fix: add check for external_emergency_stop_heartbeat_received_time to isDataReady

control/vehicle_cmd_gate/README.md

@@ -66,4 +66,6 @@
 
 ## Assumptions / Known limits
 
-TBD.
+The parameter `use_external_emergency_stop` (true by default) enables an emergency stop request from external modules.
+This feature requires a `~/input/external_emergency_stop_heartbeat` topic for health monitoring of the external module, and the vehicle_cmd_gate module will not start without the topic.
+The `use_external_emergency_stop` parameter must be false when the "external emergency stop" function is not used.

control/vehicle_cmd_gate/src/vehicle_cmd_gate.cpp

@@ -224,6 +224,13 @@ bool VehicleCmdGate::isDataReady()
     }
   }
 
+  if (use_external_emergency_stop_) {
+    if (!external_emergency_stop_heartbeat_received_time_) {
+      RCLCPP_WARN(get_logger(), "external_emergency_stop_heartbeat_received_time_ is false");
+      return false;
+    }
+  }
+
   return true;
 }