A method for sensing the motion of the wash assembly due to the dynamic unbalance of the wash laundry drum assembly in a washing machine comprising a casing and the wash assembly which comprises a tub connected in floating manner to said casing and a laundry drum assembly; said laundry drum assembly comprising a laundry drum mounted to rotate freely about a longitudinal axis of rotation inside said tub and means (8,18) for rotating said laundry drum about said axis of rotation; whereby said method further comprises the step of increasing the rotation speed (ω) of said laundry drum to a first rotation speed (ω DIST) at which the laundry adheres completely, in a fixed distribution pattern, to the inner wall of said laundry drum; said method being characterised by comprising the steps of: a) determining, when said first rotation speed (ω DIST) is reached, a first parameter (T FRICTION; A HFREF) related to the time pattern of the values of an unbalance function A=T-Jdω/dt filtered at a predetermined filtration frequency (LF; HF); T and ω being the torque and rotation speed, respectively, imparted to said laundry drum, and J being the moment of inertia of said laundry drum assembly; b) as of said first rotation speed (ω DIST), repeatedly increasing the rotation speed (ω) of the laundry drum by a predetermined value (Δω) to cover a predetermined resonance rotation speed range (D FR) of the wash assembly; c) determining, at each increase (Δω) in rotation speed (ω) within said predetermined resonance rotation speed range (D FR), a second parameter (A LF; A HF) related to the time pattern of the values of said unbalance function A=T-Jdω/dt filtered at said predetermined filtration frequency (LF; HF); d) calculating the difference (T dynLF; T dynHF) between said second parameter (A LF; A HF) and said first parameter (T FRICTION; A HFREF); e) determining a dynamic unbalance parameter (T dynLF; T dynHF) related to the dynamic unbalance torque (T dyn) of said laundry drum assembly as a function of said difference (T dynLF; T dynHF). a) determining, when said first rotation speed (ω DIST) is reached, a first parameter (T FRICTION; A HFREF) related to the time pattern of the values of an unbalance function A=T-Jdω/dt filtered at a predetermined filtration frequency (LF; HF); T and ω being the torque and rotation speed, respectively, imparted to said laundry drum, and J being the moment of inertia of said laundry drum assembly; b) as of said first rotation speed (ω DIST), repeatedly increasing the rotation speed (ω) of the laundry drum by a predetermined value (Δω) to cover a predetermined resonance rotation speed range (D FR) of the wash assembly; c) determining, at each increase (Δω) in rotation speed (ω) within said predetermined resonance rotation speed range (D FR), a second parameter (A LF; A HF) related to the time pattern of the values of said unbalance function A=T-Jdω/dt filtered at said predetermined filtration frequency (LF; HF); d) calculating the difference (T dynLF; T dynHF) between said second parameter (A LF; A HF) and said first parameter (T FRICTION; A HFREF); e) determining a dynamic unbalance parameter (T dynLF; T dynHF) related to the dynamic unbalance torque (T dyn) of said laundry drum assembly as a function of said difference (T dynLF; T dynHF).