check_nav_state.cpp

// Copyright 2024 Robin Müller
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#include <cstdint>
#include <memory>
 
#include "auto_apms_behavior_tree_core/node.hpp"
#include "px4_msgs/msg/vehicle_status.hpp"
#include "px4_ros2/utils/message_version.hpp"
 
#define INPUT_KEY_NAV_STATE "nav_state"
 
namespace auto_apms_px4
{

class CheckNavState : public auto_apms_behavior_tree::core::RosSubscriberNode<px4_msgs::msg::VehicleStatus>
{
  std::shared_ptr<px4_msgs::msg::VehicleStatus> last_msg_;
 
public:
  CheckNavState(
    const std::string & instance_name, const BT::NodeConfig & config,
    const auto_apms_behavior_tree::core::RosNodeContext & context)
  : RosSubscriberNode{instance_name, config, context, rclcpp::SensorDataQoS{}}
  {
    // Resolve the topic's message version suffix at runtime from the message definition, rather than baking it into
    // the node manifest at configure time. Since the manifest does not fix a topic, the base class cannot resolve one
    // at construction and defers creation to this constructor.
    createSubscriber("fmu/out/vehicle_status" + px4_ros2::getMessageNameVersion<px4_msgs::msg::VehicleStatus>());
  }
 
  static BT::PortsList providedPorts()
  {
    return providedBasicPorts({
      BT::InputPort<int>(INPUT_KEY_NAV_STATE, "Expected PX4 navigation state (mode id) the vehicle should be in."),
    });
  }
 
  BT::NodeStatus onTick(const std::shared_ptr<px4_msgs::msg::VehicleStatus> & last_msg_ptr) final
  {
    if (last_msg_ptr) last_msg_ = last_msg_ptr;
 
    // No vehicle status received yet - the mode cannot be confirmed.
    if (!last_msg_) return BT::NodeStatus::FAILURE;
 
    const BT::Expected<int> expected_nav_state = getInput<int>(INPUT_KEY_NAV_STATE);
    if (!expected_nav_state) {
      RCLCPP_ERROR(
        logger_, "%s - Missing required input '%s': %s", context_.getFullyQualifiedTreeNodeName(this).c_str(),
        INPUT_KEY_NAV_STATE, expected_nav_state.error().c_str());
      return BT::NodeStatus::FAILURE;
    }
 
    return last_msg_->nav_state == static_cast<uint8_t>(expected_nav_state.value()) ? BT::NodeStatus::SUCCESS
                                                                                    : BT::NodeStatus::FAILURE;
  }
};
 
}  // namespace auto_apms_px4
 
AUTO_APMS_BEHAVIOR_TREE_REGISTER_NODE(auto_apms_px4::CheckNavState)