Work machine with operator presence detection strategy

1. A method of operating a machine, comprising the steps of:

sensing indicators of operator presence in the machine, which includes sensing a seat sensor, a transmission output speed sensor and a conveyance gear sensor;

the sensing step also includes sensing depression of an inching pedal when an operator is standing, a conveyance gear is in neutral, a transmission output speed is zero, and the machine is not moving;

enabling the machine if at least one of the indicators indicates that an operator is present in the machine; and

disabling the machine if none of the indicators indicates that an operator is present in the machine.

2. The method of claim 1 including the steps of:

indicating the presence of an operator if a sensed transmission output speed is non-zero;

indicating the presence of an operator if a sensed conveyance gear is not neutral;

indicating the presence of an operator if the seat sensor is in an operator-in-seat position; and

indicating the presence of an operator if a sensed inching pedal position is greater than a predetermined threshold.

3. The method of claim 2 wherein the predetermined threshold is a ninety percent position.

4. The method of claim 3 wherein the disabling step includes the steps of:

locking out machine implements; and

engaging a parking brake of the machine.

5. The method of claim 4 wherein the machine implements includes a grader.

6. A machine comprising:

a machine body that includes an operator station;

an electronic controller connected to the machine body;

a transmission output speed sensor in communication with the electronic controller;

a conveyance gear sensor in communication with the electronic controller;

a seat sensor in communication with the electronic controller; the electronic controller includes an operator presence algorithm operable to enable the machine based on any one of a seat sensor indication, a transmission output speed sensor indication, and a conveyance gear sensor indication, and being operable to disable the machine based on a combination of all of the seat sensor indication, the transmission output speed sensor indication and the conveyance gear sensor indication; and

the operator presence algorithm being operable to enable the machine based upon an inching pedal mode of operation when the machine is not moving, an operator is standing, a conveyance gear is in neutral and a transmission speed is zero.

7. The machine of claim 6 including an inching pedal sensor in communication with the electronic controller; and

the operator presence algorithm is also operable to enable the machine based on an inching pedal sensor indication alone, and being operable to disable the machine based on the inching pedal sensor indication in combination with the seat sensor indication, the transmission output speed sensor indication and the conveyance gear sensor indication.

8. The machine of claim 7 wherein the machine body is a motor grader body; and

the at least one implement includes a grader.

9. The machine of claim 8 including a parking brake in communication with the electronic controller;

the operator presence algorithm is operable to engage the parking brake as part of disabling the machine.

10. The machine of claim 9 wherein the operator presence algorithm is operable to enable the machine if the seat sensor indication is operator-in-seat, or if the transmission output speed sensor indication is non-zero, or if the conveyance gear sensor indication is not neutral, or if the inching pedal sensor indication is pressed; and

the operator presence sensor algorithm is operable to disable the machine if the seat sensor indication is operator-not-in-seat, and the transmission output speed sensor indication is zero, and the conveyance gear sensor indication is neutral, and the inching pedal sensor indication is not-pressed.

11. An electronic controller for a machine comprising:

an operator presence algorithm operable to enable control communication between a machine implement and an operator control if at least one of a plurality of sensors has an indication that satisfies a respective predetermined criterion, and being operable to disable control communication between the machine implement and the operator control if a combination of all of the plurality of sensors have indications that fail to satisfy the respective predetermined criteria; and

the operator presence algorithm also being operable to enable the machine based upon an inching pedal mode of operation when the machine is not moving, an operator is standing, a conveyance gear is in neutral and a transmission speed is zero.

12. The electronic controller of claim 11 includes means for receiving the plurality of sensor indications, which include a seat sensor indication, a transmission output speed sensor indication and a conveyance gear sensor indication.

13. The electronic controller of claim 12 wherein the plurality of sensor indications includes an inching pedal sensor indication.

14. The electronic controller of claim 12 wherein the operator presence algorithm is operable to engage a parking brake if the combination of all of the plurality of sensors have indications that fail to satisfy the respective predetermined criteria.