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This is the fourth evolution of brick sorters! This time sorting 10 types of bricks: 5 colors and two sizes. You can simply throw a set of bricks into the sorter, and the machine will handle the rest.
Compared to sorter #2, this one is more reliable and more functional too. This robot uses both the NXT and the RCX, with the NXT as master. The RCX is controlled by the NXT, through a
legacy controller provided by mindsensors.com. I'll now discuss each of the components in the sorter in order, starting at the top,
where a set of bricks is thrown into the machine. This brick sorter was designed in July 2007.
Other brick sorters in this series:
Every time I created a new brick sorter, I tried to tackle a new design challenge, for example by adding a new functionality,
or to make the robot more reliable. Follow the links below, and read the pages in order to learn about my findings in the design process.
A detailed look at the design
Colored bricks of two sizes are put onto a conveyor belt,
which repeatedly moves forwards and a little bit backwards, making one or two bricks fall into the brick store at the time.
This mechanism is improved over the previous sorters, but it is still not perfect. Sometimes a brick may get stuck in the brick store, making it impossible for the process
to continue succesfully.
Once dropped off the conveyor belt, the bricks slide into the chute, through two turning wheels in the brick store.
If the light sensor in the chute detects any bricks, the conveyor belt at the top stops moving.
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In the chute, the bricks are all nicely aligned. Consequently, it is possible to push the first brick in the queue to the side, enabling it to slide down to the color sensor.
The sensor compartment consists of three important modules. The brick lock (removed on the image to the right), is used to keep a brick in the scanning compartment during the scan and to
release the brick when the scan is over. Depending on the size of the brick, the light sensor will see a drop in a light sensor value. A small LEGO light bulb, along with a phototransistor
are used to read the color of the brick. This gave better results than using the regular LEGO light sensor, which is unable to distinguish yellow from red, for example.
Once the brick sorter knows the size of the brick, it will turn the brick slide, allowing a brick to go in either the left or right bins.
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Once the machine knows the color of the brick to be sorted, it moves the platform with bins in a way that if a brick is released, it will fall in the correct bin.
A mindsensors.com IRlink is used to send basic commands from the NXT to the RCX.
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