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Control of Bifurcation and Chatter Suppression in Peripheral Milling Process

Bahari Kordabad, Arash | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52350 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Moradi, Hamed
  7. Abstract:
  8. Self-excitation vibration or chatter in the milling process is one of the most critical factors in reducing the tool life and surface smoothness. With the change of tool speed or depth of cut, bifurcation phenomena occur at some points (bifurcation points) such that the system behaviour becomes unstable and the chatter is observed. In this study, using nonlinear modelling for cutting forces, two main methods for active control of this process are proposed. The first is an intelligent control based on emotional learning, which is a model-free strategy. In this method, the critic generates a signal (stress signal) using error and its derivative. The purpose of this controller is to reduce the amplitude of the stress signal by updating the weights of the fuzzy neural network (TSK). The second approach is the Lyapunov-Krasovskii based strategy for time-delay processes. This controller is robust to varying the axial depth of cut and is also norm-2 optimized. Also, designing is independent of the time delay or spindle speed. Simulation results in the Simulink environment of Matlab show that both types of controls were able to stabilize the process. By applying the robustness conditions, the Lyapunov-based controller also has acceptable performance in the presence of parametric uncertainty. The bifurcation diagrams show postponing to the larger values of the axial depth of cut. Also, the controller causes a decrease in the amplitude of the limit cycles. Comparison of the Lyapunov-based controller with the emotional has shown that the transition performance and control efforts are better in the Lyapunov based controller
  9. Keywords:
  10. Peripheral Milling ; Intelligent Control ; Lyapunov-Krasovskii Function ; Time Delay ; Bifurcation ; Stability

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