Method for estimating the amount of laundry loaded in a rotating drum of a laundry washing machine

The present invention relates to a method for controlling a laundry treatment machine (1) comprising an outer casing (2), a washing group which is placed inside the outer casing (2) and comprises, in turn, a rotatable drum (6) structured for housing the laundry to be treated, an electric motor (16) for rotating the drum (6); the method comprises the steps of: controlling the electric motor (16) to cause the drum (6) to change its rotational speed according to a prefixed reference speed profile comprising at least an acceleration ramp (Ra(i)), wherein the drum (6) is accelerated from a low speed (B1) to a prefixed high speed (B2) and at least a constant speed phase (S(k)) wherein the drum speed is maintained about the high speed (B2), sampling first torque values (Ti) generated by the electric motor (16) during the acceleration ramp (Ra(i)) according to a prefixed first sample time (Δta), sampling second torque values (Tj) generated by the electric motor (16) during the constant speed phase (S(k)) according to a prefixed second sample time (Δtb), calculating a third value (TU), which is indicative of an average torque value based on said second torque values (Tj), determining a fourth value by performing an approximate integral calculus consisting of subtracting said third value (TU) from said first torque values (Ti), and determining the amount of laundry load (QL) on the basis of said fourth torque value (Torque_int).