Agricultural system and method for preventing roll-back of an agricultural vehicle on a sloped surface

1. An agricultural method for preventing roll-back of an agricultural vehicle, the agricultural vehicle including a hydrostatic transmission, a speed setting device for commanding a selected transmission speed of the hydrostatic transmission, the speed setting device being movable across a plurality of positions, with each position of the speed setting device being associated with a different transmission speed across a speed range for the agricultural vehicle according to a predetermined speed mapping for the speed setting device, the agricultural vehicle further including a brake input device movable for selectively engaging a service brake of the agricultural vehicle, the method comprising:

receiving, with one or more computing devices, an input indicative of the brake input device being used to engage the service brake;

receiving, with the one or more computing devices, a roll-back prevention input from the speed setting device indicative of a command to increase the transmission speed of the hydrostatic transmission while the service brake is engaged;

adjusting, with the one or more computing devices, an applicable speed mapping for the speed setting device from the predetermined speed mapping to a roll-back speed mapping in response to the roll-back prevention input, the roll-back speed mapping being associated with a reduced speed range as compared to the speed range for the predetermined speed mapping;

determining, with the one or more computing devices, a transmission control command associated with a current position of the speed setting device based on the roll-back speed mapping; and

controlling, with the one or more computing devices, an operation of the hydrostatic transmission to adjust the transmission speed based at least in part on the transmission control command.

2. The agricultural method of claim 1 , further comprising receiving, with the one or more computing devices, an input indicative of the agricultural vehicle being stationary.

3. The agricultural method of claim 2 , wherein receiving the roll-back prevention input comprises receiving the roll-back prevention input while the service brake is engaged and the agricultural vehicle is stationary.

4. The agricultural method of claim 2 , wherein the agricultural vehicle further comprises a speed sensor configured to generate data indicative of a ground speed of the agricultural vehicle,

wherein the input indicative of the agricultural vehicle being stationary is received from the speed sensor.

5. The agricultural method of claim 1 , further comprising:

receiving, with the one or more computing devices, a brake-release input indicative of the brake input device being released to disengage the service brake; and

adjusting, with the one or more computing devices, the applicable speed mapping for the speed setting device back to the predetermined speed mapping in response to the brake-release input.

6. The agricultural method of claim 1 , wherein the speed range for the predetermined speed mapping ranges from a first minimum speed to a first maximum speed and the reduced speed range for the roll-back speed mapping ranges from a second minimum speed to a second maximum speed, the second maximum speed being lower than the first maximum speed.

7. The agricultural method of claim 1 , wherein the agricultural vehicle comprises an agricultural sprayer.

8. The agricultural method of claim 1 , wherein the speed setting device is a speed control lever.

9. An agricultural system for preventing roll-back of an agricultural vehicle, the agricultural system comprising:

a hydrostatic transmission for selectively driving one or more wheels of the agricultural vehicle;

a speed setting device for commanding a selected transmission speed of the hydrostatic transmission, the speed setting device being movable across a plurality of positions, with each position of the speed setting device being associated with a different transmission speed across a speed range for the agricultural vehicle according to a predetermined speed mapping for the speed setting device;

a brake input device movable for selectively engaging a service brake, the service brake preventing movement of the one or more wheels when engaged, the brake input device being movable between an engaged position, associated with the service brake being engaged, and a disengaged position, associated with the service brake being disengaged; and

a computing system communicatively coupled to the hydrostatic transmission, the speed setting device, and the brake input device, the computing system being configured to:

receive an input indicative of the brake input device being used to engage the service brake;

receive a roll-back prevention input from the speed setting device indicative of a command to increase the transmission speed of the hydrostatic transmission while the service brake is engaged;

adjust an applicable speed mapping for the speed setting device from the predetermined speed mapping to a roll-back speed mapping in response to the roll-back prevention input, the roll-back speed mapping being associated with a reduced speed range as compared to the speed range for the predetermined speed mapping;

determine a transmission control command associated with a current position of the speed setting device based on the roll-back speed mapping; and

control an operation of the hydrostatic transmission to adjust the transmission speed based at least in part on the transmission control command.

10. The agricultural system of claim 9 , wherein the computing system is further configured to receive an input indicative of the agricultural vehicle being stationary.

11. The agricultural system of claim 10 , wherein the roll-back prevention input is received while the service brake is engaged and while the agricultural vehicle is stationary.

12. The agricultural system of claim 10 , further comprising a speed sensor configured to generate data indicative of a ground speed of the agricultural vehicle,

wherein the input indicative of the agricultural vehicle being stationary is received from the speed sensor.

13. The agricultural system of claim 9 , wherein the computing system is further configured to:

receive a brake-release input indicative of the brake input device being moved to the disengaged position to disengage the service brake; and

adjust the applicable speed mapping for the speed setting device back to the predetermined speed mapping in response to the brake-release input.

14. The agricultural system of claim 9 , wherein the speed range for the predetermined speed mapping ranges from a first minimum speed to a first maximum speed and the reduced speed range for the roll-back speed mapping ranges from a second minimum speed to a second maximum speed, the second maximum speed being lower than the first maximum speed.

15. The agricultural system of claim 9 , wherein the agricultural vehicle comprises an agricultural sprayer.

16. The agricultural system of claim 9 , wherein the speed setting device is a speed control lever.