The system is composed of two infrared sensor with the aim of intercept obstacles or one single descendant step in front of the user’s feet, one ultrasonic sensor to cut the first part of the calibration curve of the infrared sensor and to intercept some particular surfaces, four vibrating motors to give the signals to the user and a microcontroller to manage the input and output signals and to develop the decisions. The infrared sensors are located, as is possible to see in Fig. 1, one on the left and the other one on the right of the system, this able us to intercept the obstacles near the feet. All components are placed on a belt, wearable on the user’s body. This choice implies the presence of a great noise on the sensors signals so it will be necessary to implement a low-pass filter with the aim to clean it.