Today is a good day, The introduction of the 3rd Generation Pi is available! I cant wait to see what this does for the loop times of my vision based work on the pi.
See the main page for other information: Automated Green House Blog's Home Page
Its a great reason to continue my work on the fish feeder. In summary the feeder is a relatively advanced demand based fish feeder prototype. [We will be refining this over the next few blogs]
The Benefits of Demand based fish feeding are:
>Increased Food Conversion
>Reduced manual labour
The ability to perform demand based feeding hinges mainly on the ability to measure the feeding rate of fish. It is critical that we are able to measure the amount of pellets eaten by fish [in pellets/second] to watch for a decreasing rate of consumption. An Idealised representation of this can be seen Below, any food delivered after a fish has a full stomach is wasted food.
Figure 6 Shows the Prototype Hardware, consisting of:
>Camera [Cheap usb webcam]
>computer [Pi +OpenCv] Thanks E14 for the Pi!
>GUI [Touch Screen] Thanks E14 for the Screen!
How It Works:
The prototype was built to achieve the following:
>Measure number of food pellets in camera view
>Perfom actuation on this information to keep pellet number above a predefined amount
We need to Turn a usb camera image into machine useful information, this is done in stages...
Performance: It works as expected in simulated conditions and a real world experiment with a large fish tank without fish.
Grab an image from the USB Camera
[Sorry Cant Rotate the image...]
Blur image to unify colour
Pick highest contrast colour and turn to Gray scale image
Use a Gaussian adaptive threshold technique to turn to a black and white image
Now we have black blobs on a white background we can use a common Blob detection algorithm to identify the number of pellets in camera view.
Thats it , now we can measure the amount of food in the tank and teck how much of it a fish is eating in pellets/second...
Lots more work to come in this areas, Also the designs for the Pi &" case will be on-line [laser cut].