Read constraints from the published URDF rather than hard code them.

Also make the webui more responsive for small screens.

webui/backend/ros_node.py

@@ -1,11 +1,39 @@
 import threading
+import xml.etree.ElementTree as ET
 
 import rclpy
 from geometry_msgs.msg import Twist
 from rclpy.node import Node
+from rclpy.qos import DurabilityPolicy, QoSProfile, ReliabilityPolicy
 from sensor_msgs.msg import JointState, Range
 from std_msgs.msg import ColorRGBA, String
 
+_TRANSIENT_LOCAL_QOS = QoSProfile(
+    reliability=ReliabilityPolicy.RELIABLE,
+    durability=DurabilityPolicy.TRANSIENT_LOCAL,
+    depth=1,
+)
+
+
+def _parse_joint_limits(urdf_xml: str) -> dict:
+    """Extract lower/upper limits for pan and tilt joints from a URDF string."""
+    try:
+        root = ET.fromstring(urdf_xml)
+        limits = {}
+        for joint in root.findall('joint'):
+            name = joint.get('name')
+            if name in ('pan', 'tilt'):
+                el = joint.find('limit')
+                if el is not None:
+                    limits[name] = {
+                        'lower': float(el.get('lower', 0)),
+                        'upper': float(el.get('upper', 0)),
+                    }
+        return limits
+    except Exception as e:
+        print(f'Failed to parse URDF joint limits: {e}')
+        return {}
+
 
 class RobotBridgeNode(Node):
     def __init__(self):
@@ -16,22 +44,25 @@ class RobotBridgeNode(Node):
         self._led_color_pub = self.create_publisher(ColorRGBA, '/led/color', 10)
         self._led_effect_pub = self.create_publisher(String, '/led/effect', 10)
 
-        self.create_subscription(JointState, '/joint_states', self._on_joint_states, 10)
-        self.create_subscription(Range, '/ultrasonic/range', self._on_ultrasonic, 10)
+        self.create_subscription(JointState, '/joint_states',    self._on_joint_states,       10)
+        self.create_subscription(Range,      '/ultrasonic/range', self._on_ultrasonic,         10)
+        self.create_subscription(String,     '/robot_description', self._on_robot_description,
+                                 _TRANSIENT_LOCAL_QOS)
 
         self.on_joint_states_callbacks: list = []
         self.on_ultrasonic_callbacks: list = []
+        self.on_joint_limits_callbacks: list = []
+        self._joint_limits: dict | None = None
+
+    # ------------------------------------------------------------------
+    # Publishers
+    # ------------------------------------------------------------------
 
     def publish_cmd_vel(self, linear_x: float, angular_z: float) -> None:
-        # print(f'Publishing cmd_vel: linear_x={linear_x}, angular_z={angular_z}')
         msg = Twist()
         msg.linear.x = float(linear_x)
         msg.angular.z = float(angular_z)
-        try:
-            self._cmd_vel_pub.publish(msg)
-        except Exception as e:
-            print('Failed to publish cmd_vel:', e)
-        # self._cmd_vel_pub.publish(msg)
+        self._cmd_vel_pub.publish(msg)
 
     def publish_joint_command(self, pan: float, tilt: float) -> None:
         msg = JointState()
@@ -41,17 +72,22 @@ class RobotBridgeNode(Node):
         self._joint_cmd_pub.publish(msg)
 
     def publish_led_color(self, r: float, g: float, b: float, a: float) -> None:
-        msg = ColorRGBA()
-        msg.r = float(r)
-        msg.g = float(g)
-        msg.b = float(b)
-        msg.a = float(a)
+        msg = ColorRGBA(r=float(r), g=float(g), b=float(b), a=float(a))
         self._led_color_pub.publish(msg)
 
     def publish_led_effect(self, effect: str) -> None:
-        msg = String()
-        msg.data = effect
-        self._led_effect_pub.publish(msg)
+        self._led_effect_pub.publish(String(data=effect))
+
+    # ------------------------------------------------------------------
+    # Accessors
+    # ------------------------------------------------------------------
+
+    def get_joint_limits(self) -> dict | None:
+        return self._joint_limits
+
+    # ------------------------------------------------------------------
+    # Subscribers
+    # ------------------------------------------------------------------
 
     def _on_joint_states(self, msg: JointState) -> None:
         data = {'type': 'joint_states', 'positions': dict(zip(msg.name, msg.position))}
@@ -63,6 +99,17 @@ class RobotBridgeNode(Node):
         for cb in self.on_ultrasonic_callbacks:
             cb(data)
 
+    def _on_robot_description(self, msg: String) -> None:
+        limits = _parse_joint_limits(msg.data)
+        self.get_logger().info(f'Received /robot_description, parsed limits: {limits}')
+        if not limits:
+            self.get_logger().warn('No pan/tilt limits found in URDF — check joint names.')
+            return
+        self._joint_limits = limits
+        data = {'type': 'joint_limits', 'limits': limits}
+        for cb in self.on_joint_limits_callbacks:
+            cb(data)
+
 
 _node: RobotBridgeNode | None = None
 _spin_thread: threading.Thread | None = None
@@ -78,7 +125,7 @@ def start_ros() -> RobotBridgeNode:
 
 
 def get_node() -> RobotBridgeNode:
-    assert _node is not None, "ROS node not started"
+    assert _node is not None, 'ROS node not started'
     return _node