Baler crop speed tracking

An agricultural baler configured to move over a field and collect cut crop material and to compress, shape, and secure the collected plant material into a non-homogeneous compressed bale, the baler having a reciprocating plunger 108 moving in a baling chamber 110, wherein the baler comprises:

• at least two sensors configured to detect a variable characteristic of the baled non homogeneous crop material, wherein the sensors are positioned serially in a longitudinal path of the bale of compressed crop material as the bale moves rearwardly in the baling chamber, with sensor being spaced from sensor in a longitudinal direction by a sensor spacing distance, and wherein each of the sensors is mounted in the baling chamber in such a manner that each of the sensors detects the variable characteristic of crop material of the bale at a plurality of sample points along a sample line as the bale is pushed towards a discharge end of the baling chamber;
• and
• a controller configured to receive variable characteristic signals over time from the sensors for the plurality of sample points along the sample line and generate a sensor profile for the bale from each of the sensors, wherein the controller identifies time differences between coordinated identifying events on the sensor profiles for the sensors and using the sensor spacing distance determines a speed of movement of a bale.