Based on generalized the variation method, by introducing Hamilton function and Lagrange multiplier, this paper proposed a linear quadratic optimal control strategy for an incomplete controllable system with fixed ter...Based on generalized the variation method, by introducing Hamilton function and Lagrange multiplier, this paper proposed a linear quadratic optimal control strategy for an incomplete controllable system with fixed terminal state and time. Applying the proposed optimal control to the simple two-input dual-stage actuator magnetic head positioning system with three degrees-of-freedom, the simulation results show that the system has no residual vibration at the terminal position and time, which can reduce the total access time during head positioning process. To verify the validation of the optimal control strategy of three degrees-of-freedom spring-mass models in actual magnetic head positioning of hard disk drives, a finite element model of an actual magnetic head positioning system is presented. Substituting the optimal control force from simple three degrees-of-freedom spring-mass models into the finite element model, the simulation results show that the magnetic head also has no residual vibration at the end of track-to-track travel. That is to say, the linear quadratic optimal control technique based on simple two-input dual- stage actuator system with three degrees-of-freedom proposed in this paper is of high reliability for the industrial application of an actual magnetic head positioning system.展开更多
A broadband programmable gain amplifier(PGA) with a small gain step and low gain error has been designed in 0.13 m CMOS technology. The PGA was implemented with open-loop architecture to provide wide bandwidth. A tw...A broadband programmable gain amplifier(PGA) with a small gain step and low gain error has been designed in 0.13 m CMOS technology. The PGA was implemented with open-loop architecture to provide wide bandwidth. A two-stage gain control method, which consists of a resistor ladder attenuator and an active fine gain control stage, provides the small gain step. A look-up table based gain control method is introduced in the fine gain control stage to lower the gain error.The proposedPGAshows a decibel-linear variable gainfrom4 to20 dB with a gain step of 0.1 dB and a gain error less than˙0.05 dB. The 3-dB bandwidth and maximum IIP3 are 3.8 GHz and 17 dBm, respectively.展开更多
Sensitivity loop shaping using add-on peak filters is a simple and effective method to reject narrow-band disturbances in hard disk drive (HDD) servo systems. The parallel peak filter is introduced to provide high-g...Sensitivity loop shaping using add-on peak filters is a simple and effective method to reject narrow-band disturbances in hard disk drive (HDD) servo systems. The parallel peak filter is introduced to provide high-gain magnitude in the concerned frequency range of open-loop transfer function. Different from almost all the known peak filters that possess second-order structures, we explore in this paper bow high-order peak filters can be designed to improve the loop shaping performance. The main idea is to replace some of the constant coefficients of common second-order peak filter by frequency-related transfer functions, and then differential evolution (DE) algorithm is adopted to perform optimal design. We creatively introduce chromosome coding and fitness function design, which are original and the key steps that lead to the success of DE applications in control system design. In other words, DE is modified to achieve a novel design for hard disk drive control. Owing to the remarkable searching ability of DE, the expected shape of sensitivity function can be achieved by incorporating the resultant high-order peak filter in parallel with baseline feedback controller. As a result, a seventh-order peak filter is designed to compensate for contact-induced vibration in a high-density HDD servo system, where the benefits of high-order filter are clearly demonstrated.展开更多
In this study,a numerical approach is established to design a beam coupled to a Voice Coil Motor(VCM)with the aim to maximize the displacement in the inductive transducer.A finite element model is developed to simulat...In this study,a numerical approach is established to design a beam coupled to a Voice Coil Motor(VCM)with the aim to maximize the displacement in the inductive transducer.A finite element model is developed to simulate a VCM with different beams applying a harmonic analysis.The VCM is extracted from a recycled hard disk drive(HDD)and a parametric modal analysis is performed to identify the material parameters of the HDD and the beam.These parameters are obtained comparing the real vibration modes and natural frequencies(VCM-beam)with those determined from the finite element model.A numerical-experimental case study is carried out to demonstrate that if a beam is designed for a specific low frequency vibration between 0 and 10 Hz,the displacements are maximized in the VCM.For this purpose,real acceleration measurements taken from three individuals are used to provide the vibration signals in the numerical model.A beam is designed for one of the individuals using the natural frequency values determined from the measured signals.Results show that the displacements are maximized in the model which coincides with the natural frequency of the chosen individual.The main purpose of this research is to establish a design tool for energy harvesting purposes with VCM based on low frequency vibration sources as for example gait motions.展开更多
Ramp load/unload(L/UL)mechanisms are widely used to rest sliders in hard disk drives(HDDs).Loading/unloading a slider swiftly and smoothly is crucial in a HDD design.A novel,efficient simulation scheme is proposed to ...Ramp load/unload(L/UL)mechanisms are widely used to rest sliders in hard disk drives(HDDs).Loading/unloading a slider swiftly and smoothly is crucial in a HDD design.A novel,efficient simulation scheme is proposed to investigate the behaviors of a head disk interface(HDI)in ramp unloading processes.A dual scale model is enabled by decoupling the nano-meter scale change of an air bearing and the micro-or milli-meter scale deformation of a suspension.A modified Reynolds equation governing the air bearing was solved numerically.The slider design was characterized with performance functions.Three stages in an unloading process were analyzed with a lumped parameter suspension model.Key parameters for the model were estimated with a comprehensive finite element suspension model.Finally,simulation results are presented for a commercial HDI design.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 10472038);the Science Foundation of the Ministry of Education of China for Ph.D. Programme (No. 20050730016);the National Science Foundation of China for 0utstanding Young Researchers (No. 10025208).
文摘Based on generalized the variation method, by introducing Hamilton function and Lagrange multiplier, this paper proposed a linear quadratic optimal control strategy for an incomplete controllable system with fixed terminal state and time. Applying the proposed optimal control to the simple two-input dual-stage actuator magnetic head positioning system with three degrees-of-freedom, the simulation results show that the system has no residual vibration at the terminal position and time, which can reduce the total access time during head positioning process. To verify the validation of the optimal control strategy of three degrees-of-freedom spring-mass models in actual magnetic head positioning of hard disk drives, a finite element model of an actual magnetic head positioning system is presented. Substituting the optimal control force from simple three degrees-of-freedom spring-mass models into the finite element model, the simulation results show that the magnetic head also has no residual vibration at the end of track-to-track travel. That is to say, the linear quadratic optimal control technique based on simple two-input dual- stage actuator system with three degrees-of-freedom proposed in this paper is of high reliability for the industrial application of an actual magnetic head positioning system.
文摘A broadband programmable gain amplifier(PGA) with a small gain step and low gain error has been designed in 0.13 m CMOS technology. The PGA was implemented with open-loop architecture to provide wide bandwidth. A two-stage gain control method, which consists of a resistor ladder attenuator and an active fine gain control stage, provides the small gain step. A look-up table based gain control method is introduced in the fine gain control stage to lower the gain error.The proposedPGAshows a decibel-linear variable gainfrom4 to20 dB with a gain step of 0.1 dB and a gain error less than˙0.05 dB. The 3-dB bandwidth and maximum IIP3 are 3.8 GHz and 17 dBm, respectively.
基金supported by National Natural Science Foundation of China(Nos.61640310 and 61433011)
文摘Sensitivity loop shaping using add-on peak filters is a simple and effective method to reject narrow-band disturbances in hard disk drive (HDD) servo systems. The parallel peak filter is introduced to provide high-gain magnitude in the concerned frequency range of open-loop transfer function. Different from almost all the known peak filters that possess second-order structures, we explore in this paper bow high-order peak filters can be designed to improve the loop shaping performance. The main idea is to replace some of the constant coefficients of common second-order peak filter by frequency-related transfer functions, and then differential evolution (DE) algorithm is adopted to perform optimal design. We creatively introduce chromosome coding and fitness function design, which are original and the key steps that lead to the success of DE applications in control system design. In other words, DE is modified to achieve a novel design for hard disk drive control. Owing to the remarkable searching ability of DE, the expected shape of sensitivity function can be achieved by incorporating the resultant high-order peak filter in parallel with baseline feedback controller. As a result, a seventh-order peak filter is designed to compensate for contact-induced vibration in a high-density HDD servo system, where the benefits of high-order filter are clearly demonstrated.
文摘In this study,a numerical approach is established to design a beam coupled to a Voice Coil Motor(VCM)with the aim to maximize the displacement in the inductive transducer.A finite element model is developed to simulate a VCM with different beams applying a harmonic analysis.The VCM is extracted from a recycled hard disk drive(HDD)and a parametric modal analysis is performed to identify the material parameters of the HDD and the beam.These parameters are obtained comparing the real vibration modes and natural frequencies(VCM-beam)with those determined from the finite element model.A numerical-experimental case study is carried out to demonstrate that if a beam is designed for a specific low frequency vibration between 0 and 10 Hz,the displacements are maximized in the VCM.For this purpose,real acceleration measurements taken from three individuals are used to provide the vibration signals in the numerical model.A beam is designed for one of the individuals using the natural frequency values determined from the measured signals.Results show that the displacements are maximized in the model which coincides with the natural frequency of the chosen individual.The main purpose of this research is to establish a design tool for energy harvesting purposes with VCM based on low frequency vibration sources as for example gait motions.
文摘Ramp load/unload(L/UL)mechanisms are widely used to rest sliders in hard disk drives(HDDs).Loading/unloading a slider swiftly and smoothly is crucial in a HDD design.A novel,efficient simulation scheme is proposed to investigate the behaviors of a head disk interface(HDI)in ramp unloading processes.A dual scale model is enabled by decoupling the nano-meter scale change of an air bearing and the micro-or milli-meter scale deformation of a suspension.A modified Reynolds equation governing the air bearing was solved numerically.The slider design was characterized with performance functions.Three stages in an unloading process were analyzed with a lumped parameter suspension model.Key parameters for the model were estimated with a comprehensive finite element suspension model.Finally,simulation results are presented for a commercial HDI design.