Robust Machining Force Control With Process Compensation

Force control is an effective means of improving the quality and productivity of machining operations. Metal cutting force models are difficult to accurately generate and, thus, there is large uncertainty in the model parameters. This has lead to investigations into robust force control techniques; however, the approaches reported in the literature include known process changes (e.g., a change in the depth-of-cut) in the model parameters variations. These changes create substantial variations in the model parameters; thus, only loose performance bounds may be achieved. A novel robust force controller is presented in this paper that explicitly compensates for known process effects and accounts for the force-feed nonlinearity inherent in metal cutting operations. The controller is verified via simulation and experimental studies and the results demonstrate that the proposed controller is able to maintain tighter performance bounds than robust controllers that include known process changes in the model parameter variations.