# Tag Info

18

I'm back to a computer! Like I said in this comment, ROS is generally not mandatory. ROS is one platform among many, famous mostly due to Willow Garage giving away free robots at some point in time to whoever wrote the most ROS modules. That said, it's not the best platform possible, and is certainly nothing overly special. Particularly, the said contest ...

16

Very short answer: 2 Sensors Regarding whether reading from sensors all in one node or each separately, you should ask yourself this question: Are the sensors meaningless without the other? This question asks if the sensors are tightly coupled or not. For example, say you have a sensor that is sensitive to temperature (and you need to compensate for it). ...

16

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 changes in the configuration (add/remove package, modify a cmake variable etc.) Apart from that you also get much better and easily-readable colored cmdline output which makes the whole experience ...

12

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 as a project rather than as a file. That's it, you've got your workspace integrated :) Debugging: Debugging built files (nodes which you run through rosrun) is easy, you just normally run them ...

10

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 that address that very point. These pages explain the major broad advantages of using ROS, the core components that go to make up ROS, and also describe how ...

6

You can follow the example code here and simply add a second subscription like so: import rospy from std_msgs.msg import String def callback1(data): rospy.loginfo("Callback1 heard %s",data.data) def callback2(data): rospy.loginfo("Callback2 heard %s",data.data) def listener(): rospy.init_node('node_name') rospy.Subscriber("chatter1", ...

6

I implemented something like this in College: https://github.com/Auburn-Automow/au_automow_common/tree/master/automow_planning Basically we just passed the vertices of the boustrophedon path as goals to move_base. Here's a video of a bag file being played back: https://www.youtube.com/watch?v=R7nLgYquECg Here's the class paper we did for the planner: ...

6

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 like I should mention that most of the kinematics libraries out there are mostly targeted towards Linux. And as such, probably not too hard to compile from ...

6

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 setup.bash file. Go to the src directory of your workspace. Start CLion from the console from your src directory. Close any open projects in CLion and select Import Project from ...

6

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 defined the robot in a way where Y-axis was its front and X-axis was its sideways. After fixing this, my robot moves normally in Rviz and Gazebo both.

5

Monte Carlo localization is just another name for a particle filter. Monte Carlo methods are a broader name for computational algorithms that rely on random sampling. A particle filter is a specific application of the general Monte Carlo method for localization, and so it is simply referred to sometimes as Monte Carlo localization. If you ask Lord Google, ...

5

A kinect mounted on your robot is enough for mapping and localization. There are a few different packages that will work: rgbdslam can create a 3d map using a kinect You can use depthimage_to_laserscan to take in a depth image from the kinect and output a laser scan message which you can then use with gmapping for mapping, and the nav stack to navigate your ...

5

ROS is not a real-time operating system. The purpose of ROS was not to be like VXWorx (which is what the Mars Curiosity rover uses). ROS was developed to be a simple, generic, reusable platform for everyone to contribute to and use. Developers would be able to add their own abstracted modules, building a rich community of reusable code. The key here is ...

5

The ROSBerryPi page is quite outdated, you actually can install prebuilt ROS Groovy binaries on Raspbian. You will be better off installing prebuilt ROS binaries rather than building from source on your pi. I don't have any experience with Ubuntu on the raspi but it's running great on my Odroid UX4 (similar single board computer) and ROS Jade runs just ...

5

Yes, it will work! The electrical interface is the same between the Create 2 and the 700 series Roomba; however, the position of the mini-DIN is changed. Instead of being to the right, under the top cover, the connector can be found under a rubber gasket under the handle. As long as any Create cable can physically fit in that location (and the one iRobot ...

5

I did a little step-by-step tutorial with images, but if my other answer regarding aligning frames didn't work well for you, or the definition of "Front Plane" or "Top Plane" is confusing in Solidworks (spoiler: it is), then consider making your own axes. From the assembly tab, go to reference geometry -> axis, then select the assembly planes to make an ...

5

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

5

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 code will only involve a few trigonometric functions such as acos, asin, and atan2 (use atan2 instead of atan), and probably a couple of square and square root ...

5

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 find it too difficult most likely those are functionalities which are not necessary for your project. That being said, ROS is a middleware that makes the glue ...

5

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 used from any directory in the workspace while catkin_make only works in the top level directory. It is easy to only build a single package (+ dependencies): catkin build package_name or, when called ...

5

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 wheel speed as: left_velocity = left_rpm * (RPM_TO_RAD_PER_S * DIST_PER_RAD); right_velocity = right_rpm * (RPM_TO_RAD_PER_S * DIST_PER_RAD); linear_velocity = 0.5f * (left_velocity + right_velocity);...

5

In which order do you run your commands ? rostopic list is used to list current topics registered with the rosmaster 'node', who is launched with the roscore commands The publisher and subscriber topics are registered to the rosmaster with the python function rospy.Publisher('chatter', String, queue_size=10) for the publisher, and rospy.Subscriber("chatter"...

5

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 it in their products and ROS2 is currently under development. A lot of ROS-packages have been written by people during their studies which have moved on later, ...

5

Even though you have added source /opt/ros/kinetic/setup.bash to your .bashrc, the fact you get a "command not found" error indicates that somehow Bash can't find the roslaunch executable. To double-check your configuration, run the following command: $echo$PATH If your environment is correctly configured to run ROS Kinetic, you should see an output of ...

4

When there is miscommunications between the microcontroller and a chip, assuming the electronics are not damaged, there could be a couple of things that can go wrong. Of course, further diagnosis is required. Typical things that could go wrong are (generally, not just in your particular case): Connections: Is the chip connected to the correct power supply? ...

4

Try freenect, there are some problems with OpenNI solution. Firt, install freenect by sudo apt-get install ros-fuerte-freenect-stack After installation, connect your kinect (in USB 2.0 port) and run freenect roslaunch freenect_launch freenect.launch Then run Rviz and set Fixed frame to /camera_link, you can now add PointCloud2 window and select the ...

4

Imagine someone put you in a wheelchair and blindfolded you, then let you reach your arm out and touch a wall. You could tell how far away the wall was, but as long as you were pushed parallel to the wall, how would you know how far you had gone? You can't count steps or see the end of the hall, so you do not have a way to index your samples of where the ...

4

The MATLAB tutorial doesnt cover this aspect well about when you have matlab and gazebo running on the same linux machine with no virtual box. Change your linux ethernet interface ip address statically using: sudo ifconfig eth0 192.168.1.1 netmask 255.255.255.0 assign to ros master the same ip address using: export ROS_MASTER_URI=http://192.168.1....

4

The actual implementation of SLAM won't care about whether you are using high fidelity laser range finders or cheaper ultrasonic sensors. Both are providing range measurements with the biggest difference being the uncertainty. Of course ultrasonic sensors work on different principles so there is more to it than that, but both are providing range measurements ...

4

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 can tinker with a project like turtlebot. Last but not least there is http://answers.ros.org/ for any ROS related questions you may have. Enjoy! EDIT I took the ...

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