Help With A Unique Workflow

Agriculture
1

Hello, I will provide a brief outline of what I am trying to accomplish and I would appreciate any feedback you can provide.

TLDR; Essentially, I need a combination of both DJI field and fruit tree missions. I need a workflow where the drone will spread 8 lbs/acre in the field, but turn off AND avoid trees when it encounters them. Is there a way to accomplish this?

Equipment:

  • DJI Agras T20P with spreader attachment
  • DJI Terra Software
  • DJI Mavic 3T
  • Spike 20P Pelletized Herbicide
  • Pix4DFields

Mission Location:

  • A property in the Texas hill country that is a hunting preserve. Large grassland pastures with large, mature oak trees and low brush growing up all around

Goal:

  • Our client wants to spread this pelletized herbicide across the 500 acres of this hunting preserve at a rate of 8 lbs/acre in order to kill off the low brush growing among the grass
  • However, this herbicide can harm the oak trees so we want to leave a 15 ft. area around all of these trees where the herbicide is not spread

Process:

  • I use the DJI Mavic 3T to map out the property and create a reconstruction in DJI Terra
  • I then go into the Agricultural Application to mark all of the oak trees as buildings so the drone avoids them and turns off

Issue:

  • In order to get the drone to fly over the trees and avoid running into them, I set up the mission as a Fruit Tree mission. However, I was then alerted when setting up the drone to fly that the spreader cannot be used during a fruit tree mission.
  • So, I simply treated it like a field and relied on the Agras T20P’s obstacle avoidance system to go up and over or around trees. However, I was unable to figure out how to prevent it from spreading any of the herbicide while it is flying over a tree.

Are there any suggestions as to how I could use Pix4D to assist with this? I was thinking maybe doing a prescription map and setting the areas of the trees to 0 lbs/acre and making everything else 8 lbs/acre and then simply relying on the drone’s obstacle avoidance to maneuver around trees. Should I be that trusting on the obstacle avoidance feature?

Thanks,
Ethan

2

Hi Ethan,

interesting usecase. You have 2 options with Pix4dfields.

  1. Create a VRA map as you described and leave the tree areas with an empty rate. You can use the Magic Tool to detect all non tree areas and assign an application rate to them. This has the risk that you need to rly on obstacle avoidance of the drone. If possible you could just fly higher than the tree crowns but I am not sure if that’s feasible.

  2. Detect the trees with Magic Tool and assign them as an obstacle. Use them with an VRA map to assign rate to non tree areas. The drone will now avoid the trees and fly around them. It’s feasibly if the trees are not spaced close together and the drone could fly between them.

If you do that you should also do the reconstruction with Pix4dfields.

3

Hey Julius, thank you for the response. Unfortunately, there are a few areas where the trees are pretty thick and close together. Would marking them as an obstacle ever make the drone go over top or simply around? Also, when I went to mark obstacles on DJI terra, the flight path reconstruction had trouble trying to avoid that many obstacles. Since Pix4D doesn’t make the flight path itself, would that be an issue here as well?

4

If it’s marked as an obstacle the drone will avoid the area and fly around it. I guess the amount of obstacles will have the same effect indepent of the software they are created with.

If you leave an area with empty rate the drone should pass it. For safety you should decrease the flight speed. I have no practical experience how good the obstacle avoidance works.