[SW-642] Make it obvious when spot is running out of battery

spot_driver/CMakeLists.txt

@@ -120,6 +120,12 @@ install(
   DESTINATION lib/${PROJECT_NAME}
   RENAME spot_ros2
   )
+install(
+  PROGRAMS
+  spot_driver/spot_alerts.py
+  DESTINATION lib/${PROJECT_NAME}
+  RENAME spot_alerts
+  )
 # Install Libraries
 install(
   TARGETS

spot_driver/launch/spot_driver.launch.py

@@ -277,6 +277,15 @@ def launch_setup(context: LaunchContext, ld: LaunchDescription) -> None:
     )
     ld.add_action(robot_state_publisher)
 
+    spot_alert_node = launch_ros.actions.Node(
+        package="spot_driver",
+        executable="spot_alerts",
+        name="spot_alerts",
+        output="screen",
+        namespace=spot_name,
+    )
+    ld.add_action(spot_alert_node)
+
     rviz = IncludeLaunchDescription(
         PythonLaunchDescriptionSource([FindPackageShare(THIS_PACKAGE), "/launch", "/rviz.launch.py"]),
         launch_arguments={

spot_driver/spot_driver/spot_alerts.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+from tkinter import messagebox
+from typing import Any, List, Optional
+
+import bdai_ros2_wrappers.process as ros_process
+from bdai_ros2_wrappers.node import Node
+from rclpy.parameter import Parameter
+
+from spot_msgs.msg import (  # type: ignore
+    BatteryStateArray,
+)
+
+
+class SpotAlerts(Node):
+    """Monitors spot states and will generate a pop-up message to alert the user of warnings"""
+
+    def __init__(self, **kwargs: Any) -> None:
+        super().__init__("spot_alerts", **kwargs)
+        # Subscribers #
+        self.battery_states = self.create_subscription(
+            BatteryStateArray, "status/battery_states", self.battery_callback, 1
+        )
+
+        # Parameters #
+        self.declare_parameter("low_battery", False)
+
+    def battery_callback(self, battery_array_msg: BatteryStateArray) -> None:
+        """A callback function to check the battery percentage and send a pop-up alert when <= 10%
+        Args:
+            battery_array_msg: BatteryStateArray message received from the publisher containing BatteryState messages
+        Returns:
+            None
+        """
+        for battery_msg in battery_array_msg.battery_states:
+            if battery_msg.charge_percentage <= 10 and not self.get_parameter("low_battery").value:
+                low_battery_param = Parameter("low_battery", Parameter.Type.BOOL, True)
+                self.set_parameters([low_battery_param])
+                messagebox.showwarning(
+                    title="Warning: Low Battery {}".format(battery_msg.identifier),
+                    message=(
+                        "Battery is at {} %. Approximately {} minutes remaining.\n Please charge your Spot soon."
+                    ).format(battery_msg.charge_percentage, round(battery_msg.estimated_runtime.sec / 60)),
+                )
+
+
+@ros_process.main(prebaked=False)
+def main(args: Optional[List[str]] = None) -> None:
+    ros_process.spin(SpotAlerts)
+
+
+if __name__ == "__main__":
+    main()