From 3b552ed6531af74ae768300f5bbd4783a52d4229 Mon Sep 17 00:00:00 2001
From: mkostin <maxinkost@gmail.com>
Date: Mon, 25 Nov 2024 22:10:38 +0300
Subject: [PATCH] Create node

---
 lesson_06/step_1.py | 59 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 lesson_06/step_1.py

diff --git a/lesson_06/step_1.py b/lesson_06/step_1.py
new file mode 100644
index 0000000..dfc4094
--- /dev/null
+++ b/lesson_06/step_1.py
@@ -0,0 +1,59 @@
+import rclpy
+from rclpy.node import Node
+
+from geometry_msgs.msg import Twist
+from geometry_msgs.msg import PoseStamped, Pose
+
+from tf_transformations import euler_from_quaternion
+
+import math                                                                    
+
+def angle_diff(a1, a2):
+    a = a1-a2
+    return (a+math.pi)%(2*math.pi)-math.pi
+
+def get_yaw_from_quaternion(q):
+    return euler_from_quaternion([q.x, q.y, q.z, q.w])[2]
+
+class RurMover(Node):
+    def __init__(self):
+        super().__init__('controller')
+        self.publisher_twist = self.create_publisher(Twist, '/waterstrider/twist_command', 10)
+        self.pose_subscriber = self.create_subscription(PoseStamped, '/waterstrider/ground_truth_to_tf_waterstrider/pose', self.pose_callback, 10)
+        self.desired_heading = - math.pi / 2
+        self.SIDE_TIME = 10.0
+        self.LINEAR_SPEED = 1.0
+        self.timer = self.create_timer(self.SIDE_TIME, self.pub_timer_callback)
+
+    def pose_callback(self, msg):
+        heading = get_yaw_from_quaternion(msg.pose.orientation)
+        self.get_logger().info('Current heading: "%f"' % heading)
+        self.get_logger().info('Setpoint: "%f"' % self.desired_heading)
+        msg_pub = Twist()
+        msg_pub.linear.x = self.LINEAR_SPEED
+        error = angle_diff(self.desired_heading, heading)
+        if error < 0:
+            msg_pub.angular.z = math.radians(90.0)
+            self.get_logger().info('Turn left')
+        else:
+            msg_pub.angular.z = math.radians(-90.0)
+            self.get_logger().info('Turn right')
+        self.publisher_twist.publish(msg_pub)
+
+    def pub_timer_callback(self):
+        self.desired_heading += math.pi / 2
+        self.desired_heading %= 2 * math.pi
+        self.get_logger().info('New angle setpoint: "%f"' % self.desired_heading)
+
+def main(args=None):
+    rclpy.init(args=args)
+
+    mover = RurMover()
+
+    rclpy.spin(mover)
+
+    mover.destroy_node()
+    rclpy.shutdown()
+
+if __name__ == '__main__':
+    main()
-- 
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