Research On Integrated Design Method Of Structural Topology And PZT Active Controller For A HDD Suspension

There are many tiny structural parts with small size, high acceleration and high dynamical accuracy in microelectronical manufacturing equipments. These parts used in the extreme condition have been imposed more and more stringent performances in advanced application. It results in a situation where interactions between structure and controller are more and more significant, and because the conventional design practice along the sequential lines of structure then controller design ignores the crucial influence of their interaction on global dynamical performance, it provides limit ability to improve the dynamical performance of these parts further. How to effectively integrate mechanical structure with controller in terms of their interaction, especially how to build and solve the mathematical model of integrated structural topological design with large degrees and great computation with controller design, is coming to a challenge in researches on design methodology. HDD suspension is a very flexible tiny structure with high speed and high dynamical accuracy. As limited by space size, the flexible suspension is usually made very thin in thickness, and very sensitive to any disturbance or shock impact. At this stringent situation, even small mechanical vibration induced by seeking motion and outer disturbance may result in catastrophic error in data reading.Supported by the National Natural Science Foundation(50390063) of“Study on accurate positioning and manipulating of motion system with high acceleration for die packaging”, this dissertation is focused on the researches of structural topological optimal based on dynamical performance and stability, PZT Piezoelectric control, the integrated modeling theory and its simultaneous optimal design about structural topology and active vibration controller about tiny structural part in order to improve the dynamical performance of a HDD suspension. These researches are applied to the optimal design of structural topological design, the PZT positions and controller parameters about a HDD suspension. The detail researches are followed as below.1. The principle of head assembly and the main problems about design suspension design are introduced firstly. Structural topological design theories based on static compliance or resonance frequency, piezoelectric active control, integrated structure/controller design techniques , their application and development in HDD suspension design are also analyzed in detail.2. In order to improve the dynamical performance of plane flexible beam, the topological design approach based on structural dynamical compliance, or dynamic response and stability under shock impact are studied, and the techniques about modeling of the topological design based on structural dynamical compliance, or dynamic response and stability under shock impact and their sensitive analysis are presented. Using these methods, the formulas of gradations of optimal model which objective function is dynamic response and stability under shock impact are derived . It saves large computational time by indirectly optimization based on gradations instead of numerical method or evolutional method, and extends the theory of structural topology design. Based above, HDD suspension topological design by structural dynamical compliance, or dynamic response and stability under shock impact is performed, and the optimal results are analyzed. As a result, several new topological structures of HDD suspension are obtained. It is discovered that the topological structures based on dynamical compliance are similar to that based on static compliance, first order torsion and sway frequencies at some local areas. This shows the former results have better synthetic performance than the latter. The presented methodology of HDD suspension will give another new approach to improve dynamical performance of HDD suspension. In the meantime, it also lay a good foundation for the research on design methodology of integrated structural topology and active controller.3. The piezoelectric materials have been widely used in the field of structural active vibration control because of their excellent mechanical-electrical coupling characteristics. In this part, the interactive relationship between PZT and beam structure has been analyzed. To suppress head suspension vibration, by a cantilever as a researching object, the modeling theory about optimal locations of several PZT pieces along a cantilever surface is studied carefully, the integrated structure/control model, sensitive analysis techniques and its the formulas of gradations are presented. By above method, the computational time is reduced and the convergent instability is avoided compared to numerical method or evolutional method. It is discovered that there is a complicated interactive relationship between PZT location, length and controller in active vibration control, and shows that these parameters and their interactions, especially the interactions between structural parameters and these parameters, have decisive effect on dynamical performance. In term of the vibration feature in HDD running, it is necessary and proper that integrated optimization of structural topology and controller with multiple PZT pieces is performed in order to control several modes simultaneously. The researches also give a good theory foundation for further analysis to the interaction of integrated structural topology and PZT active controller.4. In order to further improve the characteristics of HDD suspension, the design method of integrated topology theory and active vibration control is studied. By a smart flexible beam as a researching object, the coupling relationship between structure and PZT is analyzed. The analytic techniques including simultaneous optimal modeling, partial derivative analysis and PZT overlapping constraint condition etc. are presented. Integrated optimal design of structural topology, locations of several PZT actuators/sensors and active control parameters for plate structure are performed. The decomposition of design space in iterative method is avoided because of simultaneous optimal method. In the meantime, computational efficiency is increased and the convergent instability is improved by indirectly optimization based on gradations instead of numerical method or evolutional method. It is essential to farther researches and application of general integrated mechanical/controller design. Based above, the structural topology, PZT actuators/sensors and active controller parameters for HDD suspension are simultaneously optimized by MMA(method of moving asymptotes) method. Finally, the theoretical results have been simulated and analyzed by simulation and experiment. By computation and simulation, it is found the optimal result using simultaneous method is better than that using iterative method.Above results will have important reference values to the futher researches and application on more general integrated design of mechatronical system.