| abstract |
An output-torque estimation unit obtains a value of a current input to a motor, from a power converter, and calculates an estimated output torque value which is an estimated value of output torque of the motor, from the obtained value of the current. A load estimation unit estimates a load value of a hanging cargo based on the estimated output torque value which is calculated by the output-torque estimation unit, a speed reduction ratio of a speed reducer, an effective radius of a winch drum, and the winding number which is set by the number setting unit. |