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Examples

Follow ARTag

An ARTag follower example for a stock Leo Rover

Prerequisites

Home

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Examples

Follow ARTag

An ARTag follower example for a stock Leo Rover

In this example, we will show you how to make the Leo Rover mobile robot follow an ARTag.

What to expect?

After completing this tutorial, your rover should be able to follow a printed ARTag.

Prerequisites

List of components

  1. Any computer which you can connect to the rover via ssh.
  2. Stock Leo Rover.

Mechanical integration

The only physical thing you'll need to do is to print an ARTag:

  • You can download an ARTag from here (you'll need only the one in the top-left corner), or you can follow the instruction on generating markers from ros wiki.
  • The printed ARTag needs to be 16cm x 16cm.
  • The printed ARTag needs to have a white border around it.

Here's an example of our ARTag that we used for this task:

leo rover alvar artag
Remember that the white border around the tag is necesarry. You can leave the printed tag on the peace of paper, but we do recommend, to attach it to some harder material like cardboard - this way ARTag won't bend, so it will be easier for the software to notice it.

Wiring and electronics connection

Software integration

To complete those steps, you need to connect to the rover's network first, and then log in using ssh (both covered in prerequisites).
One package in the leo_examples repository depends on ar_track_alvar package. As there is no release for the ROS version running on the rover (notetic) yet, you have to insatll it manually. To do so, type:

Installing using apt

You can install the package using apt by typing on the rover

Then you just need to source the ros workspace

Building from source

You can also get all the needed software from our leo_examples github repository. You need to clone it on the rover in the ros workspace directory (if there's no such a directory, then, first go through the ROS Development tutorial):

Now, you need to install all the dependencies for the downloaded packages:

Then, you need to source the directory and build the packages:

If your installation went without any errors, then you have successfully installed required software.

Examples

To run the example, you need to be connected to the rover via ssh. Once you do this, type in the terminal:

The rover will start following the ARTag once it detects it.

The rover will follow only the ARTag with id 0, so it's important that you print the correct one - specified in the Mechanical Integration (Don't forget about the white border).

What next?

After completing this tutorial, you can try other examples from the leo_examples repository (line follower and object detection), or try other integration from our site.

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Need help? Contact us - contact@fictionlab.pl