Once upon a time, there was a bird-owning engineer with a problem: his African Grey Parrot would, like most of their species, become very upset when away from what they considered the center of action in an area, and would start hooting and screeching for attention. His first solution was a noise-detecting squirt gun. At first this worked, and the spray of water would interrupt the screaming. Then the bird figured out how it worked and started intentionally triggering it for a quick bathtime, which parrots love. (African Greys have the intellectual capacity of a 3 year old on average, but have some skills that human children don't figure out until they're 12.)
It's not safe to let a parrot walk around unattended, one because they are immensely small and light and they will die if you step on them. (A medium sized parrot such as an African Grey weighs about one pound. The heaviest known parrot weighs 8 pounds.) Another reason is that they can chew on things on the floor, or even the floor itself, causing immense property damage. So his next idea was one that allowed the bird to travel around safely: a small motorized bird-controlled cart. The bird stands on a small perch, and pushes around a metal bar to control the cart. This way the bird could follow the humans of the house around without ever being underfoot or in the path of tempting electrical chords, rugs, or floor tiles.
The joystick component appeared to be one of the surprisingly larger engineering challenges. A parrot's beak evolved to crush nuts, is about a strong as a human with a pair of pliers, and they immensely enjoy ripping things to shreds with it. The top part can punch through wood like an awl, and the larger parrots can even destroy a steel cage. The joystick had to be designed in such a way to resist puncture, pressure, and had to endure being pulled on, all of which the bird almost assuredly tried to do.
The most challenging thing though, is that our enterprising engineer did not want to have to put this cart away every day when it's time for the bird to go to bed. The cart is designed with a computerized system that can find its way back to the charger, and slowly scoot the cart into position where it gets plugged in and charged back up for another day of bird-moving. This does so with computer-vision, which is remarkably difficult to do successfully. Also, it begins to do this the moment the parrot leaves the cart.
If I were this engineer, I would look into having this cart mass-produced.