Quo Vadis ? Stories from a home laboratory


Elektro Pioneer – remotely controlled motorized baby stroller

Some time ago, a life-changing event influenced the ways I had been organizing my free time. The focus has been moved from the home laboratory towards two young creatures. That was one of the reasons I haven't been much active with my hobby. I haven't fully given up on the small projects, just reduced the time I was spending working on them and publishing the results.

Nevertheless, the parenting can bring different ideas to the mind of an engineer, and what I would like to show in this post is one of those ideas I actually went through materializing. As some of you (parents) might know, the really important item in any house with babies is the stroller. Zillion different types, a lot of time invested in selecting the right one, but eventually the stroller quickly becomes old news.

Elektro Pioneer

Somewhere around that period I got bored with the traditional use of the strollers and decided to try to motorize it and make it remotely controllable. The prototype has been finalized in mid 2013, and in the rest of this post I will describe the whole process.

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Balcony irrigation

A couple of years ago, I have installed the automated irrigation system in our apartment. After running this setup for an year, I have discovered some problems during the everyday operation:

  • due to the small capacity of the water tank, it was required to refill the tank frequently,
  • amount of water delivered to the plants was determined by time (averaged measured value I got with calibration) and was not accurate,
  • it was not possible to irrigate plants independently,
  • couple of times the whole water tank was used for single watering thanks to basic physics in action and lack of the valves.

In a meanwhile I have decided to automate the watering of the balcony plants as well, but also to fix the problems noticed in the first implementation.

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Monitoring temperature and humidity

For almost a year I was playing with various temperature sensors and Arduino. Initially the plan was do use some cheap DHT11 sensors in order to measure soil moisture. After running number of tests I found this method not so reliable. Then, I put a number of DHT11 sensors in the house in order to measure temperature and humidity. Out of 10 sensors, only 2-3 were detecting correct temperatures. Then I tried DHT11's bigger brother DHT22. The results were much better.

The idea for this project was simple and already seen in number of different projects around the Internet:

  • install a wireless node in every room of the house and collect temperature and humidity,
  • send this data to the central node (using the same (upgraded) central node described in previous posts),
  • store data in database,
  • display data (web page, iPhone notifications).

System overview is displayed in the picture below:

System design

System design

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Hacking a weighing scale

Last couple of weekends I mainly spent at home. This was ideal opportunity to do some home maintenance (cleaning 🙁 ). Somewhere under the bed I found a weighing scale that my wife and I occasionally use. This is the simple digital weighing scale from Ikea - GRUNDTAL. During last months I stumbled upon couple of articles about automatic weight logging, so the outcome was obvious: the next home project - wireless logging weighing scale. Luckily I already had necessary tools and parts, so the next couple of days were fun.

IKEA GRUNDTAL Weghing scale

The idea was to connect the scale to Arduino Pro Mini, decode the readings from the scale, and send the weight wirelessly, using RFM12B radio module from HopeRF, to the central Homy system. There, the weight with the timestamp would be persisted into the database and published to Facebook wall.

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Homy & Roomba

Roomba has been in our home for some time now. You could even say it a part of the family; it is the liveliest piece of the furniture. We use it for cleaning our apartment and we are pretty happy with it. This cleaning device is a product of iRobot company and the model we have is Roomba 520.

Going around the Internet sites I stumbled upon a nice article about some hardware and software development that includes Roomba - RoombaDecTools. Next thing I dig out was a really nice document that describes technicalities about interfacing Roomba - Roomba Serial Command Interface (SCI) Specification. Everything was clear, a new home project was about to be born 🙂

Our Roomba

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