The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic erro...The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic error suppression method of gravimetry based on the high-precision acquisition of external velocity for compensating the horizontal error of the inertial plat-form.On the basis of platform gravity measurement,firstly,the dynamic performance of the system is enhanced by optimizing the horizontal damping network of the inertial platform and selecting its parameter.Secondly,an improved federal Kalman filtering algorithm and a fault diagnosis method are designed using strapdown inertial navigation system(SINS),odometer(OD),and laser Doppler velocimeter(LDV).Simulation validates that these methods can improve the accuracy and robustness of the external velocity acquisition.Three survey lines are selected in Tianjin,China,for the gravimetry experiments with different maneuvering levels,and the results demonstrate that after dynamic error suppression,the internal coincidence accuracies of smooth and uniform operation,obvious acceleration and deceleration operation,and high-dynamic operation are improved by 70.2%,73.6%,and 77.9%to reach 0.81 mGal,1.30 mGal,and 1.94 mGal,respectively,and the external coinci-dence accuracies during smooth and uniform operation are improved by 48.6%up to 1.66 mGal.It is shown that the pro-posed method can effectively suppress the dynamic error,and that the accuracy improvement increases with carrier maneuver-ability.However,the amount of residual error that can not be entirely eliminated increases as well,so the ground vehicle dynamic gravimetry should be maintained in the carrier for smooth and uniform operation.展开更多
A new method was proposed, in which a high-power CO2 laser modulated by high frequency was used as the driv- ing source to heat up a surface-temperature sensor. The continual beam and the pulsed beam sent out by the s...A new method was proposed, in which a high-power CO2 laser modulated by high frequency was used as the driv- ing source to heat up a surface-temperature sensor. The continual beam and the pulsed beam sent out by the same laser could be used in the same system to carry on the static calibration of the radiation thermometer and the dynamic calibration of the temperature sensor to be checked. The frequency-response characteristics of high-speed radiation thermometer surpassed that of the temperature sensor, therefore it could be used as the reference value to calibrate the latter and let system error be cor- rected. Differences in the environment of the sensor installing and the error caused by the change of thermo-physical proper- ty could be avoided. Thus, the difficult problem of traceable dynamic calibration of temperature was solved. In experiment, to obtain the frequency characteristics of the thermocouple and the dynamic performance of the K type thermocouple, which could compensate the dynamic characteristics of the sensor, the sensor was dynamically corrected by using the method, and then the mathematical model was established.展开更多
In shock wave＇s pressure testing,a dynamic compensation digital filter is designed based on particle swarm optimization （PSO） algorithm.Dynamic calibration experiment and simulation are conducted for the pressure s...In shock wave＇s pressure testing,a dynamic compensation digital filter is designed based on particle swarm optimization （PSO） algorithm.Dynamic calibration experiment and simulation are conducted for the pressure sensor.PSO algorithm is applied on Matlab platform to achieve optimization according to input and output data of the sensor as well as the reference model,and the global optimal values got by optimization become the parameters of the compensator.Finally,the dynamic compensation filter is established on LabVIEW platform.The experimental results show that the data after processing with the compensation filter truly reflects the input signal.展开更多
In this paper we address the dynamics of compensation cutting process from both Laplace s frequency domain and the time domain of the first time, using the two computer aided analyzing softwares: MATLAB and SIMULI...In this paper we address the dynamics of compensation cutting process from both Laplace s frequency domain and the time domain of the first time, using the two computer aided analyzing softwares: MATLAB and SIMULINK. Theoretical analysis and simulation experiments firstly show that not only the systematical stiffness of workpiece, spindle and tools, but also the regenerated coefficient affects the compensation displacement effect. The results show that the SREC is practicable in reality to decease the spindle induced errors in many engineering applications such as hard boring through simulation and the preliminary experiment results.展开更多
The integrated systems of unmanned surface vehicles(USVs) and remotely operated vehicles(ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV s...The integrated systems of unmanned surface vehicles(USVs) and remotely operated vehicles(ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV systems is frequently limited by strong disturbances induced by waves or currents. This paper develops a novel rigidflexible coupling multibody dynamic model that incorporates disturbances of variable-length marine cables with geometrically nonlinear motion. A hybrid Lagrangian-Eulerian absolute nodal coordinate formulation(ANCF) element is developed to accurately model subsea cables which undergo significant overall motion, substantial deformation,and mass flow during the deployment of underwater equipment. Furthermore, the governing equations of the coupled USV-umbilical-ROV system are derived, considering wave-induced forces and current disturbances. A numerical solver based on the Newmark-beta method is proposed, along with an adaptive meshing technique near the release point. After validating three experimental cases, the cable disturbances at both the USV and ROV ends—caused by ocean currents, heave motion, and simultaneous navigation—are comprehensively compared and evaluated. Finally,it is demonstrated that a PD controller with disturbance compensation can enhance the simultaneous navigation performance of USV-ROV systems.展开更多
In order to correct the test error caused by the dynamic characteristics of pressure sensor and avoid the influence of the error of sensor＇s dynamic model on compensation results,a dynamic compensation method of the ...In order to correct the test error caused by the dynamic characteristics of pressure sensor and avoid the influence of the error of sensor＇s dynamic model on compensation results,a dynamic compensation method of the pressure sensor is presented,which is based on quantum-behaved particle swarm optimization（QPSO）algorithm and the mean square error（MSE）.By using this method,the inverse model of the sensor is built and optimized and then the coefficients of the optimal compensator are got.This method is verified by the dynamic calibration with shock tube and the dynamic characteristics of the sensor before and after compensation are analyzed in time domain and frequency domain.The results show that the working bandwidth of the sensor is extended effectively.This method can reduce dynamic measuring error and improve test accuracy in actual measurement experiments.展开更多
Some dynamic factors, such as inertial forces and friction, may affect therobot trajectory accuracy. But these effects are not taken into account in robot motion controlschemes. Dynamic control methods, on the other h...Some dynamic factors, such as inertial forces and friction, may affect therobot trajectory accuracy. But these effects are not taken into account in robot motion controlschemes. Dynamic control methods, on the other hand, require the dynamic model of robot and theimplementation of new type controller. A method to improve robot trajectory accuracy by dynamiccompensation in robot motion control system is proposed. The dynamic compensation is applied as anadditional velocity feedforward and a multilayer neural network is employed to realize the robotinverse dynamics. The complicated dynamic parameter identification problem becomes a learningprocess of neural network connecting weights under supervision. The finite Fourier series is used toactivate each actuator of robot joints for obtaining training samples. Robot control system,consisting of an industrial computer and a digital motion controller, is implemented. The system isof open architecture with velocity feedforward function. The proposed method is not model-based andcombines the advantages of close-loop position control and computed torque control. Experimentalresults have shown that the method is validatities to improve the robot trajectory accuracy.展开更多
For studying the dynamic performance of subsea umbilical cable laying system and achieving the goal of cable tension and laying speed control,the rigid finite element method is used to discrete and transform the syste...For studying the dynamic performance of subsea umbilical cable laying system and achieving the goal of cable tension and laying speed control,the rigid finite element method is used to discrete and transform the system into a rigid-flexible coupling multi-body system which consists of rigid elements and spring-damping elements.The mathematical model of subsea umbilical cable laying system kinematic chain is presented with the second order Lagrange equation in the joint coordinate system,and dynamic modeling and simulation is performed with ADAMS.The dynamic analysis is conducted assuming the following three statuses:ideal laying,practical laying under wave disturbance,and practical laying with tension compensation.Results show that motion disturbances of the laying budge under sea waves,especially with heaving and pitching,will cause relatively serious fluctuations in cable tension and laying speed.Tension compensation,i.e.,active back tension torque control can restrict continuous tension increasing or decreasing effectively and rapidly,thus avoiding cable breach or buckling.展开更多
The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated b...The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network （RBF-NN）, where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square （LMS） algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine＇s performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods.展开更多
The discrete iterative map models of peak current-mode （PCM） and valley current-mode （VCM） controlled buck converters, boost converters, and buck-boost converters with ramp compensation are established and their d...The discrete iterative map models of peak current-mode （PCM） and valley current-mode （VCM） controlled buck converters, boost converters, and buck-boost converters with ramp compensation are established and their dynamical behaviours are investigated by using the operation region, parameter space map, bifurcation diagram, and Lyapunov exponent spectrum. The research results indicate that ramp compensation extends the stable operation range of the PCM controlled switching dc-dc converter to D 〉 0.5 and that of the VCM controlled switching dc-dc converter to D 〈 0.5. Compared with PCM controlled switching dc-dc converters with ramp compensation, VCM controlled switching dc-dc converters with ramp compensation exhibit interesting symmetrical dynamics. Experimental results are given to verify the analysis results in this paper.展开更多
A dynamic velocity feed-forward compensation （RBF-NN） dynamic model identification was presented for control （DVFCC） approach with RBF neural network the adaptive trajectory tracking of industrial robots. The prop...A dynamic velocity feed-forward compensation （RBF-NN） dynamic model identification was presented for control （DVFCC） approach with RBF neural network the adaptive trajectory tracking of industrial robots. The proposed control approach combined the advantages of traditional feedback closed-loop position control and computed torque control based on inverse dynamic model. The feed-forward compensator used a nominal robot dynamics as accurate dynamic model and on-line identification with RBF-NN as uncertain part to improve dynamic modeling accu- racy. The proposed compensation was applied as velocity feed-forward by an inverse velocity controller that can con- vert torque signal into velocity in the standard industrial controller. Then, the need for a torque control interface was avoided in the real-time dynamic control of industrial robot. The simulations and experiments were carried out on a gas cutting manipulator. The results show that the proposed control approach can reduce steady-state error, suppress overshoot and enhance tracking accuracy and efficiency in joint space and Cartesian space, especially under high- speed condition.展开更多
Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose spac...Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.展开更多
We present a study of the dynamic behavior of a two-sublattice spin-5/2 Ising model with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on alternating l...We present a study of the dynamic behavior of a two-sublattice spin-5/2 Ising model with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on alternating layers of a hexagonal lattice by using the Glauber-type stochastic dynamics.The lattice is formed by alternate layers of spins σ=5/2 and S=5/2.We employ the Glauber transition rates to construct the mean-field dynamic equations.First,we investigate the time variations of the average sublattice magnetizations to find the phases in the system and then the thermal behavior of the dynamic sublattice magnetizations to characterize the nature（first-or second-order） of the phase transitions and to obtain the dynamic phase transition（DPT） points.We also study the thermal behavior of the dynamic total magnetization to find the dynamic compensation temperature and to determine the type of the dynamic compensation behavior.We present the dynamic phase diagrams,including the dynamic compensation temperatures,in nine different planes.The phase diagrams contain seven different fundamental phases,thirteen different mixed phases,in which the binary and ternary combination of fundamental phases and the compensation temperature or the L-type behavior strongly depend on the interaction parameters.展开更多
Following the description of the subsided land treatment methods and the characteristics of the related land reclamation, the necessity and emergency of the land reclamation work is stressed. To cope with the related ...Following the description of the subsided land treatment methods and the characteristics of the related land reclamation, the necessity and emergency of the land reclamation work is stressed. To cope with the related problems, dynamic prediction of the ground subsidence in different time periods and areas is made based on the laws governing the rock and ground movements and line with a mine’s future mining plan. It is proposed to carry out dynamic management of subsided land reclamation work in mining area, in order to tackle the previous and current issues confronted in the processes of land requisition, compensation and land reclamation. It is intended to provide, through the above-mentioned efforts, the technical and decision-making basis for the mining authorities concerned to better solve the problems relating to land requisition and reclamation in the future, and relocation of villages for facilitating the mining of the underground coal depositing and realizing the sustainable development of mining enterprises.展开更多
An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideratio...An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect(DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second,adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer(NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.展开更多
The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easi...The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easily calculate the power factor,and Voltage controller in the microcontroller to determine whether input the compensation capacitance according to the size of power factor,the paper also analyzes the principle of capacitance compensation and calculation method. Dynamic compensation for the entire process is quick and accurate.展开更多
In this paper, compensation mechanism—a synchronic dynamic rule in language is postulated and theorized. The rule raises the acceptability of clauses by effecting the positive side of some variations with exceptional...In this paper, compensation mechanism—a synchronic dynamic rule in language is postulated and theorized. The rule raises the acceptability of clauses by effecting the positive side of some variations with exceptional expression and offsetting their negative side. This mechanism is determined by the instrumentality and systematicality of language so that its basic principle should be applicable to all exceptional expressions for particular positive effects and thus universal synchronically.展开更多
This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of t...This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of the center of gravity, controller design and implementation, etc. Physical components are also briefly discussed in this paper. Attitude dynamics of the system is inherently unstable. It is stabilized by a regulator. In addition, an observer is designed and utilized to estimate the unmeasured states. Thrust force generated by the propulsion unit is estimated by using the identified mathematical model of the unit. An experimental setup is employed to identify the mathematical model that expresses the relation between the applied input voltage to the propulsion unit and thrust produced by the propeller. Mathematical model for the attitude dynamics of Toruk is built. Then controllability and observability analysis are carried out for the system. Dynamic compensator composed of a state observer and a regulator, is designed on the mathematical model. Physical implementation on the system will be performed.展开更多
In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and...In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances.展开更多
基金supported by the Shanxi Provincial Natural Science Basic Research Program Young Talent Project(S2019-JC-QN-2408).
文摘The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic error suppression method of gravimetry based on the high-precision acquisition of external velocity for compensating the horizontal error of the inertial plat-form.On the basis of platform gravity measurement,firstly,the dynamic performance of the system is enhanced by optimizing the horizontal damping network of the inertial platform and selecting its parameter.Secondly,an improved federal Kalman filtering algorithm and a fault diagnosis method are designed using strapdown inertial navigation system(SINS),odometer(OD),and laser Doppler velocimeter(LDV).Simulation validates that these methods can improve the accuracy and robustness of the external velocity acquisition.Three survey lines are selected in Tianjin,China,for the gravimetry experiments with different maneuvering levels,and the results demonstrate that after dynamic error suppression,the internal coincidence accuracies of smooth and uniform operation,obvious acceleration and deceleration operation,and high-dynamic operation are improved by 70.2%,73.6%,and 77.9%to reach 0.81 mGal,1.30 mGal,and 1.94 mGal,respectively,and the external coinci-dence accuracies during smooth and uniform operation are improved by 48.6%up to 1.66 mGal.It is shown that the pro-posed method can effectively suppress the dynamic error,and that the accuracy improvement increases with carrier maneuver-ability.However,the amount of residual error that can not be entirely eliminated increases as well,so the ground vehicle dynamic gravimetry should be maintained in the carrier for smooth and uniform operation.
基金Research Project Supported by Shanxi Scholarship Council of China(No.2012-068)Taiyuan Science and Technology Agency(No.120247-20)Surface-temperature Sensor Dynamic Measurement and Calibration Technology Research of National Defense Fundamental Scientific Research
文摘A new method was proposed, in which a high-power CO2 laser modulated by high frequency was used as the driv- ing source to heat up a surface-temperature sensor. The continual beam and the pulsed beam sent out by the same laser could be used in the same system to carry on the static calibration of the radiation thermometer and the dynamic calibration of the temperature sensor to be checked. The frequency-response characteristics of high-speed radiation thermometer surpassed that of the temperature sensor, therefore it could be used as the reference value to calibrate the latter and let system error be cor- rected. Differences in the environment of the sensor installing and the error caused by the change of thermo-physical proper- ty could be avoided. Thus, the difficult problem of traceable dynamic calibration of temperature was solved. In experiment, to obtain the frequency characteristics of the thermocouple and the dynamic performance of the K type thermocouple, which could compensate the dynamic characteristics of the sensor, the sensor was dynamically corrected by using the method, and then the mathematical model was established.
文摘In shock wave＇s pressure testing,a dynamic compensation digital filter is designed based on particle swarm optimization （PSO） algorithm.Dynamic calibration experiment and simulation are conducted for the pressure sensor.PSO algorithm is applied on Matlab platform to achieve optimization according to input and output data of the sensor as well as the reference model,and the global optimal values got by optimization become the parameters of the compensator.Finally,the dynamic compensation filter is established on LabVIEW platform.The experimental results show that the data after processing with the compensation filter truly reflects the input signal.
文摘In this paper we address the dynamics of compensation cutting process from both Laplace s frequency domain and the time domain of the first time, using the two computer aided analyzing softwares: MATLAB and SIMULINK. Theoretical analysis and simulation experiments firstly show that not only the systematical stiffness of workpiece, spindle and tools, but also the regenerated coefficient affects the compensation displacement effect. The results show that the SREC is practicable in reality to decease the spindle induced errors in many engineering applications such as hard boring through simulation and the preliminary experiment results.
基金financially supported in part by the General Program of the National Natural Science Foundation of China (Grant No.12272221)the State Key Laboratory of Ocean Engineering (Shanghai Jiao Tong University)(Grant No. GKZD010087)。
文摘The integrated systems of unmanned surface vehicles(USVs) and remotely operated vehicles(ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV systems is frequently limited by strong disturbances induced by waves or currents. This paper develops a novel rigidflexible coupling multibody dynamic model that incorporates disturbances of variable-length marine cables with geometrically nonlinear motion. A hybrid Lagrangian-Eulerian absolute nodal coordinate formulation(ANCF) element is developed to accurately model subsea cables which undergo significant overall motion, substantial deformation,and mass flow during the deployment of underwater equipment. Furthermore, the governing equations of the coupled USV-umbilical-ROV system are derived, considering wave-induced forces and current disturbances. A numerical solver based on the Newmark-beta method is proposed, along with an adaptive meshing technique near the release point. After validating three experimental cases, the cable disturbances at both the USV and ROV ends—caused by ocean currents, heave motion, and simultaneous navigation—are comprehensively compared and evaluated. Finally,it is demonstrated that a PD controller with disturbance compensation can enhance the simultaneous navigation performance of USV-ROV systems.
基金The 11th Postgraduate Technology Innovation Project of North University of China(No.20141147)
文摘In order to correct the test error caused by the dynamic characteristics of pressure sensor and avoid the influence of the error of sensor＇s dynamic model on compensation results,a dynamic compensation method of the pressure sensor is presented,which is based on quantum-behaved particle swarm optimization（QPSO）algorithm and the mean square error（MSE）.By using this method,the inverse model of the sensor is built and optimized and then the coefficients of the optimal compensator are got.This method is verified by the dynamic calibration with shock tube and the dynamic characteristics of the sensor before and after compensation are analyzed in time domain and frequency domain.The results show that the working bandwidth of the sensor is extended effectively.This method can reduce dynamic measuring error and improve test accuracy in actual measurement experiments.
基金This project is supported by National 863 Project of China(No.9802-01).
文摘Some dynamic factors, such as inertial forces and friction, may affect therobot trajectory accuracy. But these effects are not taken into account in robot motion controlschemes. Dynamic control methods, on the other hand, require the dynamic model of robot and theimplementation of new type controller. A method to improve robot trajectory accuracy by dynamiccompensation in robot motion control system is proposed. The dynamic compensation is applied as anadditional velocity feedforward and a multilayer neural network is employed to realize the robotinverse dynamics. The complicated dynamic parameter identification problem becomes a learningprocess of neural network connecting weights under supervision. The finite Fourier series is used toactivate each actuator of robot joints for obtaining training samples. Robot control system,consisting of an industrial computer and a digital motion controller, is implemented. The system isof open architecture with velocity feedforward function. The proposed method is not model-based andcombines the advantages of close-loop position control and computed torque control. Experimentalresults have shown that the method is validatities to improve the robot trajectory accuracy.
基金Supported by the National Science and Technology Major Project:Development of Large Oil-gas Fields&Coal-bed Methane(No.2011ZX05056)
文摘For studying the dynamic performance of subsea umbilical cable laying system and achieving the goal of cable tension and laying speed control,the rigid finite element method is used to discrete and transform the system into a rigid-flexible coupling multi-body system which consists of rigid elements and spring-damping elements.The mathematical model of subsea umbilical cable laying system kinematic chain is presented with the second order Lagrange equation in the joint coordinate system,and dynamic modeling and simulation is performed with ADAMS.The dynamic analysis is conducted assuming the following three statuses:ideal laying,practical laying under wave disturbance,and practical laying with tension compensation.Results show that motion disturbances of the laying budge under sea waves,especially with heaving and pitching,will cause relatively serious fluctuations in cable tension and laying speed.Tension compensation,i.e.,active back tension torque control can restrict continuous tension increasing or decreasing effectively and rapidly,thus avoiding cable breach or buckling.
文摘The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network （RBF-NN）, where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square （LMS） algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine＇s performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods.
基金Project supported by the National Natural Science Foundation of China (Grant No.50677056)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK2009105)+1 种基金the Cultivation Project of Excellent Doctorate Dissertation of Southwest Jiaotong University,Chinathe Doctoral Innovation Foundation of Southwest Jiaotong University,China
文摘The discrete iterative map models of peak current-mode （PCM） and valley current-mode （VCM） controlled buck converters, boost converters, and buck-boost converters with ramp compensation are established and their dynamical behaviours are investigated by using the operation region, parameter space map, bifurcation diagram, and Lyapunov exponent spectrum. The research results indicate that ramp compensation extends the stable operation range of the PCM controlled switching dc-dc converter to D 〉 0.5 and that of the VCM controlled switching dc-dc converter to D 〈 0.5. Compared with PCM controlled switching dc-dc converters with ramp compensation, VCM controlled switching dc-dc converters with ramp compensation exhibit interesting symmetrical dynamics. Experimental results are given to verify the analysis results in this paper.
文摘A dynamic velocity feed-forward compensation （RBF-NN） dynamic model identification was presented for control （DVFCC） approach with RBF neural network the adaptive trajectory tracking of industrial robots. The proposed control approach combined the advantages of traditional feedback closed-loop position control and computed torque control based on inverse dynamic model. The feed-forward compensator used a nominal robot dynamics as accurate dynamic model and on-line identification with RBF-NN as uncertain part to improve dynamic modeling accu- racy. The proposed compensation was applied as velocity feed-forward by an inverse velocity controller that can con- vert torque signal into velocity in the standard industrial controller. Then, the need for a torque control interface was avoided in the real-time dynamic control of industrial robot. The simulations and experiments were carried out on a gas cutting manipulator. The results show that the proposed control approach can reduce steady-state error, suppress overshoot and enhance tracking accuracy and efficiency in joint space and Cartesian space, especially under high- speed condition.
基金supported by the National High Technology Research and Development Program of China (863 Program) (No.2012AA01A502)the National Natural Science Foundation of China (No.61179006)the Science and Technology Support Program of Sichuan Province (No.2014GZX0004)
文摘Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.
文摘We present a study of the dynamic behavior of a two-sublattice spin-5/2 Ising model with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on alternating layers of a hexagonal lattice by using the Glauber-type stochastic dynamics.The lattice is formed by alternate layers of spins σ=5/2 and S=5/2.We employ the Glauber transition rates to construct the mean-field dynamic equations.First,we investigate the time variations of the average sublattice magnetizations to find the phases in the system and then the thermal behavior of the dynamic sublattice magnetizations to characterize the nature（first-or second-order） of the phase transitions and to obtain the dynamic phase transition（DPT） points.We also study the thermal behavior of the dynamic total magnetization to find the dynamic compensation temperature and to determine the type of the dynamic compensation behavior.We present the dynamic phase diagrams,including the dynamic compensation temperatures,in nine different planes.The phase diagrams contain seven different fundamental phases,thirteen different mixed phases,in which the binary and ternary combination of fundamental phases and the compensation temperature or the L-type behavior strongly depend on the interaction parameters.
文摘Following the description of the subsided land treatment methods and the characteristics of the related land reclamation, the necessity and emergency of the land reclamation work is stressed. To cope with the related problems, dynamic prediction of the ground subsidence in different time periods and areas is made based on the laws governing the rock and ground movements and line with a mine’s future mining plan. It is proposed to carry out dynamic management of subsided land reclamation work in mining area, in order to tackle the previous and current issues confronted in the processes of land requisition, compensation and land reclamation. It is intended to provide, through the above-mentioned efforts, the technical and decision-making basis for the mining authorities concerned to better solve the problems relating to land requisition and reclamation in the future, and relocation of villages for facilitating the mining of the underground coal depositing and realizing the sustainable development of mining enterprises.
基金Project(114601034)supported by the Scholarship Award for Excellent Doctoral Students Granted by the Ministry of Education of ChinaProject(61273158)supported by the National Natural Science Foundation of China
文摘An adaptive current compensation control for a single-sided linear induction motor(SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect(DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second,adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer(NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.
文摘The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easily calculate the power factor,and Voltage controller in the microcontroller to determine whether input the compensation capacitance according to the size of power factor,the paper also analyzes the principle of capacitance compensation and calculation method. Dynamic compensation for the entire process is quick and accurate.
文摘In this paper, compensation mechanism—a synchronic dynamic rule in language is postulated and theorized. The rule raises the acceptability of clauses by effecting the positive side of some variations with exceptional expression and offsetting their negative side. This mechanism is determined by the instrumentality and systematicality of language so that its basic principle should be applicable to all exceptional expressions for particular positive effects and thus universal synchronically.
文摘This paper gives details about the controller design that aims to stabilize the novel twinrotor flying robot, Toruk. Toruk is an experimental test bench to study center of gravity steering, effect of the location of the center of gravity, controller design and implementation, etc. Physical components are also briefly discussed in this paper. Attitude dynamics of the system is inherently unstable. It is stabilized by a regulator. In addition, an observer is designed and utilized to estimate the unmeasured states. Thrust force generated by the propulsion unit is estimated by using the identified mathematical model of the unit. An experimental setup is employed to identify the mathematical model that expresses the relation between the applied input voltage to the propulsion unit and thrust produced by the propeller. Mathematical model for the attitude dynamics of Toruk is built. Then controllability and observability analysis are carried out for the system. Dynamic compensator composed of a state observer and a regulator, is designed on the mathematical model. Physical implementation on the system will be performed.
基金The National Basic Research Program of China (973 Program) (No. 2005CB221505)Open Fund of Provincial Open Laboratory for Control Engineering Key Disciplines (No. KG2009-02)
文摘In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances.
