US Patent 9730382 Vegetation cutting device

A vegetation cutting device comprises: a housing; a motor mounted in the housing having a rotatable drive shaft; a gearing system comprising a rotatable output shaft, the gearing system adapted to be driven by the drive shaft; a rotatable cuffing head mounted on the output shaft; a rotation sensor module mounted in the housing and configured to detect the rotational speed of the motor and configured to output a rotational speed signal; and a control module configured to determine the rotational speed of the cutting head based on the rotational speed signal and configured to control the speed of the motor in response to the determined rotational speed of the cutting head.