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Proportional raise and lower poppet valves used in conjunction with a microcontroller can provide closed loop control of hydraulic cylinder pressure or position. Closed loop control of headers on agricultural harvesters enables more sophisticated functionality than present techniques. Floatation (regulating the header's applied ground force) and stubble height (regulating the header's height) are two strategies which can increase crop yield. These allow for more precise tracking of ground contour variations with the header contacting or following above the ground. Machine productivity is increased by consistent and repeatable operation, reduction of operator interaction and automation of header raise and repositioning at the start of each row.

The mobile hydraulic market is increasing its use of electronics for hydraulic control systems. In order to be more cost competitive, these systems are beginning to use proportional electro-hydraulic valves as opposed to the more traditional and costly servo valves. Proportional valves may be operated in open loop fashion or in a closed loop fashion which includes feedback transducers. In either case, it is important for the system designer and ultimately the end user to understand the different types of performance that may result by utilizing various coil drive strategies with proportional control valves.