1. A computer-implemented method for a virtual sensor system, comprising: establishing a first process model indicative of interrelationships between a plurality of input parameters and a plurality of output parameters; establishing a second process model indicative of interrelationships between at least the plurality of input parameters and modeling errors of the first process model; operating the first process model to generate values of the plurality of output parameters based on the interrelationships between the plurality of input parameters and the plurality of output parameters; simultaneously operating the second model to generate estimated deviations between the values of the plurality of output parameters and desired values of the plurality of output parameters based on the interrelationships between at least the plurality of input parameters and the modeling errors of the first process model; compensating the values of the plurality of output parameters from the first process model with the estimated deviations from the second process model to generate the desired values of the plurality of output parameters; and providing the desired values of the plurality of output parameters to a control system to control a machine.