EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Gate; General Flight Cancelled / Delayed
Aircraft
Upon taxiing to [Runway] XXL; a loud banging and grinding sound with vibration and shimmy would happen intermittently on taxi with no real reason. Once crossed XXR we asked ATC if we could pull off and called Maintenance; they agreed best course of action was to gate return. Taxied back in slowly still hearing and feeling strange sounds and vibrations intermittently. Once parked a quick inspection by Maintenance revealed that while everything looked normal when still; once the aircraft was moved (they rocked it) the entire nose gear assembly wobbled and was loose. We were delayed swapped planes and continued [the] day as normal.The aircraft was received like this. It had already flown more than likely like this. There needs to be better discipline on reporting foreign sounds. Also; push crews sound like they are fighting a war when they hook up and disconnect. Maybe there is a correlation there.
EMB-145 Captain reported noticing grinding sounds and vibrations during taxi-out resulting in a return to gate for an aircraft swap.  Post maintenance inspection revealed the nose gear assembly was loose.