Artykuły w czasopismach: „Cross-coupled compensator”

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Liu, Ya Qiu, Qu Wu, Wei Peng Jing i Liang Kuan Zhu. "Cross-Coupled Synchronized Control for Bi-Cylinder Servo System". Applied Mechanics and Materials 44-47 (grudzień 2010): 1646–50. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.1646.

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The paper focuses on cylinders synchronized control in continuum press for particleboard hot-pressing. An equal-status cross-coupled synchronized controller based on disturbance and synchronizing compensators has been designed and employed to an electro-hydraulic servo system driven by bi-cylinder. The simulations demonstrate that the controller eliminates synchronizing error faster and control two motion-units to move synchronously in a cross-coupled system than the controller with no compensator. And the robust of system has been enhanced.

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El-Khatib, Z., L. MacEachern i S. A. Mahmoud. "Highly-linear CMOS cross-coupled compensator transconductor with enhanced tunability". Electronics Letters 46, nr 24 (2010): 1597. http://dx.doi.org/10.1049/el.2010.2332.

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Schindlbeck, Christopher, Christian Pape i Eduard Reithmeier. "Multi-DOF compensation of piezoelectric actuators with recursive databases". at - Automatisierungstechnik 66, nr 8 (28.08.2018): 656–64. http://dx.doi.org/10.1515/auto-2017-0136.

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Abstract Piezoelectric actuators are subject to nonlinear effects when voltage-driven in open-loop control. In particular, hysteresis and creep effects are dominating nonlinearities that significantly deteriorate performance in tracking control scenarios. In this paper, we present an online compensator suitable for piezoelectric actuators that is based on the modified Prandtl-Ishlinskii model and utilizes recursive databases for the compensation of nonlinearities. The compensator scheme is furthermore extended to systems with more than one degree of freedom (DOF) such as Cartesian manipulators by employing a decoupling control design to mitigate inherent cross-coupling disturbances. In order to validate our theoretical derivations, experiments are conducted with coupled trajectories on a commercial 3-DOF micro-positioning unit driven by piezoelectric actuators.

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Su, Ke-Han, i Ming-Yang Cheng. "Contouring accuracy improvement using cross-coupled control and position error compensator". International Journal of Machine Tools and Manufacture 48, nr 12-13 (październik 2008): 1444–53. http://dx.doi.org/10.1016/j.ijmachtools.2008.04.008.

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Su, Ke Han, Ming Yang Cheng i Yu Chen Chang. "Contouring Performance Improvement of Biaxial Motion Control Systems Using Friction and Disturbance Compensation". Advanced Materials Research 579 (październik 2012): 287–96. http://dx.doi.org/10.4028/www.scientific.net/amr.579.287.

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One of the key issues regarding multi-axis contour following tasks in modern high-precision machining applications is how to effectively reduce contour error. Generally, among existing approaches, the Cross-Coupled Control (CCC) structure is widely used in multi-axis contour following tasks to improve contouring accuracy. However, when a servomechanism is operated in reverse or low-speed motions, the inherent friction force and external disturbance effects will degrade the CCC performance. Therefore, to cope with the aforementioned problems, this paper exploits the Karnopp friction model-based compensator and the Virtual Plant Disturbance Compensator (VPDC) to improve tracking performance as well as contouring accuracy. Moreover, an integrated motion control scheme is also developed to further improve contouring performance. The proposed scheme consists of two position loop controllers with velocity command feedforward, a modified CCC, two friction force compensators, and two disturbance compensators. To evaluate the performance of the proposed approach, several free-form contour following experiments have been conducted on an X-Y table driven by two linear motors. Experimental results verify that the proposed approach can significantly enhance contouring performance for free-form contour following tasks.

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Benderskiy, B. Ya, i A. A. Chernova. "The influence of the charge shape on heat exchange of a recessed nozzle". Journal of Physics: Conference Series 2057, nr 1 (1.10.2021): 012013. http://dx.doi.org/10.1088/1742-6596/2057/1/012013.

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Abstract The paper deals with the numerical simulation of the flow of thermally conductive viscous gaseous combustion products in the flow paths of a power plant. The influence of the shape of the mass supply surface on the gas dynamics and heat exchange near the recessed nozzle of the power plant is investigated. The coupled problem of heat exchange is solved by the method of control volumes. It is shown that the compensator geometry determines the localization of both the topological features of the flow near the recessed nozzle and the position of local maximums of the heat transfer coefficient. It has been revealed that The use of a channel with a star-shaped cross section and a triangular form of compensator rays leads to an intensification of heat exchange processes near a recessed nozzle.

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Zhang, Xiuyun, Zhiqiang Wang i Tao Liu. "Anti-Disturbance Integrated Position Synchronous Control of a Dual Permanent Magnet Synchronous Motor System". Energies 15, nr 18 (13.09.2022): 6697. http://dx.doi.org/10.3390/en15186697.

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In order to solve the problem that the position synchronous performance of dual permanent magnet synchronous motor servo system is easily affected by parameter perturbation and load disturbance, an anti-disturbance integrated position synchronous control strategy of dual permanent magnet synchronous motor system is proposed. Firstly, the integral mathematical model of a dual permanent magnet synchronous motor system is established. After that, the third-order linear extended state observer is constructed to observe and compensate for disturbance in order to improve the anti-disturbance performance of the position loop. At the same time, a cross-coupled position synchronous compensator is added to improve the synchronous performance of the system, and through the Bode diagram analysis method in the frequency domain, the system stability and anti-disturbance performance are researched. Finally, the effectiveness of the proposed algorithm is verified by experimental research.

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Ahmad, Irfan, Amro Emad Awad Ali i Yasser Bin Salamah. "MIMO H_μ Feedback Controller With Feedforward Compensator for Scanning Tunneling Microscope Having 3D Cross-Coupled Piezoelectric Actuator". IEEE Access 9 (2021): 153750–66. http://dx.doi.org/10.1109/access.2021.3127575.

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Kulkarni, P. K., i K. Srinivasan. "Optimal Contouring Control of Multi-Axial Feed Drive Servomechanisms". Journal of Engineering for Industry 111, nr 2 (1.05.1989): 140–48. http://dx.doi.org/10.1115/1.3188743.

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The capability of multi-axial machine tool feed drives to follow specified trajectories accurately is an important requirement for precision machining and especially so in applications involving high contouring speeds. In current generation machine tools, contouring is achieved by coordinating the commands to the individual feed drives, and implementing closed position loop control for each axis. The present paper deals with the evaluation of a cross-coupled compensator aimed specifically at improving contouring accuracy in multi-axial feed drives. The controller design is formulated as an optimal control problem. The performance index to be minimized weights the contour error explicitly. The controller is evaluated experimentally on a microcomputer controlled two-axis positioning table. Controller performance is evaluated for straight line, cornering and circular contours at feed rates varying from 2.25 m/min to 5.63 m/min. Measures of the steady state and transient contour errors are considered. The experimental results show that the proposed controllers reduce contouring errors considerably as compared to conventional uncoupled control of the multiple axes. The control action of the optimal controller is compared with that of more conventional uncoupled controllers.

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Smith, R. D., W. F. Weldon i A. E. Traver. "Aerodynamic Loading and Magnetic Bearing Controller Robustness Using a Gain-Scheduled Kalman Filter". Journal of Engineering for Gas Turbines and Power 118, nr 4 (1.10.1996): 836–42. http://dx.doi.org/10.1115/1.2817003.

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Modeling or predicting aerodynamic loading effects on rotating equipment has been a source of concern to those who wish to examine stability or response of critical components. The rotordynamic model of the system employed for such examination assumes greater importance for active bearings than for passive ones, if only because of the additional potential for instability introduced by the controller. For many systems, aerodynamic loading may vary widely over the range of operation of the bearings, and may depend on extended system variables. Thus, potential controllers for active magnetic bearings require sufficient robustness or adaptation to changes in critical aerodynamic loading parameters, as might be embodied in cross-coupled stiffness terms for compressor impellers. Furthermore, the presence of plant or measurement noise provides additional sources of complication. Here, the previous development of a nonlinear controller for a hypothetical single-stage centrifugal gas compressor is extended by comparing the compensator performance using a multivariable Luenberger observer against that of a stationary Kalman filter, both gain-scheduled for rotational speed. For the postulated system, it was found that the slower poles of the Kalman filter did not observably detract from controller convergence and stability, while predictably smoothing out the simulated sensor noise.

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Zhang, Wanjun, Shimin Mao, Feng Zhang, Jingxuan Zhang, Jingyi Zhang i Jingyan Zhang. "Cross Coupled Contour Error Compensation Technology". IOP Conference Series: Materials Science and Engineering 394 (7.08.2018): 032031. http://dx.doi.org/10.1088/1757-899x/394/3/032031.

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Wang, Dong Yun, Cheng Guan i Li Ping Shao. "A Combined Nonlinear PID Control and Cross-Coupled Pre-Compensation Control in Hydraulic Excavator". Key Engineering Materials 480-481 (czerwiec 2011): 1542–47. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.1542.

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In position control system of hydraulic excavator, the uncoordinated speeds between joints make quite trajectory errors no matter how well each joint performs. In order to solve this problem, a cross-coupled pre-compensation method is introduced in and applied to hydraulic excavator servo control system to solve this problem. Furthermore, in order to compensate for the nonlinearities of excavator and friction resistance, a nonlinear controller with angle velocity error observer and acceleration feedback is designed. Experimental results show that the proposed control strategy is effective in improving tracking accuracy and response ability when subjected to external load.

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Li, Guozhu. "An Active Disturbance Rejection Sliding Mode Contour Tracking Control for Biaxial Moving Platform". Mobile Information Systems 2022 (27.05.2022): 1–8. http://dx.doi.org/10.1155/2022/9261251.

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A sliding mode control for active disturbance rejection was utilized for uniaxial tracking control, and a cross-coupled contour error compensation controller based on nonlinear position domain (PD) was devised for enhanced contour machining precision and robustness of biaxial moving platform. For single-axis tracking control, the total disturbance of the system was initially considered to be the external disturbance plus internal unmodeled dynamics, and the overall disturbance was estimated and compensated in real time using a linear extended state observer. A sliding mode controller was built on this foundation to obtain satisfactory uniaxial control performance. Secondly, based on the estimated value of each axis component of contour error, a nonlinear PD contour error compensation controller was designed to coordinate the tracking motion between axes and further reduced the contour error. The proposed work is compared against state-of-the-art works from literature for various metrics such as tracking error curves, average comparison of tracking errors, and cross-coupled controller parameters. The simulation results showed that the proposed method can effectively improve the contour processing accuracy of the system.

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Ursac, Iulian, Florin Constantinescu i Mihai Marin. "A Frequency Reference for Carrier Synthesis in Wireless Standard 802.11g". Scientific Bulletin of Electrical Engineering Faculty 20, nr 1 (1.04.2020): 56–61. http://dx.doi.org/10.2478/sbeef-2020-0112.

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AbstractA new approach to a frequency synthesizer is proposed: instead of a fixed frequency reference oscillator and a variable ratio frequency divider we use a variable frequency reference oscillator and a fixed ratio frequency divider. The implementation and characterization of a low phase-noise compensated oscillator used as frequency reference for a wireless transceiver is described. This circuit employs a high Q piezoelectric resonator together with a CMOS cross coupled pair amplifier. A calibration circuit for compensation of frequency errors with respect to process variation is proposed.

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Li, Xuewei, Jun Zhang, Wanhua Zhao i Bingheng Lu. "A zero phase error tracking based path precompensation method for high-speed machining". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, nr 2 (13.04.2015): 230–39. http://dx.doi.org/10.1177/0954406215582013.

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Contour error due to the dynamic characteristics of feed system has a great influence on machining accuracy, in high-speed machining. In this paper, a new path precompensation method is proposed using zero phase error tracking control algorithm to improve the contouring accuracy for multiaxis machining with large feed rates. In this method, the outputs are predicted with the identified position-loop models of feed systems, and a contour error calculator is designed to calculate contour error in each sample instance using the predicted output and reference input. In order to compensate the contour error resulting from the dynamic tracking error of feed systems, the contour error vector is decomposed orthogonally and the compensation components for individual axis are calculated using zero phase error tracking control algorithm. Simulations showed that contour errors can be significantly improved with small compensation using the new path precompensation method for linear, circular, and parabola contours. Experimental results showed that the new method can reduce contour error significantly and achieve a better compensation compared with zero phase error tracking control and cross-coupled path pre-compensation.

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Du, Fuxin, Xianying Feng, Peigang Li, Jiawei Wang, Zhaoguo Wang i Chen Yu. "Cross-coupled intelligent control for a novel two-axis differential micro-feed system". Advances in Mechanical Engineering 10, nr 6 (czerwiec 2018): 168781401877462. http://dx.doi.org/10.1177/1687814018774628.

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Nonlinear friction in a conventional drive feed system feeding at low speed is a main factor that contributes to feed drive complexity. A novel two-axis differential micro-feed system is developed in this study to overcome the accuracy limitation of conventional drive feed system. Instead of the screw-rotating-type ball screw adopted in conventional drive feed system, the transmission component of the proposed two-axis differential micro-feed system is a nut-rotating-type ball screw. In this setup, not only the screw but also the nut is driven by a servo motor. By superposing the two high-speed rotary motions (motor–drive–screw and motor–drive–nut) with an equivalent high velocity and the same rotating direction through the novel transmission mechanism, the nonlinear disturbance from the ball screw can be reduced significantly. In addition, both the axes can avoid the creeping transition zone when the table makes a zero-velocity crossing. Note that the motor load switches when the feeding direction of the table is changed, and the nonlinear friction of the table needs to be compensated. Based on this observation, we further present a cross-coupled intelligent second-order sliding mode control that includes a cross-coupled technology, a second-order sliding mode control, a wavelet fuzzy neural network estimator for the friction, and a motor load switch to improve system performance. The proposed cross-coupled intelligent second-order sliding mode control architecture is deployed on a two-axis differential micro-feed system, where numerical simulations and experiments demonstrate excellent tracking performance and friction compensation capability, achieving position tracking error reduced by 45% compared with conventional drive feed system.

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Tatebe, Hiroaki, Masao Kurogi i Hiroyasu Hasumi. "Atmospheric Responses and Feedback to the Meridional Ocean Heat Transport in the North Pacific". Journal of Climate 30, nr 15 (sierpień 2017): 5715–28. http://dx.doi.org/10.1175/jcli-d-16-0055.1.

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Atmospheric responses and feedback to meridional ocean heat transport (OHT) have been investigated using a global climate model that is interactively connected with a high-resolution regional ocean model embedded in the western North Pacific. Compared with a global climate model without the regional model, the net heat supply into the Kuroshio–Oyashio Extension (KOE) region is increased as a result of the increase of the mean northward ocean heat transport (OHT) by the western boundary currents and mesoscale eddies. Resultant sea surface temperature (SST) rise sharpens the meridional SST gradient and reinforces the cross-frontal difference of the surface heat flux and thereby enhances lower-tropospheric baroclinicity. These changes cause northward deflection and strengthening of the wintertime storm track over the North Pacific, which leads to the Pacific–North American (PNA)-like pattern anticyclonic response of the mean westerly jet. The increase of the eddy northward atmospheric heat flux (AHF) associated with the enhanced storm-track activity is compensated by the decrease of the mean northward AHF. The changes of the atmospheric circulations reduce the mean northward OHT in the eastern North Pacific that compensates the increase of the mean northward OHT in the KOE region. The atmospheric responses, which have once been excited by the SST fronts in the KOE region, stabilize the trans–North Pacific OHT. The modeling results herein suggest that basinwide Bjerknes-like compensation works in air–sea coupled processes for the formation of the climatic mean state in the North Pacific.

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Jiang, Lei, Yuejuan Li i Marvin H. Cheng. "Compensation for Cross-Coupled Dynamics of Dual Twisted-String Actuation Systems". Journal of Control Science and Engineering 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/5864918.

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Twisted-string actuation devices have been adopted in various robotic systems due to their advantages of compact size and simple structure. To precisely control the displacement of such devices, a dual-direction actuating mechanism, which provides both extension and contraction of two strings simultaneously, must be implemented. Due to the physical properties of twisted string, the actuator has problems of nonlinear length variation and cross-coupled relationships between two strings. In this study, two controllers (PID-FC and LQR-FC) were synthesized with the consideration of cross-coupling dynamics between the two axes. The experimental results demonstrate the performance of both tracking and synchronization responses of these two types of controllers.

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Cheung, Carol C., Heiko Hecht, Thomas Jarchow i Laurence R. Young. "Threshold-based vestibular adaptation to cross-coupled canal stimulation". Journal of Vestibular Research 17, nr 4 (1.04.2008): 171–81. http://dx.doi.org/10.3233/ves-2007-17403.

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Prior experiments have demonstrated that people are able to adapt to cross-coupled accelerations associated with head movements while spinning at high rotation rates (e.g., 23 rpm or 138°/s). However, while adapting, subjects commonly experience serious side effects, such as motion sickness, non-compensatory eye movements, and strong and potentially disorienting illusory body tilt or tumbling sensations. In the present study, we investigated the feasibility of adaptation using a threshold-based method, which ensured that the illusory tilt sensations remained imperceptible or just barely noticeable. This was achieved by incrementally increasing the angular velocity of the horizontal centrifuge while supine subjects made repeated consistent yaw head turns. Incremental adaptation phases started at centrifugation speeds of 3 rpm. Centrifuge speed was slowly increased in steps of 1.5 rpm until a light illusory tilt was experienced. At the end of the incremental procedure, subjects were able to make head turns while rotating 14 rpm without experiencing illusory tilt. Moreover, motion sickness symptoms could be avoided and a limited carry over of the adaptive state to stronger stimulation at 23 rpm was found. The results are compared to prior studies which adapted subjects to super-threshold stimuli.

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Yeh, Syh-Shiuh, i Pau-Lo Hsu. "Theory and Applications of the Robust Cross-Coupled Control Design". Journal of Dynamic Systems, Measurement, and Control 121, nr 3 (1.09.1999): 524–30. http://dx.doi.org/10.1115/1.2802506.

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The cross-coupled control (CCC) has been recognized as an efficient motion controller that reduces contouring errors, but theoretical analysis of it is lacking, and there is no systematic design approach for obtaining a CCC system with guaranteed control performance. Consequently, the compensators C in CCC are commonly implemented in a PID structure and their contouring accuracy is usually degraded in real applications under different operating conditions. In an attempt to overcome the CCC design limitations described above, this paper introduces a robust CCC design based on a novel formulation: the contouring error transfer function (CETF), leading to an equivalent formulation as in the feedback control design problem. Then, methods in robust control design can be readily employed to achieve robust CCC with specified stability margins and guaranteed contouring performance. Furthermore, the proposed design has been verified as being internally stable. All provided experimental results indicate that the proposed robust CCC design consistently renders satisfactory contouring accuracy under different operating conditions.

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Zhao, Qiang, Yiheng Wu, Xiaojin Zhao, Yuan Cao i Chip-Hong Chang. "A 1036-F2/Bit High Reliability Temperature Compensated Cross-Coupled Comparator-Based PUF". IEEE Transactions on Very Large Scale Integration (VLSI) Systems 28, nr 6 (czerwiec 2020): 1449–60. http://dx.doi.org/10.1109/tvlsi.2020.2980306.

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Peng, F. Y., K. S. Sun, Y. Zhou i Bin Li. "Adaptive Compensation of Spatial Contour Error Based on Neural Networks in Three-Axis Machining". Key Engineering Materials 392-394 (październik 2008): 7–12. http://dx.doi.org/10.4028/www.scientific.net/kem.392-394.7.

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The spatial contour error which exists in multi-axis machine tools is believed relative with the track-lag error existing in the single axis, the set value of feed-rate and the curvature of the contour. A spatial error model is taken for presenting a vector method to calculate the contour error in three-axis machine tool and an adaptive cross coupled controller which is based on neural network is presented. The simulation results of cross coupled control in three-axis, indicate that the contour precision can be improved effectively which exists in the machine tool, and the errors influenced by the change of curvature and the set value of feed-rate can be obviously reduced.

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Wang, Sanxiu, i Shengtao Jiang. "Contour control of biaxial motion system based on RBF neural network and disturbance observer". Advances in Mechanical Engineering 13, nr 8 (sierpień 2021): 168781402110348. http://dx.doi.org/10.1177/16878140211034842.

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Friction is the main factor which degrades the control precisions of the servo system. In this paper, a cross coupled control method based on RBF neural network and disturbance observer is proposed for multi-axis servo system with LuGre friction, in order to implement high precision tracking and contouring control. Firstly, a feedback linearization controller is designed to realize the position stable tracking for single-axis motion; then, the disturbance observer is used to observe and compensate the friction. However, in practical application, the observation gain is difficult to select, and it is easy to cause observation error. In order to enhance the tracking accuracy and system robustness, the RBF neural network is introduced to approximate the disturbance observation error online. Finally, the cross coupled control is used to coordinate the motion between the axes to improve the contour accuracy. The simulation results show that the proposed method can effectively compensate the influence of friction on the system, has good tracking accuracy and high contour control precision.

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Wang, Dongyun, Lijuan Zheng, Hongxiang Yu, Wu Zhou i Liping Shao. "Robotic excavator motion control using a nonlinear proportional-integral controller and cross-coupled pre-compensation". Automation in Construction 64 (kwiecień 2016): 1–6. http://dx.doi.org/10.1016/j.autcon.2015.12.024.

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Wang, Li Mei, Qi Yang, Yi Biao Sun i Chun Fang Liu. "Iterative Learning Cross-Coupled Control for XY Table Based on Real-Time Contour Error Estimation". Advanced Materials Research 383-390 (listopad 2011): 7054–59. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.7054.

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The contour accuracy of XY table directly driven by two linear motors was influenced by the complicated reel-time contour error model of free-form curves, uncertainty external disturbance and dynamic matching between X axis and Y axis. To establish XY table model that easily calculated and suitable for free-form curves, real-time contour error estimate method was adopted. In order to reduce uncertainty external disturbance and dynamic matching between X axis and Y axis, the iterative learning cross-coupled controller (ILCCC) was designed for current compensation on X axis and Y axis. Simulation results show that the control scheme can enhance the robustness of the system, and effectively improve the XY table of contour precision.

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Wang, Bo, Ying Chun Liang i Shen Dong. "Study on the Compound Fuzzy Motion Control for the Ultra Precision Machine Tools". Key Engineering Materials 315-316 (lipiec 2006): 813–16. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.813.

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This paper presents a sophisticated trajectory tracking algorithm based on the utilization of the compound control and fuzzy contour control for the ultra precision machine tools. The main idea is to use the compound control to broaden the bandwidth of the servo system and, therefore, improve the tracking accuracy of the single axis. Then, FUZZY cross coupled contour control is introduced to compensate for the contour error caused by imperfect dynamics of the tracking axis and the mismatch of the control parameters of the servo systems. Experiments carried out on the HCM-1 ultra precision machine tool with a T-type layout show that the integration of the compound control with the fuzzy cross coupled contour control can effectively improve the contour tracking accuracy of the ultra precision machine tool.

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Ulbrich, Heinz, Adrian Cyllik i Guido Ahaus. "Stabilization of Centrifuges with Instabilities Due to Fluid-Structure Interactions: Various Control Approaches". International Journal of Rotating Machinery 7, nr 5 (2001): 323–33. http://dx.doi.org/10.1155/s1023621x01000276.

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Partially filled centrifuges exhibit unstable behavior over particular rotational speed ranges. To remove this unstable behavior, three different control approaches are presented which are experimentally implemented using a magnetic bearing. First, by means of a PD-controller the system stiffness is changed leading to a shift of the instability region. Second, the instability region is removed by a cross coupled feed back of the rotor vibration velocities. This cross coupling directly counteracts the fluid excitation mechanism. Third, a disturbance observer is presented which allows to estimate and compensate the not exactly known fluid force.

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Liu, Weirui, Fei Ren, Yunwen Sun i Shanglei Jiang. "Contour error pre-compensation for three-axis machine tools by using cross-coupled dynamic friction control". International Journal of Advanced Manufacturing Technology 98, nr 1-4 (13.06.2018): 551–63. http://dx.doi.org/10.1007/s00170-018-2189-1.

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Fan, Yi Yan, i Xiao Yong Mei. "QoS Evaluation Model for Web Services Composition". Key Engineering Materials 500 (styczeń 2012): 311–16. http://dx.doi.org/10.4028/www.scientific.net/kem.500.311.

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With the gradual development and standardization of services-oriented computing (SOC), it becomes a rapidly growing software developing pattern to composition Web services into applications. Since Web services composition are long-lasting, loosely coupled and cross application and administrative boundaries, it is essential to choose proper services to compose the composite Web services to meet user’s requirements. This paper presents a QoS evaluation method for aggregation services when failure occurs and defines QoS evaluation model of the common aggregation patterns of transaction compensation. Experiment results show that when it is used to evaluate the QoS of composite Web services, QoS evaluation method of aggregation transaction compensation is much better than the Web services composition method based on random selection, and it is feasible and effective.

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Yao, Jing, Xiaoming Cao, Yang Zhang i Yao Li. "Cross-coupled fuzzy PID control combined with full decoupling compensation method for double cylinder servo control system". Journal of Mechanical Science and Technology 32, nr 5 (maj 2018): 2261–71. http://dx.doi.org/10.1007/s12206-018-0437-9.

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Zhao, Guo Yong, Shi Jun Wang i Wen Tao Sui. "Compensation Approach to Error of Perpendicularity and Mismatch Error of Position Loop Gains in CNC Machine". Applied Mechanics and Materials 121-126 (październik 2011): 3190–94. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3190.

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The contour precision has been an important CNC machine accuracy index along with the increase of high precision complex parts NC machining. The error of perpendicularity and the mismatch error of position loop gains among linked axes are regarded as the prime reasons to bring about CNC machine contour error. After analyzing the influence of the error of orthogonal axes perpendicularity to CNC machine contour precision, a compensation approach is set up that the following error is corrected in each sampling period, by introducing a perpendicularity deflection parameter. After analyzing the influence of the mismatch error of position loop gains to contour precision, a cross-coupled control approach based on interpolation dots is developed to enhance the matching degree among all of the linked axes. Finally, the developed compensation approaches are testified on a CNC experiment table. The experimentation results reveal that the developed compensation approaches are effective to enhance contour precision.

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Hudson, Tyler B., Tan-Hung Hou, Brian W. Grimsley i Fuh-Gwo Yuan. "Imaging of local porosity/voids using a fully non-contact air-coupled transducer and laser Doppler vibrometer system". Structural Health Monitoring 16, nr 2 (24.09.2016): 164–73. http://dx.doi.org/10.1177/1475921716668843.

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This study exploits the feasibility of imaging zones of local porosity/voids simulated by introducing microspheres during layup of a unidirectional carbon fiber–reinforced polymer composite panel. A fully non-contact hybrid system primarily composed of an air-coupled transducer and a laser Doppler vibrometer was used for imaging the local porosity/void zones from the guided wave response. To improve image resolution, several preprocessing techniques are performed. The wavefield reconstructed from the laser Doppler vibrometer measurements was first “denoised” using a one-dimensional wavelet transform in the time domain followed by a two-dimensional wavelet transform in the spatial domain. From the total wavefield, the much weaker backscattered waves were separated from the stronger incident wave by frequency–wavenumber domain filtering. In order to further enhance the signal-to-noise ratio and sharpen the image, the attenuation of incident wave propagation to the damage site was compensated through two proposed weight functions. Finally, a zero-lag cross-correlation was performed for imaging the zone where the compensated incident and backscattered waves were in phase. This improved imaging condition, the “denoised” weighted zero-lag cross-correlation, was proposed and tested for defect imaging in the composite panel with eight intentionally introduced zones of high porosity/voids of varying diameters (1.59–6.35 mm) and depths (0.36–1.08 mm). As expected, the sensitivity of the non-contact air-coupled transducer/laser Doppler vibrometer hybrid system was limited by the wavelength of the excitation signal. The system incorporated with the denoised weighted zero-lag cross-correlation imaging condition for guided wave interrogation gave similar image quality in comparison with that by the immersion C-scan.

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Fayolle, Patrice, i Dara W. Childs. "Rotordynamic Evaluation of a Roughened-Land Hybrid Bearing". Journal of Tribology 121, nr 1 (1.01.1999): 133–38. http://dx.doi.org/10.1115/1.2833794.

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Hybrid bearings represent an attractive alternative to ball bearings for use in highspeed cryogenic turbopumps. However, the internally-developed cross-coupled forces can generate instabilities responsible for a speed limitation of the machine. To reduce these forces and raise the onset speed of instability, the use of deliberately-roughened stators, already successfully tested for liquid “damper” seals, is investigated. Rotor-dynamic results are presented for a five-pocket orifice-compensated hole-pattern-land hybrid bearing tested with water at high speed and high pressure. Experimental data show a good prediction of leakage flow rate and direct damping but a significant improvement in stability compared to a conventional smooth-land hybrid bearing, resulting in an elevation of the onset speed of instability. Comparisons between measurements and predictions from a code developed by San Andres (1994) shows good predictions for flowrate and direct damping but an over prediction for the direct and cross-coupled stiffness coefficients by about 30 and 50 percent, respectively. The use of the Moody friction-factor model is thought to be mainly responsible for the poorer predictions of stiffness coefficients.

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Schmidt, Christian, Martin Buchholz i Madhukar Chandra. "Optimization of loosely coupled inductive data transfer systems by non-Foster impedance matching". Advances in Radio Science 17 (19.09.2019): 151–60. http://dx.doi.org/10.5194/ars-17-151-2019.

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Abstract. Wireless energy transfer is often used in industrial applications to power actors or sensors, for example in rotating applications as replacement for mechanical slip rings. In addition to the energy transfer, we have developed inductively coupled data transfer systems to expand the range of possible applications. The data transfer is accomplished by using loosely coupled coils on both sides of the power transfer system. In pure energy transfer systems, resonant coupling is used, meaning that the power transfer coils are both tuned to a common frequency to compensate the relatively small coupling factor between power transmitter and receiver and to achieve an impedance matching between both sides by compensating the inductive component of the transfer coils. In this case, capacitors can be connected in series or in parallel to the coils, leading to a sharp, narrow band resonance peak in the transfer function. In inductively coupled data transfer systems, this approach is often not useful because not just a pure sine wave has to be transferred but more likely a signal of a certain bandwidth. In one of our applications, a 100 Mbit s−1 Ethernet stream is transferred with an occupied bandwidth of 62.5 MHz. The coil structures used so far in our data transfer applications were intrinsically unmatched to the data transfer systems. Additionally, due to the small coupling factor between the data transfer coils, transfer losses in the range of up to 15 dB or worth had to be accepted. This is especially critical regarding the high noise level in vicinity of the energy transfer system and the cross coupling between the two transfer channels. For passive, lossless circuits, Foster's theorem states that the reactance increases monotonically with frequency. Subsequently, the inductive part of a circuit can just be exactly compensated with a capacitance for one single frequency. In contrast, active circuits like a negative impedance converter (NIC) can be used to achieve a non-Foster behaviour, for example a negative inductance can be realized. In theory, an inductance in series or parallel to a negative inductance of the same magnitude would be cancelled out for every frequency applied. For low power level applications like active receiving antennas, this approach has already been successfully used in the past to achieve improved matching of simple antenna structures over a comparably large bandwidth. We make use of non-Foster circuits, namely negative impedance converters, to compensate the inductive part of two loosely coupled inductors to achieve smaller transfer losses and better impedance matching, which should lead to a decreased transfer signal loss and higher signal to noise ratio. The results of this paper serve as a basis for this development. So far, we achieved almost complete cancellation of the reactive part introduced by the loosely coupled data transfer inductors. Unfortunately, the circuits active device used to form the negative impedance converter introduced a highly resistive element, greatly increasing the signal transfer losses. Nevertheless, the theory of loosely coupled inductors is shown in a compact form and a strategy to cancel the reactive part is presented. Simulations and measurements of a transfer system are carried out, both showing good agreement regarding the reactance cancellation. Based on this, optimised implementations will be developed in the future.

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Henry, Romain, Yann Périn, Kiril Velkov i Sergei Pavlovich Nikonov. "3-D COUPLED SIMULATION OF A VVER 1000 WITH PARCS/ATHLET". EPJ Web of Conferences 247 (2021): 06015. http://dx.doi.org/10.1051/epjconf/202124706015.

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A new OECD/NEA benchmark entitled “Reactivity compensation with diluted boron by stepwise insertion of control rod cluster” is starting. This benchmark, based on high quality measurements performed at the NPP Rostov Unit 2, aims to validate and assess high fidelity multi-physics simulation code capabilities. The Benchmark is divided in two phases: assembly wise and pin-by-pin resolution of steady-state and transient multi-physics problems. Multi-physics simulation requires the generation of parametrized few-group cross-sections. This task used to be done with deterministic (2-D) lattice codes, but in the past few years the Monte-Carlo code SERPENT has demonstrate its ability to generate accurate few-group homogenized cross-section without approximations, neither on the geometry nor in the nuclear data. Since the whole core SERPENT models for production of such cross-section libraries would be computationally costly (and the standard 2-D approach may introduce unnecessary large approximations), 3-D models of each assembly type in infinite radial lattice configurations have been created. These cross-sections are then used to evaluate effective multiplication factors for different core configurations with the diffusion code PARCS. The results are compared with the reference SERPENT calculations. In the next step, a thermal-hydraulic model with the system code ATHLET applying an assembly-wise description of the core (i.e. one channel per fuel assembly) has been developed for coupled PARCS/ATHLET transient test calculations. This paper describes in detail the models and techniques used for the generation of the few-group parameterized cross section libraries, the PARCS model and the ATHLET model. Additionally, a simple exercise with coupled code system PARCS/ATHLET is presented and analysed.

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Cheng, Yuan Ming, Chien Hsun Kuo i Jih Hua Chin. "Real-Time Interpolator and Contour Tracking in Link-Space for a 3 DOF Parallel Mechanism". Materials Science Forum 594 (sierpień 2008): 415–36. http://dx.doi.org/10.4028/www.scientific.net/msf.594.415.

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Parallel mechanisms could be hardly used in contour tracking because of their mechanism features. This study proposed a link-space real time contour tracking for a 3 DOF (Z、α and β) hydraulic parallel mechanism. The essence of this approach is to convert control points of command trajectory to link space by inverse kinematics. A real-time interpolator was created and the multi-axis cross-coupled pre-compensation control (MCCPM) was constructed for link-space contour tracking. It was shown that a contour-accurate trajectory tracking could be performed which was impossible in the original Z-α-β space. Other advantages of this link-space approach were time efficiency and the uniform tracking velocity.

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37

Liu, Weirui, Yuwen Sun, Xilin Yuan i Mansen Chen. "A new approach to the pre-compensation of contour errorsfor three-axis machine tools using an adaptive cross-coupled controller". International Journal of Advanced Manufacturing Technology 90, nr 9-12 (12.11.2016): 3711–25. http://dx.doi.org/10.1007/s00170-016-9574-4.

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Chen, Syuan-Yi, Zi-Jie Chien, Wei-Yen Wang i Hsin-Han Chiang. "Contour Tracking Control of a Linear Motors-Driven X-Y-Y Stage Using Auto-Tuning Cross-Coupled 2DOF PID Control Approach". Applied Sciences 10, nr 24 (17.12.2020): 9036. http://dx.doi.org/10.3390/app10249036.

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Linear motors (LMs) are widely used in numerous industry automation where precise and fast motions are required to convert electric energy into linear actuation without the need of any switching mechanism. This study aims to develop a control strategy of auto-tuning cross-coupled two-degree-of-freedom proportional-integral-derivative (ACC2PID) to achieve extremely high-precision contour control of a LMs-driven X-Y-Y stage. Three 2PID controllers are developed to control the mover positions in individual axes while two compensators are designed to eliminate the contour errors in biaxial motions. Furthermore, an improved artificial bee colony algorithm is employed as a powerful optimization technique so that all the control parameters can be concurrently evaluated and optimized online while ensuring the non-fragility of the proposed controller. In this way, the tracking error in each axis and contour errors of the biaxial motions can be concurrently minimized, and further, satisfactory positioning accuracy and synchronization performance can be achieved. Finally, the experimental comparison results confirm the validity of the proposed ACC2PID control system regarding the multi-axis contour tracking control of the highly uncertain and nonlinear LMs-driven X-Y-Y stage.

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Su, Jian Bin, Xue Zhong Wu, Ding Bang Xiao, Zhi Hua Chen, Zhan Qiang Hou, Xing Hua Wang, Yu Xin i Kun He. "Modeling of Vibratory Microgyroscope with Manufacture Errors Based on Parameters Identification Theory". Key Engineering Materials 562-565 (lipiec 2013): 452–57. http://dx.doi.org/10.4028/www.scientific.net/kem.562-565.452.

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This paper presents a modeling method of vibratory microgyroscope with manufacture errors based on parameters identification theroy. owing to the manufacture errors, such as quadrature error and cross-axis perturbation, the resonant vibrations of the drive mode to the sense mode are coupled not only through the Coriolis force. In reality, also by elastic forces, damping and so on. Accurate modeling and identification of manufacture errors enhance significantly the ability to compensate for the consequent errors via feedback/feedforward control strategies. In this article, a really direct model with manufacture errors of the microgyroscope is proposed and the parameters of the model are identified with Frequency-Response Analysis (FRA) and State-Space-based system-identification approach.

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Zhu, H. A., C. L. Teo i G. S. Hong. "An Uncertainty-Attenuating Controller for Mechanical Manipulators with Electromechanical Dynamics". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 207, nr 3 (sierpień 1993): 165–71. http://dx.doi.org/10.1243/pime_proc_1993_207_335_02.

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It is known that the cross-coupled non-linear electromechanical dynamics of motor-manipulator systems is more complex than when only the mechanical dynamics is considered. In this paper, control of manipulators with non-negligible motor dynamics is studied and a control strategy is developed for achieving ease of controller design and high control performance. By using the developed algorithm not only can the highly complicated electromechanical dynamics be effectively controlled, but also the motors are made ‘sensible’ to sense and compensate for the uncertain dynamics acting at the manipulator joints. What is more, as an encouraging by-result, the difficulty and complexity in modelling and controlling such systems can be reduced significantly.

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Garrick-Bethell, Ian, Thomas Jarchow, Heiko Hecht i Laurence R. Young. "Vestibular adaptation to centrifugation does not transfer across planes of head rotation". Journal of Vestibular Research 18, nr 1 (1.07.2008): 25–37. http://dx.doi.org/10.3233/ves-2008-18103.

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Out-of-plane head movements performed during fast rotation produce non-compensatory nystagmus, sensations of illusory motion, and often motion sickness. Adaptation to this cross-coupled Coriolis stimulus has previously been demonstrated for head turns made in the yaw (transverse) plane of motion, during supine head-on-axis rotation. An open question, however, is if adaptation to head movements in one plane of motion transfers to head movements performed in a new, unpracticed plane of motion. Evidence of transfer would imply the brain builds up a generalized model of the vestibular sensory-motor system, instead of learning a variety of individual input/output relations separately. To investigate, over two days 9 subjects performed pitch head turns (sagittal plane) while rotating, before and after a series of yaw head turns while rotating. A Control Group of 10 subjects performed only the pitch movements. The vestibulo-ocular reflex (VOR) and sensations of illusory motion were recorded in the dark for all movements. Upon comparing the two groups we failed to find any evidence of transfer from the yaw plane to the pitch plane, suggesting that adaptation to cross-coupled stimuli is specific to the particular plane of head movement. The findings have applications for the use of centrifugation as a possible countermeasure for long duration spaceflight. Adapting astronauts to unconstrained head movements while rotating will likely require exposure to head movements in all planes and directions.

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Rezaei, Farzan, i Seyed Javad Azhari. "Analysis and Design Procedure of a Novel Low Power Highly Linear Operational Transconductance Amplifier". Journal of Circuits, Systems and Computers 24, nr 05 (8.04.2015): 1550071. http://dx.doi.org/10.1142/s0218126615500711.

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In this paper, a new highly linear operational transconductance amplifier (OTA) is presented. Proposed OTA employs two linearization techniques of cross-coupled double differential pairs and resistive source degeneration to achieve highly linear response under low power consumption. Considering the linearity and the frequency response issues as main parameters of OTA in the communication circuits, design procedure is theoretically formulated for the best linearity and optimum frequency compensation. Proposed OTA is simulated in 0.18-μm TSMC CMOS technology by Hspice simulator. While, the power consumption is only 467 μW, applying two-tone input voltage with amplitude of 0.6 Vp-p at 10 MHz frequency results in -61 dB third-order intermodulation (IM3) distortion of the output current that still remains below -44 dB for amplitudes up to 1 Vp-p. A precise frequency response analysis is performed which has resulted in optimum values of resistor and capacitor for miller compensation. Using common mode feedback in both stages and push-pull based output stage lead to 108 dB CMRR at DC that decreases to 84.5 dB at 100 kHz frequency.

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Zhou, Xubin, Weidong Chen, Qing Xiao, Xiangsen Kong, Xingtian Liu, Liping Zhou, Yichong Dong i Quan Zhang. "A Modified Asymmetric Bouc–Wen Model-Based Decoupling Control of an XY Piezoactuated Compliant Platform with Coupled Hysteresis Characteristics". Shock and Vibration 2020 (15.12.2020): 1–15. http://dx.doi.org/10.1155/2020/6637282.

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Due to the inherent hysteresis characteristics of the smart material, the positioning accuracy of the piezo-driven manipulator was always decreased. Especially in multi-degrees-of-freedom (MDOFs) compliant manipulators driven by multismart actuators, the cross-coupled hysteresis among MDOFs decreased the positioning accuracy of such compliant platforms significantly. In this paper, the hysteresis feature identification and coupled hysteresis compensation of a piezo-driven XY manipulator was investigated. To establish the hysteresis characteristics of the piezo-driven manipulator, a modified Bouc–Wen model has been proposed, and a Genetic Algorithm-based Particle Swarm Optimization (GA-PSO) was adopted to recognize the parameters of the model. To improve the output performances of the manipulator, the decoupling controller of the XY micromanipulator was designed, and the driven voltages were modified using the estimated coupling displacements. The experiments validated that the modified Bouc–Wen model featured the ability to present the hysteresis process effectively, and the maximum prediction errors are 0.19 μm and 0.16 μm in the two directions separately. The coupled hysteresis displacement before and after implementing the decoupling controller in the X-direction was reduced from 0.56 μm to 0.15 μm, and the coupling effect is reduced by 73.2%, while in the Y-direction, the coupling effect was also decreased by 72.9%.

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Liu, Shixiang, Tianyu Lu, Teng Shang i Qunli Xia. "Dynamic Modeling and Coupling Characteristic Analysis of Two-Axis Rate Gyro Seeker". International Journal of Aerospace Engineering 2018 (22.10.2018): 1–14. http://dx.doi.org/10.1155/2018/8513684.

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A dynamic model of a two-axis rate gyro-stabilized platform-based seeker with cross-coupling, mass imbalance, and disturbance torque is developed on the basis of the working principle of seeker two-loop steady tracking theory; coordinate transformations are used to analyze the effects of seeker servo control mode on missile guidance and control systems. Frequency domain is used to identify the servo motor transfer function. Furthermore, a block diagram of the two-gimbal-coupled system is developed, and the coupling characteristics of gimbal angle are analyzed with different missile body inputs. Simulation results show that the analysis conforms with the actual movement rule of seeker gimbal and optical axis, and cross-coupling exists between the two gimbals. The lag compensation network can increase the open loop gain and increase the capacity for disturbance rate rejection. Simulations validate the theory and technology support for developing the seeker servo control model in engineering.

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45

Bułka, Bogdan R., i Jakub Łuczak. "Current Correlations in a Quantum Dot Ring: A Role of Quantum Interference". Entropy 21, nr 5 (24.05.2019): 527. http://dx.doi.org/10.3390/e21050527.

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We present studies of the electron transport and circular currents induced by the bias voltage and the magnetic flux threading a ring of three quantum dots coupled with two electrodes. Quantum interference of electron waves passing through the states with opposite chirality plays a relevant role in transport, where one can observe Fano resonance with destructive interference. The quantum interference effect is quantitatively described by local bond currents and their correlation functions. Fluctuations of the transport current are characterized by the Lesovik formula for the shot noise, which is a composition of the bond current correlation functions. In the presence of circular currents, the cross-correlation of the bond currents can be very large, but it is negative and compensates for the large positive auto-correlation functions.

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Heydarzadeh, Mohammad S., Seyed M. Rezaei, Noor A. Mardi i Ali Kamali E. "Motion control of a two-axis linear motor-driven stage in the micro-milling process". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 232, nr 1 (11.12.2016): 65–76. http://dx.doi.org/10.1177/0954408916683976.

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The application of linear motor-driven stages as the feed drivers of CNC micro milling machine tools is growing. In addition to employ high speed and high precision equipment such as linear motor-driven stages, the precision of the machined contours is highly dependent on the capabilities of the servo controllers. In this paper, the design of a precise controller for a two-axis LMDS has been investigated for micro-milling applications. In such feed drives, disturbances such as friction, force ripples, and machining forces have adverse effects on the workpiece positioning precision due to the direct drive concept behind them. Therefore, in order to have an acceptable transient response and disturbance rejection properties, a two-degree-of-freedom proportional–integral–derivative controller was employed for each axis. To design this controller, the zero-placement method was used. To compensate disturbances and machining contour errors, the utilization of Kalman filter observers, neural networks, cross-coupled controllers, and different integration of them were studied. The controllers were experimentally examined for circular motions. An integrated controller consisted of a Kalman filter disturbance observer, a cross-coupled controller, and a well-designed two-degree-of-freedom proportional–integral–derivative controller resulted in a high contouring and tracking precision. The controller could also reduce the spikes caused by the friction at the motion reversal points such as the quadrants in circle trajectories.

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Peng, Jiaying, Hongfei Tao, Hongyu Ni i Wenxu Yan. "Synchronous control of the robot for repairing broken strands of overhead ground wires". Journal of Physics: Conference Series 2216, nr 1 (1.03.2022): 012040. http://dx.doi.org/10.1088/1742-6596/2216/1/012040.

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Abstract Abstarct. Overhead ground wire broken strand repair robot is a new type of electric robot, a complex multi-motor system. Therefore, the problem of synchronous control of each mechanism in the robot needs to be solved. A dual-layer sliding mode control strategy based on a cross-coupled synchronous control structure is proposed from the perspectives of mechanical structure synchronization and algorithm synchronization in this paper. Firstly, a global fast terminal sliding mode controller with single motor is designed for permanent magnet synchronous motor; Secondly, for the dual-motor system in the pre-twisted wire winding mechanism, a cross-coupling control structure is introduced. And a dual-motor synchronous compensation controller is designed in view of the fast non-singular terminal sliding mode combined with the new approximation law; Finally, the simulation verification in MATLAB, the results show that it has a certain improvement on the tracking error and synchronization error of the system. The anti-disturbance ability of the pre-twisted wire winding mechanism against uncertain loads is improved.

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Pistorio, Francesca, Muhammad Mubasher Saleem i Aurelio Somà. "A Dual-Mass Resonant MEMS Gyroscope Design with Electrostatic Tuning for Frequency Mismatch Compensation". Applied Sciences 11, nr 3 (26.01.2021): 1129. http://dx.doi.org/10.3390/app11031129.

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The micro-electro-mechanical systems (MEMS)-based sensor technologies are considered to be the enabling factor for the future development of smart sensing applications, mainly due to their small size, low power consumption and relatively low cost. This paper presents a new structurally and thermally stable design of a resonant mode-matched electrostatic z-axis MEMS gyroscope considering the foundry constraints of relatively low cost and commercially available silicon-on-insulator multi-user MEMS processes (SOIMUMPs) microfabrication process. The novelty of the proposed MEMS gyroscope design lies in the implementation of two separate masses for the drive and sense axis using a unique mechanical spring configuration that allows minimizing the cross-axis coupling between the drive and sense modes. For frequency mismatch compensation between the drive and sense modes due to foundry process uncertainties and gyroscope operating temperature variations, a comb-drive-based electrostatic tuning is implemented in the proposed design. The performance of the MEMS gyroscope design is verified through a detailed coupled-field electric-structural-thermal finite element method (FEM)-based analysis.

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Franchek, Nancy M., Dara W. Childs i Luis San Andres. "Theoretical and Experimental Comparisons for Rotordynamic Coefficients of a High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearing". Journal of Tribology 117, nr 2 (1.04.1995): 285–90. http://dx.doi.org/10.1115/1.2831244.

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Comparisons are presented between measurements and predictions for a 76.2 mm diameter, high-speed (24,600 rpm), high-pressure (7.0 MPa), hybrid bearings using warm (54°C) water as a test fluid. “Hybrid” refers to combined hydrostatic and hydrodynamic action. Test results are presented for an orifice-fed, square-recess configuration with five recesses. Data are provided for rotordynamic coefficients including direct and cross-coupled stiffness, direct damping, direct added-mass coefficients, and the whirl-frequency ratio. Experimental results are compared to predictions from an analysis by San Andres (1990a), which accounts for both temporal and convective acceleration terms in the fluid film. San Andres’ development uses an orifice discharge coefficient to model the pressure drop from supply pressure to recess pressure. With experimentally determined discharge-coefficient values as input, good agreement is obtained between theory and experiment. However, predictions are sensitive to changes in the orifice discharge coefficients.

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Kotha, Sreeteja Reddy, Karuppanan P, Abhay Kumar Gautam i Manmath Suryavanshi. "A 0.25-V Three-stage State Feedback Bulk-driven OTA for Wide Range Load Applications". Journal of Integrated Circuits and Systems 16, nr 3 (31.12.2021): 1–9. http://dx.doi.org/10.29292/jics.v16i3.498.

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This article employs a nested state feedback compensation technique to a three-stage bulk-driven operational transconductance amplifier (OTA). The projected OTA circuit consists of a bulk-driven PMOS amplifier, gate-driven NMOS amplifier, and common source (CS) amplifier. The entire transistors in the amplifier core are configuredwith self-cascode transistor topology to increase its output impedance. All transistors are designed to operate in a weak inversion in order to dissipate less power. Cross-coupled transistor pair topology in the bulk-driven stage allows to improve the effective transconductance of OTA. The CS amplifier can drive a large load capacitor. The polarities and transconductance gains of feedback blocks are controlled appropriately to obtain the desired DC gain and bandwidth. The capacitor-less compensation strategy allows the fabrication of the OTA using the minimum area. Conventional bulk-driven miler OTA, Bulk-driven stage improved indirect-feedback OTA (BSIF OTA), Gate-driven stage added bulk-driven OTA (GSIF OTA), and proposed bulk-driven OTA topologies are designed and simulated using cadence spectre tool at 25 mV supply voltage in the 65nm CMOS process. These OTA circuits are analyzed and compared in terms of parameters like DC gain, unity-gain frequency, phase margin, CMRR, power dissipated, slew rate, and input referred noise.

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