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Fixed typos.

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Alan G. Sanchez 2 years ago
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2 changed files with 13 additions and 54 deletions
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      example_10.md
  2. +6
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      example_9.md

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example_10.md View File

@ -18,7 +18,6 @@ Within this tutorial package, there is an RViz config file with the topics for t
# Terminal 2 # Terminal 2
rosrun rviz rviz -d /home/hello-robot/catkin_ws/src/stretch_tutorials/rviz/tf2_broadcaster_example.rviz rosrun rviz rviz -d /home/hello-robot/catkin_ws/src/stretch_tutorials/rviz/tf2_broadcaster_example.rviz
``` ```
Then run the tf2 broadcaster node to visualize three static frames. Then run the tf2 broadcaster node to visualize three static frames.
```bash ```bash
@ -40,7 +39,6 @@ cd catkin_ws/src/stretch_tutorials/src/
python stow_command.py python stow_command.py
``` ```
<p align="center"> <p align="center">
<img src="images/tf2_broadcaster_with_stow.gif"/> <img src="images/tf2_broadcaster_with_stow.gif"/>
</p> </p>
@ -134,8 +132,7 @@ import tf.transformations
from geometry_msgs.msg import TransformStamped from geometry_msgs.msg import TransformStamped
from tf2_ros import StaticTransformBroadcaster from tf2_ros import StaticTransformBroadcaster
``` ```
You need to import rospy if you are writing a ROS Node. Import `tf.transformations` to get quaternion values from Euler angles. Import the `TransformStamped` from the `geometry_msgs.msg` package because we will be publishing static frames and it requires this message type. The `tf2_ros` package provides an implementation of a `tf2_ros.StaticTransformBroadcaster` to help make the task of publishing transforms easier.
You need to import rospy if you are writing a ROS [Node](http://wiki.ros.org/Nodes). Import `tf.transformations` to get quaternion values from Euler angles. Import the `TransformStamped` from the `geometry_msgs.msg` package because we will be publishing static frames and it requires this message type. The `tf2_ros` package provides an implementation of a `tf2_ros.StaticTransformBroadcaster` to help make the task of publishing transforms easier.
```python ```python
def __init__(self): def __init__(self):
@ -146,7 +143,6 @@ def __init__(self):
""" """
self.br = StaticTransformBroadcaster() self.br = StaticTransformBroadcaster()
``` ```
Here we create a `TransformStamped` object which will be the message we will send over once populated. Here we create a `TransformStamped` object which will be the message we will send over once populated.
```python ```python
@ -155,7 +151,6 @@ self.mast.header.stamp = rospy.Time.now()
self.mast.header.frame_id = 'link_mast' self.mast.header.frame_id = 'link_mast'
self.mast.child_frame_id = 'fk_link_mast' self.mast.child_frame_id = 'fk_link_mast'
``` ```
We need to give the transform being published a timestamp, we'll just stamp it with the current time, `rospy.Time.now()`. Then, we need to set the name of the parent frame of the link we're creating, in this case *link_mast*. Finally, we need to set the name of the child frame of the link we're creating. In this instance, the child frame is *fk_link_mast*. We need to give the transform being published a timestamp, we'll just stamp it with the current time, `rospy.Time.now()`. Then, we need to set the name of the parent frame of the link we're creating, in this case *link_mast*. Finally, we need to set the name of the child frame of the link we're creating. In this instance, the child frame is *fk_link_mast*.
```python ```python
@ -186,9 +181,9 @@ rospy.init_node('tf2_broadcaster')
FixedFrameBroadcaster() FixedFrameBroadcaster()
``` ```
The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. In this case, your node will take on the name talker. NOTE: the name must be a base name, i.e. it cannot contain any slashes "/".
The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. **NOTE:** the name must be a base name, i.e. it cannot contain any slashes "/".
Instantiate the class with `FixedFrameBroadcaster()`
Instantiate the `FixedFrameBroadcaster()` class.
```python ```python
rospy.spin() rospy.spin()
@ -198,7 +193,6 @@ messages come in. If we don't put this line in, then the node will not work,
and ROS will not process any messages. and ROS will not process any messages.
## tf2 Static Listener ## tf2 Static Listener
In the previous section of the tutorial, we created a tf2 broadcaster to publish three static transform frames. In this section we will create a tf2 listener that will find the transform between *fk_link_lift* and *link_grasp_center*. In the previous section of the tutorial, we created a tf2 broadcaster to publish three static transform frames. In this section we will create a tf2 listener that will find the transform between *fk_link_lift* and *link_grasp_center*.
@ -208,7 +202,6 @@ Begin by starting up the stretch driver launch file.
# Terminal 1 # Terminal 1
roslaunch stretch_core stretch_driver.launch roslaunch stretch_core stretch_driver.launch
``` ```
Then run the tf2 broadcaster node to create the three static frames. Then run the tf2 broadcaster node to create the three static frames.
```bash ```bash
@ -216,7 +209,6 @@ Then run the tf2 broadcaster node to create the three static frames.
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python tf2_broadcaster.py python tf2_broadcaster.py
``` ```
Finally, run the tf2 listener node to print the transform between two links. Finally, run the tf2 listener node to print the transform between two links.
```bash ```bash
@ -224,7 +216,6 @@ Finally, run the tf2 listener node to print the transform between two links.
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python tf2_listener.py python tf2_listener.py
``` ```
Within the terminal the transform will be printed every 1 second. Below is an example of what will be printed in the terminal. There is also an image for reference of the two frames. Within the terminal the transform will be printed every 1 second. Below is an example of what will be printed in the terminal. There is also an image for reference of the two frames.
```bash ```bash
@ -261,7 +252,7 @@ class FrameListener():
""" """
def __init__(self): def __init__(self):
""" """
A function that initializes the variables and looks up a tranformation
A function that initializes the variables and looks up a transformation
between a target and source frame. between a target and source frame.
:param self: The self reference. :param self: The self reference.
""" """
@ -306,7 +297,7 @@ from geometry_msgs.msg import TransformStamped
import tf2_ros import tf2_ros
``` ```
You need to import rospy if you are writing a ROS Node. Import the `TransformStamped` from the `geometry_msgs.msg` package because we will be publishing static frames and it requires this message type. The `tf2_ros` package provides an implementation of a `tf2_ros.TransformListener` to help make the task of receiving transforms easier.
You need to import rospy if you are writing a ROS [Node](http://wiki.ros.org/Nodes). Import the `TransformStamped` from the `geometry_msgs.msg` package because we will be publishing static frames and it requires this message type. The `tf2_ros` package provides an implementation of a `tf2_ros.TransformListener` to help make the task of receiving transforms easier.
```python ```python
tf_buffer = tf2_ros.Buffer() tf_buffer = tf2_ros.Buffer()
@ -324,7 +315,6 @@ Store frame names in variables that will be used to compute transformations.
rospy.sleep(1.0) rospy.sleep(1.0)
rate = rospy.Rate(1) rate = rospy.Rate(1)
``` ```
The first line gives the listener some time to accumulate transforms. The second line is the rate the node is going to publish information (1 Hz). The first line gives the listener some time to accumulate transforms. The second line is the rate the node is going to publish information (1 Hz).
```python ```python
@ -337,7 +327,6 @@ try:
except (tf2_ros.LookupException, tf2_ros.ConnectivityException, tf2_ros.ExtrapolationException): except (tf2_ros.LookupException, tf2_ros.ConnectivityException, tf2_ros.ExtrapolationException):
rospy.logwarn(' Could not transform %s from %s ', to_frame_rel, from_frame_rel) rospy.logwarn(' Could not transform %s from %s ', to_frame_rel, from_frame_rel)
``` ```
Try to look up the transform we want. Use a try-except block, since it may fail on any single call, due to internal timing issues in the transform publishers. Look up transform between *from_frame_rel* and *to_frame_rel* frames with the `lookup_transform()` function. Try to look up the transform we want. Use a try-except block, since it may fail on any single call, due to internal timing issues in the transform publishers. Look up transform between *from_frame_rel* and *to_frame_rel* frames with the `lookup_transform()` function.
```python ```python
@ -345,9 +334,9 @@ rospy.init_node('tf2_listener')
FrameListener() FrameListener()
``` ```
The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. In this case, your node will take on the name talker. NOTE: the name must be a base name, i.e. it cannot contain any slashes "/".
The next line, `rospy.init_node(NAME, ...)`, is very important as it tells rospy the name of your node -- until rospy has this information, it cannot start communicating with the ROS Master. **NOTE:** the name must be a base name, i.e. it cannot contain any slashes "/".
Instantiate the class with `FrameListener()`
Instantiate the `FrameListener()` class.
```python ```python
rospy.spin() rospy.spin()

+ 6
- 36
example_9.md View File

@ -8,15 +8,13 @@ Begin by running the following command in a new terminal.
# Terminal 1 # Terminal 1
roslaunch stretch_core stretch_driver.launch roslaunch stretch_core stretch_driver.launch
``` ```
Switch the mode to *position* mode using a rosservice call. Then run the `sample_respeaker.launch`.
Switch the mode to *position* mode using a rosservice call. Then run the `respeaker.launch`.
```bash ```bash
# Terminal 2 # Terminal 2
rosservice call /switch_to_position_mode rosservice call /switch_to_position_mode
roslaunch stretch_core respeaker.launch roslaunch stretch_core respeaker.launch
``` ```
Then run the voice teleoperation base node in a new terminal. Then run the voice teleoperation base node in a new terminal.
```bash ```bash
@ -24,8 +22,8 @@ Then run the voice teleoperation base node in a new terminal.
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python voice_teleoperation_base.py python voice_teleoperation_base.py
``` ```
In terminal 3, a menu of voice commands is printed. You can reference this menu layout below. In terminal 3, a menu of voice commands is printed. You can reference this menu layout below.
``` ```
------------ VOICE TELEOP MENU ------------ ------------ VOICE TELEOP MENU ------------
@ -251,15 +249,12 @@ class VoiceTeleopNode(hm.HelloNode):
self.send_command(command) self.send_command(command)
rate.sleep() rate.sleep()
if __name__ == '__main__': if __name__ == '__main__':
try: try:
node = VoiceTeleopNode() node = VoiceTeleopNode()
node.main() node.main()
except KeyboardInterrupt: except KeyboardInterrupt:
rospy.loginfo('interrupt received, so shutting down') rospy.loginfo('interrupt received, so shutting down')
``` ```
### The Code Explained ### The Code Explained
@ -270,7 +265,6 @@ This code is similar to that of the [multipoint_command](https://github.com/hell
``` ```
Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script. Every Python ROS [Node](http://wiki.ros.org/Nodes) will have this declaration at the top. The first line makes sure your script is executed as a Python script.
```python ```python
import math import math
import rospy import rospy
@ -283,10 +277,8 @@ from trajectory_msgs.msg import JointTrajectoryPoint
import hello_helpers.hello_misc as hm import hello_helpers.hello_misc as hm
from speech_recognition_msgs.msg import SpeechRecognitionCandidates from speech_recognition_msgs.msg import SpeechRecognitionCandidates
``` ```
You need to import rospy if you are writing a ROS Node. Import the `FollowJointTrajectoryGoal` from the `control_msgs.msg` package to control the Stretch robot. Import `JointTrajectoryPoint` from the `trajectory_msgs` package to define robot trajectories. The `hello_helpers` package consists of a module that provides various Python scripts used across stretch_ros. In this instance, we are importing the `hello_misc` script. Import `sensor_msgs.msg` so that we can subscribe to JointState messages. You need to import rospy if you are writing a ROS Node. Import the `FollowJointTrajectoryGoal` from the `control_msgs.msg` package to control the Stretch robot. Import `JointTrajectoryPoint` from the `trajectory_msgs` package to define robot trajectories. The `hello_helpers` package consists of a module that provides various Python scripts used across stretch_ros. In this instance, we are importing the `hello_misc` script. Import `sensor_msgs.msg` so that we can subscribe to JointState messages.
```python ```python
class GetVoiceCommands: class GetVoiceCommands:
``` ```
@ -296,8 +288,7 @@ Create a class that subscribes to the speech to text recognition messages, print
self.step_size = 'medium' self.step_size = 'medium'
self.rad_per_deg = math.pi/180.0 self.rad_per_deg = math.pi/180.0
``` ```
Set the default step size as medium and create a float value, self.rad_per_deg, to convert degrees to radians.
Set the default step size as medium and create a float value, *self.rad_per_deg*, to convert degrees to radians.
```python ```python
self.small_deg = 5.0 self.small_deg = 5.0
@ -312,7 +303,6 @@ self.big_deg = 20.0
self.big_rad = self.rad_per_deg * self.big_deg self.big_rad = self.rad_per_deg * self.big_deg
self.big_translate = 0.1 self.big_translate = 0.1
``` ```
Define the three rotation and translation step sizes. Define the three rotation and translation step sizes.
```python ```python
@ -321,16 +311,13 @@ self.sound_direction = 0
self.speech_to_text_sub = rospy.Subscriber("/speech_to_text", SpeechRecognitionCandidates, self.callback_speech) self.speech_to_text_sub = rospy.Subscriber("/speech_to_text", SpeechRecognitionCandidates, self.callback_speech)
self.sound_direction_sub = rospy.Subscriber("/sound_direction", Int32, self.callback_direction) self.sound_direction_sub = rospy.Subscriber("/sound_direction", Int32, self.callback_direction)
``` ```
Initialize the voice command and sound direction to values that will not result in moving the base. Initialize the voice command and sound direction to values that will not result in moving the base.
Set up two subscribers. The first one subscribes to the topic */speech_to_text*, looking for `SpeechRecognitionCandidates` messages. When a message comes in, ROS is going to pass it to the function `callback_speech` automatically. The second subscribes to */sound_direction* message and passes it to the `callback_direction` function. Set up two subscribers. The first one subscribes to the topic */speech_to_text*, looking for `SpeechRecognitionCandidates` messages. When a message comes in, ROS is going to pass it to the function `callback_speech` automatically. The second subscribes to */sound_direction* message and passes it to the `callback_direction` function.
```python ```python
self.sound_direction = msg.data * -self.rad_per_deg self.sound_direction = msg.data * -self.rad_per_deg
``` ```
The `callback_direction` function converts the *sound_direction* topic from degrees to radians. The `callback_direction` function converts the *sound_direction* topic from degrees to radians.
```python ```python
@ -342,7 +329,6 @@ if self.step_size == 'big':
inc = {'rad': self.big_rad, 'translate': self.big_translate} inc = {'rad': self.big_rad, 'translate': self.big_translate}
return inc return inc
``` ```
The `callback_speech` stores the increment size for translational and rotational base motion to *inc*. The increment size is contingent on the *self.step_size* string value. The `callback_speech` stores the increment size for translational and rotational base motion to *inc*. The increment size is contingent on the *self.step_size* string value.
```python ```python
@ -358,7 +344,6 @@ if self.voice_command == 'right':
if self.voice_command == 'stretch': if self.voice_command == 'stretch':
command = {'joint': 'rotate_mobile_base', 'inc': self.sound_direction} command = {'joint': 'rotate_mobile_base', 'inc': self.sound_direction}
``` ```
In the `get_command()` function, the *command* is initialized as None, or set as a dictionary where the *joint* and *inc* values are stored. The *command* message type is dependent on the *self.voice_command* string value. In the `get_command()` function, the *command* is initialized as None, or set as a dictionary where the *joint* and *inc* values are stored. The *command* message type is dependent on the *self.voice_command* string value.
```python ```python
@ -366,7 +351,6 @@ if (self.voice_command == "small") or (self.voice_command == "medium") or (self.
self.step_size = self.voice_command self.step_size = self.voice_command
rospy.loginfo('Step size = {0}'.format(self.step_size)) rospy.loginfo('Step size = {0}'.format(self.step_size))
``` ```
Based on the *self.voice_command* value, set the step size for the increments. Based on the *self.voice_command* value, set the step size for the increments.
```python ```python
@ -374,10 +358,8 @@ if self.voice_command == 'quit':
rospy.signal_shutdown("done") rospy.signal_shutdown("done")
sys.exit(0) sys.exit(0)
``` ```
If the *self.voice_command* is equal to "quit", then initiate a clean shutdown of ROS and exit the Python interpreter. If the *self.voice_command* is equal to "quit", then initiate a clean shutdown of ROS and exit the Python interpreter.
```python ```python
class VoiceTeleopNode(hm.HelloNode): class VoiceTeleopNode(hm.HelloNode):
""" """
@ -394,8 +376,7 @@ class VoiceTeleopNode(hm.HelloNode):
self.joint_state = None self.joint_state = None
self.speech = GetVoiceCommands() self.speech = GetVoiceCommands()
``` ```
A class that inherits the HelloNode class from hm, declares object from the GetVoiceCommands class, and sends joint trajectory commands.
A class that inherits the `HelloNode` class from `hm`, declares object from the `GetVoiceCommands` class, and sends joint trajectory commands.
```python ```python
def send_command(self, command): def send_command(self, command):
@ -409,21 +390,18 @@ def send_command(self, command):
point = JointTrajectoryPoint() point = JointTrajectoryPoint()
point.time_from_start = rospy.Duration(0.0) point.time_from_start = rospy.Duration(0.0)
``` ```
The `send_command` function stores the joint state message and uses a conditional statement to send joint trajectory goals. Also, assign *point* as a `JointTrajectoryPoint` message type. The `send_command` function stores the joint state message and uses a conditional statement to send joint trajectory goals. Also, assign *point* as a `JointTrajectoryPoint` message type.
```python ```python
trajectory_goal = FollowJointTrajectoryGoal() trajectory_goal = FollowJointTrajectoryGoal()
trajectory_goal.goal_time_tolerance = rospy.Time(1.0) trajectory_goal.goal_time_tolerance = rospy.Time(1.0)
``` ```
Assign *trajectory_goal* as a `FollowJointTrajectoryGoal` message type. Assign *trajectory_goal* as a `FollowJointTrajectoryGoal` message type.
```python ```python
joint_name = command['joint'] joint_name = command['joint']
trajectory_goal.trajectory.joint_names = [joint_name] trajectory_goal.trajectory.joint_names = [joint_name]
``` ```
Extract the joint name from the command dictionary. Extract the joint name from the command dictionary.
```python ```python
@ -431,27 +409,23 @@ inc = command['inc']
rospy.loginfo('inc = {0}'.format(inc)) rospy.loginfo('inc = {0}'.format(inc))
new_value = inc new_value = inc
``` ```
Extract the increment type from the command dictionary. Extract the increment type from the command dictionary.
```python ```python
point.positions = [new_value] point.positions = [new_value]
trajectory_goal.trajectory.points = [point] trajectory_goal.trajectory.points = [point]
``` ```
Assign the new value position to the trajectory goal message type. Assign the new value position to the trajectory goal message type.
```python ```python
self.trajectory_client.send_goal(trajectory_goal) self.trajectory_client.send_goal(trajectory_goal)
rospy.loginfo('Done sending command.') rospy.loginfo('Done sending command.')
``` ```
Make the action call and send goal of the new joint position. Make the action call and send goal of the new joint position.
```python ```python
self.speech.print_commands() self.speech.print_commands()
``` ```
Reprint the voice command menu after the trajectory goal is sent. Reprint the voice command menu after the trajectory goal is sent.
```python ```python
@ -466,9 +440,7 @@ def main(self):
rate = rospy.Rate(self.rate) rate = rospy.Rate(self.rate)
self.speech.print_commands() self.speech.print_commands()
``` ```
The main function instantiates the HelloNode class, initializes the subscriber,
and call other methods in both the VoiceTeleopNode and GetVoiceCommands classes.
The main function instantiates the `HelloNode` class, initializes the subscriber, and call other methods in both the `VoiceTeleopNode` and `GetVoiceCommands` classes.
```python ```python
while not rospy.is_shutdown(): while not rospy.is_shutdown():
@ -476,10 +448,8 @@ while not rospy.is_shutdown():
self.send_command(command) self.send_command(command)
rate.sleep() rate.sleep()
``` ```
Run a while loop to continuously check speech commands and send those commands to execute an action. Run a while loop to continuously check speech commands and send those commands to execute an action.
```python ```python
try: try:
node = VoiceTeleopNode() node = VoiceTeleopNode()
@ -487,7 +457,7 @@ try:
except KeyboardInterrupt: except KeyboardInterrupt:
rospy.loginfo('interrupt received, so shutting down') rospy.loginfo('interrupt received, so shutting down')
``` ```
Declare object from the VoiceTeleopNode class. Then execute the main() method/function.
Declare a `VoiceTeleopNode` object. Then execute the `main()` method.
**Previous Example** [Voice to Text](example_8.md) **Previous Example** [Voice to Text](example_8.md)
**Next Example** [Tf2 Broadcaster and Listener](example_10.md) **Next Example** [Tf2 Broadcaster and Listener](example_10.md)

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