All Questions
Tagged with rospy ros-melodic
36 questions
0
votes
1
answer
27
views
Possible wrong ussage of transformPoint method from tf
ROS VERSION: Melodic
OS VERSION: Ubuntu 18.04
package tf version: 1.12.1
I'm trying to create a node that processes a PolygonStamped object and transform each point of it to a especified frame_id in ...
- 338
0
votes
0
answers
27
views
How to publish images of a file.bag on a topic with python?
I'm a beginner with ROS, so i thank you in advance for your answers.
I have a file.bag (Video) available and I would like to publish the various frames on a specific topic at defined moments of time ...
- 1
2
votes
2
answers
104
views
does rospy support rosparam update callbacks?
Using rospy/ROS1, I would like a callback when a certain parameter on the ROS1 parameter ...
- 123
0
votes
1
answer
1k
views
"ERROR: Unable to communicate with master!" and "Unable to Register with master node"
Hello,
I have two computers on a local network. First of them has Ubuntu 18.04 as OS, ROS Melodic installed and connected to the network with an Ethernet cable. The other one has Windows 10 as OS, ...
mericgeren
0
votes
1
answer
10
views
Making rosnode_cleanup() not wait for y/n from user
I arrived at rosnode_cleanup() after looking at #q9521 and #q285530.
I need to use rosnode.rosnode_cleanup() in my Python script, but it is blocking because it ...
abhishek47
0
votes
1
answer
492
views
Wait for subscriber callback to receive message - best practice
Hello, I am wondering what is the best practice in python to wait for a subscribed topic to start publishing, before using its messages in the spin method. An simplified example of what I am doing ...
flix17
0
votes
1
answer
20
views
TypeError: cannot marshal <type 'numpy.uint8'> objects
I am unable to set parameters to the param server using the following code:
hsv = cv2.cvtColor(image,
cv2.COLOR_BGR2HSV)
rospy.set_param("lower_h", hsv[:, :,
0].min()) rospy.set_param("...
dee-mikey
0
votes
1
answer
44
views
How to correctly return an array of ints from service?
I have the following code:
RouteRemainder.srv:
---
int64[] route_remainder
routes_manager,py:
...
mbostic
0
votes
1
answer
58
views
How to correctly translate a pose along an axis?
I have a pose of my robot base_link in the map frame. I'd like to translate this 0.2 m along ...
Py
0
votes
1
answer
68
views
How to remove lag in marker publishing?
I am publishing markers in a subscriber callback so that whenever new data is received on a topic a marker is created. Markers are published and displayed well at first but after a while markers are ...
Py
0
votes
1
answer
50
views
Attempting to read Battery % via Mavros
I have a quadcopter running a Pixhawk flight controller. I am also running a RPI 4 companion board, and I have a serious of nodes setup for flight and a number of other operations. One node is my ...
nightpoison
0
votes
1
answer
2
views
Error calling Service in rospy
Been trying to call this Service implemented in the following code as such:
...
HatchEm27998
0
votes
1
answer
164
views
Confused about spinOnce and sleep
I want to go a little deeper into the "why" from a technical perspective. Not just you must do this, but why. I've looked at the rospy source code but I am still not sure about the following....
- 465
0
votes
2
answers
47
views
Minimal working example for RViz marker publishing
Does anyone know of a complete minimal working example to publish a marker that can be visualised in RViz written in Python?
...
Py
0
votes
2
answers
146
views
Is there a way to extract specific info or lines from a ROS topic?
echo /joint_states has the following output (shortened).
I made a node (using the rospy tutorial) to subscribe to /joint_states and I want the.py script to print() just the position list for use ...
etorobot
0
votes
1
answer
76
views
A ROS message that contains no data, Signal only?
Hello all,
Newbie here with ROS, and I have to say I love it. Its a lot of fun and I can only imagine the possibilities. With that said.
I haven't had any luck finding anything of its kind, but does ...
nightpoison
0
votes
1
answer
99
views
Get timestamp of current message starting from zero in rospy
I seem to have a misunderstanding regarding time in ros, especially sim-time.
Aim
I process a rosbag that contains many pointcloud2s and want to transform the timestamps of the incoming pointcloud to ...
jo-jstrm
0
votes
2
answers
134
views
How to use ROS in Colab?
Now I'm a complete newbie when it comes to both ROS and Colab.
I found this code a while ago, and I want to use it in Google Colab because using the drive makes things easy due to the immensely large ...
Fares Mhaya
0
votes
1
answer
23
views
unknown error handler name 'rosmsg'
I m trying the rosserial tutorials from the official site in ros melodic. While running the Serial_node.py I m getting this error :
...
Saurabh Rahatekar
0
votes
1
answer
11
views
how does one index array in rospy?
I need the size of a custom array msg type. (The type is geometry_msgs/PoseStamped[] PoseStampedArray.)
I need to iterate on the msg if it is not empty and I would very much like to get the last ...
gbohus
0
votes
1
answer
19
views
How to deal with multiple subscribers and callbacks for different topics in rospy?
Hello I have a code snippet here which 8 subscribers for 8 different message types. Earlier I used to have only four subscribersand it used to run very fast but with 8 subscribers the subscription of ...
mkb_10062949
0
votes
1
answer
12
views
Smach get value from subscriber topic
I'm pretty new to ROS, and I'm working with SMACH. I have an Arduino UNO with 4 LEDs (green ,yellow, red and blue) and one button.
What I'm trying to achieve is a sort of traffic light simulator. My ...
rubbun
0
votes
1
answer
18
views
How to access ChannelFloat32 in python?
Hello, I'm on melodic and try to subscribe to a ChannelFloat32 message, but I neither can import the type nor have an Idea how to access that. How can I do that?
Originally posted by bionade24 on ROS ...
bionade24
0
votes
1
answer
194
views
Best way of publishing to /clock topic type rosgraph_msgs/Clock?
Ultimately I need to publish an accelerated time to the /clock topic which the rest of my simulation nodes are using. I have managed to concoct two separate launch files;
the first launch file ...
Craigstar
0
votes
1
answer
408
views
Import error for rospy in Python3.6 script
I've tried import rospy into a python script that requires python3.6, but it gives me the error:
ModuleNotFoundError: No module named 'rospy'
I'm able to successfully import the rospy into a python3.5 ...
mysqo
0
votes
1
answer
4
views
subscriber callback in a python class is overwriting the class variables with the most recent data before the first callback processing finishes
I am on ROS Melodic. When a subscriber is receiving data at a faster rate than it could process, the class variables are being updated before the callback process is finished.
For example, when I run ...
abstracto
0
votes
2
answers
11
views
Service Server and Client not working when launch by launch file
Hello all.
I am using a pandas data frame to format instructions and the data frame is hosted in a service server. I then have a client that is imported into a position supervising node. The client is ...
mhyde64
0
votes
1
answer
26
views
OccupancyGrid not getting published - Python
Hi, so I want to publish an occupancy grid of a map.png file I have.
After running this node, I do rostopic list but it doesn't show me any published map. Can someone tell what am I doing wrong?
...
ros-noob
0
votes
1
answer
43
views
get all the active namespaces rospy | roscpp
In my project, multiple robots may be spawned both at launch and at runtime, each under a certain namespace. Generally, that is 'robot_ID' where ID == a robot-...
davidem
0
votes
1
answer
26
views
Link in rviz teleports between original and transformed position with tf2
Here's a video of what I'm referring to.
I'm using rviz to display a transformation using a tf2 broadcaster, but link1 keeps popping back and forth between its specified location from the URDF, and ...
Victoria Bentell
0
votes
1
answer
10
views
Moveit Commander Plan Fail
I'm using rospy and moveit_commander to control a robot. It works wonderfully, except I cannot find a way in the API to handle a path planning failure. The ...
rklutz
0
votes
2
answers
11
views
Cancel rospy action with Ctrl+C
Hi to everyone,
i'm using a class in which some methods call actions as SimpleActionClient.
I create a node in the same executable i create the class instance and leave if the signal handling.
When i ...
muttidrhummer
0
votes
1
answer
315
views
Difference between rospy.spin and rospy.sleep
Hi There!
Whats the difference between rospy.spin nad rospy.sleep? Does rospy.rate affect rospy.spin?
Originally posted by Marseiliais on ROS Answers with karma: 31 on 2019-09-02
Post score: 3
Marseiliais
0
votes
2
answers
219
views
Importing std_msgs.msg with Python
Hi guys, I am following the ROS Beginner's Tutorials, on the part Writing a Simple Publisher and Subscriber (Python). In the publisher code given, there is a line which says from std_msgs.msg import ...
Ricky98
0
votes
1
answer
3
views
Where I can find a list of dependencies?
I don't know where find or what dependencies to use when I will create a package dependencies. It's possible create a depends? For example, in the Tutorial I see rospy, roscpp and std_msgs. Where I ...
Jose-Araujo
0
votes
1
answer
107
views
Unable to publish PoseStamped message
I am trying to publish a PoseStamped message via a node running in Python. I am listening for this message on another tab in my terminal.
Python node:
...
Subodh Malgonde