Controller

.gitignore

@@ -5,4 +5,6 @@ rb_ws/bags
 docker-compose.yml~
 *TEMP_DO_NOT_EDIT.txt
 rb_ws/src/buggy/bags/*                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
-*.bag
+*.bag
+.vision*/*
+vision/data*/*

rb_ws/src/buggy/buggy/controller/controller_node.py

@@ -0,0 +1,161 @@
+import threading
+import sys
+
+import numpy as np
+
+import rclpy
+from rclpy.node import Node
+
+from std_msgs.msg import Float32, Float64, Bool
+from nav_msgs.msg import Odometry
+
+sys.path.append("/rb_ws/src/buggy/buggy")
+from util.trajectory import Trajectory
+from controller.stanley_controller import StanleyController
+
+class Controller(Node):
+
+    def __init__(self):
+        """
+        Constructor for Controller class.
+
+        Creates a ROS node with a publisher that periodically sends a message
+        indicating whether the node is still alive.
+
+        """
+        super().__init__('controller')
+        self.get_logger().info('INITIALIZED.')
+
+
+        #Parameters
+        self.declare_parameter("dist", 0.0) #Starting Distance along path
+        start_dist = self.get_parameter("dist").value
+
+        self.declare_parameter("traj_name", "buggycourse_safe.json")
+        traj_name = self.get_parameter("traj_name").value
+        self.cur_traj = Trajectory(json_filepath="/rb_ws/src/buggy/paths/" + traj_name) #TODO: Fixed filepath, not good
+
+        start_index = self.cur_traj.get_index_from_distance(start_dist)
+
+        self.declare_parameter("controller_name", "stanley")
+
+        controller_name = self.get_parameter("controller_name").value
+        print(controller_name.lower)
+        if (controller_name.lower() == "stanley"):
+            self.controller = StanleyController(start_index = start_index, namespace = self.get_namespace(), node=self) #IMPORT STANLEY
+        else:
+            self.get_logger().error("Invalid Controller Name: " + controller_name.lower())
+            raise Exception("Invalid Controller Argument")
+
+        # Publishers
+        self.init_check_publisher = self.create_publisher(Bool,
+            "debug/init_safety_check", 1
+        )
+        self.steer_publisher = self.create_publisher(
+            Float64, "input/steering", 1
+        )
+        self.heading_publisher = self.create_publisher(
+            Float32, "auton/debug/heading", 1
+        )
+
+        # Subscribers
+        self.odom_subscriber = self.create_subscription(Odometry, 'self/state', self.odom_listener, 1)
+        self.traj_subscriber = self.create_subscription(Odometry, 'self/cur_traj', self.traj_listener, 1)
+
+        self.lock = threading.Lock()
+
+        self.odom = None
+        self.passed_init = False
+
+        timer_period = 0.01  # seconds (100 Hz)
+        self.timer = self.create_timer(timer_period, self.loop)
+
+    def odom_listener(self, msg : Odometry):
+        '''
+        This is the subscriber that updates the buggies state for navigation
+        msg, should be a CLEAN state as defined in the wiki
+        '''
+        with self.lock:
+            self.odom = msg
+
+    def traj_listener(self, msg): #TYPE UNKOWN AS OF NOW?? CUSTOM TYPE WHEN #TODO: FIGURE OUT BEFORE MERGE
+        '''
+        This is the subscriber that updates the buggies trajectory for navigation
+        '''
+        with self.lock:
+            self.cur_traj, self.controller.current_traj_index = Trajectory.unpack(msg)
+
+    def init_check(self):
+        """
+        Checks if it's safe to switch the buggy into autonomous driving mode.
+        Specifically, it checks:
+            if we can recieve odometry messages from the buggy
+            if the covariance is acceptable (less than 1 meter)
+            if the buggy thinks it is facing in the correct direction wrt the local trajectory (not 180 degrees flipped)
+
+        Returns:
+           A boolean describing the status of the buggy (safe for auton or unsafe for auton)
+        """
+        if (self.odom == None):
+            self.get_logger().warn("WARNING: no available position estimate")
+            return False
+
+        elif (self.odom.pose.covariance[0] ** 2 + self.odom.pose.covariance[7] ** 2 > 1**2):
+            self.get_logger().warn("checking position estimate certainty")
+            return False
+
+        #Originally under a lock, doesn't seem necessary?
+        current_heading = self.odom.pose.pose.orientation.z
+        closest_heading = self.cur_traj.get_heading_by_index(self.cur_traj.get_closest_index_on_path(self.odom.pose.pose.position.x, self.odom.pose.pose.position.y))
+
+        self.get_logger().info("current heading: " + str(np.rad2deg(current_heading)))
+        msg = Float32()
+        msg.data = np.rad2deg(current_heading)
+        self.heading_publisher.publish(msg)
+
+        #Converting headings from [-pi, pi] to [0, 2pi]
+        if (current_heading < 0):
+            current_heading = 2 * np.pi + current_heading
+        if (closest_heading < 0):
+            closest_heading = 2 * np.pi + closest_heading
+
+        if (abs(current_heading - closest_heading) >= np.pi/2):
+            self.get_logger().warn("WARNING: INCORRECT HEADING! restart stack. Current heading [-180, 180]: " + str(np.rad2deg(current_heading)))
+            return False
+
+        return True
+
+    def loop(self):
+        if not self.passed_init:
+            self.passed_init = self.init_check()
+            msg = Bool()
+            msg.data = self.passed_init
+            self.init_check_publisher.publish(msg)
+            if self.passed_init:
+                self.get_logger().info("Passed Initialization Check")
+            else:
+                return
+
+        self.heading_publisher.publish(Float32(data=np.rad2deg(self.odom.pose.pose.orientation.z)))
+        steering_angle = self.controller.compute_control(self.odom, self.cur_traj)
+        steering_angle_deg = np.rad2deg(steering_angle)
+        self.steer_publisher.publish(Float64(data=float(steering_angle_deg)))
+
+
+
+def main(args=None):
+    rclpy.init(args=args)
+
+    controller = Controller()
+
+    rclpy.spin(controller)
+
+    # Destroy the node explicitly
+    # (optional - otherwise it will be done automatically
+    # when the garbage collector destroys the node object)
+    controller.destroy_node()
+    rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()

rb_ws/src/buggy/buggy/controller/controller_superclass.py

@@ -0,0 +1,49 @@
+from abc import ABC, abstractmethod
+import sys
+
+from nav_msgs.msg import Odometry
+
+
+sys.path.append("/rb_ws/src/buggy/buggy")
+from util.trajectory import Trajectory
+
+class Controller(ABC):
+    """
+    Base class for all controllers.
+
+    The controller takes in the current state of the buggy and a reference
+    trajectory. It must then compute the desired control output.
+
+    The method that it does this by is up to the implementation, of course.
+    Example schemes include Pure Pursuit, Stanley, and LQR.
+    """
+
+    # TODO: move this to a constants class
+    NAND_WHEELBASE = 1.3
+    SC_WHEELBASE = 1.104
+
+    def __init__(self, start_index: int, namespace : str, node) -> None:
+        self.namespace = namespace
+        if namespace.upper() == '/NAND':
+            Controller.WHEELBASE = self.NAND_WHEELBASE
+        else:
+            Controller.WHEELBASE = self.SC_WHEELBASE
+
+        self.current_traj_index = start_index
+        self.node = node
+
+    @abstractmethod
+    def compute_control(
+        self, state_msg: Odometry, trajectory: Trajectory,
+    ) -> float:
+        """
+        Computes the desired control output given the current state and reference trajectory
+
+        Args:
+            state: (Odometry): state of the buggy, including position, attitude and associated twists
+            trajectory (Trajectory): reference trajectory
+
+        Returns:
+            float (desired steering angle)
+        """
+        raise NotImplementedError

rb_ws/src/buggy/buggy/controller/stanley_controller.py

@@ -0,0 +1,150 @@
+import sys
+import numpy as np
+
+from sensor_msgs.msg import NavSatFix
+from geometry_msgs.msg import Pose as ROSPose
+from nav_msgs.msg import Odometry
+
+sys.path.append("/rb_ws/src/buggy/buggy")
+from util.trajectory import Trajectory
+from controller.controller_superclass import Controller
+from util.pose import Pose
+
+import utm
+
+
+class StanleyController(Controller):
+    """
+    Stanley Controller (front axle used as reference point)
+    Referenced from this paper: https://ai.stanford.edu/~gabeh/papers/hoffmann_stanley_control07.pdf
+    """
+
+    LOOK_AHEAD_DIST_CONST = 0.05 # s
+    MIN_LOOK_AHEAD_DIST = 0.1 #m
+    MAX_LOOK_AHEAD_DIST = 2.0 #m
+
+    CROSS_TRACK_GAIN = 1.3
+    K_SOFT = 1.0 # m/s
+    K_D_YAW = 0.012 # rad / (rad/s)
+
+    def __init__(self, start_index, namespace, node):
+        super(StanleyController, self).__init__(start_index, namespace, node)
+        self.debug_reference_pos_publisher = self.node.create_publisher(
+            NavSatFix, "auton/debug/reference_navsat", 1
+        )
+        self.debug_error_publisher = self.node.create_publisher(
+            ROSPose, "auton/debug/error", 1
+        )
+
+    def compute_control(self, state_msg : Odometry, trajectory : Trajectory):
+        """Computes the steering angle determined by Stanley controller.
+        Does this by looking at the crosstrack error + heading error
+
+        Args:
+            state_msg: ros Odometry message
+            trajectory (Trajectory): reference trajectory
+
+        Returns:
+            float (desired steering angle)
+        """
+        if self.current_traj_index >= trajectory.get_num_points() - 1:
+            self.node.get_logger.error("[Stanley]: Ran out of path to follow!")
+            raise Exception("[Stanley]: Ran out of path to follow!")
+
+        current_rospose = state_msg.pose.pose
+        current_speed = np.sqrt(
+            state_msg.twist.twist.linear.x**2 + state_msg.twist.twist.linear.y**2
+        )
+        yaw_rate = state_msg.twist.twist.angular.z
+        heading = current_rospose.orientation.z
+        x, y = current_rospose.position.x, current_rospose.position.y #(Easting, Northing)
+
+        front_x = x + StanleyController.WHEELBASE * np.cos(heading)
+        front_y = y + StanleyController.WHEELBASE * np.sin(heading)
+
+        # setting range of indices to search so we don't have to search the entire path
+        traj_index = trajectory.get_closest_index_on_path(
+            front_x,
+            front_y,
+            start_index=self.current_traj_index - 20,
+            end_index=self.current_traj_index + 50,
+        )
+        self.current_traj_index = max(traj_index, self.current_traj_index)
+
+
+        lookahead_dist = np.clip(
+            self.LOOK_AHEAD_DIST_CONST * current_speed,
+            self.MIN_LOOK_AHEAD_DIST,
+            self.MAX_LOOK_AHEAD_DIST)
+
+        traj_dist = trajectory.get_distance_from_index(self.current_traj_index) + lookahead_dist
+
+        ref_heading = trajectory.get_heading_by_index(
+            trajectory.get_index_from_distance(traj_dist))
+
+        error_heading = ref_heading - heading
+        error_heading = np.arctan2(np.sin(error_heading), np.cos(error_heading)) #Bounds error_heading
+
+        # Calculate cross track error by finding the distance from the buggy to the tangent line of
+        # the reference trajectory
+        closest_position = trajectory.get_position_by_index(self.current_traj_index)
+        next_position = trajectory.get_position_by_index(
+            self.current_traj_index + 0.0001
+        )
+        x1 = closest_position[0]
+        y1 = closest_position[1]
+        x2 = next_position[0]
+        y2 = next_position[1]
+        error_dist = -((x - x1) * (y2 - y1) - (y - y1) * (x2 - x1)) / np.sqrt(
+            (y2 - y1) ** 2 + (x2 - x1) ** 2
+        )
+
+
+        cross_track_component = -np.arctan2(
+            StanleyController.CROSS_TRACK_GAIN * error_dist, current_speed + StanleyController.K_SOFT
+        )
+
+        # Calculate yaw rate error
+        r_meas = yaw_rate
+        r_traj = current_speed * (trajectory.get_heading_by_index(trajectory.get_index_from_distance(traj_dist) + 0.05)
+        - trajectory.get_heading_by_index(trajectory.get_index_from_distance(traj_dist))) / 0.05
+
+        #Determine steering_command
+        steering_cmd = error_heading + cross_track_component + StanleyController.K_D_YAW * (r_traj - r_meas)
+        steering_cmd = np.clip(steering_cmd, -np.pi / 9, np.pi / 9)
+
+
+        #Calculate error, where x is in orientation of buggy, y is cross track error
+        current_pose = Pose(current_rospose.position.x, current_rospose.position.y, heading)
+        reference_error = current_pose.convert_point_from_global_to_local_frame(closest_position)
+        reference_error -= np.array([StanleyController.WHEELBASE, 0]) #Translae back to back wheel to get accurate error
+
+        error_pose = ROSPose()
+        error_pose.position.x = reference_error[0]
+        error_pose.position.y = reference_error[1]
+        self.debug_error_publisher.publish(error_pose)
+
+        # Publish reference position for debugging
+        try:
+            reference_navsat = NavSatFix()
+            lat, lon = utm.to_latlon(closest_position[0], closest_position[1], 17, "T")
+            reference_navsat.latitude = lat
+            reference_navsat.longitude = lon
+            self.debug_reference_pos_publisher.publish(reference_navsat)
+        except Exception as e:
+            self.node.get_logger().warn(
+                "[Stanley] Unable to convert closest track position lat lon; Error: " + str(e)
+            )
+
+        return steering_cmd
+
+
+
+
+
+
+
+
+
+
+