Back in 2010, I started reading a book titled Vehicles - Experiments in Synthetic Psychology written by Valentino Braitenberg in 1984.
Braitenberg was a cyberneticist and wrote this book as a series of thought experiments about simple vehicles that exhibit complex "personality" traits.
I got into this book because it excited me that something so simple as a vehicle with two sensors and two motors could "act" afraid, aggressive, exploratory, or even as if it loved a light source.
The most simple Braitenberg vehicle has a single sensor (light, CO2, Infrared, etc.) and a single motor (wheel, propeller, etc.).
The more the sensor is excited, the faster the motor runs. So, in the case of the basic vehicle (assuming a light sensor and a wheel), it would approach a light source quickly, then move slowly through the light, and start moving faster once it was out of the light. It would "prefer" the darkness, much like a cockroach. So, is the vehicle as intelligent as a cockroach?
The next level of vehicle is one with two sensors and two motors, with differing arrangements of sensors and motor connections.
Vehicle a can be said to be afraid of the light, while vehicle b could be considered aggressive towards the light.
The book outlines many more experiments by adding different types of sensors and connecting them to the motors in different configurations to come up with complex simulated behaviors for such a simple design.
I've been tempted in the past to buy some motors and try some of these out myself. I think the FPGA would be a great platform to do this with because it would be easy to wire a sensor directly to a motor. Of course, I guess an Arduino or Raspberry Pi would be easier, since they already have SPI and I²C built in (which most sensors use for communication).
I like to sit and think about these vehicles and I still wonder, is this the most basic form of artificial intelligence? I like to imagine that you could replace a motor with a complex network of other motors and get more advanced behavior out of a vehicle. The book is fascinating and I highly recommend it if you're into robots, artificial intelligence, or programming.
Here is a short video on YouTube on the topic.