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  • Author Author: shabaz
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Building a Robot! (Simulated)

shabaz

After having built a couple of small wheeled platforms (a crude attempt called XMP-1 and a slightly better one called XMP-2) I was curious what simulation tools were out there specifically geared toward robotics design.

This is just a quick summary of one of the simulation tools that are available, called Gazebo.

 

Gazebo was incredibly easy to get going – a single command line will install it onto Linux, and when run it is easy to add bits and pieces from the toolbar and get going.

I’ve yet to work through the tutorials but I’m hoping to eventually simulate XMP-2 so I can write better code easily.

 

Here is a screenshot of Gazebo, and a quick video showing some basic physics, pushing the robot into coke cans.

image

 

Video:

 

More complex movements are possible too. Here is a robot gripper with torque being applied to part of it:

image

Video:

 

The simulation includes gravity and friction and many attributes are configurable.

The models can be created in XML files, and the tutorials look comprehensive.

The example below from a tutorial shows a snippet of a robot, where a box-shaped chassis is needed. The <pose> element contains the position (xyz, and orientation in three dimensions). The <collision> and <geometry> elements contain a <box> element which defines a box of size 0.4x0.2x0.1m in this example.

Usually they are the same; one element is used for the graphics, and the other is for the collision-detection algorithm to use.

image

 

The simulation can be connected up to real hardware or software through the use of an application programming interface (API), so it is possible to test robotics software before you've built the hardware, or you can interface your sensors and start programming movements.

It all looks extremely interesting!

Check out the second part by clicking here, which goes into detail about how to construct a model (based on a real hardware robot called XMP-2) and how to control it using external stimulus.

Parents

  • Hi Shabaz!

     

    It sounds strange but I had serious problems installing Gazebo with the single-command. Used a newly fresh installation of Ubuntu 14.04.3 LT (the last updated) and I get serious issues of dependencies. Maybe there is something I have missed or not read in the Gazebo installation tutorial. What method did you used? The shell script I have downloaded it from the main gazebo site ...

     

    Enrico

  • in reply to balearicdynamics

    Hi Enrico,

     

    Oh, that's odd. I'm running 14.04.3 LTS too (64-bit), when I used the one-liner, it did hang for ages (I wondered if it was working) but eventually it successfully exited.

     

    $ lsb_release -a

    No LSB modules are available.

    Distributor ID: Ubuntu

    Description: Ubuntu 14.04.3 LTS

    Release: 14.04

    Codename: trusty

     

    But, mine was initially a 14.04.1 install, and later updated. For an unrelated project I had issues with 14.04.2 at the time I installed that version of Linux, so I had specifically install 14.04.1 and then update. 14.04.2 fresh install was bad. I can't remember why.

     

    I'll try on a freshly downloaded install of 14.04.3 and get back to you shortly.

  • in reply to shabaz

    Hi Shabaz,

     

    don't worry that the result with the fresh installation is almost the same you are describing.

     

    First I have tried with a VM with Ubuntu 12.x and I got bad responses, only the latest versions of Ubuntu was supported. So I have updated the version to 14.04.3 LT and after some hours, kernel recompiling etc I have relaunched the installation and all was wrong. Always the same problem, the gazebo6-common package can't be installed due a problem. So first of all I decided to move to a new VM with a just downloaded fresh installation of Ubutu 14.04.3 LT. The next information refers to this Linux version updated and upgraded.

     

    Checking the installed packages instead the Gazebo6-commons libraries was already present and normally installed. The issue is generated by the gazebo6-standard-plugin-base that can't install in a circular problem:

     

    • gazebo6 depends on the gazebo6-plugin-base and the plugins package depends on gazebo6
    • The unresolved dependency comes from gazebo6-commons
    • The gazebo6-common package is already installed

    And so on...

     

    The next try was to investigate on the added repository. The issue (maybe an issue of the mentioned one-comman setup) is that the automatically added repository is not he osrfoundation.org stable version but a similar one including pre-release and bet versions. The next image shows the two packages where the first is actually disabled in my machine

    image

    The enabled package instead is the stable version mentioned in the Ubuntu step-by-step installation tutorial in the gazebo page. After this change a lot of troubled packages installed correctly without great problems, but remained the issue of the gazebo6-commong. That remain unsolved. To investigate in a more comfortable way and accessing to many parameters at the same time and fast I have installed Synaptics Getting a more explicit message I discovered that the installed package gazebo6-common is the immediately next subversion than the one expected by the gazebo6 application dependencies. AFAIK this is an issue of the setup system that I hope they will update soon. Alternatively it is a general issue of Ubuntu: it is not rare that Canonical remove the  old versions packages creating these problems.

     

    At this point, as my goal was to launch the Gazebo application, I saw that there are not so great differences between the version 5 (the last real stable) and the most recent 6 that seems almost young.

     

    With the osrfoundation.org repository added to the aps-get system from synaptics the various versions of gazebo are all visibile. The procedure that I followed is the following:

     

    • Removed all the installed components of gazebo6
    • Selected only the gazebo5 package. All the other gazebo5 components are selected and proposed automatically, and I have confirmed
    • Launched the Installation.

     

    All worked fine and the program started.

     

    I suggest that if you make a fresh installation of Ubuntu14.04.3 LT, install sudo apt-get install synaptic then add the osrd foundation.org repository (the one checked in the image above) and try the procedure I have followed for gazebo5 with gazebo6.

     

    I hope this will help. Enrico

Comment
  • in reply to shabaz

    Hi Shabaz,

     

    don't worry that the result with the fresh installation is almost the same you are describing.

     

    First I have tried with a VM with Ubuntu 12.x and I got bad responses, only the latest versions of Ubuntu was supported. So I have updated the version to 14.04.3 LT and after some hours, kernel recompiling etc I have relaunched the installation and all was wrong. Always the same problem, the gazebo6-common package can't be installed due a problem. So first of all I decided to move to a new VM with a just downloaded fresh installation of Ubutu 14.04.3 LT. The next information refers to this Linux version updated and upgraded.

     

    Checking the installed packages instead the Gazebo6-commons libraries was already present and normally installed. The issue is generated by the gazebo6-standard-plugin-base that can't install in a circular problem:

     

    • gazebo6 depends on the gazebo6-plugin-base and the plugins package depends on gazebo6
    • The unresolved dependency comes from gazebo6-commons
    • The gazebo6-common package is already installed

    And so on...

     

    The next try was to investigate on the added repository. The issue (maybe an issue of the mentioned one-comman setup) is that the automatically added repository is not he osrfoundation.org stable version but a similar one including pre-release and bet versions. The next image shows the two packages where the first is actually disabled in my machine

    image

    The enabled package instead is the stable version mentioned in the Ubuntu step-by-step installation tutorial in the gazebo page. After this change a lot of troubled packages installed correctly without great problems, but remained the issue of the gazebo6-commong. That remain unsolved. To investigate in a more comfortable way and accessing to many parameters at the same time and fast I have installed Synaptics Getting a more explicit message I discovered that the installed package gazebo6-common is the immediately next subversion than the one expected by the gazebo6 application dependencies. AFAIK this is an issue of the setup system that I hope they will update soon. Alternatively it is a general issue of Ubuntu: it is not rare that Canonical remove the  old versions packages creating these problems.

     

    At this point, as my goal was to launch the Gazebo application, I saw that there are not so great differences between the version 5 (the last real stable) and the most recent 6 that seems almost young.

     

    With the osrfoundation.org repository added to the aps-get system from synaptics the various versions of gazebo are all visibile. The procedure that I followed is the following:

     

    • Removed all the installed components of gazebo6
    • Selected only the gazebo5 package. All the other gazebo5 components are selected and proposed automatically, and I have confirmed
    • Launched the Installation.

     

    All worked fine and the program started.

     

    I suggest that if you make a fresh installation of Ubuntu14.04.3 LT, install sudo apt-get install synaptic then add the osrd foundation.org repository (the one checked in the image above) and try the procedure I have followed for gazebo5 with gazebo6.

     

    I hope this will help. Enrico

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