Patent ID: 7062368

Claim:
A combine comprising: a. a chassis; b. an internal combustion engine mounted on the chassis; c. a drive system coupled to the engine, the drive system including: i. a hydraulic pump coupled to the engine to be driven thereby; ii. a hydraulic motor in fluid communication with the hydraulic pump to be driven thereby; iii. a multi-speed gearbox having a plurality of selectable gear ratios; iv. a rotor driven by the gearbox and configured to thresh agricultural products; and d. an electronic control system including: i. at least one speed sensor coupled to the drive system to generate a first sensor signal indicative of at least one of a rotational speed and a non-rotational speed; and ii. an electronic controller coupled to the at least one speed sensor and storing a digitized mathematical model of at least a portion of the drive system, including a microprocessor being configured to electronically combine the first sensor signal with the digitized mathematical model to estimate a speed ratio and to use the estimated system parameter to dynamically update a digital feedback control algorithm in real lime and to execute the updated feedback control algorithm, wherein execution of the digital feedback control algorithm includes comparison of the estimate of the speed ratio to a target speed for the speed ratio, wherein the target speed varies as a function of at least one of the rotational speed and the non-rotational speed.