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The main theme of this paper is to propose fast online optimal bandwidth search and controller tuning techniques for servo motor drives. The proposed controller tuning method derives the controller gains by searching the optimal bandwidth and identifying the inertia. The optimal bandwidth search can be achieved before oscillation occurs. It will be shown that the gains of speed controller of servo drives are tuned automatically to reflect the load variation. Experimental results derived from digital signal processor-controlled permanent magnet synchronous motor servo drives will be shown. The results demonstrate online optimal bandwidth search and autogain tuning can be achieved without motor and load information in prior . These results fully support the developed techniques and claims.

This paper presents a MEMS mirror actuated by four suspended electro-thermal bimorphs. The dimension of the mirror platform is 250 µm × 250 µm. The MEMS mirror design is created based on process modeling following strict fabrication constraints. Transient and dynamic characteristics of the micromirror device are analyzed using coupled electro-thermal-mechanical finite element models and schematic behavior models, respectively. The design is optimized using experimental design and response surface methodology to achieve large actuation displacement and small lateral shift. The micromirror device is shown to have a uniform mirror platform deflection, a large resonant frequency adequate to support the high servo bandwidth control, as well as an excellent linear relation between the micromirror deflection and the input electric power. The proposed electro-thermal MEMS mirror is capable of generating a mirror displacement of 8.25 µm under a 3 V pulse voltage input, and can potentially be used as a fine...

Synchronization errors directly deteriorate the machining accuracy of metal parts and the existed method cannot keep high synchronization precision because of external disturbances. A new double position servo synchronous driving scheme based on semi-closed-loop cross-coupling integrated feedforward control is proposed. The scheme comprises a position error cross-coupling feedforward control and a load torque identification with feedforward control. A digital integrated simulation system for the dual servo synchronous drive system is established. Using a 20 t servo broacher, performance analysis of the scheme is conducted based on this simulation system and the simulation results show that systems with traditional parallel or single control have problems when the worktable works with an unbalanced load. However, the system with proposed scheme shows good synchronous performance and positional accuracy. Broaching tests are performed and the experimental results show that the maximum dual axis synchronization error of the system is only 8 μm during acceleration and deceleration processes and the error between the actual running position and the given position is almost zero. A double position servo synchronous driving scheme is presented based on cross-coupled integrated feedforward compensation control, which can improve the synchronization precision.

This paper proposes a new algorithm for estimating the resonant frequency of adaptive notch filters used in servo systems. Notch filters and adaptive notch filters are widely used in commercial servo systems for suppressing a resonance which is a major obstacle in improving their performance. However, the conventional frequency estimation algorithm gives a dynamic behavior that is proportional to the difference between the square of the estimated frequency and the square of the actual frequency. This can cause the estimation dynamics to be too slow for low-frequency resonances, if both low- and high-frequency resonances are present and if the estimator gain is designed for a high frequency. This paper develops a new algorithm to give a dynamic behavior that is proportional to the difference in the estimated frequency and actual frequency. This allows selecting the estimation parameters independent from the value of resonant frequencies. The developed algorithm is implemented to a production servo controller and applied to a production printed-circuit-board inspection system. The experimental results show that the developed algorithm is much more effective in suppressing the resonances of both low- and high-frequencies, compared to the pervious algorithm. Furthermore, the ability to suppress vibration allows increasing the feedback gain, which in turn allows improving the tack time performance from 190 ms to 100 ms. All experiments reported in this paper were performed in an actual industrial environment using a production system, and the developed algorithms are applied to the production system.

The dependence of the optimal energy-consumption duration of termination control of a dc servo drive on the angular-displacement magnitude and servo-drive parameters was determined. A new formula making it possible to calculate the optimal duration of time of termination control of the servo drive was obtained. The curves of dependences of energy consumption during termination control of the dc servo drive on the duration of the termination control were plotted.

In this paper, we propose a new control scheme that provides position and velocity profile tracking control for next-generation servo track writing (STW). Whereas conventional servo track writers require controllers that perform fast positioning control with fast track seeking and regulation, spiral servo track writers require accurate position and velocity profile tracking control to achieve high quality servo patterns on the media disk. Because STW timing eventually renders geometrically accurate servo patterns, both position and velocity error signals should be regulated within small bounds in a constant velocity region. Regulation via an integral sliding mode controller (SMC) is known to provide good tracking performance; however, use of a high switching gain is inappropriate for an actuator with resonance modes. In this paper, we therefore apply integral sliding mode control with a disturbance observer to STW. The relationship between eigenvalues and control gains is mathematically analyzed to improve dynamic tracking response. To verify the utility of the proposed position and velocity profile tracking control, we perform a comparative study between the proposed and conventional control methods and experimentally validate the performance of the proposed method.

The inertia of the stacked multi-degree-of-freedom platform imposes limitation on the achievable motion speed. To overcome this barrier, the unstable design becomes very attractive. This research presents a novel single-deck dual-axis linear motor platform that is capable of fast long-range motion. The platform is equipped with air-bearing design to achieve backlash-free operation. As a result, the positioning rigidity depends entirely on the performance of the servo system. A force distribution control is used to decouple the difference axis dynamics. This research also proposes a chain scattering description (CSD) setup to allow a pseudo-derivative feedback (PDF) control framework that is commonly used in industrial motion control for achieving high servo rigidity. An interesting finding is that our experiments show that without the help of complex piggyback piezoelectric stage, the single-deck platform design, with a stroke as large as 20 mm, can already reach a servo accuracy of ±60 and ±80 nm in the x- and y-axis and 600 μarcsec in the yaw axis.

As being independent of the magnitude of reference input signal, the conventional concept of servo bandwidth stemming from electronics fails to reflect the ability of the multiple degree-of-freedom (DOF) mechatronic system to perform vibration control. Considering the magnitude and frequency of reference input signal, a novel definition of mechatronic servo bandwidth of the Stewart platform-based active vibration isolator for a super antenna is proposed firstly. Then its mechatronic servo bandwidth is theoretically evaluated according to electrical and mechanical performances by using an optimization method. Experiments were conducted on the Stewart platform prototype, and the results validate the definition of and solution to the mechatronic servo bandwidth. From the application point of view, the mechatronic servo bandwidth can be employed to measure the manipulating rapidity of a multiple DOF mechatronic system and the range of vibrations that an isolator is able to overcome. HighlightsTo describe the rapidity of multiple-DOF mechatronic system, we presented a novel definition on mechatronic servo bandwidth of Stewart platform.We developed a general method of analytically determining the mechatronic servo bandwidth according to the dynamical formulations.We determined the mechatronic servo bandwidth analytically and experimentally.The results mentioned above agree with each other.

In a tape system, the core of the reel-to-reel and track-following servomechanisms is the servo channel, which processes the servo signal generated by a servo reader reading a timing-based servo pattern. The servo channel estimates essential servo parameters, including tape velocity, head lateral position, and longitudinal tape position. The achievable precision of the various estimates determines how densely data can be placed on tape. In this paper, the architecture and the design of a high-performance synchronous servo channel (SSC) are presented. The channel performance is evaluated by means of analytical bounds on the estimation error, simulations, and experimental results, which demonstrate that the proposed servo channel is instrumental to achieve head positioning with nanometer accuracy and reliable detection of longitudinal position information in tape systems. Methods for the estimation of servo parameters with enhanced precision and of dynamic tape-to-head skew by dual SSCs operating on adjacent servo bands are also presented and their performance evaluated.

Dual-stage servo control loops are modeled for hard disk drives (HDDs) with the consideration of time delay which is due to the time taken for position error signal measurement and controller computing. The time delays are involved in controller design and the closed servo control loop is investigated to show the effects of the time delay on servo control performance. The studied actuation system is a PZT milliactuator based dual-stage servo system. The delay time within and over the sampling interval is separately considered for 62.5 kHz sampling rate. To show the effect of sampling rate on servo control performance, a control system designed with 40 kHz sampling rate is also studied. As a result, significant improvement of servo performance is attained with this increased sampling rate and a reasonable time delay for the dual-stage actuation system.

We demonstrate a novel system that uses a piezoelectric transducer (PZT)-actuated mirror for laser stabilization. A combination of a simple mechanical design and electronic circuits is used to realize an ultra-flat frequency response, which enables an effective feedback bandwidth of 500 kHz. The PZT also performed well when used in a mode-locked laser with a GHz repetition rate, to which it is difficult to apply an electro-optic modulator (EOM).

The bit-error-rate performance of free space optical communication systems with binary phase shift keying modulation and coherent homodyne detection is performed. Besides the turbulence-induced wave-front phase error and the amplitude fluctuation, the servo bandwidth of adaptive optics system is investigated. It is shown that Greenwood frequency is large enough for the servo bandwidth of adaptive optics system when the detected photons per bit are more than 100. However, if the photons per bit are less than 70, the Greenwood frequency is only sufficient for weak scintillation. We should increase the servo bandwidth to almost twice the value of Greenwood frequency at least in order to obtain an acceptable BER performance when the scintillation index is larger than 0.7. In addition, we also investigate the aperture averaging effects when the receiving aperture is larger than the coherent length.

To increase a servo bandwidth of a head-positioning control system in hard disk drives, a triple-stage actuator system was developed with thermal actuators. This positioning control system consists of a voice coil motor (VCM), piezoelectric (PZT) actuators, and a thermal-positioning actuator. The thermal-positioning actuator is good for control in high frequency range because it has little negative impact caused by mechanical resonances. However, the thermal-positioning actuator causes flying-height fluctuations that may lead to worsening of the magnetic recording performances. To overcome this issue, this paper presents a control system that employs the feedforward control scheme on a thermal flying-height control system. Simulation results showed that the proposed method was able to compensate for the flying-height fluctuations during the track-following control by about 87 %.

This paper introduces a mathematical model for Pulse-Width Modulated Amplifier for DC Servo Motor. The relationship between pulse-width modulated (PWM) signal and reference rotation speed is specified, and a general model of motor represented by transfer function is also put forward. When the input signal changes, the rotation speed of the servo motor will change accordingly. By changing zeros and poles, transient performance of this system is discussed in detail, and optimal ranges of the parameters is recommended at the end of discussion.

The paper deals with the design of an ideal positioning servo system. To achieve this aim, we will derive transfer functions of the PID controller and the second-order low-pass filter while using typical fault frequencies for PID controller with a low pass filter. Consequently, an overall frequency characteristic of the open servo system will be depicted. This characteristic will be further used to determine the amplitude and phase safety, which determine the degree of stability system.

Summary This paper extends the existing proximate time-optimal servomechanism control methodology to the more typical second-order servo systems with a damping element. A parameterized design of expanded proximate time-optimal servomechanism control law with a speed-dependent linear region is presented for rapid and smooth set-point tracking using a bounded input signal. The control scheme uses the time-optimal bang-bang control law to accomplish maximum acceleration or braking whenever appropriate and then smoothly switches into a linear control law to achieve a bumpless settling. The closed-loop stability is analyzed, and then the control scheme is applied to the position–velocity control loop in a permanent magnet synchronous motor servo system for set-point position regulation. Numerical simulation has been conducted, followed by experimental verification based on a TMS320F2812 digital signal controller board. The results confirm that the servo system can track a wide range of target references with superior transient performance and steady-state accuracy. Copyright © 2015 John Wiley & Sons, Ltd.

The main theme of this paper is to propose a self-commissioning technique for high bandwidth servo drives. The presented self-commissioning technique include auto-identification of servo motor parameters and on-line calculation of controller gains of servo drives. The electrical parameters required for current controller, including stator resistance and inductance are identified under standstill. And followed by deriving the mechanical parameters for determining the speed and position controllers. The gains for current controllers are determined based upon the magnitude optimal method as the delay is considered while retaining the maximum phase margin. And the gains for speed controller are derived based upon symmetrical optimum method to increase the bandwidth as taking the current loop into consideration for speed gain design. Comparing with conventional self-commissioning method, the proposed method provides real alignment of rotor axis along the q-axis for q-axis inductance identification. Moreover, the proposed method gives significant bandwidth improvement of servo drives. Experimental results derived from DSP-controlled PMSM servo drives system will be shown. The results demonstrate high bandwidth servo drives can be achieved by the proposed self-commissioning technique. These results fully support the developed techniques and claims.

The controller design of servo drives for bandwidth improvement will presented in this paper. The delay issues caused by calculation, fdter and PWM generation, etc. are addressed. The controllers of current loop, speed loop and position loop are designed considering the delay and phase margin. Experimental results show the bandwidth for current, speed and position loops of servo drives are significantly improved as compared to those using conventional methods. For the servo drives with switching frequency of 20 kHz, as compared to traditional design method, the achievable control bandwidth for the presented method of position control loop is improved from 20 Hz to 116 Hz.

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the pneumatic proportional servo valve to drive the large stroke asymmetric rod-less pneumatic actuator. Due to the pressure differences between two chambers, the pneumatic actuator will operate. The highly nonlinear mathematical models of the large stroke asymmetric pneumatic system were analyzed and developed. The functional approximation technique based on the sliding mode controller (FASC) is developed as a controller to solve the uncertain time-varying nonlinear system. The MATLAB Simulink real-time system was a main control unit of a hardware-in-the-loop system proposed to establish driver blocks for analog and digital I/O, a linear encoder, a CPU and a large stroke asymmetric pneumatic rod-less system. By the position sensor, the position signals of the cylinder will be measured immediately. The measured signals will be viewed as the feedback signals of the pneumatic servo system for the study of real-time positioning control and path tracking control. Finally, real-time control of a large stroke asymmetric pneumatic servo system with measuring system, a large stroke asymmetric pneumatic servo system, data acquisition system and the control strategy software will be implemented. Thus, upgrading the high position precision and the trajectory tracking performance of the large stroke asymmetric pneumatic servo system will be realized to promote the high position precision and path tracking capability. Experimental results show that fifth order paths in various strokes and the sine wave path are successfully implemented in the test rig. Also, results of variable loads under the different angle were implemented experimentally.

A dual-stage actuator system in a hard disk drive will be expected to meet more stringent servo bandwidth requirements for higher recording density in the near future. To simplify the control design, most of the work on the dual-stage actuator track-seeking control is based on the rigid model. However, light-weight materials are used in practice; because of the existence of flexible modes in the system, the challenges involved in designing a reasonable controller need to be addressed. This article proposes a high-order non-singular terminal sliding mode control scheme to suppress undesirable flexural vibrations, while improving the head positioning speed and accuracy. Initially, a model of the system is built and then the flexible dual-stage actuator system is decomposed into input–output and internal sub-systems, to design the high-order non-singular terminal sliding mode controller. Simulation results show that the settling time in track-seeking is reduced and the tracking precision is improved with the proposed method.

Servo systems are essential components of current magnetic storage hard disk drives (HDDs). In this paper, we demonstrate a novel servo scheme using a field-programmable gate array (FPGA). Adjacent magnetic tracks with two different frequencies are recorded on the magnetic disk and are used as servo tracks to encode the position information. A discrete Fourier transform is employed to decode the magnetic head position and to obtain the position error signal (PES). The PES is defined in terms of the difference of the magnitudes of the two frequencies. The relationship between the displacement and the PES is obtained by offline calibration. A real-time signal acquisition and processing system using a commercial FPGA, analog-to-digital converter chips, and digital-to-analog converter chips is built to do the high-speed spectrum analysis and generate the PES. The PES is transmitted to a laboratory virtual instrument engineering workbench (LabVIEW) real-time control target to implement the control algorithm. The computed control output from the real-time control target is amplified to drive a piezoelectric stage, which moves the magnetic head along the radial direction to compensate for the position error. A simple repetitive and proportional-integral-derivative control algorithm is implemented for head positioning and to verify this new servo scheme in this paper. With the controller, most of the major disturbances, such as the harmonics of the spindle runout, have been effectively attenuated compared with an open-loop control scheme.

For the shaking table system, the 90o phase shift frequency of the servo valve system is close to the oil column resonance frequency, the bandwidth under the influence of servo valve features was so narrow that it cannot meet requirements. Multi-variable control is presented in this paper by introducing the jerk feedback on the basis of the three-variable control. The theoretical derivation and the system simulation show that: the jerk feedback can reduce the oil column resonance frequency, and decrease the influence of the system performance caused by the servo valve characteristics.

The loop controller of double position fully closed makes the AC servo drive system acquire a very high position accuracy and speed following which is hard to be achieved for time-varying parameters, load disturbance, AC motors and severely nonlinear controlled objects. For the system, the dynamic nature can be ensured by the inner position loop adopting PI regulation of half closed loop structure, while the stability and the immunity can be achieved by closed loop structures with the rings outside adopting dual-mode fuzzy control. This article analyzes the cause of positioning errors for servo motor and semi-closed loop structure. The article also explains how to design a two position closed-loop servo system based on fuzzy control by adopting the AC servo motor drive, the motor shaft back-end incremental photoelectric encoder to form the inner position loop and using the motion control card, the inner ring of servo system and the work platform of grating ruler to make up the outer position loop. Based on double position loop composed of three-dimensional laser processing gear, the accuracy of the three-axis linkage workbench position control and the speed following can be ensured, thus meeting the requirement of the laser subsurface engraving machine for high speed and high precision motion.

The traditional rocket and missile actuator usually uses the hydromantic servo system or pneumatic servo system, because of their better dynamic characteristic and structural adaptability. While with heavy weight, complex structure and expensive cost, it is difficult to realize. The permanent magnet active current servo motor has many advantages, such as high torque, small inertia, high efficiency, the high ratio of power to inertia, cramped construction, firmness, easy maintaining and high reliability. The electrical servo system using the permanent magnet active current servo motor as the power unit satisfies the need of the tactical missile gas vane and air vane servo system, because the range of its transmitted power is wide, its response is quick, and control power is low. This paper analyzed the pole shoe’s shape optimization characteristic against the interior permanent magnet synchronous motor for actuator, presents the design method and main process of permanent magnet synchronous motor for actuator using the field-circuit method. Optimal design can be acquired by the equivalent magnetic circuit method and the finite-element method conveniently and precisely. The analytical result of the prototype motor validated the feasibility of the optimization design.

Along with improvement of capability of the precision measurement radar, the servo system with more high capability is needed. A large antenna reduces rigidity and structural resonance frequency of antenna system, and it is even possible to make radar lose the target. Based on analyzing Ship-borne servo system, the model of servo system has been set up and intelligent integral has been applied in the Position Control Loop. The result of simulation shows that this method can decrease overshoot of the servo system and improve the quickness of the servo system.

With the rapid development of the electro-hydraulic servo control technology, the application of electro-hydraulic servo valve has become more and more widely. Servo amplifier is an important part of the electro-hydraulic servo control system to drive and control servo valve. This essay introduces the principle and the function of servo-amplifier, and designs a servo amplifier with the functions of proportional amplifier, zero adjustment, feedback and current limitation. The performance analysis and validation for the servo amplifier are carried out by using simulation software EDA .On the basis of the simulation, the servo amplifier is fabricated, and its performance is tested. The results indicate that the servo amplifier has features of stable current output, good linearity, rapid response, and fully meet designing requirements.

A traditional aerial optoelectronic platform consists of inside and outside multilayer gimbals, while an internal gimbal and drive components occupy the internal space where optical sensors are located. In order to improve the replaceability of optical sensors and to increase their available space, this paper introduces a nonorthogonal aerial optoelectronic platform based on three axes, we carried out research on its drive control method. A three-dimensional structure of an aerial optoelectronic platform was designed. A noncontact drive of a linear voice coil motor was introduced, and a drive control scheme of a proportional integral and a disturbance observer was adopted. Finally, simulations and experiments were carried out. Results showed that the aerial optoelectronic platform could effectively release three times the image sensor space, and the servo bandwidth was 60.2 Hz, which was much better than that of traditional two-axis and four-gimbal platforms. The stability accuracy of the system reached 4.9958 micron rad, which was obviously better than that of traditional gimbals. This paper provides a reference for the design of new optoelectronic platforms.

We demonstrate a mode-locked Er:fiber laser with a compact fiber-pigtailed optical bench containing a free-space electro-optic modulator for high-speed feedback control. The achieved servo bandwidth of the beat frequency between a given comb component and a reference laser is approximately 850 kHz. The realization of a narrow-linewidth and highly stable frequency comb is confirmed by measuring both in-loop and out-of-loop beat frequencies. We also demonstrate the frequency measurement of two iodine-stabilized Nd:YAG lasers through the narrow-linewidth comb without stability degradation. The developed optical frequency comb can work continuously for weeks without maintenance.

The accuracy of the servo system is dependent on the speed or band width of the closed loop control system. To achieve the high speed closed loop operation, hardware oriented control is preferred and it is achieved by means of an ASIC (Application Specific Integrated Chip). The servo system is used to drive a two axis robotic arm moving in a plane where two PMSM motor with servo control provides the required motion. Robotic applications require quick and accurate changes in driving torque so that the required motion behaviour is attained. Quick change in operating flux is required for fast and accurate servo control. Conventional scalar control drives cannot achieve quick response time and hence vector control is employed. The IRMCK201 ASIC used in the application has the Vector Control algorithm hard wired into it for complete servo control of a single PMSM. It takes the position and current feed back by using shaft encoder, hall sensor and IR2175 Current sensing IC. It can set up communication with a host controller through either high speed serial, SPI or Parallel protocols. The inverter unit is implemented using an Intelligent Power Module (IPM) and it is driven by the Space Vector Modulation signals from IRMCK201. The work shows that highly efficient servo drive can be implemented using IRMCK201 and Host controller with PMSM.

In this paper, we propose a new control scheme, position and velocity profile tracking control for new generation servo track writing (STW). While conventional servo track writers need controllers that perform fast positioning control with fast track seek and regulation, spiral servo track writers require accurate position and velocity profile tracking control for high quality servo patterns on the media disk. Since STW timing eventually renders geometrically accurate servo patterns, in constant velocity region both position and and velocity error signals should be regulated within small bounds. It is known that regulation via integral sliding mode controller (SMC) provides a good tracking performance, but using a high switching gain is not appropriate for a system having resonance modes. In this paper, thus we apply sliding mode control with disturbance observer to STW. To verify utility of the proposed position/velocity profile track control, we conducted some experiments using a state-of-the-art STW system. Comparative study with the conventional control method was made. The performance of proposed method was experimentally validated.

Mechanical and electrical properties of a DDV(Direct Drive servo Valve) with electric feedback are analysed via reverse analysis technique in this work. The DDV is disassembled and mechanical parameters, such as spool mass, spring stiffness and port size are identified. The servo amplifier, which is built in the valve, is reversely analysed and the control scheme and gains for several control actions are also identified. The electrical feedback for spool displacement improves much better the valve performance, such as hysteresis and dynamic bandwidth frequency, than an ordinary mechanical feedback valve. Integrating control action with very large gain was adopted in the valve amplifier, and it seemed to give high performance.

This paper presents a mode switching control (MSC) scheme in discrete-time domain for fast and precise set-point tracking in servo systems subject to control saturation and unknown disturbance. The basic idea is to combine the proximate time-optimal servomechanism (PTOS) and the composite nonlinear feedback (CNF) control, using the output position as the only measurable information for feedback. The PTOS is responsible for fast targeting in servo systems when the tracking error is large, and once the system trajectory enters into some specified region, the CNF will take over the control to ensure a smooth settling without compromising the fast transient performance. A reduced-order extended state observer is adopted to estimate the speed signal for feedback and the disturbance for compensation. The asymptotical stability of the proposed MSC scheme is analyzed and the switching conditions are provided. Simulation and experimental results on a permanent magnet synchronous motor (PMSM) servo system verify that the proposed control scheme is effective in improving the tracking performance for a wide range of target set-points.

The design is to control DC servo motor and design a DC servo control system by the computer.It measures the DC servo motors parameter by measuring element (displace sensor) and transforms some forms of information by using A/D conventer to the CPU.The CPU will compare the input signal and measuring signal and if there is error, according to the predetermined control law to produce a control signal to control motor ,the system makes input signal and measuring signal keep consistent. Control algorithm use digital PID controller .

Analyzed working principle of servo control system and applications of direct current (i.e. DC) servo motor in the two-dimensional (i.e. 2D) digital control system, used embedded PC104 processor as the central processing unit, selected DC servo motor whose model was J320LYX04C as azimuth axis motor, and DC servo motor whose model was J215LYX03E as pitch axis motor, constituted the executive body for servo system, and designed a driving and control system which can control the two-dimension turntable rotating precisely in space and lead CCD image sensor to catch and track target. Tests show that the system positioning accuracy meet the given requirements and the system with high reliability runs smoothly in the real application.

For traditional direct drive volume control electro-hydraulic servo system, the servo motors rotary inertia is limited strictly, the speed of response is slow and the actuators reciprocating motion characteristics are not consistent. In order to solve these problems, this paper designs a kind of high power direct drive differential volume control electro-hydraulic servo system. It is instructive for design of hydraulic system which demands high output power, changes direction of motion frequently, needs high response frequency and requires the speed of reciprocating motion keep consistent.

A control method for position servo control of Transverse flux machine (TFM) by controlling armature current Root-Mean-Square (RMS) and initial phase is proposed in this paper. Specifically, the voltage balance equation of TFM is provided, and the phasor diagrams are analyzed to achieve the expression of electromagnetic power of TFM. The expression indicates that the electromagnetic torque is determined by armature current RMS and the initial phase. A position servo control system of TFM is established based on the expression. The results of the position servo control curves show that the position servo control system of TFM is effective.

The error of gain of servo control system transfer function is larger by the method of frequency measurement, In this paper, By appying voltage on the both ends of the motor, measure DC response of system to tmeasure the DC gain of control object.Experimental results show that the gain accuracy by the measurement method increases 2.5 times than the traditional measurement.

Most current researches working on improving stiffness focus on the application of control theories. But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated, so the control action is lagged. Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms. In this paper, the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed. On this basis, the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward. And a scheme using double servo valves to realize flow feedforward compensation is presented, in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time. The two valves are arranged in parallel to control the cylinder jointly. Furthermore, the model of flow compensation is derived, by which the product of the amplitude and width of the valve’s pulse command signal can be calculated. And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations. Using the proposed scheme, simulations and experiments at different positions with different force changes are conducted. The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time. That is, system dynamic load stiffness is evidently raised. This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.

A speed control servo system based on STM32 is designed in order to realize the rapid, accurate, smooth speed control of rotary table. the system uses embedded microprocessor STM32F103 as the core, using the absolute encoder as the position sensor.The system achieved control of motor speed by PWM (pulse width modulation).Speed and current double loops control is used,and the expert PID control is used as the control algorithm. Through the analysis of the experimental results can be seen that the system has good stability, and the static and dynamic indicators meet the design accuracy.This design basically has reached the requirement of the servo motor speed control system.

in this paper, a very low cost two-axis position servo system is developed. This system is controlled by DSP. We study the stability of the position servo control system. We use the PI control algorithm in our application. We achieved twice switching frequency by using PWM signals to share the switching dissipation ePWM module of the DSP. A numerical consideration is given. The simulation results demonstrate the stability of the proposed method.

With the growth of hard disk storage, it would be difficult to meet the specification of the high track density with conventional single actuator. Therefore the next generation of high speed hard disk drive uses the concept of dual-stage actuated hard disk drive where a secondary actuator is mounted onto the VCM actuator. This helps to achieve higher servo bandwidth and, therefore, more precise tracking. Improved tracking error allows higher track density and hence higher storage capacity. Piezoelectric actuator has been a popular choice as the secondary stage. However, the piezoelectric actuators exhibit an unavoidablecharacteristic of hysteresis which causes inaccuracies and oscillations in the system responses.In this paper, the hysteresis behaviour is investigated for asuspension based PZT actuator which is used as the secondary actuator of HDD available in the market. The Generalized Prandtl-Ishlinskii (GPI) hysteresis model which is a phenomenological based model is obtained usingnon-linear least square curve-fitting. In the secondexperiment, a second order linear dynamics model of the PZT actuator is obtained using frequency response identificationmethod. High frequency resonance modes of the PZT actuator are eliminated using a notch filter. By integrating the obtained GPI hysteresis model with this second-order lineardynamics, a nonlinear dynamic model and an inverse feedforward controller are developed.Preliminary simulation results demonstrate that inverse feedforward controller can be appliedfor precise tracking of triangular and multiple frequency sinusoidal trajectories.

directional antenna is widely used in the measurement and control for Short range UAV because of its high gain in the range of beam angle, the speed of UAV is very fast, so the requirements for speed and acceleration of directional antenna is very high, step motors are usually in the traditional directional antenna systems, which works in the open loop and has low positioning accuracy, slow speed response and dynamic regulation, In order to meet the requirements of the directional antenna servo system, the design of servo control system for Azimuth of directional antenna based on PMSM and CAN bus communication is introduced in this paper . The test results indicate that the dynamic response of antenna servo system is very quick and tracking accuracy is very high. which can be well applied in the target tracking system.

This work proposes a novel strategy for middle frequency resonance detection and reduction for the speed control of industrial servo systems. The report includes an analysis of the drawbacks of the traditional resonance reduction method based on an adaptive notch filter in the middle frequency range, and the main drawback is summarized as the difference between the resonance frequency and the oscillation frequency. In the proposed method, a self-tuning low-pass filter with a corner frequency determined using FFT results and several self-tuning rules is introduced in the speed feedback path. Consequently, the effective range of the adaptive filter is extended across the middle frequency range. The simulation and experimental results show that the frequency detection is accurate, and the resonances are successfully reduced during steady-state and dynamic speeds.

This work presents a new approach to high performance velocity servo system design. The approach is based on a discrete-time sliding mode (DSM) control with disturbance compensation. For the purpose of design, the controlled plant is approximated by first-order model. The traditional, as well as the integral type of DSM control is considered. The disturbance compensator is based on the fact that the matched disturbances are directly reflected in the previous value of the switching function. In this paper, slow varying disturbances are estimated by a parallel connection of first- and second-order estimators. The integral type of DSM velocity servo system with such combined compensator can track references and significantly reject bounded disturbances, both up to cubic parabola type. The proposed control system is chattering-free. Theoretically obtained results are verified by simulations and experiments.

The position error signal (PES) in current hard disk drives is generated from the embedded servo data and used as the input for the track following controller. The servo pattern design and the decoding are both quite complicated in terms of the servo writing and servo detection, but they are important for the system dynamics study and track following controller design. In this paper, a novel scheme based on discrete fourier transformation (DFT) to decode the servo signal from a special magnetic servo pattern and generate the PES is proposed. In the scheme adjacent magnetic tracks with different frequencies are recorded to the disk and used as servo tracks to encode the position information. Simulation results show that the amplitudes at the two writing frequencies in the readback spectrum depend on the magnetic head position. The quadrature PES defined by the difference of the amplitudes is almost linear between the two adjacent tracks The simulation and off-line experimental results analysis agree with each other and prove the feasibility of this scheme. A real-time signal acquiring and processing system with a commercial field programmable gate array (FPGA) and ADC/DAC chips was built, and the proposed scheme was implemented in the FPGA to do the high-speed signal analysis. The magnetic head position information is extracted from the readback spectrum in the FPGA and transferred to a PC host for real-time graphic display using a labview interface. The system demonstrates an ability to generate the PES at 25 K samples per second with a resolution around 3 nm. The sampling rate can be enhanced further to 125 kHz if more servo sectors are written to the disk. This system provides a re-configurable research stage for studying the dynamic behavior of hard disk drives and for developing the control algorithm for track following.

This paper presents a control design methodology for high-precision positioning. In particular, the compensation for the effects of vibration modes and nonlinear friction on the positioning performance is taken into account in this methodology. In the controller design, the servo bandwidth of the feedback control loop should be expanded to compensate for nonlinear friction, while robust stability with respect to frequency variations in the vibration modes should be ensured. In this study, therefore, strain feedback for vibration modes is adopted to provide robustness with respect to frequency variations and to improve the disturbance suppression performance by expanding the bandwidth of a disturbance observer. This strain feedback is based on the use of a piezoelectric element. The efficiency of the proposed positioning control approach has been verified by conducting experiments using a prototype for industrial table drive systems. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 46–55, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21306

An integral part of modern servo drive is a position measuring system. This article is focused on processing of resolvers and capacitive sensors signals, whose quadrature output signals are the modulated in double-sideband amplitude modulation. Well known, the disadvantage of the amplitude modulation is low noise immunity. One of the sources of the noise is switching of power transistors of inverter. This noise can leads to reduction of position feedback resolution and bandwidth. The article presents the high resolution and high bandwidth signal processing algorithm. The proposed algorithm suggests the choice of the sensor excitation frequency, based on the analyze of the noise spectrum of the inverter pulse-width modulation frequency, and includes fast synchronous demodulation and adaptive observer-based converter to estimate the feedback position. The proposed demodulation method allows sampling and demodulating of sensor signals with frequency limited only by conversion and processing time of analog-to-digital converter. The adaptive observer-based digital part of measuring system compensates the phase lag of demodulated signals and increases position feedback resolution for a given system dynamics. The proposed method was implemented in the planar servo drive with the capacitive position measuring system. The result demonstrates the 15 bit resolution into 640 цm signal period and 1 kHz bandwidth of position feedback with excitation frequency of 12 kHz.

Archival demands for digital tape storage systems require smaller spacing between data tracks on the magnetic tape to allow for more data storage on a single cartridge. Increasing track density while maintaining track following provides a challenge for the servo control of the tape drive. In particular, interchangeable tape cartridges and time-varying tape reel diameters during operation cause variable disturbances during servo control. In this paper we show how a tape servo control algorithm can be regulated to handle changes in disturbance dynamics during servo operation of the tape drive. The approach is based on adaptive regulation by exploiting a Youla-Kucera parameterization of the servo controller and an explicit minimization of the Position Error Signal (PES) during servo operation in real-time. Theoretical results on the stability of the feedback system and real-time application results on an Linear Tape-Open (LTO) drive are included in the paper. The result show a significant reduction of the variance of the PES over different tape cartridges and a constant PES variance during a complete reel-in operation of the tape drive.

We present an approach to locking of optical cavities with piezoelectric actuated mirrors based on a simple and effective mechanical decoupling of the mirror and actuator from the surrounding mount. Using simple elastic materials (e.g. rubber or soft silicone gel pads) as mechanical dampers between the piezo-mirror compound and the surrounding mount, a firm and stable mounting of a relatively large mirror (8mm diameter) can be maintained that is isolated from external mechanical resonances, and is limited only by the internal piezo-mirror resonance of > 330 KHz. Our piezo lock showed positive servo gain up to 208 KHz, and a temporal response to a step interference within < 3 μs.