Modeling and predictive control of chatter instabilities in single point turning.

Persistent Link:
http://hdl.handle.net/10150/187130
Title:
Modeling and predictive control of chatter instabilities in single point turning.
Author:
Anwar, Sohel.
Issue Date:
1995
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Based on the concept of long range prediction in the context of self-tuning control theory, a generalized predictive kinetic energy controller (GPKEC) suitable for applications to high speed machining processes is developed. A three dimensional lumped mass model capable of representing both tool and workpiece dynamics in a single point turning operation on a lathe machine is first developed to accurately reflect their interactions in a machining process. Based on the linearized uncoupled one dimensional model for the machining dynamics and noting that feed can effectively be used to control the unstable machine-tool dynamics, a single-input single-output (SISO) discrete time predictive control law (GPKEC) is derived by minimizing the predicted incremental kinetic energy of the cutting process. The instantaneous feed is used as the control variable of this controller which is calculated using the feedback of instantaneous displacement of the tool tip in the feed direction. It is observed from the simulation results that the proposed GPKEC controller is capable of suppressing the unstable and marginally stable system dynamics in their incipient stages, even in the presence of uncertain disturbances. The GPKEC strategy is also found to be robust against modeling or estimation errors. In order to verify the simulation results, a number of experimental runs are carried out. An estimate of acceleration signal, instead of displacement, in the feed direction is used as feedback signal due to practical reasons. A servomotor, which is connected to the main feed drive shaft through a high performance timing (HPT) belt, has been used to control the instantaneous feed of a cutting process. It is observed that there has been a good agreement between the experimental and simulation results. The experimental results show that the GPKEC strategy can effectively suppress the chatter vibration in a machining process. It is also observed from experimental results that the proposed controller is robust against overparametrization, estimation errors, uncertain inputs, system noise, and even against changes in the system dynamics.
Type:
text; Dissertation-Reproduction (electronic)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Aerospace and Mechanical Engineering; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Chandra, Abhijit

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleModeling and predictive control of chatter instabilities in single point turning.en_US
dc.creatorAnwar, Sohel.en_US
dc.contributor.authorAnwar, Sohel.en_US
dc.date.issued1995en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractBased on the concept of long range prediction in the context of self-tuning control theory, a generalized predictive kinetic energy controller (GPKEC) suitable for applications to high speed machining processes is developed. A three dimensional lumped mass model capable of representing both tool and workpiece dynamics in a single point turning operation on a lathe machine is first developed to accurately reflect their interactions in a machining process. Based on the linearized uncoupled one dimensional model for the machining dynamics and noting that feed can effectively be used to control the unstable machine-tool dynamics, a single-input single-output (SISO) discrete time predictive control law (GPKEC) is derived by minimizing the predicted incremental kinetic energy of the cutting process. The instantaneous feed is used as the control variable of this controller which is calculated using the feedback of instantaneous displacement of the tool tip in the feed direction. It is observed from the simulation results that the proposed GPKEC controller is capable of suppressing the unstable and marginally stable system dynamics in their incipient stages, even in the presence of uncertain disturbances. The GPKEC strategy is also found to be robust against modeling or estimation errors. In order to verify the simulation results, a number of experimental runs are carried out. An estimate of acceleration signal, instead of displacement, in the feed direction is used as feedback signal due to practical reasons. A servomotor, which is connected to the main feed drive shaft through a high performance timing (HPT) belt, has been used to control the instantaneous feed of a cutting process. It is observed that there has been a good agreement between the experimental and simulation results. The experimental results show that the GPKEC strategy can effectively suppress the chatter vibration in a machining process. It is also observed from experimental results that the proposed controller is robust against overparametrization, estimation errors, uncertain inputs, system noise, and even against changes in the system dynamics.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAerospace and Mechanical Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairChandra, Abhijiten_US
dc.contributor.committeememberOusterhout, Karl B.en_US
dc.contributor.committeememberVincent, Thomas L.en_US
dc.identifier.proquest9531148en_US
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