Ultrasonic object detection and distance measurement makes sense where light (as a carrier) does not work properly, e.g. in sunlight or smoky environments. More your information, I had a close look at suitable sensing ICs recently, see full story here. In fact, Digi-key is offering two recommendable TI solutions TUS4440/70 and PGA460 which seem to be good choices for most target applications at reasonable prices.
Cheers,
Kersten
