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Calculates current heading #88

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Calculates current heading #88

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58cdc2f
Made changes to calculate current heading.
Krithik1 Feb 14, 2024
8788e40
Changes according to PR comments
Krithik1 Feb 20, 2024
2944157
Merge remote-tracking branch 'origin' into user/Krithik1/Publish_Desi…
Krithik1 Feb 20, 2024
c7fe341
Add named arguments in GEODESIC.inv function
Krithik1 Feb 20, 2024
052962f
Merge branch 'main' into user/Krithik1/Publish_Desired_Heading
patrick-5546 Mar 9, 2024
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21 changes: 19 additions & 2 deletions local_pathfinding/node_navigate.py
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Original file line number Diff line number Diff line change
@@ -1,11 +1,14 @@
"""The main node of the local_pathfinding package, represented by the `Sailbot` class."""

import rclpy
from pyproj import Geod
from rclpy.node import Node

import custom_interfaces.msg as ci
from local_pathfinding.local_path import LocalPath

GEODESIC = Geod(ellps="WGS84")


def main(args=None):
rclpy.init(args=args)
Expand Down Expand Up @@ -175,8 +178,22 @@ def get_desired_heading(self) -> float:
self.gps, self.ais_ships, self.global_path, self.filtered_wind_sensor, self.planner
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This is about line 175:

The function description says we should return something that violates the heading convention in the case of an error, but the heading convention allows $-180 \degree < \text{heading} \leq 180 \degree$.

Can you please change the return value on line 175 to something outside those bounds? I'd suggest 404 since that's a common error number for websites haha

)

# TODO: create function to compute the heading from current position to next local waypoint
return 0.0
current_waypoint = self.gps.lat_lon
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I believe self.gps.lat_lon is the current GPS position of the boat, which is generally not one of the waypoints. I think Jay might be working on code to determine the next local waypoint, but we can sync up with him tomorrow

next_waypoint = None
waypoints = self.local_path.waypoints
for i in range(len(waypoints)):
if waypoints[i] == current_waypoint and i < len(waypoints) - 1:
next_waypoint = waypoints[i + 1]
break
if next_waypoint is None:
return 0.0
heading = GEODESIC.inv(
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I think GEODESIC.inv() has multiple returns (documentation), and I think you only want the forward azimuth (image at bottom)

I believe Patrick is a fan of this kind of syntax for this situation: _, value, _ = myfunc(), where myfunc() returns a touple:

def myfunc():
	return (1, 2, 3)

In this example, print(value) outputs 2.

image

lats1=current_waypoint.latitude,
lons1=current_waypoint.longitude,
lats2=next_waypoint.latitude,
lons2=next_waypoint.longitude,
)[0]
return heading
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Would it be possible to add some tests for this function?

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For the tests, should I create a new test_node_navigate.py file and manually set the value of self.gps to calculate the desired heading?

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I think this would be the best way to test this:

  1. Create a helper function to get_desired_heading() that accepts "simple" arguments like waypoints or lists of waypoints, rather than "complicated" arguments like self (which is a whole sailbot object). get_desired_heading() will basically just call the helper function.
  2. Create test_node_navigate.py like you suggested, and just test the helper function. I'd suggest using simple tests like when the desired heading is $0 \degree$ or $90 \degree$, and maybe some more complicated tests where the "actual" value is computed with geodesic.inv() as well.


def update_params(self):
"""Update instance variables that depend on parameters if they have changed."""
Expand Down