Monthly Archives: October 2014

Low cost Hector_mapping with Xtion, 9DRazor IMU and no hardware odometry

This weekend I had the chance to indoor slam by simply walking through my flat with an [amazon asin=B005UHB8EK&text=Asus Xtion] (150 EUR), an 9DRazor (+3.3 FTDI and Cable around 100 EUR) and a common [amazon asin=B004URCE4O&text=Laptop].

By setting up ROS Indigo and using existing software I now can create a simple 2D map of my flat and thanks to the PhD Programm Heterogeneous Cooperating Teams of Robots (Hector) of the TU-Darmstadt, which I slightly modified to fit the low cost setup, the results are quite impressive.

The Xtion is not capable of delivering a 360 degree view, which is why i needed to walk slowly. By changing the setup from a weak ARM to an powerful Intel i5, data rates and size was way better than the aMoSeRo was capable of:

For the ROS interested folks here some ROS related graphs:

It has been a weekend project, therefore the source and some semantic things are not beautiful but working.  E.g. the TF Tree is statically imitating the suggested setup on the Hector Wiki.

Maybe we could profit from using two Xtions and merging the /scans together. By that we would achieve a 300 EUR replacement of a at least 1000 EUR 2D Laser Scanner and would be able to 3D PointCloud everything later.

Thesis passed.

I finished my thesis and passed. As a consequence, I soon will publish my work on this website. Unfortunately the German laws according to copyright forbid to use pictures taken by others without according licenses or paying money. I am currently thinking of replacing certain pictures by a bit worse, but free versions of them, before uploading it. I maybe also will divide the 50 pages into semantic parts and publish is as static part of the website soon.

Colloquium

I am going to demonstrate the complete thesis and the aMoSeRo on:

Monday 20th, October 2014 – 10.00 am
URZ-3409 – Universitätsrechenzentrum
Bernhard-von-Cotta-Straße 1
09599 Freiberg

 Maps

Synchronize the time in ROS offline environments without chrony

As our [amazon &title=CubieTruck&text=CubieTruck] is faced with strange issues when using chrony and internet access is not a general prerequisite on ROS setups, i needed to figure out a new way to synchronize the time with no internet ntp server available. For some reasons, even my local ntp was broken, which is why I try to set the time according to the ros master on all clients by this simple bash command:

it simply extracts the IPv4 part of the $ROS_MASTER_URI environment and uses ntpdate to set the time on the excecuting client system.

In case you only want to know the exact time derivation consider using the ntpdate parameter -q which only emulates the request.