Forage harvester

A method of determining a need for actuating a knife sharpening apparatus in a forage harvester comprising a chopping drum having a plurality of knife blades, a knife sharpening apparatus, a discharge spout, image capture apparatus for generating a captured image of processed crop in the discharge spout, an electronic control unit configured to determine data relating to aspects of the crop flow from the captured image, and a memory for storing data relating to the aspects of crop flow as control data, comprising:

• capturing a series of images of the processed crop flowing in the discharge spout;
• processing a first image or a first set of images in the series of captured images to acquire initial data relating to the aspects of crop flow from the first image or first set of images and storing the data as control data;
• periodically processing subsequent images in the series of captured images to determine subsequent data relating to aspects of the crop flow;
• comparing the subsequent data relating to aspects of the crop flow with the control data to determine whether any deviation detected between the subsequent data and the control data exceeds a predetermined deviation;
• and
• if any deviation detected exceeds the predetermined deviation then causing a signal to be generated indicating a need for actuating a knife sharpening apparatus.

A computer implemented method comprising:

• acquiring initial data relating to aspects of crop flow;
• storing the initial data as control data;
• periodically determining subsequent data relating to aspects of the crop flow;
• comparing the subsequent data relating to aspects of the crop flow with the control data to determine whether any deviation detected exceeds a predetermined deviation;
• and
• if any deviation detected exceeds the predetermined deviation, causing a signal to be generated indicating a need for actuating a knife sharpening apparatus.