turtlebot3 VS turtlebot3_simulations

You could try downloading the package: https://github.com/ROBOTIS-GIT/turtlebot3/tree/humble-devel and just build / run in your iron workspace.

git clone https://github.com/ROBOTIS-GIT/turtlebot3.git -b foxy-devel

To give more context, I am using ROS2 (robot operating system) to build a small mobile robot for hobby/learning. To learn by ready other code, I am looking at a very popular ROS project called Turtlebot3.

You can copy and modify the (turtlebot3)[https://github.com/ROBOTIS-GIT/turtlebot3] repo as basis. They have different robot models for gazibo simulation and starting point for ros navigation.

- if you want to later make a more complicated robot (that uses cameras, has robotic arm etc.) you'd want to look into ROS (robot operating system). If you are in/going to university I highly recommend you join an engineering design team. For an example project you can refer to https://github.com/ROBOTIS-GIT/turtlebot3

The tutorial I was using (which comes straight from nav2) says to run ros2 launch nav2_bringup navigation_launch.py . However, when I went to tune Turtlebot3 via the .param file, it did no change whatsoever. This is because, by default, the file uses up this param file that is significantly different than burger.yaml; After changing it the costmap looks completely different. After reading the source code for the .launch file of the Turtlebot3 nav package for galactic and nav2, I've found out that running ros2 launch nav2_bringup navigation_launch.py params_file:=[PATH_TO_BURGER_YAML] works and completely fixes this issue.

If you're looking for an example of setting the local planner then the turtlebot3 (which I've seen you're using in your delivery_robot_sample package) has an example here: https://github.com/ROBOTIS-GIT/turtlebot3/blob/master/turtlebot3_navigation/launch/move_base.launch

The TurtleBot3 does all of this and has a simulation repo for Gazebo. It also works with both ROS and ROS2 with very nice official documentation on their website.

amcl: ros__parameters: use_sim_time: True alpha1: 0.2 alpha2: 0.2 alpha3: 0.2 alpha4: 0.2 alpha5: 0.2 base_frame_id: "base_footprint" beam_skip_distance: 0.5 beam_skip_error_threshold: 0.9 beam_skip_threshold: 0.3 do_beamskip: false global_frame_id: "map" lambda_short: 0.1 laser_likelihood_max_dist: 2.0 laser_max_range: 100.0 laser_min_range: -1.0 laser_model_type: "likelihood_field" max_beams: 60 max_particles: 2000 min_particles: 500 odom_frame_id: "odom" pf_err: 0.05 pf_z: 0.99 recovery_alpha_fast: 0.0 recovery_alpha_slow: 0.0 resample_interval: 1 robot_model_type: "omnidirectional" #holonomic save_pose_rate: 0.5 sigma_hit: 0.2 tf_broadcast: true transform_tolerance: 1.0 update_min_a: 0.2 update_min_d: 0.25 z_hit: 0.5 z_max: 0.05 z_rand: 0.5 z_short: 0.05 scan_topic: scan amcl_map_client: ros__parameters: use_sim_time: True amcl_rclcpp_node: ros__parameters: use_sim_time: True bt_navigator: ros__parameters: use_sim_time: True global_frame: map robot_base_frame: base_link odom_topic: /odom bt_loop_duration: 10 default_server_timeout: 20 enable_groot_monitoring: True groot_zmq_publisher_port: 1666 groot_zmq_server_port: 1667 # 'default_nav_through_poses_bt_xml' and 'default_nav_to_pose_bt_xml' are use defaults: # nav2_bt_navigator/navigate_to_pose_w_replanning_and_recovery.xml # nav2_bt_navigator/navigate_through_poses_w_replanning_and_recovery.xml # They can be set here or via a RewrittenYaml remap from a parent launch file to Nav2. plugin_lib_names: - nav2_compute_path_to_pose_action_bt_node - nav2_compute_path_through_poses_action_bt_node - nav2_follow_path_action_bt_node - nav2_back_up_action_bt_node - nav2_spin_action_bt_node - nav2_wait_action_bt_node - nav2_clear_costmap_service_bt_node - nav2_is_stuck_condition_bt_node - nav2_goal_reached_condition_bt_node - nav2_goal_updated_condition_bt_node - nav2_initial_pose_received_condition_bt_node - nav2_reinitialize_global_localization_service_bt_node - nav2_rate_controller_bt_node - nav2_distance_controller_bt_node - nav2_speed_controller_bt_node - nav2_truncate_path_action_bt_node - nav2_goal_updater_node_bt_node - nav2_recovery_node_bt_node - nav2_pipeline_sequence_bt_node - nav2_round_robin_node_bt_node - nav2_transform_available_condition_bt_node - nav2_time_expired_condition_bt_node - nav2_distance_traveled_condition_bt_node - nav2_single_trigger_bt_node - nav2_is_battery_low_condition_bt_node - nav2_navigate_through_poses_action_bt_node - nav2_navigate_to_pose_action_bt_node - nav2_remove_passed_goals_action_bt_node - nav2_planner_selector_bt_node - nav2_controller_selector_bt_node - nav2_goal_checker_selector_bt_node bt_navigator_rclcpp_node: ros__parameters: use_sim_time: True controller_server: ros__parameters: use_sim_time: True controller_frequency: 20.0 min_x_velocity_threshold: 0.001 min_y_velocity_threshold: 0.001 #holonomic min_theta_velocity_threshold: 0.001 failure_tolerance: 0.3 progress_checker_plugin: "progress_checker" goal_checker_plugins: ["general_goal_checker"] # "precise_goal_checker" controller_plugins: ["FollowPath"] # Progress checker parameters progress_checker: plugin: "nav2_controller::SimpleProgressChecker" required_movement_radius: 0.5 movement_time_allowance: 10.0 # Goal checker parameters #precise_goal_checker: # plugin: "nav2_controller::SimpleGoalChecker" # xy_goal_tolerance: 0.25 # yaw_goal_tolerance: 0.25 # stateful: True general_goal_checker: stateful: True plugin: "nav2_controller::SimpleGoalChecker" xy_goal_tolerance: 0.25 yaw_goal_tolerance: 0.25 # DWB parameters FollowPath: plugin: "dwb_core::DWBLocalPlanner" debug_trajectory_details: True min_vel_x: 0.0 min_vel_y: 0.0 max_vel_x: 0.26 max_vel_y: 0.26 #holonomic max_vel_theta: 1.0 min_speed_xy: 0.0 max_speed_xy: 0.26 min_speed_theta: 0.0 # Add high threshold velocity for turtlebot 3 issue. # https://github.com/ROBOTIS-GIT/turtlebot3_simulations/issues/75 acc_lim_x: 2.5 acc_lim_y: 2.5 #holonomic acc_lim_theta: 3.2 decel_lim_x: -2.5 decel_lim_y: -2.5 #holonomic decel_lim_theta: -3.2 vx_samples: 20 vy_samples: 20 #holonomic vtheta_samples: 20 sim_time: 1.7 linear_granularity: 0.05 angular_granularity: 0.025 transform_tolerance: 0.2 xy_goal_tolerance: 0.25 trans_stopped_velocity: 0.25 short_circuit_trajectory_evaluation: True stateful: True critics: ["RotateToGoal", "Oscillation", "BaseObstacle", "GoalAlign", "PathAlign", "PathDist", "GoalDist", "Twirling"] Twirling.scale: 0.0 BaseObstacle.scale: 0.02 PathAlign.scale: 32.0 PathAlign.forward_point_distance: 0.1 GoalAlign.scale: 24.0 GoalAlign.forward_point_distance: 0.1 PathDist.scale: 32.0 GoalDist.scale: 24.0 RotateToGoal.scale: 32.0 RotateToGoal.slowing_factor: 5.0 RotateToGoal.lookahead_time: -1.0 controller_server_rclcpp_node: ros__parameters: use_sim_time: True local_costmap: local_costmap: ros__parameters: update_frequency: 5.0 publish_frequency: 2.0 global_frame: odom robot_base_frame: base_link use_sim_time: True rolling_window: true width: 3 height: 3 resolution: 0.05 footprint: "[ [0.185, 0.157], [0.185, -0.157], [-0.185, -0.157], [-0.185, -0.157] ]" plugins: ["obstacle_layer", "inflation_layer"] inflation_layer: plugin: "nav2_costmap_2d::InflationLayer" cost_scaling_factor: 3.0 inflation_radius: 0.55 obstacle_layer: plugin: "nav2_costmap_2d::ObstacleLayer" enabled: True observation_sources: scan scan: topic: /scan max_obstacle_height: 2.0 clearing: True marking: True data_type: "LaserScan" static_layer: map_subscribe_transient_local: True always_send_full_costmap: True local_costmap_client: ros__parameters: use_sim_time: True local_costmap_rclcpp_node: ros__parameters: use_sim_time: True global_costmap: global_costmap: ros__parameters: update_frequency: 1.0 publish_frequency: 1.0 global_frame: map robot_base_frame: base_link use_sim_time: True robot_radius: 0.22 resolution: 0.05 track_unknown_space: true plugins: ["static_layer", "obstacle_layer", "inflation_layer"] obstacle_layer: plugin: "nav2_costmap_2d::ObstacleLayer" enabled: True observation_sources: scan scan: topic: /scan max_obstacle_height: 2.0 clearing: True marking: True data_type: "LaserScan" raytrace_max_range: 3.0 raytrace_min_range: 0.0 obstacle_max_range: 2.5 obstacle_min_range: 0.0 static_layer: plugin: "nav2_costmap_2d::StaticLayer" map_subscribe_transient_local: True inflation_layer: plugin: "nav2_costmap_2d::InflationLayer" cost_scaling_factor: 3.0 inflation_radius: 0.55 always_send_full_costmap: True global_costmap_client: ros__parameters: use_sim_time: True global_costmap_rclcpp_node: ros__parameters: use_sim_time: True map_server: ros__parameters: use_sim_time: True yaml_filename: "test.yaml" map_saver: ros__parameters: use_sim_time: True save_map_timeout: 5.0 free_thresh_default: 0.25 occupied_thresh_default: 0.65 map_subscribe_transient_local: True planner_server: ros__parameters: expected_planner_frequency: 20.0 use_sim_time: True planner_plugins: ["GridBased"] GridBased: plugin: "nav2_navfn_planner/NavfnPlanner" tolerance: 0.5 use_astar: false allow_unknown: true planner_server_rclcpp_node: ros__parameters: use_sim_time: True recoveries_server: ros__parameters: costmap_topic: local_costmap/costmap_raw footprint_topic: local_costmap/published_footprint cycle_frequency: 10.0 recovery_plugins: ["spin", "backup", "wait"] spin: plugin: "nav2_recoveries/Spin" backup: plugin: "nav2_recoveries/BackUp" wait: plugin: "nav2_recoveries/Wait" global_frame: odom robot_base_frame: base_link transform_timeout: 0.1 use_sim_time: true simulate_ahead_time: 2.0 max_rotational_vel: 1.0 min_rotational_vel: 0.4 rotational_acc_lim: 3.2 robot_state_publisher: ros__parameters: use_sim_time: True waypoint_follower: ros__parameters: loop_rate: 20 stop_on_failure: false waypoint_task_executor_plugin: "wait_at_waypoint" wait_at_waypoint: plugin: "nav2_waypoint_follower::WaitAtWaypoint" enabled: True waypoint_pause_duration: 200

https://github.com/ROBOTIS-GIT/turtlebot3_simulations/blob/galactic-devel/turtlebot3_gazebo/launch/spawn_turtlebot3.launch.py

I recently added this github repo as a submodule in my project repo. I cannot open the root folder of the repo in my project repo here. I looked at this answer and it says that both the name and the commit hash should appear as links but that does not seem to be the case for me. I directly cloned the submodule repo into my project, so I had to first do git rm --cached catkin_ws/src/turtlebot3_simulations/ and then execute git submodule add https://github.com/ROBOTIS-GIT/turtlebot3\_simulations/tree/noetic-devel catkin_ws/src/turtlebot3_simulations/ to add the submodule. This is my first time using submodules and I am not sure what I am doing wrong. Looking for any kind of hints on what I did wrong and what is the correct way to fix this. Thank you!

1) What exactly is a Nodehandle? Why are they only in C++ and not in Python? 2) In many C++ header files of a ROS package (for example this one), I have seen people declaring 2 NodeHandles namely, nh_ and nh_priv_. Why are there 2 NodeHandles in the same code and what does the underscore _ at the end of both the identifiers mean? Would like to know about these in more detail, resources would be amazing to get. Help is appreciated, TIA