Tag Archives: openni2_camera

ROS is about: simulation, simulation and simulation …

ROS needs to know everything about the physics of a robot. It starts with dimension to avoid collusions – both with the outside world and the robot itself (e.g. if it is using two robot arms at once).  Further it is relevant where the sensors are – or in my case where the [amazon &title=Asus Xtion&text=Asus Xtion] is located in relation to the robots base. Another interesting information are the robots joints. Its needed to drive the wheels and to rotate the camera. For all that, a detailed description and representation of the robot in a format that a computer understands is essential.

Today I’ve made a hugh step in the simulation field, so struggeling with the motors in the real world for the last few days doesn’t feel too bad – at least I can generate some nice pictures now:

For me an interesting journey started, with a lot ups and downs – currently I am really excited where we will be in 18 weeks – because 2 weeks of my thesis already passed.

Raspberry Pi Robot with ROS, Xtion, OpenNi2 and rviz providing 3d point cloud data

That’s one small step for a man, one giant leap for a small raspberry powered ROS robot.

Okay – maybe thats a bit too big – but I am in a good mood. I compiled the latest openni2_camera ros driver on the little arm cpu of the [amazon asin=B00LPESRUK&text=[amazon &title=Raspberry Pi&text=Raspberry Pi]]. Before that, I used the driver provided by kalectro (see source), which is an older fork but prepared for raspberry.

As a result of that, I’ve got some new features like the IR-Image stream I visualized with rviz :

Raspberry Pi Robot with ROS

Raspberry Pi Robot with ROS

or the handy little parameter with which it is possible to skip some frames which reduces the load a bit:

Now, running roscore on my laptop – I had some sensor_msg/Images I needed to convert into 3d depth data. After some little issues with faulty XML-launch files, I finally got openni2_launch up and running, which is a handy little launchfile using rgb_launch providing every data format you’ll can get out of the [amazon &title=Xtion&text=Asus Xtion].

Now I’ve had a /camera/depth/points topic, with a pointcloud2 datatype. Which is really nice because rviz can visualize it:

Raspberry Pi Robot with ROS - Xtion

Raspberry Pi Robot with ROS – Xtion

Houston, we’ve had a problem.

Yes, there were times when it was possible to land on the moon by the power of a daily life calculator – but todays robots need more than that 🙂 So my aged Intel Centrino Core 2 Duo ASUS-F3J with 1,7Ghz each core isn’t able to do more than I reached today. It pops to 100% processing and after some time it collapses totally.

So todays lesson learned is:

Robots are distributed systems – by every measure.

So I’ll need more power.. again…

Raspberry Pi Robot #1

I’ve completed a new version today. It is a bit smaller and heavier, but already running ros hydro (I will write a small tutorial soon how to achieve that) with OpenNI2 and the ros-package openni2-camera. With that its possible to stream data to another computer visualizing the depth image of the [amazon &title=Asus Xtion&text=Asus Xtion] in rviz. I had some trouble solving and compiling all drivers, dependencies like ros-packages and libs like openCV (see Howto).

When the camera node is running the Raspberry is faced at with a processing load of 100%. The used network bandwidth is about 200-300 kb/s.

I suppose the raspberry Pi needs to be replaced by something stronger soon.

But for my first week in robotics, it’s something 🙂