Re: [Flightgear-devel] Generic Autopilot Rework Proposal

[Scott G. <sc...@gm...>]

Hi Josh,

Yes, there is interest. Let us know then the demo is ready.

You said you made a prototype.  It would be good to understand what is 
required to mature it into a solution that could be committed.

Scott


On 1/9/22 1:00 PM, Josh Davidson wrote:
> Hi,
> For years the generic AP has irritated me as it just flies very 
> poorly. In my view a generic AP should be able to fly most aircraft 
> with plausible FDM, but the generic AP can barely do that. (No offense 
> intended to the original creator)
>
> I created some prototype of a reworked generic AP last year but forgot 
> about it, it was designed to be able to fly any aircraft with a 
> plausible FDM.
>
> To be clear - this is not anything like IT-AUTOFLIGHT. IT-AUTOFLIGHT 
> is designed to facilitate development of realistic airliners 
> autopilots, which is totally different goal then a default generic AP.
>
> This generic AP I wrote last year was designed to be a _drop-in 
> replacement_ of the existing - no aircraft side edits required. It 
> uses the existing properties to maintain compatibility and is designed 
> to fly as many types as possible. The control system design is very 
> specifically made so that different FDMs and feeling aircraft can 
> still be flown with some stability.
>
> The primary issues with the current generic:
> - Unstable response in all heading/route manager, altitude, and speed 
> on pitch control
> - Overshoots/undershoots due to bad integrator use/cascade design
> - Oscillation/vibration on sensitive aircraft
> - Oscillation/overshoots on heavier flying aircraft
> - Bad pitch control handling
> - A few more I can't remember now
>
> I made a quick demo showing the heading, altitude, and trim issues: 
> https://youtu.be/9b1e9aVzT7Q <https://youtu.be/9b1e9aVzT7Q>
> Did not have time to film/demo all the other issues, this is just a 
> small subset of the issues. If weather comes into play, it just gets 
> much more unstable
>
> I also think some configurability can be added, for example, whether 
> to use the baro altimeter or the standard altitude shown in the HUD 
> and /position. This would not require any aircraft side changes for 
> the default behavior. Meaning, when the setting is not there, the file 
> falls back on the default behavior (ex, standard altitude prop), and 
> when the setting is there, it uses the defined behavior. That way any 
> airplanes use the default behavior, and also there is some minimal 
> configurability possible by the developer.
>
> Appreciate your thoughts and feedback, and if there is interest, I 
> will put together a demo using the prototype file I created, and you 
> can tell me what you think! I really think this would improve alot of 
> the "unfinished" planes that are borderline un-autopilotable with the 
> current generic AP.
>
> Kind Regards,
>
> -- 
> Josh Davidson
>
>
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