Woof woof, and that's it! Your dog is the new Alibaba as far as unlocking doors are concerned, the magical spell being just its usual bark. New pet owner and Raspberry-Pi enthusiast David Hunt wanted to let his dog attend its early morning piss-call without having to depend on anyone, and he found a creative DIY solution in a rigged door that automatically opened with just a bark- a creation he's named Pi-Rex. In order to simplify the whole procedure, Hunt chucked the expensive camera gadgetry for a more affordable noise-detector circuit, backed up by Raspberry Pi and motor driver PCB circuit. When the mini computer detects the bark, the circuit prompts the actuator and a simple pulley system to open the door to a bladder-discharging heaven.
Here's how David recounts the process-
Also, the code to read in the GPIO from the audio circuit has been given away by Hunt in his website, so if you want to give your own dog this much freedom, you know where to look. Now it's a great invention, considering that your dog won't have to bark pointlessly in the morning, but if that dog is THE only "security" you have at your place, I'd recommend you to think a dozen times before making it this door.
Watch the video below: