Joe, you haven't given us much information to go on. Where and how does the sprinkler system tee from the main supply line? Have you tried anchoring the pipes? What's happening is when the controller operates a valve, the sudden closure causes the pressure to vibrate the pipes. Did you install a backflow preventor? These are required when you have a cross connection with domestic water. Was your system professionally designed or is it something you stuck together? Give us something. Photos would be nice.