HeRo - Revision history

Caioconti: /* HeRo ROS Tutorial */

2024-11-22T17:01:56Z

‎HeRo ROS Tutorial

Caioconti: /* Create ROS Package for HeRo */

2024-11-22T03:02:37Z

‎Create ROS Package for HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T23:13:19Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T23:11:38Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T23:04:15Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T22:58:17Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T22:51:00Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T22:47:35Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T22:35:39Z

‎Controlling HeRo

Caioconti: /* Controlling HeRo */

2024-11-21T22:31:22Z

‎Controlling HeRo

@@ Line 11: / Line 11: @@
 == HeRo ROS Tutorial ==
-In this tutorial, we will create a new script to navigate the HeRo and utilize its sensors to avoid obstacles. To follow along, you must have ROS installed; for this tutorial, I will be using ROS Noetic.
+In this tutorial, we will create a new script to navigate the HeRo. To follow along, you must have ROS installed; for this tutorial, we will be using ROS Noetic.
 The HeRo main page already has excellent tutorials for setting up the HeRo. You can follow the steps here:

@@ Line 120: / Line 120: @@
 Now, we create a new function with a publisher, to publish constantly a velocity of 0.01 in the x direction. We want to publish in the <code>/hero_i/vellocity_controller/cmd_vel</code> topic, changing "i" with the number of your HeRo. To publish in a topic, it is needed to create the type of message expected, to see which message type the topic expects:
-<code>rostopic info /hero_i/position_controller/cmd_vel</code>
+<code>rostopic info /hero_i/velocity_controller/cmd_vel</code>
 And to see how this type of message is structured:

← Older revision		Revision as of 23:13, 21 November 2024
Line 391:		Line 391:
	</pre>		</pre>

−	Keep in mind that HeRo's (x,y)=(0,0) corresponds to the position where it was powered on. It's important to note that HeRo lacks precise pose estimation by itself. Ideally, an external camera setup would be used to provide more accurate position feedback. As a result, you might observe HeRo stopping at a location that differs from the expected destination. However, according to HeRo's internal estimation, it may have reached the correct position. To verify HeRo's perception of its position, you can use the <code>echo</code> command on the odometry topic.	+	Keep in mind that HeRo's (x,y)=(0,0) corresponds to the position where it was powered on. It's important to note that HeRo lacks precise pose estimation by itself. Ideally, an external camera setup would be used to provide more accurate position feedback. As a result, you might observe HeRo stopping at a location that differs from the expected destination. However, according to HeRo's internal estimation, it may have reached the correct position. To verify HeRo's perception of its position, you can either use the <code>echo</code> command on the odometry topic or run the subscriber node we created earlier.

← Older revision		Revision as of 23:11, 21 November 2024
Line 383:		Line 383:
	rate.sleep()		rate.sleep()
	</pre>		</pre>
		+
		+	Now, set the desired (x,y) coordinates for HeRo to achieve and run the node. Remember to <code>chmod +x tutorial_control.py</code>.
		+
		+	<pre>
		+	source devel/setup.bash
		+	rosrun hero_tutorial tutorial_control.py
		+	</pre>
		+
		+	Keep in mind that HeRo's (x,y)=(0,0) corresponds to the position where it was powered on. It's important to note that HeRo lacks precise pose estimation by itself. Ideally, an external camera setup would be used to provide more accurate position feedback. As a result, you might observe HeRo stopping at a location that differs from the expected destination. However, according to HeRo's internal estimation, it may have reached the correct position. To verify HeRo's perception of its position, you can use the <code>echo</code> command on the odometry topic.

@@ Line 347: / Line 347: @@
 # Define rate
 rate = rospy.Rate(5)
 </pre>

@@ Line 321: / Line 321: @@
 </pre>
-The <code>run</code> function intiates the node, publisher and subscriber.
+The <code>run</code> function first initializes the node, sets up a publisher to send angular and linear velocities to HeRo, and creates a subscriber to retrieve pose information from HeRo.
 <pre>
@@ Line 332: / Line 332: @@
-We want the subscriber to get the HeRo pose, therefore, we simply return its data to a class variable in the subscriber callback.
+Since we need HeRo's pose for control, the subscriber callback function is used to retrieve the pose data and store it in a class variable for easy access during computations.
 <pre>
-    def callback(self, data):
+def callback(self, data):
          self.odom = data
 </pre>

← Older revision		Revision as of 22:51, 21 November 2024
Line 321:		Line 321:
	</pre>		</pre>

−	~~running the~~ <code>run</run> ~~function~~, ~~firstly initiates~~	+	The <code>run</code> function intiates the node, publisher and subscriber.
		+
		+	<pre>
		+	def run(self):
		+	# Initiate node and create publish and subscriber
		+	rospy.init_node('hero_control')
		+	rospy.Subscriber('hero_3/odom', Odometry, self.callback)
		+	self.pub = rospy.Publisher('hero_3/velocity_controller/cmd_vel', Twist, queue_size=1)
		+	</pre>
		+
		+
		+	We want the subscriber to get the HeRo pose, therefore, we simply return its data to a class variable in the subscriber callback.
		+
		+	<pre>
		+	def callback(self, data):
		+	self.odom = data
		+	</pre>

← Older revision		Revision as of 22:47, 21 November 2024
Line 303:		Line 303:

	The function <code>euler_from_quaternion</code> converts quaternions into Euler angles, while <code>control</code> is a position proportional controller that calculates linear and angular velocities. We create a class to enable the use of subscriber data for online computation of control outputs. Alternatively, global variables could be used, but this method is less structured.		The function <code>euler_from_quaternion</code> converts quaternions into Euler angles, while <code>control</code> is a position proportional controller that calculates linear and angular velocities. We create a class to enable the use of subscriber data for online computation of control outputs. Alternatively, global variables could be used, but this method is less structured.
		+
		+	In the main function, we simply instantiate an object of the class we defined and call its run function, where the core functionality is executed.
		+
		+	<pre>
		+	if __name__ == '__main__':
		+	obj = ControlHero()
		+	obj.run()
		+	</pre>
		+
		+	The class is initialized with key variables that are accessible throughout its methods, functioning similarly to global variables but within the scope of the class. In our case, these variables include the messages we want to send and receive, as well as the desired final position (x,y) for HeRo.
		+	<pre>
		+	def __init__(self):
		+	self.cmd_vel = Twist()
		+	self.odom = Odometry()
		+	self.x_end = 0.15
		+	self.y_end = 0.00
		+	</pre>
		+
		+	running the <code>run</run> function, firstly initiates

@@ Line 200: / Line 200: @@
 from geometry_msgs.msg import Twist
-def normalizeAngle(angle):
+def normalize_angle(angle):
      return np.mod(angle+np.pi, 2*np.pi) - np.pi
@@ Line 234: / Line 234: @@
      dy = y_end - y
      rho = np.sqrt(dx**2 + dy**2)
-     alpha = normalizeAngle(-theta + np.arctan2(dy,dx))
+     alpha = normalize_angle(-theta + np.arctan2(dy,dx))
      if abs(alpha) > np.pi/2:
           kr = -kr
-          alpha = normalizeAngle(alpha - np.pi)
+          alpha = normalize_angle(alpha - np.pi)
      v = kr*rho
@@ Line 302: / Line 302: @@
 </pre>
-The function <code>euler_from_quaternion</code> converts quaternions into Euler angles, while <code>control</code> is a position proportional controller that calculates linear and angular velocities.
+The function <code>euler_from_quaternion</code> converts quaternions into Euler angles, while <code>control</code> is a position proportional controller that calculates linear and angular velocities. We create a class to enable the use of subscriber data for online computation of control outputs. Alternatively, global variables could be used, but this method is less structured.

← Older revision		Revision as of 22:31, 21 November 2024
Line 301:		Line 301:
	obj.run()		obj.run()
	</pre>		</pre>
		+
		+	The function <code>euler_from_quaternion</code> converts quaternions into Euler angles, while <code>control</code> is a position proportional controller that calculates linear and angular velocities.