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Industrial Electronics, IEEE Transactions on

Issue 3 • Date Jun 1995

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Displaying Results 1 - 14 of 14
  • Internal model control (IMC) approach for designing disk drive servo-controller

    Page(s): 248 - 256
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    This paper presents a design procedure for disk drive servomechanism using an internal model control (IMC) structure. A typical disk drive actuator can be modeled as second order dynamics for low frequencies. However the response at higher frequencies shows resonant behavior which is difficult to model. We discuss the use of IMC structure for designing servo-controllers for disk drives. In this method, a second order nominal model of the plant is used to design an H 2-optimal controller to attain minimum integral-error-square (ISE) performance. Then to maintain robust stability at higher frequencies, sufficient roll-off at such frequencies is provided by an H optimization procedure. Here, the H2-optimal control is augmented by a low pass filter with sufficient high-frequency roll-off to ensure robust stability and robust performance. A multiplicative uncertainty bound is defined using the data of the disk drive servo plant's frequency response and the response of the nominal model, and this is then used to decide robust stability and robust performance bounds. Tuning of only one parameter of the IMC filter makes this design method easy and convenient. Simulation results for the designed controller are presented View full abstract»

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  • Magnetic recording-head positioning at very high track densities using a microactuator-based, two-stage servo system

    Page(s): 222 - 233
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1348 KB)  

    The storage capacities and areal densities found in magnetic disk drives are increasing very rapidly. Data is recorded in ever-narrower tracks which must be followed with extreme precision. Also, the advent of portable applications exposes these smaller drives to higher levels of vibration and shock. A description is given of the many factors which contribute to recording track misregistration (TMR) in today's drives. The mechanics of the drive and actuator and the architecture of the servo control system are also described. A projection is made for the TMR sensitivities and control system at an areal density of 10 Gb/in2, having roughly 25000 tracks/in. A two-stage servo may be needed to achieve such track densities. This would comprise a high bandwidth microactuator for rapid position corrections of the recording head, coupled with a conventional actuator. The characteristics of such a microactuator are discussed, and operational examples of fabricated electroplated microactuators, driven electrostatically, are shown. The mechanical behavior of the devices and some of the factors which would affect their implementation are also described View full abstract»

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  • Advanced optical disk mastering and its application for extremely high-density magnetic recording

    Page(s): 257 - 262
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    As the demand for recording density becomes stronger, mastering technology becomes more important along with its level of mechanical precision. To visualize such an important technology, the author presents one of the latest examples of optical disk mastering technologies in the application of preembossed magnetic disks. The preembossed magnetic disks have emerged from the integration of two existing technologies: one is magnetic recording technology and the other is optical disk technology. The effect of precision machining for such development is described in detail, along with suggested possible directions of further development in precision mechatronics View full abstract»

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  • Improved and less load dependent three-phase current-controlled inverter with hysteretic current controllers

    Page(s): 325 - 330
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A concept of the so-called inner feedback in three-phase current-controlled inverters with hysteretic current controllers is introduced. Stability of the inverter at various frequencies under two different applied loads have been studied. An inertial feedback loop is added to each controller. This modification affects operating characteristics of the inverter by enforcing a switching pattern of low dependence on the load, resulting in significantly improved quality of the output current View full abstract»

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  • Silicon micromachined SCALED technology

    Page(s): 234 - 239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    Silicon micromachining technology will play an important role in the fabrication of high-bandwidth servo controlled microelectromechanical (mechatronic) components for super-compact disk drives. At the University of California, Los Angeles, and the California Institute of Technology, for the last three years, we have initiated a number of industry-supported joint research projects to develop the necessary technology building blocks for an integrated drive design of the future. These efforts include a silicon read/write head microgimbal with integrated electrical and mechanical interconnects, which targets the next-generation 30% form factor pico-sliders, and an electromagnetic piggyback microactuator in super-high-track-density applications, both of which utilize state-of-the-art silicon micromachining fabrication techniques View full abstract»

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  • New digital compensation technique for the design of a microcomputer compensated crystal oscillator

    Page(s): 307 - 315
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The study of the stability of frequency sources is a matter of major interest due to the evolution of communication and instrumentation systems resulting in increasing the number of channels in a limited spectrum, and reducing size and power consumption. The paper relates laboratory experiences that explain the behavior versus temperature of thickness-mode quartz crystal resonators (AT- and SC-cut crystals) that are applied to the control of frequency sources, and the performance of digital compensation techniques. Prototypes of microcomputer-compensated crystal oscillators (MCXO's) have been developed to compare the compensation performance using the resonator as the temperature sensor against the use of an external sensor and verify the reduction of compensation errors due to thermal lags and hysteresis. The design of a CMOS integrated circuit for the MCXO is also included. A frequency correction method that does not modify the crystal resonance has been implemented in the circuit. This allows sensing of the temperature by means of the crystal and improving its long-term stability (aging). A new frequency comparator is also introduced. Its aim is to obtain the difference between two very close frequencies at its output, without being affected by the phase variations that the new frequency correction method and the digital circuit introduce. This detector has been implemented to get a high-resolution thermometric frequency and to realize a frequency-locked loop that includes a crystal controlled local oscillator, allowing the use of the MCXO as a good short-term stability source View full abstract»

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  • Design of a perturbation estimator using the theory of variable-structure systems and its application to magnetic levitation systems

    Page(s): 281 - 289
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    A perturbation estimator using the theory of variable structure systems is proposed to enhance the robustness of a pole-placement controller design. In its ideal form, the pole-placement design using feedback-linearization technique achieves a desired performance in nonlinear time-varying systems. However, its performance deteriorates rapidly with the presence of disturbance and parametric uncertainties, referred to as perturbation. The estimate generated by the proposed perturbation estimator is incorporated as an additional input to rectify the uncertainties in the nominal control model of the pole-placement design. The proposed scheme requires neither the measurement of the time derivative of the state vector nor the precise knowledge of system parameters, hut rather the bounds on system perturbation. Chatter and the adverse effects of conservative bounds on system perturbation, often encountered in conventional sliding-mode control (SMC), are alleviated for the controlled plant by the proposed scheme. The benefits of this scheme are demonstrated in this study practically on a magnetic levitation system and its performance is compared with that of the conventional SMC scheme View full abstract»

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  • Discrete-time LQG/LTR design and modeling of a disk drive actuator tracking servo system

    Page(s): 240 - 247
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    This paper presents the discrete-time LQG/LTR design of a disk drive track following servo system. The servo compensator designed through linear-quadratic Gaussian control combined with loop transfer recovery (LQG/LTR) consists of a Kalman filter for state estimation and state feedback for control. The desired tracking servo performance is first formulated through a frequency shaped return ratio of the Kalman filter and subsequently recovered at the output of the plant/compensator loop through the automatic design of a discrete-time linear quadratic (LQ) regulator. Particular attention has been given to modeling the calculation time delay and bias force estimation. The excellent robustness and performance characteristics of a continuous time LQG/LTR design are theoretically unachievable due to the extremely low sampling rate and nonminimum phase plant characteristics. However, both time and frequency domain simulations show that reasonable stability margins and performance can still be recovered. This technique nearly eliminates all the trial and error typical of a conventional pole placement design of a similar system. The direct discrete-time design can handle extremely low sampling rates associated with embedded servo systems. The technique can also be used for designing multi-rate and multi-input servo systems View full abstract»

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  • The accumulator in integral-cycle AC power control

    Page(s): 331 - 334
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The letter suggests and supports the use of the accumulator, consisting of a parallel adder and a parallel-in/parallel-out register, as an AC-line cycle selector for integral-cycle power control. It indicates that the accumulator is the optimum cycle selector, meaning that the cycle distribution over time is as regular as theoretically possible; this property of the accumulator ensures that the low-frequency ripple in the output power is kept to a minimum View full abstract»

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  • Closed loop low-velocity regulation of hybrid stepping motors amidst torque disturbances

    Page(s): 316 - 324
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    To regulate the velocity of hybrid stepper motor motion control systems, a control law which exploits the nonlinear dynamics to create an analog positional control in conjunction with a traditional linear control is introduced. This nonlinear approach allows a much coarser position sensor to be used, including position estimates based on back EMF measurements. The form of the control law admits the use of a wide variety of compensators, whereas earlier laws use only velocity damping compensation. Two specific compensators, i.e., velocity damping and integral control are analyzed in detail, then compared to each other and to open loop microstepping control. It is shown that velocity damping allows the design of the eigenvalues of the closed loop system and provides a linear system approach about a specified operating point. Unfortunately, this operating point includes the value of external DC torque (drag) present, so the closed loop dynamics cannot be guaranteed amidst steady state torque fluctuations. Integral feedback (within a PID controller) improves upon velocity damping by not only allowing the design of the closed loop eigenvalues, but also by completely linearizing the system regardless of external DC torque values. Furthermore, the integral feedback produces zero steady state position error (as expected from linear control theory) and significantly decreases the tendency of the motor to lose step. Experimental results validate the analyses View full abstract»

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  • Robust servo-system based on two-degree-of-freedom control with sliding mode

    Page(s): 272 - 280
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    A robust servo system, based on a combination of linear robust control and sliding mode control is proposed. This new control system can be said to be a nonlinear system (sliding mode control system) which has a inner loop of linear control (two-degree-of-freedom control). Due to this inner loop of linear control, a disturbance is strongly suppressed but not completely. Then, the outer loop of sliding mode control eliminates this disturbance suppression error. In this paper, a linear robust-servo design of two-degree-of-freedom control system is shown. Sliding mode control is applied to this system and the disturbance suppression characteristics are discussed. Through simulations and experiments, it is proved that the introduction of nonlinear control (sliding mode) drastically improves the disturbance suppression characteristics of a linear system (two-degree-of-freedom control) View full abstract»

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  • Passive and active stereo vision for smooth surface detection of deformed plates

    Page(s): 300 - 306
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    Passive stereo vision is proposed for operation in a complimentary manner with active stereo vision for detection of smooth surfaces of deformed plates. Passive stereo vision is used to obtain the boundary of the smooth surfaces, whereas active stereo vision with the projection of structured light is applied to detect the details of the surfaces. An inherent problem in passive stereo vision, called the false boundary problem, is identified. The problem is solved by calibrating the structured light in active stereo vision and dynamically placing the cameras in passive stereo vision. The matching criteria in active stereo vision and the sensing process of the proposed approach are presented. An experiment was conducted to test the effectiveness of the proposed approach View full abstract»

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  • The representation of AC machine dynamics by complex signal flow graphs

    Page(s): 263 - 271
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    Induction motors are modeled by nonlinear higher-order dynamic systems of considerable complexity. The dynamic analysis based on the complex notation exhibits a formal correspondence to the description using matrices of axes-oriented components; yet differences exist. The complex notation appears superior in that it allows the distinguishing between the system eigenfrequencies and the angular velocity of a reference frame which serves as the observation platform. The approach leads to the definition of single complex eigenvalues that do not have conjugate values associated with them. The use of complex state variables further permits the visualization of AC machine dynamics by complex signal flow graphs. These simple structures assist to form an understanding of the internal dynamic processes of a machine and their interactions with external controls View full abstract»

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  • Variable slope pulse pump controller for stepping position servo control system using frequency-locked technique

    Page(s): 290 - 299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    A stepping position servomotor system based on frequency-locked technique is proposed for high-performance incremental position control. A novel microcomputer-based variable slope pulse pump controller (VSPPC) using multi-rate sampling technique is exploited. The proposed VSPPC can adaptively generate motor motion profile, and it can replace the traditional PID controller for applications in stepping motor position control. System models are constructed for stability study and computer simulation. A prototype is designed and implemented to verify the theoretical studies and examine the performance of the proposed system. Position and speed responses of a realized system for 0-50 cm movement with 10 mm resolution is investigated. With the variable slope technique employed in VSPPC, the acquisition time for long-distance movement is reduced significantly and is close to that of short-range movement. In particular, the position acquisition time has improved about 67-79% compared to the conventional position control system View full abstract»

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Aims & Scope

IEEE Transactions on Industrial Electronics encompasses the applications of electronics, controls and communications, instrumentation and computational intelligence for the enhancement of industrial and manufacturing systems and processes.

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Editor-in-Chief
Carlo Cecati
DISIM - Univ. degli Studi dell'Aquila
67100 Aquila, Italy
c.cecati@ieee.org
Phone: +39 0862 434 450
Fax: +39 0862 1960 411