Computer Vision and Robotics Demo with Raspberry Pi

SetupThis spring, I spent some time at SAP’s commercial hackerspace. I wanted to explore how computer vision can be used with embedded devices and robotics. I built a demo that can detect QR codes and similar symbols and point a laser at them. Possible applications of this are putting QR codes on objects to help the robot locate them and grab or manipulate objects. Another possible use case is local navigation. A robot could infer its own location and orientation in space by detecting QR codes with known locations.
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Work in progress: Location based online game

Screenshot (21)This is a game prototype I’m currently working on. The game is played online, on a real world map and the location of the player is also the location ingame, just like in Ingress.
I know that making an online game like this is an ambitious goal and it will probably never be finished, but this prototype is a good way for me to test the game mechanic and see what works and what doesn’t.

The prototype is a web app and doesn’t yet use the player’s location, meaning they can interact anywhere on the map. If all works out, I’ll make a mobile client, which will be the actual game.

The game is about finding resources and mining them. I’m trying to make the resource locations meaningful and related to the real world. So I wrote an engine that procedurally distributes resources on the map, based on map data provided by Open Street Map. This allows me to define rules like “Resource 1 can be found at water fountains near public parks”, or “Resource 2 can be found only in forests and only within 100 meters of a school” and so on. Here is an example:
Screenshot (5)

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Game prototypes

I’d like to share two game prototypes I made a few years ago. The first one is based on Tetris:

It was written in C++ with bare-bones OpenGL. Once you press shift, the game enters a “fast mode”, where the down button takes a piece all the way down and if you don’t press it for three seconds, it will drop where it is. This is meant to be a fast-paced version of the original Tetris.

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Raspberry Pi powered fishtank

My fishtank is now internet-connected. It is run by a Raspberry Pi that can do three things: Feed the fish, switch the lights and take pictures.

To feed the fish, the Raspberry Pi sends commands to an automatic fishfeeder that I modified. It can empty any container in any order. This is achieved by an Arduino Pro Mini, two servos and a motor (more). The plate prevents hot air from flowing into the feeder. In an early iteration of the project, this made the food sticky and kept it from falling into the tank. Switching the lights is done using a remote light switch and 433Mhz transmitter. Finally, there is a webcam that is connected directly to the Raspberry Pi to take pictures. Continue reading

Connecting my fish tank to the Internet of Things – Part 1: Hacking an automatic fish feeder


I bought a used automatic fish feeder from ebay. This device is completely mechanic and very old (older than 1989). It has 27 containers for fish food and a disc that does one rotation per day. By sticking pins into that disc one can trigger one or more feedings per day. A pin will rotate an outer ring with the containers by one unit. One container always faces down, emptying its contents. So if the outer ring has made one revolution, all containers have been emptied. Continue reading