Lapping Control of Hard Disk Drive Heads: Part II—Control

2000 ◽  
Author(s):  
Youping Mei ◽  
Kim A. Stelson
Keyword(s):  
Numerical Modeling ◽  
Hard Disk Drive ◽  
Process Model ◽  
Disk Drive ◽  
Parameter Uncertainties ◽  
System Experiment ◽  
Pressure Dynamics ◽  
Trajectory Following ◽  
Good Preparation

Abstract Using numerical modeling as a tool, the pressure dynamics of bar lapping is identified. The process model is constructed based on the pressure dynamics and the Preston model. A controller is then designed using a trajectory following formulation. Simulation of the controller designed as such shows that it is robust to parameter uncertainties. This controller is implemented on a Seagate lapping system. Experiment results show that the proposed method is less sensitive to the quality of the preparation processes. However, the gains should be appropriately adjusted for optimal performance. With good preparation processes and appropriate gains, performance of the two methods are statistically comparable. Otherwise, the proposed method performs better. The proposed method is inferior to the existing method only when its gains are improperly adjusted.

Lapping Control of Hard Disk Drive Heads

2000 ◽  
Vol 123 (3) ◽  
pp. 439-448 ◽  
Author(s):  
Youping Mei ◽  
Kim A. Stelson
Keyword(s):  
Hard Disk Drive ◽  
Process Model ◽  
Estimation Method ◽  
Hard Disk ◽  
Disk Drive ◽  
Surface Shape ◽  
Constitutive Relationship ◽  
Parameter Uncertainties ◽  
Foundation Model ◽  
Pressure Dynamics

Bar lapping is a key process in fabricating computer hard disk drive heads. The purpose is to remove a small amount of material so that the transducer stripe height variation across the bar is minimized. In this article a method of simulating the material removal process is established. The Preston model is identified to be a reasonable constitutive relationship relating lapping rate to pressure and relative velocity. A pressure estimation method is established based on the modified beam on elastic foundation model (MBOEF) to incorporate the effect of surface shape. Simulation is conducted based on the proposed constitutive relationship and MBOEF. Results show good agreement with production observations. Hence the simulation model is used as a tool for identifying the structure of the lapping control model. The pressure dynamics of bar lapping is then identified. The process model is constructed based on the pressure dynamics and the Preston model. A controller is then designed using a trajectory following formulation. Simulation of the controller shows that it is robust to parameter uncertainties. This controller is implemented on a Seagate lapping system. Experiment results show that the proposed method is less sensitive than the existing method to the quality of the bar preparation processes prior to lapping. However, the gains should be appropriately adjusted for optimal performance. With good preparation processes and appropriate gains, performance of the proposed and existing methods are statistically comparable. Otherwise, the proposed method performs better. The proposed method is inferior to the existing method only when its gains are improperly adjusted.

Hard disk drive failure prediction using SMART attribute

2021 ◽  
Author(s):  
Vikas Tomer ◽  
Vedna Sharma ◽  
Sonali Gupta ◽  
Devesh Pratap Singh
Keyword(s):  
Hard Disk Drive ◽  
Failure Prediction ◽  
Hard Disk ◽  
Disk Drive

Determinants of Paternal Engagement: Investigating Low-Income Fathers’ Caregiving, Play, and Verbal Engagement With Infants

2021 ◽  
pp. 0192513X2110315
Author(s):  
Jessica L. McCaig ◽  
Heidi E. Stolz ◽  
Siera J. Reimnitz ◽  
Megan Baumgardner ◽  
Rebecca G. Renegar
Keyword(s):  
Low Income ◽  
Process Model ◽  
Home Visiting ◽  
Strong Support ◽  
Children And Families ◽  
Father Engagement ◽  
Physical Play ◽  
Contextual Determinants ◽  
Paternal Engagement

Extant research highlights the importance of early paternal engagement for children and families. Thus, there is strong support for the exploration of predictors of low-income father engagement. Informed by Belsky’s process model of parenting, this study explores contextual determinants of father–infant engagement (i.e., verbal engagement, physical play, and caregiving) including the unique contributions of the child, the father, and the broader social context. We utilized survey data from a sample of 183 non-residential, cohabitating, and married low-income fathers of infants participating in a home-visiting intervention. Results demonstrated that infant age was associated with increased caregiving and verbal engagement, fathers’ total work hours were negatively correlated with verbal engagement, fathers’ depressive symptoms were linked to increased physical play, and the quality of the coparenting alliance was related to physical play and caregiving. Findings may inform programs designed to promote paternal engagement during infancy.

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