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Re: [Paparazzi-devel] New auto_pitch mode

From: kochevar
Subject: Re: [Paparazzi-devel] New auto_pitch mode
Date: Mon, 27 Jun 2005 14:43:48 -0700
User-agent: Internet Messaging Program (IMP) 4.0-cvs

Nice work and looks good.  However it seems like the climb_pitch_sum_err is
missing.  should have lines similar to this

climb_sum_err += err;
    if (climb_sum_err > MAX_CLIMB_SUM_ERR) climb_sum_err = MAX_CLIMB_SUM_ERR;
    if (climb_sum_err < - MAX_CLIMB_SUM_ERR) climb_sum_err = -

Quoting Pascal <address@hidden>:


A new longitudinal mode have been added in the autopilot; its aim is to
control the vertical climb only using the pitch, with a constant
throttle command. This mode is compatible with the "alt" (the default),
"climb" and "glide" vertical mode's.

Syntax in a flight plan: set the "pitch" value to "auto" along with a
"gaz"  value (required).
For example:

     <go pitch="auto" gaz="0.75" wp="1"/>

or, if you want to crash ASAP (roll=30°, vertical speed=-2 m/s, full

     <attitude roll="30" vmode="climb" climb="-2" pitch="auto" gaz="1.0"

New parameters are needed in the airframe description to handle this mode:
In the PID section, some limits on the desired pitch:

    <define name="MAX_PITCH" value="0.25"/>
    <define name="MIN_PITCH" value="-0.35"/>

and in the ALT section, two gains for the new controller. Unit of PGAIN
is rad/(m/s) .

    <define name="PITCH_PGAIN" value="-0.1"/>
    <define name="PITCH_IGAIN" value="1.0"/>

Some details: The source code has been patched in pid.c:climb_pid_run()
: The "auto_pitch" boolean flag is used to select the standard
controller (FALSE, desired_gaz computed from desired_climb,
desired_pitch almost constant) or the new one (TRUE, desired_gaz
constant, desired_pitch computed from desired_climb).

Warning:  the single test on this new code has been done with gcc: We
cannot simulate it with the current simulator. So be ready to switch
back to auto1 mode ...

Comments are welcome.


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