House cats live luxurious lifestyles and can’t bear even the slightest discomfort. For most kitties, “comfort” means lying in the sun while napping. Your cat probably has a couple of favorite sleeping spots in your home that are directly in the sun. But alas, there is a problem: the sun doesn’t stay put in the sky and those toasty sunbeams move throughout day, forcing kitty to move slightly in order to remain in the light. That is obviously a travesty that cannot be abided, which is why Jonathan Diamond robotified his cat’s favorite sleeping stool so that it follows the sunlight throughout the day.
As Diamond explains, his cat Nala is particularly needy and will start whining if her stool isn’t in direct sunlight. This has forced Diamond to move the stool several times during the day in order to appease his furry little tyrant. Fortunately, he had some spare time over the holidays and wisely used that time to motorize the stool. A couple of simple sensors are used to monitor light levels, giving the stool the ability to follow the sun mostly autonomously. Nala can remain perched on the stool all day without worry that the retreating sunlight will interrupt her nap.
Instead of motorizing the caster wheels of the stool, Diamond chose to go with a winch-like setup that drags the stool across the room. The motor for the winch is controlled by a NodeMCU ESP8266 board through an L298 dual H-bridge motor driver breakout board. This setup can only pull the stool in one direction across the floor, which means Diamond has to “reset” it every day by moving it back across the room. But that’s certainly less work than moving it multiple times each day. A couple of light sensors are attached to either side of the stool to determine when it should move. If the “downwind” sensor is detecting strong light while the other sensor is not, that indicates that the stool needs to move. The winch motor is then run until the “upwind” sensor detects strong sunlight, which causes the winch to stop. The result is all-day comfort for Nala without annoying interruptions for Diamond.