The Johns Hopkins Beast was an early robot built in the 1960s at the Johns Hopkins University Applied Physics Laboratory. The machine had a rudimentary intelligence and the ability to survive on its own. As it wandered through the white halls of the laboratory, it would seek black wall outlets. When it found one it would plug in and recharge.
The robot was cybernetic. It did not use a computer. Its control circuitry consisted of dozens of transistors controlling analog voltages. It used photocell optics and sonar to navigate. The transistors were used to create NOR logic gates that implemented the Boolean logic to tell it what to do when a specific sensor was activated. The transistors were also used to create timing gates to tell it how long to do something. Power transistors were used to control the power to the motion treads, the boom, and the charging mechanism.
The sonar guidance system was developed for Mod I and improved for Mod II. It used two ultrasonic transducers to determine distance, location within the halls, and obstructions in its path. This provided "The Beast" with bat-like guidance.