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Robust Control of Self-Excited Vibration in Machining Arm

Hesabi Hesari, Abbas | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48174 (08)
  4. University: Sharif University of Technology
  5. Department: Mechaical Engineering
  6. Advisor(s): Moradi, Hamed; Movahhedi, Mohammad Reza
  7. Abstract:
  8. Nowadays, applications of industrial robots are significantly increasing due to their flexibility, programmable, accuracy, rapidity and etc. Among these, machining robots play an important role at manufacturing industries. One of the main concerns of the researchers, is the tip vibrations of robot arms. In most times, these vibrations are self-excited, unpredictable and intolerable. Thus, finding a method for reducing vibration should be investigated. The purpose of vibration control is vibration suppression to enhance the reliability of the system. The aim of this project is the modeling of the machining robot arm in turning process and then application of robust control to reduce vibrations. In this model, the machining robot arm is modeled by Euler-Bernoulli cantilever beam. For vibration control, the laminate piezoelectric actuator is installed on the top of the beam. Due to electromechanical coupling of piezoelectric actuator and cantilever beam, Hamilton method is used for deriving the equations of motion. The source of vibrations in machining process, is modeled in the form of self-excited vibrations with time delay term. Due to convenience in modeling of time delay in frequency domain, equations of motion are obtained by Laplace transformation. Next, time delay term is approximated by pade approximation. In the following, by application of robust control law (designed via μ-synthesis based on DK-iteration algorithm), and in presence of uncertainty in the machining process, tip vibrations of machining arm are controlled. MATLAB software is used for simulations
  9. Keywords:
  10. Active Vibration Suppression ; Piezoelectric Actuator ; Robust Control ; Self-Excited Vibration ; Machining Arm

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