The Raspberry Pi is so powerful and has so many GPIO lines it does not need many external components to be turned into this ultrasonic-assisted walking cane for the blind and visually impaired. It not only features buzzer/vibrator warning outputs for object distance but also a loudpseaker or earphones for speach synthesis through a voice synthesizer software running on the Pi.  This distance measuring assistant will greet you, measure distances to objects continuously and read the values out loud. It can be programmed to activate alarms when the measured distance crosses a user-programmed limit. Got a pair of U/S distance sensors and an RPi ready? Then go.   Rather than designing a dedicated PCB, Elektor Labs used their ELPB-NG (that's Elektor Labs Prototyping Board New Generation) for the project. It's available from the Elektor Store.