Re: [Flightgear-devel] PI Simple Controller: Initial Integrator Value

[James T. <ja...@fl...>]

> On 8 Feb 2021, at 03:05, Josh Davidson <jos...@gm...> wrote:
> 
> Recently been working on the KAP140 rewrite with the c182 guys + WoodSToKk. One of the problems is the machine does not start from the current servo location, because the pi-simple-controller element does not allow any sort of initial integrator value setting (like jsbsim, or how the "pid-controller" starts his integrator from where <output> left).
> 
> Why not pid-controller?
> Because I don't want velocity style here, absolutely and simple pi works best in this system (at least... for now, I still can make something maybe)
> 
> Why not jsbsim?
> Because we want the KAP140 to work on both Yasim and Jsbsim aircrafts.
> 
> So I propose to add a tag or value which is if omitted, uses the default of "0" that allows us to define a property or value (or expression etc) for the initial integrator value.

That seems possible indeed: I think Julian also did some work in this area in the past year, but for the full PID. So I’d recommend, at least use the same property name and conventions.

Other thing: for all autopilot changes, please add a unit-test (see my digital filter example) for the new functionality. Of course I can help you setting that up, and unit-tests usually make development faster (since you don’t need to run FlightGear to work on the code)

Kind regards,
James