For sensing the proximity, i am using this LV-maxSonar-EZ0.
* Ultrasonic range finder.
* 2.5V-5.5V, < 3mA
* Outputs: Serial, Analog Voltage & Pulse Width.
It is a size of a dime. The circuit is pretty simple as below. I will suture as picture above and connect with Arduino as below.
This circuit is same as potentiometer, another physical input of my project, so I’ll use bread board to connect both potentiometer and Range finder to 5v-Gnd. I’ll connect potentiometer to analog 2 and LV to analog 1.