1. A virtual sensor network system comprising: a memory configured to: store a virtual sensor model, an output parameter value default rate of change, and an output parameter value threshold rate of change; and a processor configured to: receive, as input parameter values, physical parameter values of a machine measured from a physical sensor; generate output parameter values based on the input parameter values and the virtual sensor model; make a comparison between a rate of change of the output parameter values to the output parameter value threshold rate of change; and generate a default output parameter value based on the comparison.