did finally crash. I have had a look through the log file and can see some drops in altitude and something about vibration compensation but I am baffled why this happened. If someone has time I would be very grateful if you could look through my log and maybe let me know what happened and hopefully how to prevent from reoccurrence.
If there is any info you need from me, please let me know.

Thanks in advance, John.

[https://tinyurl.com/mvaw2k3w]

Vibes are high with 100’s of clipping events. Vibration Compensation was triggered. When this happens control will be very loose.
Vibe FS
It doesn’t look like you have done the Initial Parameter Setup or any tuning either. Most is at default.

Hi Dave,

Thanks for replying. Do you know what would cause my params to reset to default?
I haven’t flown my quad for maybe a month or so and the last flight (manual using Tx) I do remember the response being sluggish.
So if I go through the initial setup again and tuning I should be good to go again?

No. But you will need to reduce the vibration levels before proceeding with tuning.
Reduce Vibes
Configure the Initial Setup Parameters
Configure the Dynamic Notch Filter
Auto Tune. Or manual tune if you are up on that.

Well it’s a strange one as to why this has happened but only losing 2 props I can consider myself fortunate. Thanks for your advice on vibrations, etc, I have done all these things previously and had it flying quite nicely so hopefully I will be able to go through all the setup again.
Thanks again.
John