Tweak 2024 robot drivetrain radius

From spinning the robot in place, we observe a shorter effective radius
(the actual measured radius also is much closer to the updated value
 than the old one).

Change-Id: If27dff091624ac9570dd6e72cf183bde298c0ed7
Signed-off-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>
diff --git a/y2024/control_loops/python/drivetrain.py b/y2024/control_loops/python/drivetrain.py
index 0e75589..282b146 100644
--- a/y2024/control_loops/python/drivetrain.py
+++ b/y2024/control_loops/python/drivetrain.py
@@ -16,7 +16,7 @@
     J=6.5,
     mass=68.0,
     # TODO(austin): Measure radius a bit better.
-    robot_radius=0.39,
+    robot_radius=0.32,
     wheel_radius=2 * 0.0254 * 3.7592 / 3.825,
     motor_type=control_loop.KrakenFOC(),
     num_motors=2,