Low frequency vibration type washing machine and method

A low frequency vibration type washing machine is disclosed that is capable of detecting the range of linear reciprocating movement of its drive shaft to control the vibration range of its low frequency oscillating vibrator to be constant, and sensing water level in its washing tub to control the water level. The washing machine includes a low frequency oscillating vibrator adapted to vibrate in a washing tub while being subjected to a water level pressure. The vibrator thereby generates a resonance phenomenon in a multi-phase medium contained in the washing tub. The washing machine also includes a linear motor adapted to drive the low frequency oscillating vibrator, a water level/vibration amplitude sensing unit adapted to detect a vertical vibration amplitude of the vibrator to sense the water level and the vibration amplitude in the washing tub, a commanding unit adapted to output a signal corresponding to a vibration amplitude selected by a user, and a control unit adapted to recognize the water level from an output signal of the sensing unit, compare the output signal of the sensing unit with an output signal of the commanding unit, and control the linear motor so that the vibrator vibrates at a vibration amplitude approximating the output signal of the commanding unit.