output to diminish the difference fig6 illustrates a control algorithm routine of the software of the microcontroller 52 which compares the ground speed as sensed by the hall effect pickup unit 46 to the set speed recorded in memory of the microcontroller and which uses pid proportional integral derivatives feedback control mathematics to diminish the difference by controlling the speed output of the hydrostatic transmission the routine changes the output signal from the microcontroller to the proportional control valves to reduce or increase the hydrostatic transmission speed output the cruise control function can be turned off by 1 depressing the brakes 2 depressing the reverse foot pedal 3 turning off the switch that activates cruise control 4 repeatedly depressing the switch to decrement the speed set point below the lowest set point allowed by the software to resume to the previously set speed the operator must first initiate some forward motion using the normal foot pedal controls the increase decrease switch 64 also functions as the resume switch when the cruise control function is in the turned off mode once moving the operator can then momentarily depress the switch 64 and the microcontroller will control the vehicle speed to increase or decrease to the previous set speed using the cruise control algorithm in the microcontroller fig7 illustrates the proportional relationship between the vehicle speed and the vehicle speed change for manually selected increment decrement speed change steps using the speed selector switch 64 the cruise control set speed can be manually increased or decreased incrementally by a percentage of the current set.