Surface accuracy control in end milling using adaptive state tracking

A geometric adaptive control system for the end milling process is developed based on adaptive state tracking. The control specification is given by an external reference trajectory, which represents the desired geometry of the finished workpiece. The machining system is represented by a state-space model which includes the flexibilities of both the cutter and the workpiece. The Recursive Prediction Error (RPE) method is used for joint state and parameter estimation of the state innovations model and the necessary adaptive state tracking control law is derived. In this study, on-line assessment of workpiece geometry is considered not realizable in practice, and only the cutting force is assumed measurable.The desired control is achieved by manipulating the position command for the servo loop so that the actual tool position follows the desired workpiece geometry. Simulations are obtained for the proposed geometric adaptive control system and the results are shown to be quite satisfactory.