I’ve been yearning for a new project for a while now.
Thought I’d try something more physical this time. Opening a window (for the cat).
I’m thinking I could maybe even start with an old windscreen wiper motor and an H Bridge motor control board.
For sensors, I could use blinkered motion sensors, but I think the cat is smart enough to use a button/level it paws for access.
Safety: The actuator mechanism will be 3M sticky padded onto the plastic window frame. That should provide enough Ns to move the window, and not much more. If I keep the actuator speed low, the current should be low. If the current rises, the system unpowers the actuator. There will be enough flex to free a squeezed cat. It can re-enable after a 1 minute pause.
The actuator limits can be determined by motor current, so that “safety mechanism” above would be inherent in the design. “Move the actuator” “Stop if current exceeds 1 amp”. So it will run the motor until it hit the physical limits when the motor current spikes, the MCU shuts it off. The same would happen if the cat was standing with her head alone in the window when it starts to close. If the cat is still there when the window pinches her, the current will spike and the motor will stop… assuming the window is closed of course.
Security: No impact. The window still has a manual lock for when the house needs to be secure. The opener can be disabled or just left on, as … again… current will spike, motor shuts off.
Control:
Scheduled opening/closing.
Cat paw lever opening/closing.
If cat opens window. Wait 1 minute then close window.
If window is activated more than twice in a 5 minute period, ignore until 5 minute period expires. (stops the cat playing with it and stops accidental triggering operating it all day.
Monitoring. Off course the MCU in control is aware of what’s going on, but it will be in cohorts over MQTT with the HA/Automation services. A magnetic sensor on the window itself could be used to monitor how well it acheives it’s task and even an ESP32Cam trigger to watch what’s happening could be cute.
Thoughts? Examples of similar?