I was only partially involved in the hardware part. I was writing the VHDL code for the FPGA. The goal was to identify multiple obstacles in a range to 20m. So not detect a wall but more like a laser scanning for objects. There were quite some experiments in shaping the ultrasonic wave to achieve better results. To be honest I don't remember all of it, this was like 15 years ago when I was doing research at the university.