Added reference position generator

my_double_integrator/reference_position_generator.py

+import rclpy
+from rclpy.node import Node
+from std_msgs.msg import Float64
+
+
+class ReferencePositionGen(Node):
+    def __init__(self):
+        super().__init__('reference_position_gen')
+        self.declare_parameter('rate', 1.0)
+        self.declare_parameter('amplitude', 1.0)
+
+        self.rate = self.get_parameter('rate').value
+        self.amplitude = self.get_parameter('amplitude').value
+
+        self.reference_pub = self.create_publisher(Float64, 'desired_position', 10)
+        self.timer = self.create_timer(1.0 / self.rate, self.publish_reference)
+        self.time = 0.0
+
+    def publish_reference(self):
+        msg = Float64()
+        msg.data = self.amplitude * self.time  # Linearly increasing reference
+        self.reference_pub.publish(msg)
+        self.time += 1.0 / self.rate
+
+
+def main(args=None):
+    rclpy.init(args=args)
+    node = ReferencePositionGen()
+    rclpy.spin(node)
+    node.destroy_node()
+    rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()