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Description:
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Motion control systems are usually designed to track trajectories and /or regulate about a desired point . Most of the other objectives , like minimizing the tracking time or minimizing the energy expended , are secondary which quantify the above described objectives . The control problem in hard disk drives is tracking and seeking the desired tracks . Recent increase in the storage capacity demands higher accuracy of the read /write head . Dual stage actuators as compared to conventional single actuator increases the accuracy of the read /write head in hard disk drives . A scaled up version of the dual stage actuator is considered as the test bed for this thesis . Friction is present in all electromechanical systems .
This thesis deals with modelling of the dual stage actuator test bed . A linear model predicts the behavior of the & #64257 ;ne stage . Friction is signi & #64257 ;cant in the coarse stage . Considerable time has been spent to model the coarse stage as a friction based model . Initially , static friction models were considered to model the friction . Dynamic models , which describe friction better when crossing zero velocity were considered . By analyzing several experimental data it was concluded that the friction was dependent on position and velocity as compared to conventional friction models which are dependent on the direction of motion . Static and Coulomb friction were modelled as functions of velocity and position . This model was able to predict the behavior of the coarse stage satisfactorily for various initial conditions . A friction compensation scheme based on the modelled friction is used to linearize the system based on feedback linearization techniques . |