I have now duplicated my code that I have done for one HC-SR04 set-up in order to now have two ultrasonic sensors acting as left/right eyes for the blind user. I will later work on how to combine reading the two sensors on one micro-controller board (probably a raspberry pi) in order to save space on the device. I will then work on using 4 sensors for front/right/left/back of the user in order to try to achieve a full 360 sensor set up.