[[searchwing-px4-analyse]]

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searchwing-px4-analyse [2018/10/28 22:40]
natwati [Points that require discussion]
searchwing-px4-analyse [2018/10/28 23:43] (current)
natwati [Points that require discussion]
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 In case actual position waypoints are used (and not loiter waypoints) the position controller will use the logic documented in "A New Nonlinear Guidance Logic for Trajectory Tracking"​ (S. Park, J. Deyst, and J. P. How, Aug 2004). The L1 distance defined in the default parameter only allows an offset correction of about 70% within 5 seconds (and 90% within 10s). This would be a 100 (200) meter distance for a ground speed of 20 m/s. In case actual position waypoints are used (and not loiter waypoints) the position controller will use the logic documented in "A New Nonlinear Guidance Logic for Trajectory Tracking"​ (S. Park, J. Deyst, and J. P. How, Aug 2004). The L1 distance defined in the default parameter only allows an offset correction of about 70% within 5 seconds (and 90% within 10s). This would be a 100 (200) meter distance for a ground speed of 20 m/s.
  
-The PX4 firmware ​only supports one mission ​at a timeIf the mission needs to be updated ​a full clear is required. Afterwards the mission needs to be uploaded using multiple mavlink messages and roundtrip times (see [[https://​mavlink.io/​en/​protocol/​mission.html|Mission Protocol]]). ​The behavior ​of the PX4 controlled ​plane during ​this phase still needs to be examined+The PX4 firmware ​does not support altering an ongoing ​mission. ​This requires ​a full clear of the mission. Afterwards the mission needs to be uploaded using multiple mavlink messages and roundtrip times (see [[https://​mavlink.io/​en/​protocol/​mission.html|Mission Protocol]]).\\ 
 +If all commands ​of a mission have been executed and the plane is in mission mode it will loiter. Missions can be paused in hold mode which causes the plane to loiter. 
 + 
 +The PX4 firmware implements the possibility to upload a second mission in the background while another mission is active. QGroundControl does not support ​this and forces the user to pause the mission when uploading a new mission. 
  
 ===== Points that require discussion ===== ===== Points that require discussion =====
  
   * How to command flying to a moving location?   * How to command flying to a moving location?
-  * What happens during upload of missions? 
   * Is an increased responsiveness of L1 position control during approach required?   * Is an increased responsiveness of L1 position control during approach required?
-  * A predicted route of the ship could be used to generate a trajectory that passes though all points the landing spot could be located at. This seems possible as no sudden deviation of the predicted route is to be expected ​for a ship. +  * A predicted route of the ship could be used to generate a trajectory that passes though all points the landing spot could be located at. This seems possible as no sudden deviation of the predicted route is to be expected ​from a ship. 
-  * Expected waves and wind (possibly from this source: [[http://​users.ntua.gr/​mathan/​pdf/​Pages_from%20_WIND_WAVE_ATLAS_MEDITERRANEAN_SEA_2004.pdf|WIND_WAVE_ATLAS_MEDITERRANEAN_SEA]]+  * Expected waves and wind should be investigated ​(possibly from this source: [[http://​users.ntua.gr/​mathan/​pdf/​Pages_from%20_WIND_WAVE_ATLAS_MEDITERRANEAN_SEA_2004.pdf|WIND_WAVE_ATLAS_MEDITERRANEAN_SEA]]
 +  * Can geofencing provide sufficient accuracy to prevent a collision with the ship?
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  • by natwati