A little history
Grey Walter's tortoises, 1948
The British neurophysiologist William Grey Walter built two robot «tortoises» — Elmer and Elsie. Under the shell — a photocell, a bump contact, two motors and two radio valves instead of a brain. The tortoise drove towards light, and when it bumped into an obstacle it backed off and turned. No program: the behaviour came straight from how the wires connected the sensors to the motors. Our «bug» from lesson 2 is their direct descendant.
A cart that follows a wire, the 1950s
The first factory robot carts drove along a wire set into the floor: two sensors left and right of it, and if the wire «drifts» towards one, the cart steers. In the 1950s the American company Barrett Electronics released such a towing tractor — and ever since, warehouses and factories have been full of carts that follow a wire, a painted stripe or a magnetic tape. Lesson 5 is the same, only the line is drawn on paper.
Braitenberg vehicles, 1984
The neuroscientist Valentino Braitenberg wrote a little book, «Vehicles»: carts whose sensors are connected straight to the motors — sometimes crosswise, sometimes through a «NOT». One runs away from light, another is «drawn» to it, a third is «afraid» of walls. Simple logic between sensor and wheel looks like character from the outside. Our line follower is a Braitenberg vehicle: each wheel listens to its own sensor.
Ultrasound: from a camera to robots
In 1978 Polaroid released a camera that measured the distance to its subject with ultrasound — it beeped and counted how soon the echo came back. That range finder quickly spread through robot labs. Today its heir is the cheap HC-SR04 module: pulse the TRIG pin, and the ECHO pin gives a pulse whose length is the distance. Exactly the sensor our robot has.
The robot vacuum, 2002
The first mass-market robot vacuum drove almost like our «bug»: straight until the bumper, then a turn by a random angle and on — in half an hour such a «random bounce» covers the whole room. And sensors underneath noticed the edge of the stairs. In this kit — the same robot, but you can see its whole «brain»: fifteen chips on the canvas.