From 3473fa1e1d0daad804201416d07107f60ed0f41e Mon Sep 17 00:00:00 2001
From: marvin-oh <62216628+marvin-oh@users.noreply.github.com>
Date: Thu, 6 Jun 2024 15:31:54 +0900
Subject: [PATCH] Fix: missing gravity term in set_trajectory() function

---
 sciencebirdsagents/Utils/trajectory_planner.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sciencebirdsagents/Utils/trajectory_planner.py b/sciencebirdsagents/Utils/trajectory_planner.py
index e4201f9..5f2dae9 100644
--- a/sciencebirdsagents/Utils/trajectory_planner.py
+++ b/sciencebirdsagents/Utils/trajectory_planner.py
@@ -152,10 +152,13 @@ def set_trajectory(self, sling, release_point):
         # find the launch angle
         self._theta = atan2(self._release.Y - self._ref.Y, self._ref.X - self._release.X)
 
+        # gravity
+        g = 0.48 * 9.81 / self.scale_factor
+
         # work out initial velocities and coefficients of the parabola
         self._ux = self._velocity * cos(self._theta)
         self._uy = self._velocity * sin(self._theta)
-        self._a = -0.5 / (self._ux * self._ux)
+        self._a = -0.5 / (self._ux * self._ux) * g
         self._b = self._uy / self._ux
 
         # work out points of the trajectory