Regulated quality diffusion revisited

In many manufacturing applications, the regulation of a quality process to attain a given target is of central interest. In a recent paper, Liu and Nam present a model of optimal quality regulation. The underlying quality process evolves due to regulation actions and superimposed random disturbances. Optimal regulation is sought to minimize the regulation costs and the mean squared deviation from the desired target over a finite time horizon. Unfortunately the model is correctly analyzed in Liu and Nam, and we therefore present the correct results in the following paper.