Control Law

Dear Chris and all,

I am currently using Ardupilot as part of my investigation into UAVs for my degree course.

My aim is to add some additional sensors to aid in landing.

It's apparent you use a PID controllers from your very well commented code.

My question is this: any chance I could get my hands on the control design and plant (E*) transfer functions if you have them handy? It would help me a great deal.

Thanks from your newest UAV pilot,

Nick

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Replies

  • Developer
    @Nick - I doubt anyone on the planet has gone to the trouble to figure out the plant transfer function for an Easystar. Gain values have been derived from trial and error, and may not be optimal in a theoretical sense.

    The closest answer to your question would be to look at the Easystar header file for 2.5.04 and look at the pitch servo gains. You will need to go through the code carefully to track units.
  • I'm using an Easystar with a sonar sensor, and I'm not sure about a "deep stall" but I will endeavor to create some sort of smooth flare manoeuvre.

    However, although I wholeheartedly value your input, it's not a solution I am after; rather the PID control design, closed loop transfer functions and plant (Easystar) transfer function (if available! - and I do hope so - I mean if not how did Chris et al arrive at the values listed in the easystar_25.h file?) so that I may design my own landing control system based on these known characteristics.

    If you discovered the values tough good old trial and error then any estimate of system response would be beneficial - pitch most importantly. I could try obtaining these values through a flight sim recording but suspect the results would be ropey at best.

    Many thanks.
  • What kind of sensors are you considering?? Laser? Sonic? What kind of Landing? Deep Stall? What kind of airframe? The more data you give in your questions, the better we can point you to a solution.
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