Didn’t see that. Could be caused by trying to figure stuff out at 2:30 in the morning!
I’ll look again. If I can get this in something other than Kindle, my wallet is doomed!
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I’m sorry, but I can’t find that. Can you help me find it? Do you have to be logged in ?
Browse to https://www.packtpub.com/iot-hardware/hands-on-ros-for-robotics-programming
No log in or signup necessary.
Click either “Buy eBook” or “print + eBook”
Click “Add to Cart”
Click “shopping cart”
Click “Checkout”
…
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Sorry for the delay in answering. I’m Bernardo, the author of the book.
Regarding the SLAM question, you are right, the sensor to use is the low cost EAI YDLIDAR X4 that you can find in Aliexpress.
You can also implement SLAM with the Pi Camera using ORB-SLAM2 algorithm. You can find the details at https://github.com/raulmur/ORB_SLAM2
While writing the book I was assessing this option to avoid increase the hardware cost, but after carrying out a deep review I found that ORB-SLAM2 is more a research topic than a ready made implementation for makers, that it is the scope of the book. I didn’t want the readers to loose in the complexities of building a 3D represetation of the sorroudings from 2D images. This is quite not intuitiv, while LIDAR works off-the-shelf with ROS and the implementation is fast and easy to understand because it directly provides a 3D representation of the environment.
From my personal point of view: the many hours you should devote to implement ORB-SLAM2
is not worth versus using a low cost LIDAR, whose cost is already below 100$
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Regarding Medium.com, I am writer and it is the platform of choice I use to public other articles on general topics. For GoPiGo3 and ROS I decided to publish the articles for free, you do not have to pay for reading them, and I will answer questions about the book in this forum. So anytime, you want to contact the author, just use Dexter GoPiGo forum 
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Cool! Welcome! AND a gigantic"Thank you!"
Where are you located? I’m curious because AliExpress may not be useful to people who are located outside Russia - and I didn’t see a lot of other sources when I gave it a quick look.
BTW, If you’re interested, here’s a link to the users manual:
Thank you
I live in Spain and I bought YDLIDAR several months ago.
You can get YDLIDAR X4 in Aliexpress with free shipping to the United States https://www.aliexpress.com/item/32908156152.html?spm=a2g0s.9042311.0.0.27fc4c4dXvP7kn
You can also get it on Amazon.com www.amazon. com/-/es/ydlidar-Lidar-tel%C3%A9metro-l%C3%A1ser-costo/dp/B078Y964ZS
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I - finally - found that after I posted. It is unfortunate that - since I am presently in Russia, these searches don’t always work without a VPN connection to the U.S.
BTW, (and completely off topic), if you ever decide to work on a software/hardware project for general distribution, it would be an honor and privilege to help you with the English language parts of the project.
Finalmente, encontré eso después de publicar. Es lamentable que, dado que ** I ** estoy actualmente en Rusia, estas búsquedas no siempre funcionan sin una conexión VPN a los EE. UU.
Por cierto, (y completamente fuera de tema), si alguna vez decide trabajar en un proyecto de software / hardware para distribución general, sería un honor y un privilegio ayudarlo con las partes del proyecto en inglés.
Thanks for the book - I’m working my way through it. I’m in Chapter 4 and there is an issue when I try “gui := True” – the wheels don’t show up (there is a white wheel-shaped space in the middle of the body). I mention this not for an answer per se, but what is the best place for a discussion thread - here or on GitHub (using “issues” perhaps)? Would be good to have a consistent place for the community that I hope forms around the book.
Thanks,
/K
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For the immediate issue I found this:
http://wiki.ros.org/joint_state_publisher
By including joint_state_publisher_gui as an exec_depend in the package.xml (and running catkin_make), and then creating a new launch file that used joint_state_publisher_gui, and installing ros-melodic-joint-state-publisher-gui with apt I was able to get the sliders to manipulate the joints. I tried it first without the install since I wasn’t getting any error messages about a missing package, but it didn’t work. Once I installed it worked fine. So there probably needs to be an update somewhere (at least for those of us trying Melodic).
There is still the broader issue of where is the best place to go for questions like this. As may be surmised from the above, I do have a little ROS experience. Someone entering this completely new might be stymied. Would be good to have a community forum for questions, discussions, and sharing experiences.
Thanks,
/K
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Particularly as this involves the GoPiGo, (and ROS), these fora are an excellent place to discuss projects.
As far as errata for this book are concerned, brjapon can direct you to wherever he wants to handle that. Sometimes publishers maintain errata sites for technical books they publish, other errata are collected by the authors themselves.
Since it is such an interesting topic, and since others have expressed an interest in the book, perhaps you can make brief mentions of problems that you have found - and solved - here as well.
Thanks!
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@jimrh
I agree - this would seem to be the best forum for a book discussion. Do hashtags work to add a tag? #HoRfRP may be too obscure. Maybe just #HandsonRos?
/K
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We have to get @cleoqc to add a “Tag: HandsOnROS” to the available tags, then all posts can be tagged. Perhaps also a generic “Tag: ROS” would be appropriate also.
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@cyclicalobsessive Having a generic “Tag:ROS” would be nice, and seems like “Tag:HandsOnROS” would also be helpful.
/K
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HandsonRos, and ROS, have both been created. Can you folks use them? Somehow I thought they were restricted to admin.
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We can, for sure. Plus I tested that these two new tags show up for new posts.
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Only admins and the OP can change or add tags on existing posts.
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I’ve downgraded the requirement to tag. Now members (but not new users) can tag a topic.
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Great - thanks. I’ll try with my next post.
/K
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Bernardo, what a great book! I am deep into reading it and using it. Could you show us your hardware setup for using the ydlidar? How did you attach it mechanically and electrically to the GoPiGo3? I am trying to get it to work myself right now and I am wondering whether the GPG3 has enough power with its battery pack to power the YDLIDAR too. What was your experience?
Thanks again for a great book!
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