YASMIN is a project focused on implementing robot behaviors using Finite State Machines (FSM). It is available for ROS 2, Python and C++.

ROS 2 Distro	Branch	Build status	Docker Image	Documentation
Foxy	`main`
Galatic	`main`
Humble	`main`
Iron	`main`
Jazzy	`main`
Rolling	`main`

Key Features

ROS 2 Integration: Integrates with ROS 2 for easy deployment and interaction.
Support for Python and C++: Available for both Python and C++, making it flexible for a variety of use cases.
Rapid Prototyping: Designed for fast prototyping, allowing quick iteration of state machine behaviors.
Predefined States: Includes states for interacting with ROS 2 action clients, service clients, and topics.
Data Sharing with Blackboards: Utilizes blackboards for data sharing between states and state machines.
State Management: Supports cancellation and stopping of state machines, including halting the current executing state.
Web Viewer: Features an integrated web viewer for real-time monitoring of state machine execution.

Installation

Debian Packages

To install YASMIN and its packages, use the following command:

sudo apt install ros-$ROS_DISTRO-yasmin ros-$ROS_DISTRO-yasmin-*

Building from Source

Follow these steps to build the source code from this repository:

cd ~/ros2_ws/src
git clone https://github.com/uleroboticsgroup/yasmin.git
cd ~/ros2_ws
rosdep install --from-paths src --ignore-src -r -y
cd ~/ros2_ws
colcon build

Note for Deprecated or Rolling ROS 2 Distros

If you are using a deprecated ROS 2 distribution (e.g., Foxy or Galactic) or the Rolling distribution, install the example interfaces:

sudo apt install -y ros-$ROS_DISTRO-example-interfaces

Docker

If your operating system doesn't support ROS 2, docker is a great alternative. You can use an image from Dockerhub or create your own images. First of all, to build the image you have to use the following command:

## Assuming you are in the YASMIN project directory

docker build -t yasmin .

To use a shortcut the docker build, you may use the following command:

## Assuming you are in the YASMIN project directory

make docker_build

After the image is created, run a docker container with the following command:

docker run -it --net=host --ipc=host --privileged --env="DISPLAY" --env="QT_X11_NO_MITSHM=1" --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw" --volume="${XAUTHORITY}:/root/.Xauthority" --entrypoint /bin/bash yasmin

To use a shortcut the docker run, you may use following command:

## Assuming you are in the YASMIN project directory

make docker_run

Demos

There are some examples, for both Python and C++, that can be found in yasmin_demos.

Python

Vanilla Demo (FSM)

ros2 run yasmin_demos yasmin_demo.py

Click to expand

import time
import rclpy
 
import yasmin
from yasmin import State
from yasmin import Blackboard
from yasmin import StateMachine
from yasmin_ros.ros_logs import set_ros_loggers
from yasmin_viewer import YasminViewerPub
 
 
# Define the FooState class, inheriting from the State class
class FooState(State):
    """
    Represents the Foo state in the state machine.
 
    Attributes:
        counter (int): Counter to track the number of executions of this state.
    """
 
    def __init__(self) -> None:
        """
        Initializes the FooState instance, setting up the outcomes.
 
        Outcomes:
            outcome1: Indicates the state should continue to the Bar state.
            outcome2: Indicates the state should finish execution and return.
        """
        super().__init__(["outcome1", "outcome2"])
        self.counter = 0
 
    def execute(self, blackboard: Blackboard) -> str:
        """
        Executes the logic for the Foo state.
 
        Args:
            blackboard (Blackboard): The shared data structure for states.
 
        Returns:
            str: The outcome of the execution, which can be "outcome1" or "outcome2".
 
        Raises:
            Exception: May raise exceptions related to state execution.
        """
        yasmin.YASMIN_LOG_INFO("Executing state FOO")
        time.sleep(3)  # Simulate work by sleeping
 
        if self.counter < 3:
            self.counter += 1
            blackboard["foo_str"] = f"Counter: {self.counter}"
            return "outcome1"
        else:
            return "outcome2"
 
 
# Define the BarState class, inheriting from the State class
class BarState(State):
    """
    Represents the Bar state in the state machine.
    """
 
    def __init__(self) -> None:
        """
        Initializes the BarState instance, setting up the outcome.
 
        Outcomes:
            outcome3: Indicates the state should transition back to the Foo state.
        """
        super().__init__(outcomes=["outcome3"])
 
    def execute(self, blackboard: Blackboard) -> str:
        """
        Executes the logic for the Bar state.
 
        Args:
            blackboard (Blackboard): The shared data structure for states.
 
        Returns:
            str: The outcome of the execution, which will always be "outcome3".
 
        Raises:
            Exception: May raise exceptions related to state execution.
        """
        yasmin.YASMIN_LOG_INFO("Executing state BAR")
        time.sleep(3)  # Simulate work by sleeping
 
        yasmin.YASMIN_LOG_INFO(blackboard["foo_str"])
        return "outcome3"
 
 
# Main function to initialize and run the state machine
def main():
    """
    The main entry point of the application.
 
    Initializes the ROS 2 environment, sets up the state machine,
    and handles execution and termination.
 
    Raises:
        KeyboardInterrupt: If the execution is interrupted by the user.
    """
    yasmin.YASMIN_LOG_INFO("yasmin_demo")
 
    # Initialize ROS 2
    rclpy.init()
 
    # Set ROS 2 loggers
    set_ros_loggers()
 
    # Create a finite state machine (FSM)
    sm = StateMachine(outcomes=["outcome4"])
 
    # Add states to the FSM
    sm.add_state(
        "FOO",
        FooState(),
        transitions={
            "outcome1": "BAR",
            "outcome2": "outcome4",
        },
    )
    sm.add_state(
        "BAR",
        BarState(),
        transitions={
            "outcome3": "FOO",
        },
    )
 
    # Publish FSM information for visualization
    YasminViewerPub("yasmin_demo", sm)
 
    # Execute the FSM
    try:
        outcome = sm()
        yasmin.YASMIN_LOG_INFO(outcome)
    except KeyboardInterrupt:
        if sm.is_running():
            sm.cancel_state()
 
    # Shutdown ROS 2 if it's running
    if rclpy.ok():
        rclpy.shutdown()
 
 
if __name__ == "__main__":
    main()

Service Demo (FSM + ROS 2 Service Client)

ros2 run yasmin_demos add_two_ints_server

ros2 run yasmin_demos service_client_demo.py

Click to expand

import rclpy
from example_interfaces.srv import AddTwoInts
 
import yasmin
from yasmin import CbState
from yasmin import Blackboard
from yasmin import StateMachine
from yasmin_ros import ServiceState
from yasmin_ros.ros_logs import set_ros_loggers
from yasmin_ros.basic_outcomes import SUCCEED, ABORT
from yasmin_viewer import YasminViewerPub
 
 
class AddTwoIntsState(ServiceState):
    """
    A state that calls the AddTwoInts service to add two integers.
 
    This class is a state in a finite state machine that sends a request
    to the AddTwoInts service, retrieves the response, and updates the
    blackboard with the result.
 
    Attributes:
        service_type (type): The service type being used (AddTwoInts).
        service_name (str): The name of the service.
        outcomes (list): The list of possible outcomes for this state.
    """
 
    def __init__(self) -> None:
        """
        Initializes the AddTwoIntsState.
 
        Calls the parent constructor with the specific service type,
        service name, request handler, outcomes, and response handler.
        """
        super().__init__(
            AddTwoInts,  # srv type
            "/add_two_ints",  # service name
            self.create_request_handler,  # cb to create the request
            ["outcome1"],  # outcomes. Includes (SUCCEED, ABORT)
            self.response_handler,  # cb to process the response
        )
 
    def create_request_handler(self, blackboard: Blackboard) -> AddTwoInts.Request:
        """
        Creates the service request from the blackboard data.
 
        Args:
            blackboard (Blackboard): The blackboard containing the input values.
 
        Returns:
            AddTwoInts.Request: The request object populated with values from the blackboard.
        """
        req = AddTwoInts.Request()
        req.a = blackboard["a"]
        req.b = blackboard["b"]
        return req
 
    def response_handler(
        self, blackboard: Blackboard, response: AddTwoInts.Response
    ) -> str:
        """
        Processes the response from the AddTwoInts service.
 
        Updates the blackboard with the sum result from the response.
 
        Args:
            blackboard (Blackboard): The blackboard to update with the sum.
            response (AddTwoInts.Response): The response from the service call.
 
        Returns:
            str: The outcome of the operation, which is "outcome1".
        """
        blackboard["sum"] = response.sum
        return "outcome1"
 
 
def set_ints(blackboard: Blackboard) -> str:
    """
    Sets the integer values in the blackboard.
 
    This function initializes the blackboard with two integer values to be added.
 
    Args:
        blackboard (Blackboard): The blackboard to update with integer values.
 
    Returns:
        str: The outcome of the operation, which is SUCCEED.
    """
    blackboard["a"] = 10
    blackboard["b"] = 5
    return SUCCEED
 
 
def print_sum(blackboard: Blackboard) -> str:
    """
    Logs the sum value from the blackboard.
 
    This function retrieves the sum from the blackboard and logs it.
 
    Args:
        blackboard (Blackboard): The blackboard from which to retrieve the sum.
 
    Returns:
        str: The outcome of the operation, which is SUCCEED.
    """
    yasmin.YASMIN_LOG_INFO(f"Sum: {blackboard['sum']}")
    return SUCCEED
 
 
def main():
    """
    The main function to execute the finite state machine (FSM).
 
    This function initializes the ROS 2 environment, sets up logging,
    creates the FSM with defined states, and executes the FSM.
 
    Raises:
        KeyboardInterrupt: If the user interrupts the program.
    """
    yasmin.YASMIN_LOG_INFO("yasmin_service_client_demo")
 
    # Init ROS 2
    rclpy.init()
 
    # Set ROS 2 logs
    set_ros_loggers()
 
    # Create a FSM
    sm = StateMachine(outcomes=["outcome4"])
 
    # Add states
    sm.add_state(
        "SETTING_INTS",
        CbState([SUCCEED], set_ints),
        transitions={SUCCEED: "ADD_TWO_INTS"},
    )
    sm.add_state(
        "ADD_TWO_INTS",
        AddTwoIntsState(),
        transitions={
            "outcome1": "PRINTING_SUM",
            SUCCEED: "outcome4",
            ABORT: "outcome4",
        },
    )
    sm.add_state(
        "PRINTING_SUM",
        CbState([SUCCEED], print_sum),
        transitions={
            SUCCEED: "outcome4",
        },
    )
 
    # Publish FSM info
    YasminViewerPub("YASMIN_SERVICE_CLIENT_DEMO", sm)
 
    # Execute FSM
    try:
        outcome = sm()
        yasmin.YASMIN_LOG_INFO(outcome)
    except KeyboardInterrupt:
        if sm.is_running():
            sm.cancel_state()
 
    # Shutdown ROS 2
    if rclpy.ok():
        rclpy.shutdown()
 
 
if __name__ == "__main__":
    main()

Action Demo (FSM + ROS 2 Action)

ros2 run yasmin_demos fibonacci_action_server

ros2 run yasmin_demos action_client_demo.py

Click to expand

import rclpy
from example_interfaces.action import Fibonacci
 
import yasmin
from yasmin import CbState, Blackboard, StateMachine
from yasmin_ros import ActionState
from yasmin_ros.ros_logs import set_ros_loggers
from yasmin_ros.basic_outcomes import SUCCEED, ABORT, CANCEL
from yasmin_viewer import YasminViewerPub
 
 
class FibonacciState(ActionState):
    """
    Class representing the state of the Fibonacci action.
 
    Inherits from ActionState and implements methods to handle the
    Fibonacci action in a finite state machine.
 
    Attributes:
        None
    """
 
    def __init__(self) -> None:
        """
        Initializes the FibonacciState.
 
        Sets up the action type and the action name for the Fibonacci
        action. Initializes goal, response handler, and feedback
        processing callbacks.
 
        Parameters:
            None
 
        Returns:
            None
        """
        super().__init__(
            Fibonacci,  # action type
            "/fibonacci",  # action name
            self.create_goal_handler,  # callback to create the goal
            None,  # outcomes. Includes (SUCCEED, ABORT, CANCEL)
            self.response_handler,  # callback to process the response
            self.print_feedback,  # callback to process the feedback
        )
 
    def create_goal_handler(self, blackboard: Blackboard) -> Fibonacci.Goal:
        """
        Creates the goal for the Fibonacci action.
 
        This method retrieves the input value from the blackboard and
        populates the Fibonacci goal.
 
        Parameters:
            blackboard (Blackboard): The blackboard containing the state
            information.
 
        Returns:
            Fibonacci.Goal: The populated goal object for the Fibonacci action.
 
        Raises:
            KeyError: If the expected key is not present in the blackboard.
        """
        goal = Fibonacci.Goal()
        goal.order = blackboard["n"]  # Retrieve the input value 'n' from the blackboard
        return goal
 
    def response_handler(self, blackboard: Blackboard, response: Fibonacci.Result) -> str:
        """
        Handles the response from the Fibonacci action.
 
        This method processes the result of the Fibonacci action and
        stores it in the blackboard.
 
        Parameters:
            blackboard (Blackboard): The blackboard to store the result.
            response (Fibonacci.Result): The result object from the Fibonacci action.
 
        Returns:
            str: Outcome of the operation, typically SUCCEED.
 
        Raises:
            None
        """
        blackboard["fibo_res"] = (
            response.sequence
        )  # Store the result sequence in the blackboard
        return SUCCEED
 
    def print_feedback(
        self, blackboard: Blackboard, feedback: Fibonacci.Feedback
    ) -> None:
        """
        Prints feedback from the Fibonacci action.
 
        This method logs the partial sequence received during the action.
 
        Parameters:
            blackboard (Blackboard): The blackboard (not used in this method).
            feedback (Fibonacci.Feedback): The feedback object from the Fibonacci action.
 
        Returns:
            None
 
        Raises:
            None
        """
        yasmin.YASMIN_LOG_INFO(f"Received feedback: {list(feedback.sequence)}")
 
 
def print_result(blackboard: Blackboard) -> str:
    """
    Prints the result of the Fibonacci action.
 
    This function logs the final result stored in the blackboard.
 
    Parameters:
        blackboard (Blackboard): The blackboard containing the result.
 
    Returns:
        str: Outcome of the operation, typically SUCCEED.
 
    Raises:
        None
    """
    yasmin.YASMIN_LOG_INFO(f"Result: {blackboard['fibo_res']}")
    return SUCCEED
 
 
def main():
    """
    Main function to execute the ROS 2 action client demo.
 
    This function initializes the ROS 2 client, sets up the finite state
    machine, adds the states, and starts the action processing.
 
    Parameters:
        None
 
    Returns:
        None
 
    Raises:
        KeyboardInterrupt: If the user interrupts the execution.
    """
    yasmin.YASMIN_LOG_INFO("yasmin_action_client_demo")
 
    # Initialize ROS 2
    rclpy.init()
 
    # Set up ROS 2 logs
    set_ros_loggers()
 
    # Create a finite state machine (FSM)
    sm = StateMachine(outcomes=["outcome4"])
 
    # Add states to the FSM
    sm.add_state(
        "CALLING_FIBONACCI",
        FibonacciState(),
        transitions={
            SUCCEED: "PRINTING_RESULT",
            CANCEL: "outcome4",
            ABORT: "outcome4",
        },
    )
    sm.add_state(
        "PRINTING_RESULT",
        CbState([SUCCEED], print_result),
        transitions={
            SUCCEED: "outcome4",
        },
    )
 
    # Publish FSM information
    YasminViewerPub("YASMIN_ACTION_CLIENT_DEMO", sm)
 
    # Create an initial blackboard with the input value
    blackboard = Blackboard()
    blackboard["n"] = 10  # Set the Fibonacci order to 10
 
    # Execute the FSM
    try:
        outcome = sm(blackboard)
        yasmin.YASMIN_LOG_INFO(outcome)
    except KeyboardInterrupt:
        if sm.is_running():
            sm.cancel_state()  # Cancel the state if interrupted
 
    # Shutdown ROS 2
    if rclpy.ok():
        rclpy.shutdown()
 
 
if __name__ == "__main__":
    main()

Monitor Demo (FSM + ROS 2 Subscriber)

ros2 run yasmin_demos monitor_demo.py

Click to expand

import rclpy
from rclpy.qos import qos_profile_sensor_data
from nav_msgs.msg import Odometry
 
import yasmin
from yasmin import Blackboard
from yasmin import StateMachine
from yasmin_ros import MonitorState
from yasmin_ros.ros_logs import set_ros_loggers
from yasmin_ros.basic_outcomes import TIMEOUT
from yasmin_viewer import YasminViewerPub
 
 
class PrintOdometryState(MonitorState):
    """
    MonitorState subclass to handle Odometry messages.
 
    This state monitors Odometry messages from the specified ROS topic,
    logging them and transitioning based on the number of messages received.
 
    Attributes:
        times (int): The number of messages to monitor before transitioning
                     to the next outcome.
 
    Parameters:
        times (int): The initial count of how many Odometry messages to
                     process before changing state.
 
    Methods:
        monitor_handler(blackboard: Blackboard, msg: Odometry) -> str:
            Handles incoming Odometry messages, logging the message and
            returning the appropriate outcome based on the remaining count.
    """
 
    def __init__(self, times: int) -> None:
        """
        Initializes the PrintOdometryState.
 
        Parameters:
            times (int): The number of Odometry messages to monitor before
                         transitioning to the next outcome.
        """
        super().__init__(
            Odometry,  # msg type
            "odom",  # topic name
            ["outcome1", "outcome2"],  # outcomes
            self.monitor_handler,  # monitor handler callback
            qos=qos_profile_sensor_data,  # qos for the topic subscription
            msg_queue=10,  # queue for the monitor handler callback
            timeout=10,  # timeout to wait for messages in seconds
        )
        self.times = times
 
    def monitor_handler(self, blackboard: Blackboard, msg: Odometry) -> str:
        """
        Handles incoming Odometry messages.
 
        This method is called whenever a new Odometry message is received.
        It logs the message, decrements the count of messages to process,
        and determines the next state outcome.
 
        Parameters:
            blackboard (Blackboard): The shared data storage for states.
            msg (Odometry): The incoming Odometry message.
 
        Returns:
            str: The next state outcome, either "outcome1" to continue
                 monitoring or "outcome2" to transition to the next state.
 
        Exceptions:
            None
        """
        yasmin.YASMIN_LOG_INFO(msg)
 
        self.times -= 1
 
        if self.times <= 0:
            return "outcome2"
 
        return "outcome1"
 
 
def main():
    """
    Main function to initialize and run the ROS 2 state machine.
 
    This function initializes ROS 2, sets up logging, creates a finite state
    machine (FSM), adds states to the FSM, and executes the FSM. It handles
    cleanup and shutdown of ROS 2 gracefully.
 
    Exceptions:
        KeyboardInterrupt: Caught to allow graceful cancellation of the
                          state machine during execution.
    """
    yasmin.YASMIN_LOG_INFO("yasmin_monitor_demo")
 
    # Initialize ROS 2
    rclpy.init()
 
    # Set ROS 2 logs
    set_ros_loggers()
 
    # Create a finite state machine (FSM)
    sm = StateMachine(outcomes=["outcome4"])
 
    # Add states to the FSM
    sm.add_state(
        "PRINTING_ODOM",
        PrintOdometryState(5),
        transitions={
            "outcome1": "PRINTING_ODOM",
            "outcome2": "outcome4",
            TIMEOUT: "outcome4",
        },
    )
 
    # Publish FSM information
    YasminViewerPub("YASMIN_MONITOR_DEMO", sm)
 
    # Execute FSM
    try:
        outcome = sm()
        yasmin.YASMIN_LOG_INFO(outcome)
    except KeyboardInterrupt:
        if sm.is_running():
            sm.cancel_state()
 
    # Shutdown ROS 2
    if rclpy.ok():
        rclpy.shutdown()
 
 
if __name__ == "__main__":
    main()

Nav2 Demo (Hierarchical FSM + ROS 2 Action)

ros2 run yasmin_demos nav_demo.py

Click to expand

import random
import rclpy
from geometry_msgs.msg import Pose
from nav2_msgs.action import NavigateToPose
 
import yasmin
from yasmin import CbState
from yasmin import Blackboard
from yasmin import StateMachine
from yasmin_ros import ActionState
from yasmin_ros.ros_logs import set_ros_loggers
from yasmin_ros.basic_outcomes import SUCCEED, ABORT, CANCEL
from yasmin_viewer import YasminViewerPub
 
# Constants for state outcomes
HAS_NEXT = "has_next"  
END = "end"  
 
 
class Nav2State(ActionState):
    """
    ActionState for navigating to a specified pose using ROS 2 Navigation.
 
    Attributes:
        None
 
    Methods:
        create_goal_handler(blackboard: Blackboard) -> NavigateToPose.Goal:
            Creates the navigation goal from the blackboard.
    """
 
    def __init__(self) -> None:
        """
        Initializes the Nav2State.
 
        Calls the parent constructor to set up the action with:
        - Action type: NavigateToPose
        - Action name: /navigate_to_pose
        - Callback for goal creation: create_goal_handler
        - Outcomes: None, since it will use default outcomes (SUCCEED, ABORT, CANCEL)
        """
        super().__init__(
            NavigateToPose,  # action type
            "/navigate_to_pose",  # action name
            self.create_goal_handler,  # callback to create the goal
            None,  # outcomes
            None,  # callback to process the response
        )
 
    def create_goal_handler(self, blackboard: Blackboard) -> NavigateToPose.Goal:
        """
        Creates a goal for navigation based on the current pose in the blackboard.
 
        Args:
            blackboard (Blackboard): The blackboard instance holding current state data.
 
        Returns:
            NavigateToPose.Goal: The constructed goal for the navigation action.
        """
        goal = NavigateToPose.Goal()
        goal.pose.pose = blackboard["pose"]
        goal.pose.header.frame_id = "map"  # Set the reference frame to 'map'
        return goal
 
 
def create_waypoints(blackboard: Blackboard) -> str:
    """
    Initializes waypoints in the blackboard for navigation.
 
    Args:
        blackboard (Blackboard): The blackboard instance to store waypoints.
 
    Returns:
        str: Outcome indicating success (SUCCEED).
    """
    blackboard["waypoints"] = {
        "entrance": [1.25, 6.30, -0.78, 0.67],
        "bathroom": [4.89, 1.64, 0.0, 1.0],
        "livingroom": [1.55, 4.03, -0.69, 0.72],
        "kitchen": [3.79, 6.77, 0.99, 0.12],
        "bedroom": [7.50, 4.89, 0.76, 0.65],
    }
    return SUCCEED
 
 
def take_random_waypoint(blackboard: Blackboard) -> str:
    """
    Selects a random set of waypoints from the available waypoints.
 
    Args:
        blackboard (Blackboard): The blackboard instance to store random waypoints.
 
    Returns:
        str: Outcome indicating success (SUCCEED).
    """
    blackboard["random_waypoints"] = random.sample(
        list(blackboard["waypoints"].keys()), blackboard["waypoints_num"]
    )
    return SUCCEED
 
 
def get_next_waypoint(blackboard: Blackboard) -> str:
    """
    Retrieves the next waypoint from the list of random waypoints.
 
    Updates the blackboard with the pose of the next waypoint.
 
    Args:
        blackboard (Blackboard): The blackboard instance holding current state data.
 
    Returns:
        str: Outcome indicating whether there is a next waypoint (HAS_NEXT) or if
             navigation is complete (END).
    """
    if not blackboard["random_waypoints"]:
        return END
 
    wp_name = blackboard["random_waypoints"].pop(0)  # Get the next waypoint name
    wp = blackboard["waypoints"][wp_name]  # Get the waypoint coordinates
 
    pose = Pose()
    pose.position.x = wp[0]
    pose.position.y = wp[1]
    pose.orientation.z = wp[2]
    pose.orientation.w = wp[3]
 
    blackboard["pose"] = pose  # Update blackboard with new pose
    blackboard["text"] = f"I have reached waypoint {wp_name}"
 
    return HAS_NEXT
 
 
# main function
def main() -> None:
    """
    Initializes the ROS 2 node, sets up state machines for navigation, and executes the FSM.
 
    Handles cleanup and shutdown of the ROS 2 node upon completion.
    """
    yasmin.YASMIN_LOG_INFO("yasmin_nav2_demo")
 
    # Initialize ROS 2
    rclpy.init()
 
    # Set ROS 2 loggers for debugging
    set_ros_loggers()
 
    # Create state machines
    sm = StateMachine(outcomes=[SUCCEED, ABORT, CANCEL])
    nav_sm = StateMachine(outcomes=[SUCCEED, ABORT, CANCEL])
 
    # Add states to the state machine
    sm.add_state(
        "CREATING_WAYPOINTS",
        CbState([SUCCEED], create_waypoints),
        transitions={
            SUCCEED: "TAKING_RANDOM_WAYPOINTS",
        },
    )
    sm.add_state(
        "TAKING_RANDOM_WAYPOINTS",
        CbState([SUCCEED], take_random_waypoint),
        transitions={
            SUCCEED: "NAVIGATING",
        },
    )
 
    nav_sm.add_state(
        "GETTING_NEXT_WAYPOINT",
        CbState([END, HAS_NEXT], get_next_waypoint),
        transitions={
            END: SUCCEED,
            HAS_NEXT: "NAVIGATING",
        },
    )
    nav_sm.add_state(
        "NAVIGATING",
        Nav2State(),
        transitions={
            SUCCEED: "GETTING_NEXT_WAYPOINT",
            CANCEL: CANCEL,
            ABORT: ABORT,
        },
    )
 
    sm.add_state(
        "NAVIGATING",
        nav_sm,
        transitions={
            SUCCEED: SUCCEED,
            CANCEL: CANCEL,
            ABORT: ABORT,
        },
    )
 
    # Publish FSM information for visualization
    YasminViewerPub("YASMIN_NAV_DEMO", sm)
 
    # Execute the state machine
    blackboard = Blackboard()
    blackboard["waypoints_num"] = 2  # Set the number of waypoints to navigate
 
    try:
        outcome = sm(blackboard)  # Run the state machine with the blackboard
        yasmin.YASMIN_LOG_INFO(outcome)
    except KeyboardInterrupt:
        sm.cancel_state()  # Handle manual interruption
 
    # Shutdown ROS 2
    if rclpy.ok():
        if sm.is_running():
            rclpy.shutdown()
 
 
if __name__ == "__main__":
    main()

Cpp

Vanilla Demo

ros2 run yasmin_demos yasmin_demo

Click to expand

#include <chrono>
#include <iostream>
#include <memory>
#include <string>
 
#include "rclcpp/rclcpp.hpp"
#include "yasmin/logs.hpp"
#include "yasmin/state.hpp"
#include "yasmin/state_machine.hpp"
#include "yasmin_ros/ros_logs.hpp"
#include "yasmin_viewer/yasmin_viewer_pub.hpp"
 
using namespace yasmin;
 
class FooState : public yasmin::State {
public:
  int counter;
 
  FooState() : yasmin::State({"outcome1", "outcome2"}), counter(0){};
 
  std::string
  execute(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) override {
    YASMIN_LOG_INFO("Executing state FOO");
    std::this_thread::sleep_for(std::chrono::seconds(3));
 
    if (this->counter < 3) {
      this->counter += 1;
      blackboard->set<std::string>("foo_str",
                                   "Counter: " + std::to_string(this->counter));
      return "outcome1";
 
    } else {
      return "outcome2";
    }
  };
};
 
class BarState : public yasmin::State {
public:
  BarState() : yasmin::State({"outcome3"}) {}
 
  std::string
  execute(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) override {
    YASMIN_LOG_INFO("Executing state BAR");
    std::this_thread::sleep_for(std::chrono::seconds(3));
 
    YASMIN_LOG_INFO(blackboard->get<std::string>("foo_str").c_str());
 
    return "outcome3";
  }
};
 
int main(int argc, char *argv[]) {
  YASMIN_LOG_INFO("yasmin_demo");
  rclcpp::init(argc, argv);
 
  // Set ROS 2 logs
  yasmin_ros::set_ros_loggers();
 
  // Create a state machine
  auto sm = std::make_shared<yasmin::StateMachine>(
      std::initializer_list<std::string>{"outcome4"});
 
  // Cancel state machine on ROS 2 shutdown
  rclcpp::on_shutdown([sm]() {
    if (sm->is_running()) {
      sm->cancel_state();
    }
  });
 
  // Add states to the state machine
  sm->add_state("FOO", std::make_shared<FooState>(),
                {
                    {"outcome1", "BAR"},
                    {"outcome2", "outcome4"},
                });
  sm->add_state("BAR", std::make_shared<BarState>(),
                {
                    {"outcome3", "FOO"},
                });
 
  // Publish state machine updates
  yasmin_viewer::YasminViewerPub yasmin_pub("yasmin_demo", sm);
 
  // Execute the state machine
  try {
    std::string outcome = (*sm.get())();
    YASMIN_LOG_INFO(outcome.c_str());
  } catch (const std::exception &e) {
    YASMIN_LOG_WARN(e.what());
  }
 
  rclcpp::shutdown();
 
  return 0;
}

Service Demo (FSM + ROS 2 Service Client)

ros2 run yasmin_demos add_two_ints_server

ros2 run yasmin_demos service_client_demo

Click to expand

#include <iostream>
#include <memory>
#include <string>
 
#include "example_interfaces/srv/add_two_ints.hpp"
#include "rclcpp/rclcpp.hpp"
 
#include "yasmin/cb_state.hpp"
#include "yasmin/logs.hpp"
#include "yasmin/state_machine.hpp"
#include "yasmin_ros/basic_outcomes.hpp"
#include "yasmin_ros/ros_logs.hpp"
#include "yasmin_ros/service_state.hpp"
#include "yasmin_viewer/yasmin_viewer_pub.hpp"
 
using std::placeholders::_1;
using std::placeholders::_2;
using namespace yasmin;
 
std::string
set_ints(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) {
  blackboard->set<int>("a", 10);
  blackboard->set<int>("b", 5);
  return yasmin_ros::basic_outcomes::SUCCEED;
}
 
std::string
print_sum(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) {
  fprintf(stderr, "Sum: %d\n", blackboard->get<int>("sum"));
  return yasmin_ros::basic_outcomes::SUCCEED;
}
 
class AddTwoIntsState
    : public yasmin_ros::ServiceState<example_interfaces::srv::AddTwoInts> {
public:
  AddTwoIntsState()
      : yasmin_ros::ServiceState<example_interfaces::srv::AddTwoInts>(
            "/add_two_ints",
            std::bind(&AddTwoIntsState::create_request_handler, this, _1),
            {"outcome1"},
            std::bind(&AddTwoIntsState::response_handler, this, _1, _2)){};
 
  example_interfaces::srv::AddTwoInts::Request::SharedPtr
  create_request_handler(
      std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) {
 
    auto request =
        std::make_shared<example_interfaces::srv::AddTwoInts::Request>();
    request->a = blackboard->get<int>("a");
    request->b = blackboard->get<int>("b");
    return request;
  };
 
  std::string response_handler(
      std::shared_ptr<yasmin::blackboard::Blackboard> blackboard,
      example_interfaces::srv::AddTwoInts::Response::SharedPtr response) {
 
    blackboard->set<int>("sum", response->sum);
    return "outcome1";
  };
};
 
int main(int argc, char *argv[]) {
  YASMIN_LOG_INFO("yasmin_service_client_demo");
  rclcpp::init(argc, argv);
 
  // Set up ROS 2 logging.
  yasmin_ros::set_ros_loggers();
 
  // Create a state machine with a specified outcome.
  auto sm = std::make_shared<yasmin::StateMachine>(
      std::initializer_list<std::string>{"outcome4"});
 
  // Cancel the state machine on ROS 2 shutdown.
  rclcpp::on_shutdown([sm]() {
    if (sm->is_running()) {
      sm->cancel_state();
    }
  });
 
  // Add states to the state machine.
  sm->add_state("SETTING_INTS",
                std::make_shared<yasmin::CbState>(
                    std::initializer_list<std::string>{
                        yasmin_ros::basic_outcomes::SUCCEED},
                    set_ints),
                {
                    {yasmin_ros::basic_outcomes::SUCCEED, "ADD_TWO_INTS"},
                });
  sm->add_state("ADD_TWO_INTS", std::make_shared<AddTwoIntsState>(),
                {
                    {"outcome1", "PRINTING_SUM"},
                    {yasmin_ros::basic_outcomes::SUCCEED, "outcome4"},
                    {yasmin_ros::basic_outcomes::ABORT, "outcome4"},
                });
  sm->add_state("PRINTING_SUM",
                std::make_shared<yasmin::CbState>(
                    std::initializer_list<std::string>{
                        yasmin_ros::basic_outcomes::SUCCEED},
                    print_sum),
                {
                    {yasmin_ros::basic_outcomes::SUCCEED, "outcome4"},
                });
 
  // Publish state machine visualization.
  yasmin_viewer::YasminViewerPub yasmin_pub("YASMIN_ACTION_CLIENT_DEMO", sm);
 
  // Execute the state machine.
  try {
    std::string outcome = (*sm.get())();
    YASMIN_LOG_INFO(outcome.c_str());
  } catch (const std::exception &e) {
    YASMIN_LOG_WARN(e.what());
  }
 
  rclcpp::shutdown();
 
  return 0;
}

Action Demo (FSM + ROS 2 Action)

ros2 run yasmin_demos fibonacci_action_server

ros2 run yasmin_demos action_client_demo

Click to expand

#include <iostream>
#include <memory>
#include <string>
 
#include "example_interfaces/action/fibonacci.hpp"
 
#include "yasmin/cb_state.hpp"
#include "yasmin/logs.hpp"
#include "yasmin/state_machine.hpp"
#include "yasmin_ros/action_state.hpp"
#include "yasmin_ros/basic_outcomes.hpp"
#include "yasmin_ros/ros_logs.hpp"
#include "yasmin_ros/yasmin_node.hpp"
#include "yasmin_viewer/yasmin_viewer_pub.hpp"
 
using std::placeholders::_1;
using std::placeholders::_2;
using Fibonacci = example_interfaces::action::Fibonacci;
using namespace yasmin;
 
std::string
print_result(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) {
 
  auto fibo_res = blackboard->get<std::vector<int>>("sum");
 
  fprintf(stderr, "Result received:");
 
  for (auto ele : fibo_res) {
    fprintf(stderr, " %d,", ele);
  }
 
  fprintf(stderr, "\n");
 
  return yasmin_ros::basic_outcomes::SUCCEED;
}
 
class FibonacciState : public yasmin_ros::ActionState<Fibonacci> {
 
public:
  FibonacciState()
      : yasmin_ros::ActionState<Fibonacci>(
            "/fibonacci",
            std::bind(&FibonacciState::create_goal_handler, this, _1),
            std::bind(&FibonacciState::response_handler, this, _1, _2),
            std::bind(&FibonacciState::print_feedback, this, _1, _2)){};
 
  Fibonacci::Goal create_goal_handler(
      std::shared_ptr<yasmin::blackboard::Blackboard> blackboard) {
 
    auto goal = Fibonacci::Goal();
    goal.order = blackboard->get<int>("n");
    return goal;
  };
 
  std::string
  response_handler(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard,
                   Fibonacci::Result::SharedPtr response) {
 
    blackboard->set<std::vector<int>>("sum", response->sequence);
    return yasmin_ros::basic_outcomes::SUCCEED;
  };
 
  void
  print_feedback(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard,
                 std::shared_ptr<const Fibonacci::Feedback> feedback) {
    (void)blackboard;
 
    std::stringstream ss;
    ss << "Next number in sequence received: ";
    for (auto number : feedback->sequence) {
      ss << number << " ";
    }
 
    fprintf(stderr, "%s\n", ss.str().c_str());
  };
};
 
int main(int argc, char *argv[]) {
 
  YASMIN_LOG_INFO("yasmin_action_client_demo");
  rclcpp::init(argc, argv);
 
  // Set ROS 2 logging
  yasmin_ros::set_ros_loggers();
 
  // Create the state machine
  auto sm = std::make_shared<yasmin::StateMachine>(
      std::initializer_list<std::string>{"outcome4"});
 
  // Cancel state machine on ROS 2 shutdown
  rclcpp::on_shutdown([sm]() {
    if (sm->is_running()) {
      sm->cancel_state();
    }
  });
 
  // Add states to the state machine
  sm->add_state("CALLING_FIBONACCI", std::make_shared<FibonacciState>(),
                {
                    {yasmin_ros::basic_outcomes::SUCCEED, "PRINTING_RESULT"},
                    {yasmin_ros::basic_outcomes::CANCEL, "outcome4"},
                    {yasmin_ros::basic_outcomes::ABORT, "outcome4"},
                });
  sm->add_state("PRINTING_RESULT",
                std::make_shared<yasmin::CbState>(
                    std::initializer_list<std::string>{
                        yasmin_ros::basic_outcomes::SUCCEED},
                    print_result),
                {
                    {yasmin_ros::basic_outcomes::SUCCEED, "outcome4"},
                });
 
  // Publisher for visualizing the state machine
  yasmin_viewer::YasminViewerPub yasmin_pub("YASMIN_ACTION_CLIENT_DEMO", sm);
 
  // Create an initial blackboard and set the Fibonacci order
  std::shared_ptr<yasmin::blackboard::Blackboard> blackboard =
      std::make_shared<yasmin::blackboard::Blackboard>();
  blackboard->set<int>("n", 10);
 
  // Execute the state machine
  try {
    std::string outcome = (*sm.get())(blackboard);
    YASMIN_LOG_INFO(outcome.c_str());
  } catch (const std::exception &e) {
    YASMIN_LOG_WARN(e.what());
  }
 
  rclcpp::shutdown();
 
  return 0;
}

Monitor Demo (FSM + ROS 2 Subscriber)

ros2 run yasmin_demos monitor_demo

Click to expand

#include <iostream>
#include <memory>
#include <string>
 
#include "nav_msgs/msg/odometry.hpp"
#include "rclcpp/rclcpp.hpp"
 
#include "yasmin/logs.hpp"
#include "yasmin/state_machine.hpp"
#include "yasmin_ros/basic_outcomes.hpp"
#include "yasmin_ros/monitor_state.hpp"
#include "yasmin_ros/ros_logs.hpp"
#include "yasmin_viewer/yasmin_viewer_pub.hpp"
 
using std::placeholders::_1;
using std::placeholders::_2;
using namespace yasmin;
 
class PrintOdometryState
    : public yasmin_ros::MonitorState<nav_msgs::msg::Odometry> {
 
public:
  int times;
 
  PrintOdometryState(int times)
      : yasmin_ros::MonitorState<nav_msgs::msg::Odometry>(
            "odom",                   // topic name
            {"outcome1", "outcome2"}, // possible outcomes
            std::bind(&PrintOdometryState::monitor_handler, this, _1,
                      _2), // monitor handler callback
            10,            // QoS for the topic subscription
            10,            // queue size for the callback
            10             // timeout for receiving messages
        ) {
    this->times = times;
  };
 
  std::string
  monitor_handler(std::shared_ptr<yasmin::blackboard::Blackboard> blackboard,
                  std::shared_ptr<nav_msgs::msg::Odometry> msg) {
 
    (void)blackboard; // blackboard is not used in this implementation
 
    YASMIN_LOG_INFO("x: %f", msg->pose.pose.position.x);
    YASMIN_LOG_INFO("y: %f", msg->pose.pose.position.y);
    YASMIN_LOG_INFO("z: %f", msg->pose.pose.position.z);
 
    this->times--;
 
    // Transition based on remaining times
    if (this->times <= 0) {
      return "outcome2";
    }
 
    return "outcome1";
  };
};
 
int main(int argc, char *argv[]) {
 
  YASMIN_LOG_INFO("yasmin_monitor_demo");
  rclcpp::init(argc, argv);
 
  // Set up ROS 2 loggers
  yasmin_ros::set_ros_loggers();
 
  // Create a state machine with a final outcome
  auto sm = std::make_shared<yasmin::StateMachine>(
      std::initializer_list<std::string>{"outcome4"});
 
  // Cancel state machine on ROS 2 shutdown
  rclcpp::on_shutdown([sm]() {
    if (sm->is_running()) {
      sm->cancel_state();
    }
  });
 
  // Add states to the state machine
  sm->add_state(
      "PRINTING_ODOM", std::make_shared<PrintOdometryState>(5),
      {
          {"outcome1",
           "PRINTING_ODOM"},        // Transition back to itself on outcome1
          {"outcome2", "outcome4"}, // Transition to outcome4 on outcome2
          {yasmin_ros::basic_outcomes::TIMEOUT,
           "outcome4"}, // Timeout transition
      });
 
  // Publisher for visualizing the state machine's status
  yasmin_viewer::YasminViewerPub yasmin_pub("YASMIN_MONITOR_DEMO", sm);
 
  // Execute the state machine
  try {
    std::string outcome = (*sm.get())();
    YASMIN_LOG_INFO(outcome.c_str());
  } catch (const std::exception &e) {
    YASMIN_LOG_WARN(e.what());
  }
 
  rclcpp::shutdown();
 
  return 0;
}

YASMIN Viewer

The YASMIN Viewer provides a convenient way to monitor YASMIN's Finite State Machines (FSM). It is built using Flask and ReactJS and includes a filter to focus on a single FSM at a time.

Getting Started

ros2 run yasmin_viewer yasmin_viewer_node

Once started, open http://localhost:5000/ in your browser to view your state machines.

Custom host and port

You can specify a custom host and port by using the following command:

ros2 run yasmin_viewer yasmin_viewer_node --ros-args -p host:=127.0.0.1 -p port:=5032

After running the command, access your state machines at http://127.0.0.1:5032/.

Citations

@InProceedings{10.1007/978-3-031-21062-4_43,
author="Gonz{\'a}lez-Santamarta, Miguel {\'A}.
and Rodr{\'i}guez-Lera, Francisco J.
and Matell{\'a}n-Olivera, Vicente
and Fern{\'a}ndez-Llamas, Camino",
editor="Tardioli, Danilo
and Matell{\'a}n, Vicente
and Heredia, Guillermo
and Silva, Manuel F.
and Marques, Lino",
title="YASMIN: Yet Another State MachINe",
booktitle="ROBOT2022: Fifth Iberian Robotics Conference",
year="2023",
publisher="Springer International Publishing",
address="Cham",
pages="528--539",
abstract="State machines are a common mechanism for defining behaviors in robots where each behavior is based on identifiable stages. There are several libraries available for easing the implementation of state machines in ROS 1, however, the community was focused on SMACH or SMACC. Although these tools are still predominant, there are fewer alternatives for ROS 2. Besides, Behavior Trees are spreading fast, but there is a niche for using State Machines. Here, YASMIN is presented as yet another library specifically designed for ROS 2 for easing the design of robotic behaviors using state machines. It is available in C++ and Python, and provides some default states to speed up the development, in addition to a web viewer for monitoring the execution of the system and helping in the debugging.",
isbn="978-3-031-21062-4"
}

@misc{yasmin,
  doi = {10.48550/ARXIV.2205.13284},
  url = {https://arxiv.org/abs/2205.13284},
  author = {González-Santamarta, Miguel Ángel and Rodríguez-Lera, Francisco Javier and Llamas, Camino Fernández and Rico, Francisco Martín and Olivera, Vicente Matellán},
  keywords = {Robotics (cs.RO), FOS: Computer and information sciences, FOS: Computer and information sciences},
  title = {YASMIN: Yet Another State MachINe library for ROS 2},
  publisher = {arXiv},
  year = {2022},
  copyright = {Creative Commons Attribution Non Commercial No Derivatives 4.0 International}
}

Table of Contents

Key Features

Installation

Debian Packages

Building from Source

Note for Deprecated or Rolling ROS 2 Distros

Docker

Demos

Python

Vanilla Demo (FSM)

Service Demo (FSM + ROS 2 Service Client)

Action Demo (FSM + ROS 2 Action)

Monitor Demo (FSM + ROS 2 Subscriber)

Nav2 Demo (Hierarchical FSM + ROS 2 Action)

Cpp

Vanilla Demo

Service Demo (FSM + ROS 2 Service Client)

Action Demo (FSM + ROS 2 Action)

Monitor Demo (FSM + ROS 2 Subscriber)

YASMIN Viewer

Getting Started

Custom host and port

Citations