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Fixed typos in the follow_joint_trajectory markdown file.

noetic
Alan G. Sanchez 2 years ago
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      follow_joint_trajectory.md

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follow_joint_trajectory.md View File

@ -7,15 +7,12 @@ Stretch ROS driver offers a [`FollowJointTrajectory`](http://docs.ros.org/en/api
<img src="images/stow_command.gif"/> <img src="images/stow_command.gif"/>
</p> </p>
Begin by running the following command in the terminal in a terminal. Begin by running the following command in the terminal in a terminal.
```bash ```bash
# 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 stow command node. Switch the mode to *position* mode using a rosservice call. Then run the stow command node.
```bash ```bash
@ -24,9 +21,9 @@ rosservice call /switch_to_position_mode
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python3 stow_command.py python3 stow_command.py
``` ```
This will send a `FollowJointTrajectory` command to stow Stretch's arm.
This will send a `FollowJointTrajectory` command to stow Stretch's arm.
### The Code ### The Code
```python ```python
@ -47,7 +44,7 @@ class StowCommand(hm.HelloNode):
def issue_stow_command(self): def issue_stow_command(self):
''' '''
Function that makes an action call and sends stow postion goal.
Function that makes an action call and sends stow position goal.
:param self: The self reference. :param self: The self reference.
''' '''
stow_point = JointTrajectoryPoint() stow_point = JointTrajectoryPoint()
@ -92,7 +89,6 @@ Now let's break the code down.
``` ```
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 Python3 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 Python3 script.
```python ```python
import rospy import rospy
from control_msgs.msg import FollowJointTrajectoryGoal from control_msgs.msg import FollowJointTrajectoryGoal
@ -100,11 +96,10 @@ from trajectory_msgs.msg import JointTrajectoryPoint
import hello_helpers.hello_misc as hm import hello_helpers.hello_misc as hm
import time import time
``` ```
You need to import rospy if you are writing a ROS Node. Import the FollowJointTrajectoryGoal from the [control_msgs.msg](http://wiki.ros.org/control_msgs) package to control the Stretch robot. Import JointTrajectoryPoint from the [trajectory_msgs](http://wiki.ros.org/trajectory_msgs) package to define robot trajectories. The [hello_helpers](https://github.com/hello-robot/stretch_ros/tree/master/hello_helpers) package consists of a module the provides various Python scripts used across [stretch_ros](https://github.com/hello-robot/stretch_ros). In this instance we are importing the hello_misc script.
You need to import `rospy` if you are writing a ROS [Node](http://wiki.ros.org/Nodes). Import the `FollowJointTrajectoryGoal` from the [control_msgs.msg](http://wiki.ros.org/control_msgs) package to control the Stretch robot. Import `JointTrajectoryPoint` from the [trajectory_msgs](http://wiki.ros.org/trajectory_msgs) package to define robot trajectories. The [hello_helpers](https://github.com/hello-robot/stretch_ros/tree/master/hello_helpers) package consists of a module the provides various Python scripts used across [stretch_ros](https://github.com/hello-robot/stretch_ros). In this instance we are importing the `hello_misc` script.
```python ```python
class StowCommand(hm.HelloNode): class StowCommand(hm.HelloNode):
def __init__(self): def __init__(self):
hm.HelloNode.__init__(self) hm.HelloNode.__init__(self)
``` ```
@ -125,7 +120,7 @@ The `issue_stow_command()` is the name of the function that will stow Stretch's
trajectory_goal.trajectory.header.stamp = rospy.Time(0.0) trajectory_goal.trajectory.header.stamp = rospy.Time(0.0)
trajectory_goal.trajectory.header.frame_id = 'base_link' trajectory_goal.trajectory.header.frame_id = 'base_link'
``` ```
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` is defined by the positions set in *stow_point*. Specify the coordinate frame that we want (base_link) and set the time to be now.
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` is defined by the positions set in *stow_point*. Specify the coordinate frame that we want (*base_link*) and set the time to be now.
```python ```python
self.trajectory_client.send_goal(trajectory_goal) self.trajectory_client.send_goal(trajectory_goal)
@ -167,7 +162,6 @@ Begin by running the following command in the terminal in a 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 multipoint command node. Switch the mode to *position* mode using a rosservice call. Then run the multipoint command node.
```bash ```bash
@ -176,7 +170,6 @@ rosservice call /switch_to_position_mode
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python3 multipoint_command.py python3 multipoint_command.py
``` ```
This will send a list of `JointTrajectoryPoint` message types to move Stretch's arm. This will send a list of `JointTrajectoryPoint` message types to move Stretch's arm.
### The Code ### The Code
@ -253,7 +246,7 @@ if __name__ == '__main__':
``` ```
### The Code Explained ### The Code Explained
Seeing that there are similarities between the multipoint and stow command nodes, we will only breakdown the different components of the multipoint_command node.
Seeing that there are similarities between the multipoint and stow command nodes, we will only breakdown the different components of the `multipoint_command` node.
```python ```python
point0 = JointTrajectoryPoint() point0 = JointTrajectoryPoint()
@ -282,7 +275,7 @@ trajectory_goal.trajectory.points = [point0, point1, point2, point3, point4, poi
trajectory_goal.trajectory.header.stamp = rospy.Time(0.0) trajectory_goal.trajectory.header.stamp = rospy.Time(0.0)
trajectory_goal.trajectory.header.frame_id = 'base_link' trajectory_goal.trajectory.header.frame_id = 'base_link'
``` ```
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` is defined by a list of the 6 points. Specify the coordinate frame that we want (base_link) and set the time to be now.
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` is defined by a list of the 6 points. Specify the coordinate frame that we want (*base_link*) and set the time to be now.
## Single Joint Actuator ## Single Joint Actuator
@ -314,7 +307,6 @@ Begin by running the following command in the terminal in a 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 single joint actuator node. Switch the mode to *position* mode using a rosservice call. Then run the single joint actuator node.
```bash ```bash
@ -323,10 +315,8 @@ rosservice call /switch_to_position_mode
cd catkin_ws/src/stretch_tutorials/src/ cd catkin_ws/src/stretch_tutorials/src/
python3 single_joint_actuator.py python3 single_joint_actuator.py
``` ```
This will send a list of `JointTrajectoryPoint` message types to move Stretch's arm. This will send a list of `JointTrajectoryPoint` message types to move Stretch's arm.
The joint, *joint_gripper_finger_left*, is only needed when actuating the gripper. The joint, *joint_gripper_finger_left*, is only needed when actuating the gripper.
@ -389,7 +379,7 @@ if __name__ == '__main__':
``` ```
### The Code Explained ### The Code Explained
Since the code is quite similar to the multipoint_command code, we will only review the parts that differ.
Since the code is quite similar to the `multipoint_command` code, we will only review the parts that differ.
Now let's break the code down. Now let's break the code down.
@ -413,7 +403,7 @@ trajectory_goal.trajectory.points = [point0]#, point1]
trajectory_goal.trajectory.header.stamp = rospy.Time(0.0) trajectory_goal.trajectory.header.stamp = rospy.Time(0.0)
trajectory_goal.trajectory.header.frame_id = 'base_link' trajectory_goal.trajectory.header.frame_id = 'base_link'
``` ```
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` set by your list of points. Specify the coordinate frame that we want (base_link) and set the time to be now.
Set *trajectory_goal* as a `FollowJointTrajectoryGoal` and define the joint names as a list. Then `trajectory_goal.trajectory.points` set by your list of points. Specify the coordinate frame that we want (*base_link*) and set the time to be now.
**Next Tutorial:** [Perception](perception.md) **Next Tutorial:** [Perception](perception.md)

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