Adaptive Pole Placement Force Control of End Milling

This paper presents the design, simulation and experimental evaluation of a discrete time adaptive pole placement (APP) controller for end milling. In this controller design, the specification of the reference resultant force level and maximum feedrate constraint are based on surface finish/error considerations through use of a mechanistic dynamic process model for prediction of the cutting forces and the geometry of the end milled wall and floor surfaces. In addition, an analog signal processing circuit which holds the peak resultant force signal over each spindle revolution permits application of the controller to both slot and peripheral end milling. Experimental results show good agreement with the simulated APP controller force regulation performance and surface profile geometries. The APP approach is demonstrated to be an effective control strategy whether the process zeros are stable or not.