مدل سازي مكاترونيكي ميراگرهاي هوشمند وبكارگيري آن ها در كنترل نيمه فعال ارتعاشات ماشين ابزار

چكيده انگليسي :

Mechatronic Modeling of Smart Dampers and Their Application on Semi active Control of Machine Tool Vibrations Davood Sajedipour d sajedipour@me iut ac ir 19 January 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Saeed Behbahani behbahani@cc iut ac ir Abstract Enhancing the efficiency of the metal cutting processes is a vital need in the manufacturing technology In this context chatter vibration is considered as a limiting factor in enhancing metal cutting efficiency because its occurrence causes many harm effects such as poor surface finish premature tool wear and potential damage to the machine or the tool This thesis presents a novel semi active intelligent control technique for chatter vibration supersession using tunable magnetorheological MR dampers Improvement of chatter safe cutting conditions by using of a MR damper in a turning process is studied and an appropriate optimized fuzzy control strategy is presented Chatter is a self excited unstable vibration which is generated mainly due to regenerative effect during machining processes Structural dynamic characteristics in particular magnitude phase and real and imaginary parts of the frequency response function are the main parameters which specify the stability lobes diagram i e the border between stable and unstable cutting conditions In the present work chatter reduction is achieved by altering these factors semi actively by means of a MR damper inserted between a vibration free component of the machine and the tool holder In other words the control approach which is the subject of this study is chatter suppression by semi active methods In this approach dynamic properties of some parts of the machine can be changed Insertion of variable dampers in the system is a common approach in the semi active control systems Smart MR dampers are a good example of variable dampers where the damping characteristics of the damper are varied by the input voltage to the damper First simulation software is developed for studying the vibration of a lathe machine tool A lumped model for MR damper is presented using modified Bouc Wen model The developed software is capable to consider the regenerative effect i e in the calculation of the dynamic chip thickness the current wave and the past wave left on the surface of the workpiece due to the machine vibration are taken into account Since the overall system is nonlinear due to incorporation of MR damper and a nonlinear controller the common frequency domain stability lobes generation techniques cannot be applied here A new approach for on line chatter detection based on a new defined chatter detection index CDI is presented to recognize the chatter conditions and to generate stability lobes diagram It is based on the analysis of vibration signals of the system Next MR damper model and chatter simulation software are integrated to study the influence of MR damper on the stability lobes diagram Finally a fuzzy controller is designed to choose the best voltage for MR damper at each instant to prevent chatter occurrence The proposed controller is a semi active controller which requires much less power in comparison with other control approaches Also this system provides safer solution in comparison with active controllers because if a problem occurs in the energy source or control system MR damper converts to a passive damper and it can still be effective in chatter reduction An optimization by the use of Genetic Algorithm GA is done to optimize fuzzy membership functions MFs in order to reduce total energy requirement and enhance stability conditions The obtained results show that the proposed method has been successful in reducing the chatter conditions and improving the stability of turning operation by very low energy consumption Keywords Magnetorheological damper machine tool vibrations chatter semi active control fuzzy systems optimization

ساجدي پور، داود

مدل سازي مكاترونيكي ميراگرهاي هوشمند وبكارگيري آن ها در كنترل نيمه فعال ارتعاشات ماشين ابزار

ميراگرمگنتوررئولو ژيك , چتر , سيستم هاي فازي , بهينه سازي