Controller for an agricultural machine

1. A controller for detecting an unwanted object in an agricultural machine, wherein the agricultural machine includes a pair of rollers for receiving crop material therebetween, the pair of rollers defining a variable roller opening therebetween, wherein the controller is configured to:

receive a roller-opening-value that is representative of a size of the roller opening;

determine a strength-value based on the roller-opening-value and a roller-speed-value, wherein the roller-speed-value is representative of a rate of change of the roller-opening-value, with respect to time;

compare the strength-value with a threshold-value; and

if the strength-value exceeds the threshold-value, then provide an output signal that is indicative of an unwanted object being detected, wherein the controller is configured to determine the strength-value based on one of:

a maximum-roller-opening-value and the roller-speed-value, wherein the maximum-roller-opening-value is a maximum value of the roller-opening-value in a preceding window of time; and

the roller-opening-value and a maximum-magnitude-roller-speed-value, wherein the maximum-magnitude-roller-speed-value is a highest magnitude of the roller-speed-value in a preceding window of time.

2. The controller of claim 1 , wherein the controller is configured to:

receive (i) an operating-characteristic-signal that is representative of an operating characteristic of the agricultural machine or (ii) a crop-characteristic-signal that is representative of a crop characteristic of the crop material that is to be harvested; and

set a sensitivity of the controller for providing the output signal that is indicative of an unwanted object being detected, based on the operating-characteristic-signal or the crop-characteristic-signal.

3. The controller of claim 2 , wherein the controller is configured to set the threshold-value in order to set the sensitivity of the controller.

4. The controller of claim 2 , wherein the controller is configured to:

set a scaling-factor based on the operating-characteristic-signal or the crop-characteristic-signal, in order to set the sensitivity of the controller; and

determine the strength-value by applying the scaling-factor to the roller-opening-value or the roller-speed-value.

5. The controller of claim 2 , wherein the controller is configured to set the sensitivity as a value that is in an auto-sensitivity-range, which represents a subset of a maximum range of sensitivities that can be applied.

6. The controller of claim 1 , wherein the controller is configured to:

process a plurality of roller-opening-values to determine an average-roller-movement that is representative of an average amount of roller movement over a period of time; and

set a sensitivity of the controller based on the average-roller-movement.

7. The controller of claim 1 , wherein the controller is configured to:

receive a detection-count-value that is representative of a number of detections that occur in a preceding period of time; and

set a sensitivity of the controller based on the detection-count-value.

8. The controller of claim 1 , wherein the controller is configured to:

receive a manual-sensitivity-change-signal that is representative of operator input; and

decrease a sensitivity of the controller based on the manual-sensitivity-change-signal.

9. A system for an agricultural machine, comprising:

the controller of claim 1 ; and

an angle sensor that is associated with a non-driven end of one of the pair of rollers, wherein the angle sensor is configured to provide an angle-signal that is indicative of the size of the roller opening, and

wherein the controller is configured to process the angle-signal in order to determine the roller-opening-value and the roller-speed-value.

10. A controller for detecting an unwanted object in an agricultural machine, wherein the agricultural machine includes a pair of rollers for receiving crop material therebetween, the pair of rollers defining a variable roller opening therebetween, wherein the controller is configured to:

receive a roller-opening-value that is representative of a size of the roller opening;

determine a strength-value based on the roller-opening-value and a roller-speed-value, wherein the roller-speed-value is representative of a rate of change of the roller-opening-value, with respect to time;

compare the strength-value with a threshold-value; and

if the strength-value exceeds the threshold-value, then provide an output signal that is indicative of an unwanted object being detected, wherein the strength-value comprises an opening-strength-value, the threshold-value comprises an opening-threshold, and the controller is configured to carry out at least one of the following two sets of steps:

set one:

determine the opening-strength-value based on the roller-opening-value and a maximum-positive-roller-speed-value, wherein the maximum-positive-roller-speed-value is a highest positive value of the roller-speed-value in a preceding window of time;

compare the opening-strength-value with the opening-threshold; and

if the opening-strength-value exceeds the opening-threshold, then provide the output signal that is indicative of an unwanted object being detected; and

set two:

determine the opening-strength-value based on the roller-opening-value and a maximum-positive-roller-speed-value;

determine a closing-strength-value based on a roller-opening-value and a maximum-negative-roller-speed-value;

compare the opening-strength-value with the opening-threshold; and

compare the closing-strength-value with a closing-threshold; and

if: (i) the opening-strength-value exceeds the opening-threshold; and (ii) the closing-strength-value exceeds the closing-threshold, then provide the output signal that is indicative of an unwanted object being detected.

11. A controller for detecting an unwanted object in an agricultural machine, wherein the agricultural machine includes a pair of rollers for receiving crop material therebetween, the pair of rollers defining a variable roller opening therebetween, wherein the controller is configured to:

receive a roller-opening-value that is representative of a size of the roller opening;

determine a strength-value based on the roller-opening-value and a roller-speed-value, wherein the roller-speed-value is representative of a rate of change of the roller-opening-value, with respect to time;

compare the strength-value with a threshold-value; and

if the strength-value exceeds the threshold-value, then provide an output signal that is indicative of an unwanted object being detected, wherein the strength-value comprises a closing-strength-value, the threshold-value comprises a closing-threshold, and the controller is configured to:

determine the closing-strength-value based on the roller-opening-value and a maximum-negative-roller-speed-value, wherein the maximum-roller-negative-speed-value is a largest negative value of the roller-speed-value in a preceding window of time;

compare the closing-strength-value with the closing-threshold; and

if the closing-strength-value exceeds the closing-threshold, then provide the output signal that is indicative of an unwanted object being detected.

12. A controller for detecting an unwanted object in an agricultural machine, wherein the agricultural machine includes a pair of rollers for receiving crop material therebetween, the pair of rollers defining a variable roller opening therebetween, wherein the controller is configured to:

receive a roller-opening-value that is representative of a size of the roller opening;

determine a strength-value based on the roller-opening-value and a roller-speed-value, wherein the roller-speed-value is representative of a rate of change of the roller-opening-value, with respect to time;

compare the strength-value with a threshold-value; and

if the strength-value exceeds the threshold-value, then provide an output signal that is indicative of an unwanted object being detected, wherein the controller is configured to:

determine a maximum-magnitude-roller-speed-value as a highest magnitude of the roller-speed-value in a preceding window of time; and

if (i) the strength-value exceeds the threshold-value, and (ii) the maximum-positive-roller-speed-value exceeds a speed-threshold-value, then provide an output signal that is indicative of an unwanted object being detected.