US Patent 7918158 Baler with automatic sensor calibration

A baler comprises a baling chamber and a sensor arrangement. The sensor arrangement comprises at least one sensor arranged to provide information about a mechanical property of a bale built in the baling chamber and a control unit receiving signals from the sensor. The control unit is operable to automatically calibrate the signals from the sensor based upon at least one signal from the sensor received in at least one known state of the sensor.