Method and Apparatus for Adaptive Control of a Disk Drive in the Presence of Non-linear Magnetic Bias

According to a preferred aspect of the instant invention, there is provided a system and method of moving a disc drive arm in the presence of nonlinear magnetic bias. Further, in another preferred embodiment the instant method will be adaptive and/or self-corrective and is especially useful when used with disc drive hardware other than the hardware that was used to model the control law

Disk drive actuator design and control for robust non-operational shock performance

As disk drives become more of a commodity based product, quality and cost control have become top industry priorities. Disk drive manufacturers are now heavily focused on efforts to reduce costs while maintaining quality and improving performance. Shock damage of the head/disk interface is one area that causes many quality issues and cost constraints. The most damaging shocks, which can be both linear and rotational in nature, occur during the non-operational state. Several methods are used to combat shocks, many of which preserve servo control performance at the expense of cost increases and reliability issues. The research investigates the combination of improved mechanical designs and advanced control methods to improve servo controller performance while maintaining shock resistance, improving product quality, and providing cost reduction.A voice coil motor actuator is designed to meet specific seek performance requirements. A low cost, magnetic bias feature on the actuator arm is independently designed to compensate for non-operational rotary shock. Because the resulting bias is nonlinear and uncertain, a model-based adaptive controller was developed to meet the seek performance requirements and simultaneously handle effects of the nonlinear bias. Extensive experiments were conducted to characterize the actuator physical parameters and verify the controller performance. A representative sample of the results is presented and discussed.To address linear shock resistance, the research investigates the feasibility of a ramp load/unload (L/UL) controller using a conventional, non-L/UL disk drive actuator. Therefore, disk drives with lower cost, higher torque actuators can realize the linear shock resistance benefits of ramp loading. A unique disk drive actuator is designed and optimized for L/UL operation. While on the ramp, there exists a set in the state space where the actuator dynamics are uncontrollable. A sufficient condition is determined that guarantees actuator passage through the uncontrollable region. A state trajectory is generated that, when tracked, moves the actuator through the uncontrollable set for a successful load onto the disk at the desired load velocity. Exponentially stable state-feedback and output feedback controllers are designed for tracking. Experiments are performed to validate and verify the new design

An Assessment of Integrated Flywheel System Technology

The current state of the technology in flywheel storage systems and ancillary components, the technology in light of future requirements, and technology development needs to rectify these shortfalls were identified. Technology efforts conducted in Europe and in the United States were reviewed. Results of developments in composite material rotors, magnetic suspension systems, motor/generators and electronics, and system dynamics and control were presented. The technology issues for the various disciplines and technology enhancement scenarios are discussed. A summary of the workshop, and conclusions and recommendations are presented

Coriolis effects in bladed discs

New aero-engine architectures are currently being developed to satisfy the increasing demand for fuel-efficiency and lower noise, pushing the boundaries of todays design practice. These unproven designs require additional effort to ensure safety to high-cycle fatigue and flutter, widely acknowledged as a main risk for turbomachinery components. This calls for a new focus on phenomena that have been little investigated in the past due to their minor relevance for traditional designs, like the Coriolis effect. The Coriolis effect can cause an increase in the number of resonance frequencies, and generate global travelling-wave modes that can affect performance and flutter stability. Experimentally validated prediction and analysis methods are essential to ensure the accurate evaluation of the impact of the Coriolis effect on future engine designs. The major finite element (FE) software packages were systematically assessed, and proven to provide reliable simulations of the dynamics of bladed discs when the Coriolis effect is included. Experimental modal tools for the detection and identification of the Coriolis effect are also needed, to provide accurate interpretation of the data for model validation and updating. For this purpose, a dedicated rotating test rig was designed and manufactured. A novel Multiple Input Multiple Output testing framework was developed, based on the use of an array of strain gauges and piezoelectric actuators in combination with a poly-reference identification method, for the extraction of the full set of modal parameters arising in a bladed disc from the Coriolis force. The new technique allowed the successful recovery of Campbell diagrams, damping and strain mode shapes. Left displacement eigenvectors, which appear in the FRF formulation due to the Coriolis effect, could also be extracted and validated for the first time. An accurate comparison was conducted between the measurement data and the FE results, and confirmed the reliability of the new approach.Open Acces

Improved performance of hard disk drive servomechanism using digital multirate control

Ph.DDOCTOR OF PHILOSOPH

Third International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors

12th International Conference on Vibrations in Rotating Machinery

Since 1976, the Vibrations in Rotating Machinery conferences have successfully brought industry and academia together to advance state-of-the-art research in dynamics of rotating machinery. 12th International Conference on Vibrations in Rotating Machinery contains contributions presented at the 12th edition of the conference, from industrial and academic experts from different countries. The book discusses the challenges in rotor-dynamics, rub, whirl, instability and more. The topics addressed include: - Active, smart vibration control - Rotor balancing, dynamics, and smart rotors - Bearings and seals - Noise vibration and harshness - Active and passive damping - Applications: wind turbines, steam turbines, gas turbines, compressors - Joints and couplings - Challenging performance boundaries of rotating machines - High power density machines - Electrical machines for aerospace - Management of extreme events - Active machines - Electric supercharging - Blades and bladed assemblies (forced response, flutter, mistuning) - Fault detection and condition monitoring - Rub, whirl and instability - Torsional vibration Providing the latest research and useful guidance, 12th International Conference on Vibrations in Rotating Machinery aims at those from industry or academia that are involved in transport, power, process, medical engineering, manufacturing or construction

Modeling, Analysis, and Optimization Issues for Large Space Structures

Topics concerning the modeling, analysis, and optimization of large space structures are discussed including structure-control interaction, structural and structural dynamics modeling, thermal analysis, testing, and design