opticflow_hover module

Hovers the drone based on optical flow made for Linux video Devices.

Computes Pitch- and roll attitude from downward looking camera looking at a textured floor.

• Sonar is required.
• Another module sending the VELOCITY_ESTIMATE ABI message (usually computed from optic flow) is required.
• Controller can hold position

Example for airframe file

Add to your firmware section:

<module name="opticflow_hover"/>

Module configuration options

Airframe file section

• section name: VISION prefix: VISION_
  • name PHI_PGAIN value: 400
    Description: Optic flow proportional gain on the roll velocity error
  • name PHI_IGAIN value: 20
    Description: Optic flow integrated gain on the summed roll velocity error
  • name THETA_PGAIN value: 400
    Description: Optic flow proportional gain on the pitch velocity error
  • name THETA_IGAIN value: 20
    Description: Optic flow integrated gain on the summed pitch velocity error
  • name DESIRED_VX value: 0
    Description: The desired velocity in the body frame x direction
  • name DESIRED_VY value: 0
    Description: The desired velocity in the body frame y direction

Module functions

Init Functions

These initialization functions are called once on startup.

• guidance_opticflow_hover_init()

Files

Header Files

The following headers are automatically included in modules.h

• guidance_opticflow_hover.h

Source Files

• modules/guidance_opticflow/guidance_opticflow_hover.c

Raw opticflow_hover.xml file:

<!DOCTYPE module SYSTEM "module.dtd">
 
<module name="opticflow_hover" dir="guidance_opticflow">
  <doc>
    <description>
        Hovers the drone based on optical flow made for Linux video Devices.
 
        Computes Pitch- and roll attitude from downward looking camera looking at a textured floor.
        - Sonar is required.
        - Another module sending the VELOCITY_ESTIMATE ABI message (usually computed from optic flow) is required.
        - Controller can hold position
    </description>
 
    <!-- Satbilization parameters and gains -->
    <section name="VISION" prefix="VISION_">
      <define name="PHI_PGAIN" value="400" description="Optic flow proportional gain on the roll velocity error"/>
      <define name="PHI_IGAIN" value="20" description="Optic flow integrated gain on the summed roll velocity error"/>
      <define name="THETA_PGAIN" value="400" description="Optic flow proportional gain on the pitch velocity error"/>
      <define name="THETA_IGAIN" value="20" description="Optic flow integrated gain on the summed pitch velocity error"/>
      <define name="DESIRED_VX" value="0" description="The desired velocity in the body frame x direction"/>
      <define name="DESIRED_VY" value="0" description="The desired velocity in the body frame y direction"/>
    </section>
  </doc>
 
  <settings>
    <dl_settings NAME="Vision stabilization">
      <!-- Satabilization loop parameters and gains -->
      <dl_settings name="vision_stab">
        <dl_setting var="opticflow_stab.phi_pgain" module="guidance_opticflow/guidance_opticflow_hover" min="0" step="1" max="10000" shortname="kp_v_phi" param="VISION_PHI_PGAIN"/>
        <dl_setting var="opticflow_stab.phi_igain" module="guidance_opticflow/guidance_opticflow_hover" min="0" step="1" max="1000" shortname="ki_v_phi" param="VISION_PHI_IGAIN"/>
        <dl_setting var="opticflow_stab.theta_pgain" module="guidance_opticflow/guidance_opticflow_hover" min="0" step="1" max="10000" shortname="kp_v_theta" param="VISION_THETA_PGAIN"/>
        <dl_setting var="opticflow_stab.theta_igain" module="guidance_opticflow/guidance_opticflow_hover" min="0" step="1" max="1000" shortname="ki_v_theta" param="VISION_THETA_IGAIN"/>
        <dl_setting var="opticflow_stab.desired_vx" module="guidance_opticflow/guidance_opticflow_hover" min="-5" step="0.01" max="5" shortname="desired_vx" param="VISION_DESIRED_VX"/>
        <dl_setting var="opticflow_stab.desired_vy" module="guidance_opticflow/guidance_opticflow_hover" min="-5" step="0.01" max="5" shortname="desired_vy" param="VISION_DESIRED_VY"/>
      </dl_settings>
    </dl_settings>
  </settings>
 
  <dep>
    <depends>cv_opticflow|px4flow</depends>
  </dep>
 
  <header>
    <file name="guidance_opticflow_hover.h"/>
  </header>
  <init fun="guidance_opticflow_hover_init()"/>
  <makefile>
    <file name="guidance_opticflow_hover.c"/>
    <test firmware="rotorcraft"/>
  </makefile>
 
</module>