Rotorcraft Configuration

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The airframe configuration file is located in conf/airframes and contains all the hardware and software settings for an aircraft. All gains, trims, and behavior settings are defined with standard XML elements. Optionally you can also add a raw Makefile section.

XML Parameters

Commands

The commands lists the abstract commands you need to control the aircraft. For most multicopter you just need: 

<commands>
  <axis name="PITCH" failsafe_value="0"/>
  <axis name="ROLL" failsafe_value="0"/>
  <axis name="YAW" failsafe_value="0 />
  <axis name="THRUST" failsafe_value="0"/>
</commands>

Each command is also associated with a failsafe value which will be used if no controller is active, for example during initialization of the autopilot board.

Mode

In the mode section you can set the autopilot modes associated with your 3-way mode switch on your RC. 

<section name="MODE" prefix="MODE_">
  <define name="MANUAL" value="AP_MODE_ATTITUDE_DIRECT" />
  <define name="AUTO1" value="AP_MODE_ATTITUDE_Z_HOLD" />
  <define name="AUTO2" value="AP_MODE_HOVER_Z_HOLD" />
</section>

Bat

This section give characteristics for the monitoring of the main power battery.

The CATASTROPHIC_BAT_LEVEL (was previously LOW_BATTERY) value defines the voltage at which the autopilot will lock the throttle at 0% in autonomous mode (kill_throttle mode). This value is also used by the ground server to issue a CATASTROPHIC alarm message on the bus (this message will be displayed in the console of the GCS). CRITIC and LOW values will also used as threshold for CRITIC and WARNING alarms. They are optional and the respective defaults are 10.0 and 10.5V.

The MAX_BAT_LEVEL may be specified to improve the display of the battery gauge in the strip or in "papgets". Note that this definition is optional, with a default value of 12.5V. 

<section name="BAT">
  <define name="MILLIAMP_PER_PERCENT" value="0.86" />
  <define name="CATASTROPHIC_BAT_LEVEL" value="9.3" unit="V" />
  <define name="MAX_BAT_LEVEL" value="12.0" unit="V" />
  <define name="BATTERY_SENS" value="0.246" integer="16" />
  <define name="BATTERY_OFFSET" value="0" />
</section>


Simulation

Values from this section can be used to tweak the SITL simulation. The NPS (New Paparazzi Sim) currently uses JSBSim as for the flight dynamic modeling, but other FDMs are possible. 

<section name="SIMULATOR" prefix="NPS_">
  <define name="ACTUATOR_NAMES" value="{"front_motor", "back_motor", "right_motor", "left_motor"}" />
  <define name="INITIAL_CONDITITONS" value=""reset00"" />
  <define name="SENSORS_PARAMS" value=""nps_sensors_params_booz2_a1.h"" />
</section>

Modules

The modules allow to add new code in a flexible way with initialisation, periodic and event functions without modifying the main AP loop. 

<modules main_freq="512">
 <load name="sys_mon.xml"/>
</modules>
  • The main_freq parameter (in Hz) allows to specify the frequency of the main loop. Default is 60 Hz, for rotorcraft you should use 512 Hz.

Firmware and Hardware definitions

This is one example of a pretty standard quadcopter firmware definition:

File: conf/airframes/myplane.xml 
  <firmware name="rotorcraft">
    <target name="sim" board="pc">
      <subsystem name="fdm"   type="nps"/>
    </target>

    <target name="ap" board="booz_1.0"/>

    <define name="USE_ADAPT_HOVER"/>
    <define name="GUIDANCE_H_USE_REF"/>

    <subsystem name="radio_control" type="ppm"/>
    <subsystem name="actuators"     type="mkk"/>
    <subsystem name="imu"           type="b2_v1.1"/>
    <subsystem name="gps"           type="ublox"/>
    <subsystem name="ahrs"          type="cmpl"/>
    <subsystem name="ins"           type="hff"/>
  </firmware>

Select your Board

The airframe file must include the description of the controller board and it's low-level settings. This is done in the firmware section by specifying the board attribute for the target "ap" (autopilot).

Select the appropriate board: "twog_1.0", "tiny_2.11", "tiny_2.1", "tiny_1.1", "tiny_0.99", "booz_1.0", "lisa_l_1.0", "lisa_l_1.1", "pc"


File: conf/airframes/myplane.xml 
  <firmware name="rotorcraft">
    <target name="sim" 			board="pc"/>
    <target name="ap" 			board="booz_1.0"/>
     ...
  </firmware>

Radio Control

The Paparazzi autopilot can interface directly with the PWM signal from any standard hobby R/C receiver. Signal decoding configuration settings for this are stored in the Radio Control file.

Just specify the appropriate subsystem in your firmware section:

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="sim" 			board="pc"/>
    <target name="ap" 			board="booz_1.0"/>
     ...
    <subsystem name="radio_control"     type="ppm"/>
  </firmware>

On the autopilots with a STM32 processor (lisa) you can use the type spektrum.

GPS

The serial port settings must match that of the GPS and are configured here along with the necessary files to interpret the u-blox UBX binary protocol:

For rotorcraft you can use the ublox type for both lea-4p and lea-5h.

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" 			board="tiny_2.11"/>
     ...
    <subsystem name="gps"               type="ublox"/>
  </firmware>

The correct UART is already defined by default according to your board. The default modem baudrate is 38400baud.

If you use different baud rates set the according parameters, e.g.

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" 			board="booz_1.0"/>
     ...
    <subsystem name="gps"               type="ublox_lea4p">
      <configure name="GPS_BAUD"          value="B9600"/>
    </subsystem>
  </firmware>

Note:

  • u-blox GPS modules are factory configured for 9600 baud, 38,400 baud is recommended along with the other required changes. The GPS can be accessed directly thrugh the UART Tunnel and Configured with u-center

IMU

Add the imu subsystem with the type you are using. Currently possible IMU subsystems are "b2_v1.0", "b2_v1.1", "b2_v1.2", "crista" and "aspirin". Other IMUs can be used through modules or you can just add a subsystem makefile for your own.

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" 		board="booz_1.0"/>
     ...
    <subsystem name="imu"       type="b2_v1.0"/>
  </firmware>

AHRS

The AHRS subsystem specifies which attitude estimation filter you are using, e.g. for the complementary filter:

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" board="booz_1.0"/>
     ...
    <subsystem name="ahrs" type="cmpl"/>
  </firmware>

INS

The optional INS (Integrated Navigation System) subsystem contains estimations filter to e.g. fuse GPS and IMU data for better position and speed estimates.

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" board="booz_1.0"/>
     ...
    <subsystem name="ins" type="hff"/>
  </firmware>

You can also compensate for GPS lag in hff (horizontal filter float) if it is known (in seconds):

File: conf/airframes/myplane.xml 
  <firmware name="fixedwing">
    <target name="ap" board="booz_1.0"/>
     ...
    <subsystem name="ins" type="hff">
      <define name="GPS_LAG=0.2"/>
    </subsystem>
  </firmware>

Beware, this code is kinda bad/ugly and should be replaced/improved!

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