Patent ID: 8651301

Claim:
A method of controlling a rotation speed of a motor of a speed-controllable hoist drive, the hoist drive comprising a cable, a hoisting member connected to the cable, and a speed-controllable motor which is operationally connected to the cable for lifting a load by means of the hoisting member, the method comprising receiving a lift speed instruction ({circumflex over (ω)}′ m ); forming a final speed instruction ({circumflex over (ω)} m ) by using initial information containing the lift speed instruction ({circumflex over (ω)}′ m ); using the final speed instruction ({circumflex over (ω)} m ) as a speed instruction for the rotation speed of the motor of the speed-controllable hoist drive; the method further comprising monitoring a position derivative of an actual value of a cable force (dF/dz), and the initial information for forming the final speed instruction ({circumflex over (ω)} m ) comprising the position derivative of the actual value of the cable force (dF/dz), which is a derivative of an actual value of a cable force with respect to a position of the hoisting member, the position of the hoisting member being determined based on information (n m ) relating to rotation of the motor.