Example 14: Check for NaN in write method

Since activation of the "hardware" takes some time, the resource manager
might try to write the initial NaN value to the hardware. This commit adds
a check to the write method for that.

example_14/hardware/rrbot_actuator_without_feedback.cpp

@@ -183,21 +183,23 @@ hardware_interface::return_type RRBotActuatorWithoutFeedback::read(
 hardware_interface::return_type ros2_control_demo_example_14::RRBotActuatorWithoutFeedback::write(
   const rclcpp::Time & /*time*/, const rclcpp::Duration & /*period*/)
 {
-  // START: This part here is for exemplary purposes - Please do not copy to your production code
-  RCLCPP_INFO(
-    rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Writing command: %f", hw_joint_command_);
-
-  // Simulate sending commands to the hardware
-  std::ostringstream data;
-  data << hw_joint_command_;
-  RCLCPP_INFO(
-    rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Sending data command: %s",
-    data.str().c_str());
-  send(sock_, data.str().c_str(), strlen(data.str().c_str()), 0);
+  if (!std::isnan(hw_joint_command_))
+  {
+    // START: This part here is for exemplary purposes - Please do not copy to your production code
+    RCLCPP_INFO(
+      rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Writing command: %f", hw_joint_command_);
 
-  RCLCPP_INFO(rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Joints successfully written!");
-  // END: This part here is for exemplary purposes - Please do not copy to your production code
+    // Simulate sending commands to the hardware
+    std::ostringstream data;
+    data << hw_joint_command_;
+    RCLCPP_INFO(
+      rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Sending data command: %s",
+      data.str().c_str());
+    send(sock_, data.str().c_str(), strlen(data.str().c_str()), 0);
 
+    RCLCPP_INFO(rclcpp::get_logger("RRBotActuatorWithoutFeedback"), "Joints successfully written!");
+    // END: This part here is for exemplary purposes - Please do not copy to your production code
+  }
   return hardware_interface::return_type::OK;
 }