Pyragas-type feedback control for chatter mitigation in high-speed milling

Chatter is an instability phenomenon in high-speed milling that limits machining productivity by the induction of tool vibrations. In this paper, a design methodology for loworder Pyragas-type delayed feedback controllers is proposed. These controllers enable dedicated shaping of the chatter stability boundary such that working points of higher machining productivity become feasible while avoiding chatter. The control design problem is cast into a nonsmooth optimization problem, which is solved using bundle methods. Distinct benefits of this approach are the a priori ?xing of the controller order, the limitation of the control action, and the fact that no finite-dimensional model approximations and online chatter estimation techniques are required. A representative example illustrates the merit of the proposed methodology in terms of increasing the chatter-free depth of cut, thereby enabling signi?cant increases in the productivity of milling processes

Active chatter control for high-speed milling using mu-synthesis

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Experimental validation of robust chatter control for high-speed milling processes

This chapter presents results on the design and experimental implementation and testing of robust controllers for the high-speed milling process for the purpose of avoiding chatter vibrations. Chatter vibrations are intimately related to the delay nature of the cutting process inherent to milling and should be avoided to ensure a high product quality. A design approach based on μ-synthesis is used to synthesize a controller that avoids chatter vibrations in the presence of model uncertainties and while respecting key performance specifications. The experimental validation of this controller on a benchmark setup, involving a spindle system including an active magnetic bearing, shows that chatter can be robustly avoided while significantly increasing the material removal rate, i.e., the productivity

Chatter control in the high-speed milling process using μ-synthesis

Chatter is an instability phenomenon in machiningprocesses which limits productivity and results in inferior workpiece quality, noise and rapid tool wear. The increasing demand for productivity in the manufacturing community motivates the development of an active control strategy to shape the chatter stability boundary of manufacturing processes. In this work a control methodology for the high-speed milling process that alters the chatter stability boundary such that the number of chatter-free operating points is increased and a higher productivity can be attained. The methodology developed in thispaper is based on a robust control approach using -synthesis.Hereto, the most important process parameters (depth of cut and spindle speed) are treated as uncertainties. Effectiveness of the methodology is demonstrated by means of illustrative examples

Passive Flutter Suppression Using a Nonlinear Tuned Vibration Absorber

The objective of the present study is to mitigate, or even completely eliminate, the limit cycle oscillations in mechanical systems using a passive nonlinear absorber, termed the nonlinear tuned vibration absorber (NLTVA). An unconventional aspect of the NLTVA is that the mathematical form of its restoring force is not imposed a priori, as it is the case for most existing nonlinear absorbers. The NLTVA parameters are determined analytically using stability and bifurcation analyses, and the resulting design is validated numerically using the MATCONT software. The proposed developments are illustrated using a Van der Pol-Du ng primary system