Stochastic Optimal Control of a Machining Process

A control theoretic approach to a problem in manufacturing is considred. The problem is the control of a machining process, specifically a simple drilling operation, with respect to economic criteria. Feed speed selection and tool replacement policies are to be determined. A stochastic model for tool wear, called a diffusion-threshold model, is utilized. This tool wear model allows the machining economics problem to be formulated as a stochastic optimal control problem incorporating feedback of too wear measurements. A one step cost funtional is considered, and the optimal policy is described. An example problem based on actual tool data is presented.