TomGeorge:
Hi, have you got filter and bypass capacitors around the voltage regulators, see their data sheet for info.
Can you post a CAD or picture of a hand-drawn circuit diagram in jpg,pdf or png for us please.
Even though you are supplying the voltregs off a battery, the perfomance of the regulators relys on noise and load transient filtering.
? have used voltage regulators with capacitors 330nF at the input side and 100nF ath the outside. Sorry that I have no visual material to upload now. My question is that If this Ultrasonic sensor works properly when Arduino is powered by USB why it misfunctions when it is powered by battery? Each part works well but not Ultrasonic sensor.