Sensors are used for estimating the state of the autonomous system as well as its operating environment. As shown in the chapter on intelligent control depending on particular architecture sensor data processing might vary from architecture to architecture, but all of them implement the simple Sense-Decide-Act cycle. In general, sensors provide information measuring the same phenomena as sensors of biological systems – light, sound, physical orientation, muscle stretch etc… In terms of information acquired by the sensor, they might be grouped into internal and external sensors, where internal provide data on the state of the autonomous system itself, while external sensors provide data on operation environment of the autonomous system. The most commonly used sensor types are discussed below ^[1].

This group of sensors uses ultrasound waves and their feature of reflection from objects/obstacles. Knowing the sound wave propagation time, it is possible to calculate the distance to the first obstacle on the wave’s route. To do it, it is necessary to measure the time between emission and receiving time moments of the sound impulse. Therefore, the senor in its essence is a do-called time of flight sensors or simply ToF.