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21 votes
Accepted

ROS: catkin_make vs. catkin build

The main difference is the isolated environment that you get with catkin build. This makes the whole build configuration much more compartmentalized and robust to ...
bergercookie's user avatar
12 votes

How to setup CLion for ROS?

Start CLion from a commandline with your sourced ROS workspace (i.e. after calling source devel/setup.bash) Open a project's CMakeLists.txt, and tell it to open it ...
Martin Pecka's user avatar
11 votes
Accepted

Why do we need ROS?

I think it is safe to say that ROS adds a lot of value to many robotics applications, but it definitely isn't appropriate for every robotics application In fact, the ROS website has a series of pages ...
sempaiscuba's user avatar
  • 1,074
8 votes

ROS: catkin_make vs. catkin build

Apart from the isolated build, it is much more convenient to use: Independent packages are build in parallel which can make it much faster. catkin build can be ...
luator's user avatar
  • 183
8 votes

Alternative to ROS?

I think you are getting confused between the basic ROS possibilities and some more advanced libraries which are integrated but do not need to be used by users without 'advanced' requirements. If you ...
N. Staub's user avatar
  • 1,412
7 votes
Accepted

How secure is ROS2?

Rather than trying to explain the nuances of ROS 2 security, I think its better to mention that ROS 2 uses the DDS standard for its security paradigm. If you're working on something important like ...
Steve Macenski's user avatar
6 votes

Are Rospy subscriber callbacks executed sequentially for a single topic?

I prototyped a bit to investigate this behaviour. Ran the following node: ...
user28122's user avatar
6 votes
Accepted

What exactly is a nodelet?

Regular nodes share data by passing messages over TCP. Nodelets share data by sharing a pointer to a block of memory. So, for a regular node, you've got to collect all the data, pack it into a ROS ...
Chuck's user avatar
  • 16k
6 votes

What is the definition of the contents of PointCloud2?

I get why you are confused. Looking at the definition of PointCloud2, you see that the field that holds the "actual" point cloud data is a 1-dimensional array. Now,...
robotsfoundme's user avatar
6 votes
Accepted

Robot moving sideways in RVIZ ROS

I have found the problem after some long search on the internet. The problem was that in Rviz, X-axis is defined as front of the robot and Y-axis is defined as the sideways. However, in my URDF I ...
Franky's user avatar
  • 536
6 votes

Inverse kinematics for differential robot knowing linear and angular velocities

Your linear velocity should be the average of both wheel values. Assuming there's some wheel radius of WHEEL_RADIUS, as you've stated, then you should get each ...
Chuck's user avatar
  • 16k
6 votes

How to setup CLion for ROS?

Integrating CLion with ROS is actually straight forward and works out of the box if one knows how to do it: With your console, go into your ROS workspace and source the respective ...
Jarno's user avatar
  • 311
6 votes

Programming Inverse Kinematics in C++

I agree with SteveO that there is nothing wrong with reinventing the wheel if you want to learn about wheels. And for a single application, 4 DoF arm, the IK is probably not too hard. But I feel ...
Ben's user avatar
  • 5,865
5 votes
Accepted

cartesian velocity control loop implementation

The orientation error is not simply subtraction of your current pose and the desired pose. Given $\mathbf{R}_{a}, \ \mathbf{R}_{d} \in \text{SO}(3) $, where $\mathbf{R}_{d}$ is your desired ...
domo_arigato's user avatar
5 votes
Accepted

Is using a robotic operating system still considered bare-metal C?

Bare metal programming is defined by not using any abstractions that might be provided by an OS and working directly with the hardware. Wikipedia Technopedia. ROS provides an even higher level ...
Tully's user avatar
  • 25.1k
5 votes
Accepted

What is the Point of Monocular SLAM

I would say true scale actually doesn't really matter. A good way to reason about this is actually video games. If you play a racing game(or really any kind of 3D game) do you care that the world has ...
edwinem's user avatar
  • 1,871
5 votes
Accepted

roslaunch not found

Even though you have added source /opt/ros/kinetic/setup.bash to your .bashrc, the fact you get a "command not found" error ...
xperroni's user avatar
  • 1,363
5 votes
Accepted

Is ROS still maintained are any other trendy alternatives?

ROS Melodic supports 18.04, the current LTS-version of Ubuntu, so it's perfectly up to date. ROS has a huge active community in Academia and(!) Industry (ROSIndustrial), many robotic companies use ...
FooTheBar's user avatar
  • 1,375
5 votes

rostopic list not showing topic

In which order do you run your commands ? rostopic list is used to list current topics registered with the rosmaster 'node', ...
lmathieu's user avatar
5 votes
Accepted

Programming Inverse Kinematics in C++

It is rather straightforward to implement inverse kinematics for a particular manipulator in C++. Of course, you need to begin with the inverse kinematic equations themselves. Putting those into ...
SteveO's user avatar
  • 4,396
5 votes
Accepted

What is the difference between ROSberry Pi builds?

Well this is embarrassing. I didn't realize they are in fact different distributions not variants. Also found the page where you can find out more about them: http://wiki.ros.org/Distributions
Xavier Guay's user avatar
5 votes

What are the prerequisites for learning ROS?

It sounds like you're excited to learn ROS. The best way to learn ROS well is to dive in and learn any necessary bits along the way. Once you finish going through EVERYTHING in the ROS tutorials you ...
Jacksonkr's user avatar
  • 295
4 votes
Accepted

Does a stable library exist for docking robots using images?

There's a lot of solutions out there already for this. I'll start by suggesting AR tags not QR tags. They're better optimized for localizing. The Alvar library is commonly used for tracking AR tags. ...
Tully's user avatar
  • 25.1k
4 votes
Accepted

Why does ROS2 claim to be "real time"?

"Realtime" is a fairly vague term. What ROS is referring to is often termed "soft realtime" because it is able to calculate control actions as fast enough to keep up with the robot'...
ryan0270's user avatar
  • 2,814
4 votes
Accepted

What are the numbers to the left when logging with ROS_INFO_STREAM?

The first number is the walltime (sec seconds and nsec nanoseconds since January 1, 1970 UTC). The second number is the simulated time (also sec.nsec) since you started your simulation environment. (...
lwohlhart's user avatar
  • 156
4 votes

What is the definition of the contents of PointCloud2?

I totally agree that the documentation is poor and it took me quite some time to understand what is going on. I recorded a rosbag for "velodyne_points" topic using a Velodyne VLP-16. The ...
beluga's user avatar
  • 41
4 votes

Alternative to ROS?

Arduino is not really relevant since its output is a bare-metal microcontroller code. You can gain experience with more complex microcontroller systems by using a realtime OS on your arduino board. I ...
hauptmech's user avatar
  • 4,445
4 votes
Accepted

ROS for an autonomous boat

ROS will work fine for this task. It will add some additional overhead for your Raspberry Pi but it is fairly small provided you only install the Robotic or Base configuration instead of the Full ...
Joshua Whitley's user avatar
4 votes
Accepted

Integrating GPS into Graph SLAM (how orientation fixed?)

You can use a very low information matrix value at the orientation elements of your state, given that the information matrix is the inverse of the covariance matrix. The covariance matrix ...
Ricardo Achilles's user avatar
4 votes
Accepted

Suggestion for relevant non-complex simulator

just use matlab or and python with a set of fixed features in space represented as points. Don't do any vision processing. At this point any vision processing would be overkill. you are making this ...
holmeski's user avatar
  • 1,853

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