Cruise control speed step transient control

[Timboj]

Happy to delete this one if there is a way to do this already.

I've find my cruise control step down in speed to be quite harsh through the drivetrain. Not surprising given the near instant reduction in throttle opening.

Step up is fine because of course the engine has to overcome the weight of the car etc.

Would it be possible to add transient control for the step changes?

[Adamw]

Can you attach a log and tune, I've only used cruise control in a couple of quite similar cars so not a large exposure, but I did use it a lot in those and it worked really nicely, quite a bit better than any OEM cruise I have used, so Id like to see what is causing that, maybe its just a set up issue like too much derivative rather than something missing from the functionality?   

[Timboj]

Thanks Adam.

Latest log and tune attached: 

https://drive.google.com/file/d/16MhOtrrQnJ1GM8GoN_fnRY8yJJ07MMGt/view?usp=sharing https://drive.google.com/file/d/18rv9MHV4kP9CgmubLSF_khE6ufJfqoWS/view?usp=sharing

Admittedly since my first post I'd made some PID changes to my eThrottle and when creating the log today, it was performing better. Near the end of the cruise control activation my step downs were a little harsher than the first few but overall an improvement I think.

Keen to hear whether you think the log looks normal/acceptable.

[Adamw]

I think the cruise PID is just a bit too aggressive.  You can see below how noisy TPS delta gets when cruise is active, even at the fixed speed, then where you change the set speed you see the big spikes in both directions.  Basically the throttle is fighting every tiny deviation in speed.  That over-excited TPS is also constantly triggering accel enrichment so you are probably burning more fuel than it should be too. 

Try halving your existing cruise proportional gain.  I think Integral and derivate probably are ok but please set the "PID setup" to cruise control before the next log so we have some better data.   

[Timboj]

Thanks Adam. That drop in PID seemed to make a difference in feel. The log still looks a little darty. What metric would you use to call it 'okay'?

https://drive.google.com/file/d/16MhOtrrQnJ1GM8GoN_fnRY8yJJ07MMGt/view?usp=sharing https://drive.google.com/file/d/1QUwV3fSPIPYeTUW4Pky5sOU2HUr4DNCg/view?usp=sharing

[Timboj]

@Adamw Any input on this one?

Seems like this could be moved out of 'Wishlist' as well if you can be bothered.

[Adamw]

The throttle is much more stable in that log, and the cruise looks good to me.  Does it feel ok? 

I think you could still drop the proportional even further if you thought it still felt too harsh as I dont see any signs of delayed response yet.