Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embed...Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embedded in the capsule accurately in advance,which can cause inconvenience to practical application.To solve this problem,this paper proposes a magnetic tracking system with the capability of measuring themagnetic moment of the PM automatically.The system is constructed based on a 4×4 magnetic sensor array,whose sensing data is analyzed to determine the magnetic moment by referring to a magnetic dipole model.Withthe determined magnetic moment,a method of fusing the linear calculation and Levenberg-Marquardt algorithmsis proposed to determine the 3D position and 2D attitude of the PM.The experiments verified that the proposedsystem can achieve localization errors of 0.48 mm,0.42 mm,and 0.83 mm and orientation errors of 0.66◦,0.64◦,and 0.87◦for a PM(∅10 mm×10 mm)at vertical heights of 5 cm,10 cm,and 15 cm from the magnetic sensorarray,respectively.展开更多
This work deals with the estimation of solar radiation through a solar tracker aimed at evaluating the effect of solar tracking on the solar deposit in Burkina Faso. Using a two-axis solar tracking system, we experime...This work deals with the estimation of solar radiation through a solar tracker aimed at evaluating the effect of solar tracking on the solar deposit in Burkina Faso. Using a two-axis solar tracking system, we experimentally measured solar radiation at our Joseph KI-ZERBO University site and compared it with that obtained by a numerical simulation run using Fortran programming software based on a mathematical model by Brichambaut. The results obtained from the mathematical and experimental studies show that, with a solar tracker, on a clear-sky day, solar irradiation is between 800 W·m−2 and 1000 W·m−2 between about 8 a.m. and 4 p.m., i.e. a duration of 8 hours of insolation. Analysis of the numerical and experimental results shows very good quantitative and qualitative agreement, with an average relative error of 18%.展开更多
Aim To solve the time delay problem in the optoelectronic tracking system, improving the tracking accuracy. Methods The discount least square algorithm was applied to forecast the tracking error caused by the 40?ms ...Aim To solve the time delay problem in the optoelectronic tracking system, improving the tracking accuracy. Methods The discount least square algorithm was applied to forecast the tracking error caused by the 40?ms delay, and the predicting algorithm was improved by the adaptive discount method.Results The tracking errors of the two methods were compared, and an optimal controller with the improved adaptive discount predicting algorithm was adopted for simulation. Conclusion The predicting algorithms, especially the adaptive discount predicting algorithm, can decrease the tracking error greatly, and the desired tracking prediction can be achieved both in the transient state and in the steady state.展开更多
The high rolling speed of a missile heavily affects the stabilizing capability of the inertial platform in the laser tracking system （LTS） of the missile. In this paper, a rotational stabilizing platform （RSP） and...The high rolling speed of a missile heavily affects the stabilizing capability of the inertial platform in the laser tracking system （LTS） of the missile. In this paper, a rotational stabilizing platform （RSP） and a fuzzy-PID controller is designed to stabilize the inertial platform. This controller integrates the advantages of both fuzzy controller and classic PID controller. A comparison study is carried out to illustrate the advantages of the proposed fuzzy-PID controller over the classic PID controller. Numerical results indicate that the fuzzy-PID controller outperforms the classic one in effectively handling nonlinear disturbances and quickly stabilizing the inertial platform at the sudden change of missile roiling speed.展开更多
In this paper, a tracking system with space virtual feedback （SVF） is presented. The whole tracking system is closed by the space virtual feedback line that is the line of sight （LOS）, but the parts in the system,...In this paper, a tracking system with space virtual feedback （SVF） is presented. The whole tracking system is closed by the space virtual feedback line that is the line of sight （LOS）, but the parts in the system, such as the tracking subsystem and the servo subsystem, are in the state of open-loop. Because the SVF tracking model is used, the correcting loops can be removed in this system architecture. So the tracking speed and accuracy of the system are greatly improved.展开更多
Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in m...Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.展开更多
In this paper, we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mut...In this paper, we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mutual information rate between the feedback signal and the reference input signal is used to quantify information about the reference signal that is available for feedback. This mutual information rate must be maximized in order to improve the tracking performance. The mutual information is shown to be upper bounded by a quantity that depends on the unstable eigenvalues of the plant and on the channel capacity. If the channel capacity reaches a lower limit, the feedback signal becomes completely uncorrelated with the reference signal, rendering feedback useless. We also find a lower bound on the expected squared tracking error in terms of the entropy of a random reference signal. We show a misleading case where the mutual information rate does not predict the expected effect of nonminimum phase zeros. However, mutual information rate helps generalize the concept that there is a tradeoff when tracking and disturbance rejection are simultaneous goals, and a constraint communication channel is present in the feedback loop. Examples and simulations are provided to demonstrate some of the results.展开更多
This paper developed a theoretical model substantially based on the principle that only the normal component of solar radiation is actually converted into electrical energy. This theoretical model helped to predict mi...This paper developed a theoretical model substantially based on the principle that only the normal component of solar radiation is actually converted into electrical energy. This theoretical model helped to predict minimum and maximum daily energy gain (compared to static PV system tilted with certain angle) when using dual axis PV solar tracking systems, at any given location on earth without prior experimental data. Based on equations derived from model, minimum and maximum energy gain </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> computed and summarized in tables of minimum and maximum. Furthermore</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the model equations could be used to set up future experimental studies related to the matter.展开更多
Dynamic characteristics and tracking precision are studied in the photoelectric tracking system and a linear active disturbance rejection control( LADRC) scheme is proposed for position loop. A current and speed contr...Dynamic characteristics and tracking precision are studied in the photoelectric tracking system and a linear active disturbance rejection control( LADRC) scheme is proposed for position loop. A current and speed controller is designed by a transfer function model,which is obtained by adaptive differential evolution. Model error,friction and nonlinear factor existing in position loop are treated as ‘disturbance',which is estimated and compensated by generalized proportional integral( GPI)observer. Comparative results are provided to demonstrate the remarkable performance of the proposed method. It turns out that the proposed scheme is successful and has superior features,such as quick dynamic response,low overshoot and high tracking precision. Furthermore,with the proposed method,friction is suppressed effectively.展开更多
The worldwide research status of head tracking is introduced and the works made in the research of the predictive algorithm and in the exploration of the rule of the head tracking are set forth. A time delay model f...The worldwide research status of head tracking is introduced and the works made in the research of the predictive algorithm and in the exploration of the rule of the head tracking are set forth. A time delay model for the telerobotic scout system is built. In respect of eliminating error caused by time delay and making reasonable prediction to the data stream, many methods are experimented in order to realize the aim of real time tracking. The application of extrapolation algorithm and auto recursive algorithm in the orientation tracking is described in detail. These two algorithms are realized in Matlab environment. Through analysis of the curves generated by using these two predictive algorithms, an appropriate method was applied in the telerobotic scout system. The effect is satisfying.展开更多
Robot welding is an important developing direction of welding automation and intelligentization, and automatic seam tracking technology is one of principal research domains. Nowadays, seam tracking system with structu...Robot welding is an important developing direction of welding automation and intelligentization, and automatic seam tracking technology is one of principal research domains. Nowadays, seam tracking system with structured light vision becomes a hot research. Structured light vision seam tracking products abroad are generally very expensive and can only be applied on special occasions. In China, the research of structured light vision seam tracking system is still just on the stage of experiments. A robot real-time seam tracking system with line structured light vision is designed. The hardware system is set up, a filtering method for line structure seam image is improved, and compared with common filtering, it has better effect and characteristic of real time. Two methods, fast template matching and fast Hough transform, to recognize the image coordinates of seam center are improved. Two new image recognition methods, structure element matching and comer detecting, are proposed. The comparison of seam image recognition shows that fast template matching and comer detecting are more precise and stable than the other two methods, and comer detecting is the best in real time. A simultaneous calibration for camera parameters and robot hand-eye is also proposed, and calculation shows that the calibration is effective and feasible. The robot seam tracking tests for linear and folded lap-joint are performed, which are based on the above four image recognition methods, and the results indicate that four image recognition methods are all applicable to real-time seam tracking, and the whole system sufficed for the requirements of real-time seam tracking. Automatic seam tracking with line structured light vision is feasible and has good versatility.展开更多
This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used t...This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used to control linear and angular velocities on the midpoint of the front frame. The novel controller based on the error dynamics model is eventually realized to track the path high-precisely with constant speed. The results of simulation and experiment show that the LQR-GA controller has a better tracking performance than the existing methods under a low speed of 3 m/s. In this paper, kinematics model and simulation control models based on co-simulation of ADAMS and Matlab/Simulink are established to verify the proposed strategy. In addition, a real vehicle experiment is designed to further more correctness of the conclusion. With the proposed controller and considering the steering model in the simulation, the control performance is improved and matches the actual situation better. The research results contribute to the development of automation of ADT.展开更多
The attitude tracking control problem for a satellite with parameter uncertainties and external disturbances is considered in this paper. For this class of multi-input multi-output uncertain nonlinear systems, a desig...The attitude tracking control problem for a satellite with parameter uncertainties and external disturbances is considered in this paper. For this class of multi-input multi-output uncertain nonlinear systems, a design method of robust output tracking controllers is proposed based on the upper-bounds of the uncertainties. Using the input/output feedback linearization approach and Lyapunov method, a control law is designed, which guarantees that the system output exponentially tracks the given desired output. The proposed controller is easy to compute and complement. Simulation results show that, in the closed-loop system, precise attitude control is accomplished in spite of the uncertainties in the system.展开更多
The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional ...The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop（PLL）, which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying（BPSK） and Quadrature Phase Shift Keying（QPSK） signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals,respectively. With these critical standard deviations, lock thresholds are increased from à12 andà4 d B to 3 and à2 d B, respectively.展开更多
Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cann...Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the effec tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensorbased monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We devel oped a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensorbased motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual realitybased neurorehabili tation system.展开更多
The velocity tracking control of a hydraulic servo system is studied. Sincethe dynamics of the system are highly nonlinear and have large extent of model uncertainties, suchas big changes in load and parameters, a der...The velocity tracking control of a hydraulic servo system is studied. Sincethe dynamics of the system are highly nonlinear and have large extent of model uncertainties, suchas big changes in load and parameters, a derivation and integral sliding mode variable structurecontrol scheme (DI-SVSC) is proposed. An integral controller is introduced to avoid the assumptionthat the derivative of desired signal must be known in conventional sliding mode variable structurecontrol, a nonlinear derivation controller is used to weaken the chattering of system. The designmethod of switching function in integral sliding mode control, nonlinear derivation coefficient andcontrollers of DI-SVSC is presented respectively. Simulation shows that the control approach is ofnice robustness and improves velocity tracking accuracy considerably.展开更多
A tracking system composed of three multiwires proportional chambers(MWPCs) for the external target facility of the Cooler Storage Ring is reported in this paper. The active areas of the MWPCs are 518 mm 9400 mm, 582 ...A tracking system composed of three multiwires proportional chambers(MWPCs) for the external target facility of the Cooler Storage Ring is reported in this paper. The active areas of the MWPCs are 518 mm 9400 mm, 582 mm 9 450 mm, and 710 mm 9 500 mm Each MWPC consists of a series of alternately placed cathode and anode wire planes and can measure position along the directions of-30°, 0°, and 30° relative to horizontal. The construction and operation of the detectors are described, and a method for track reconstruction is introduced. A track-finding efficiency of about 62% and a spatial resolution of 1.21 mm have been achieved. The pion and proton can be identified clearly with the tracking system combined with a time-of-flight system.展开更多
Grey modeling can be used to predict the behavioral development of a system and find out the lead control values of the system. By using fuzzy inference, PID parameters can be adjusted on line by the fuzzy controller ...Grey modeling can be used to predict the behavioral development of a system and find out the lead control values of the system. By using fuzzy inference, PID parameters can be adjusted on line by the fuzzy controller with PID parameters self-tuning. According to the characteristics of target tracking system in a robot weapon, grey prediction theory and fuzzy PID control ideas are combined. A grey prediction mathematical model is constructed and a fuzzy PID controller with grey prediction was developed. Simulation result shows fuzzy PID control algorithm with grey prediction is an efficient method that can improve the control equality and robustness of traditional PID control and fuzzy PID control, and has much better performance for target tracking.展开更多
Seam image processing is the basis of the realization of automatic laser vision seam tracking system, and it has become one of the important research directions. Adding windows processing, gray processing, fast median...Seam image processing is the basis of the realization of automatic laser vision seam tracking system, and it has become one of the important research directions. Adding windows processing, gray processing, fast median filtering, binary processing and image edge extraction are used to pretreat the seam image. In the post-processing of seam image, the feature points of the target image are succesfully detected by using center line extraction and feature points detection algorithm based on slope analysis. The whole processing time is less than 150 ms, and the real-time processing of seam image can be implemented.展开更多
基金the National Natural Science Foundation of China(Nos.52275038 and 61803347)the Shanxi Province Science Foundation for Excellent Youth(No.202203021224007)+1 种基金the Key Research and Development Plan of Shanxi Province(No.201903D321164)the Opening Foundation of Shanxi Key Laboratory of Advanced Manufacturing Technology(No.XJZZ202101)。
文摘Magnetic tracking technologies have a promising application in detecting the real-time position andattitude of a capsule endoscope.However,most of them need to measure the magnetic moment of a permanentmagnet(PM)embedded in the capsule accurately in advance,which can cause inconvenience to practical application.To solve this problem,this paper proposes a magnetic tracking system with the capability of measuring themagnetic moment of the PM automatically.The system is constructed based on a 4×4 magnetic sensor array,whose sensing data is analyzed to determine the magnetic moment by referring to a magnetic dipole model.Withthe determined magnetic moment,a method of fusing the linear calculation and Levenberg-Marquardt algorithmsis proposed to determine the 3D position and 2D attitude of the PM.The experiments verified that the proposedsystem can achieve localization errors of 0.48 mm,0.42 mm,and 0.83 mm and orientation errors of 0.66◦,0.64◦,and 0.87◦for a PM(∅10 mm×10 mm)at vertical heights of 5 cm,10 cm,and 15 cm from the magnetic sensorarray,respectively.
文摘This work deals with the estimation of solar radiation through a solar tracker aimed at evaluating the effect of solar tracking on the solar deposit in Burkina Faso. Using a two-axis solar tracking system, we experimentally measured solar radiation at our Joseph KI-ZERBO University site and compared it with that obtained by a numerical simulation run using Fortran programming software based on a mathematical model by Brichambaut. The results obtained from the mathematical and experimental studies show that, with a solar tracker, on a clear-sky day, solar irradiation is between 800 W·m−2 and 1000 W·m−2 between about 8 a.m. and 4 p.m., i.e. a duration of 8 hours of insolation. Analysis of the numerical and experimental results shows very good quantitative and qualitative agreement, with an average relative error of 18%.
文摘Aim To solve the time delay problem in the optoelectronic tracking system, improving the tracking accuracy. Methods The discount least square algorithm was applied to forecast the tracking error caused by the 40?ms delay, and the predicting algorithm was improved by the adaptive discount method.Results The tracking errors of the two methods were compared, and an optimal controller with the improved adaptive discount predicting algorithm was adopted for simulation. Conclusion The predicting algorithms, especially the adaptive discount predicting algorithm, can decrease the tracking error greatly, and the desired tracking prediction can be achieved both in the transient state and in the steady state.
基金the China Aerospace Science and Innovation Foundation(No. 06CASC0407)
文摘The high rolling speed of a missile heavily affects the stabilizing capability of the inertial platform in the laser tracking system （LTS） of the missile. In this paper, a rotational stabilizing platform （RSP） and a fuzzy-PID controller is designed to stabilize the inertial platform. This controller integrates the advantages of both fuzzy controller and classic PID controller. A comparison study is carried out to illustrate the advantages of the proposed fuzzy-PID controller over the classic PID controller. Numerical results indicate that the fuzzy-PID controller outperforms the classic one in effectively handling nonlinear disturbances and quickly stabilizing the inertial platform at the sudden change of missile roiling speed.
文摘In this paper, a tracking system with space virtual feedback （SVF） is presented. The whole tracking system is closed by the space virtual feedback line that is the line of sight （LOS）, but the parts in the system, such as the tracking subsystem and the servo subsystem, are in the state of open-loop. Because the SVF tracking model is used, the correcting loops can be removed in this system architecture. So the tracking speed and accuracy of the system are greatly improved.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51708152)the Science and Technology Innovation Committee of Shenzhen Municipality(Grant No.JCYJ20170811155435737).
文摘Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.
基金supported by Conacytthe second author was partly supported by NSF award under the FIND initiative CNS 0626380
文摘In this paper, we obtain information theoretical conditions for tracking in linear time-invariant control systems. We consider the particular case where the closed loop contains a channel in the feedback loop. The mutual information rate between the feedback signal and the reference input signal is used to quantify information about the reference signal that is available for feedback. This mutual information rate must be maximized in order to improve the tracking performance. The mutual information is shown to be upper bounded by a quantity that depends on the unstable eigenvalues of the plant and on the channel capacity. If the channel capacity reaches a lower limit, the feedback signal becomes completely uncorrelated with the reference signal, rendering feedback useless. We also find a lower bound on the expected squared tracking error in terms of the entropy of a random reference signal. We show a misleading case where the mutual information rate does not predict the expected effect of nonminimum phase zeros. However, mutual information rate helps generalize the concept that there is a tradeoff when tracking and disturbance rejection are simultaneous goals, and a constraint communication channel is present in the feedback loop. Examples and simulations are provided to demonstrate some of the results.
文摘This paper developed a theoretical model substantially based on the principle that only the normal component of solar radiation is actually converted into electrical energy. This theoretical model helped to predict minimum and maximum daily energy gain (compared to static PV system tilted with certain angle) when using dual axis PV solar tracking systems, at any given location on earth without prior experimental data. Based on equations derived from model, minimum and maximum energy gain </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> computed and summarized in tables of minimum and maximum. Furthermore</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the model equations could be used to set up future experimental studies related to the matter.
基金Supported by the National High Technology Research and Development Programme of China(No.2015AA8082065)the National Natural Science Foundation of China(No.61205143)
文摘Dynamic characteristics and tracking precision are studied in the photoelectric tracking system and a linear active disturbance rejection control( LADRC) scheme is proposed for position loop. A current and speed controller is designed by a transfer function model,which is obtained by adaptive differential evolution. Model error,friction and nonlinear factor existing in position loop are treated as ‘disturbance',which is estimated and compensated by generalized proportional integral( GPI)observer. Comparative results are provided to demonstrate the remarkable performance of the proposed method. It turns out that the proposed scheme is successful and has superior features,such as quick dynamic response,low overshoot and high tracking precision. Furthermore,with the proposed method,friction is suppressed effectively.
文摘The worldwide research status of head tracking is introduced and the works made in the research of the predictive algorithm and in the exploration of the rule of the head tracking are set forth. A time delay model for the telerobotic scout system is built. In respect of eliminating error caused by time delay and making reasonable prediction to the data stream, many methods are experimented in order to realize the aim of real time tracking. The application of extrapolation algorithm and auto recursive algorithm in the orientation tracking is described in detail. These two algorithms are realized in Matlab environment. Through analysis of the curves generated by using these two predictive algorithms, an appropriate method was applied in the telerobotic scout system. The effect is satisfying.
基金supported by National Natural Science Foundation of China (Grant No. 50175027)Guangdong Provincial Natural Science Foundation of China(Grant No. 0133002)
文摘Robot welding is an important developing direction of welding automation and intelligentization, and automatic seam tracking technology is one of principal research domains. Nowadays, seam tracking system with structured light vision becomes a hot research. Structured light vision seam tracking products abroad are generally very expensive and can only be applied on special occasions. In China, the research of structured light vision seam tracking system is still just on the stage of experiments. A robot real-time seam tracking system with line structured light vision is designed. The hardware system is set up, a filtering method for line structure seam image is improved, and compared with common filtering, it has better effect and characteristic of real time. Two methods, fast template matching and fast Hough transform, to recognize the image coordinates of seam center are improved. Two new image recognition methods, structure element matching and comer detecting, are proposed. The comparison of seam image recognition shows that fast template matching and comer detecting are more precise and stable than the other two methods, and comer detecting is the best in real time. A simultaneous calibration for camera parameters and robot hand-eye is also proposed, and calculation shows that the calibration is effective and feasible. The robot seam tracking tests for linear and folded lap-joint are performed, which are based on the above four image recognition methods, and the results indicate that four image recognition methods are all applicable to real-time seam tracking, and the whole system sufficed for the requirements of real-time seam tracking. Automatic seam tracking with line structured light vision is feasible and has good versatility.
基金the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-15-023A1)the National Key R&D Program Project(Nos.2016YFC0802905 and 2018YFC0604403)
文摘This paper designs a novel controller to improve the path-tracking performance of articulated dump truck(ADT). By combining linear quadratic regulator(LQR) with genetic algorithm(GA), the designed controller is used to control linear and angular velocities on the midpoint of the front frame. The novel controller based on the error dynamics model is eventually realized to track the path high-precisely with constant speed. The results of simulation and experiment show that the LQR-GA controller has a better tracking performance than the existing methods under a low speed of 3 m/s. In this paper, kinematics model and simulation control models based on co-simulation of ADAMS and Matlab/Simulink are established to verify the proposed strategy. In addition, a real vehicle experiment is designed to further more correctness of the conclusion. With the proposed controller and considering the steering model in the simulation, the control performance is improved and matches the actual situation better. The research results contribute to the development of automation of ADT.
文摘The attitude tracking control problem for a satellite with parameter uncertainties and external disturbances is considered in this paper. For this class of multi-input multi-output uncertain nonlinear systems, a design method of robust output tracking controllers is proposed based on the upper-bounds of the uncertainties. Using the input/output feedback linearization approach and Lyapunov method, a control law is designed, which guarantees that the system output exponentially tracks the given desired output. The proposed controller is easy to compute and complement. Simulation results show that, in the closed-loop system, precise attitude control is accomplished in spite of the uncertainties in the system.
基金co-supported by the National Basic Research Program of China (No. 2014CB340205)the Natural Science Foundation of Shaanxi Provincial Department of Education (No. 2016JM6016)the National Natural Science Foundation of China (No. 61473228)
文摘The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop（PLL）, which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying（BPSK） and Quadrature Phase Shift Keying（QPSK） signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals,respectively. With these critical standard deviations, lock thresholds are increased from à12 andà4 d B to 3 and à2 d B, respectively.
基金supported by Foundation Rafael del Pino, Foundation of the Spanish National Hospital for Paraplegic Research and Integration (FUHNPAIIN) and INDRA systemssupported by CONSOLIDER-INGENIO 2010 program HYPERCSD 2009-00067. MICINN(Spain)
文摘Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the effec tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensorbased monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We devel oped a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensorbased motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual realitybased neurorehabili tation system.
文摘The velocity tracking control of a hydraulic servo system is studied. Sincethe dynamics of the system are highly nonlinear and have large extent of model uncertainties, suchas big changes in load and parameters, a derivation and integral sliding mode variable structurecontrol scheme (DI-SVSC) is proposed. An integral controller is introduced to avoid the assumptionthat the derivative of desired signal must be known in conventional sliding mode variable structurecontrol, a nonlinear derivation controller is used to weaken the chattering of system. The designmethod of switching function in integral sliding mode control, nonlinear derivation coefficient andcontrollers of DI-SVSC is presented respectively. Simulation shows that the control approach is ofnice robustness and improves velocity tracking accuracy considerably.
基金supported by the National Natural Science Foundation of China(Nos.U1332207,11222550,11405242 and 11305222)
文摘A tracking system composed of three multiwires proportional chambers(MWPCs) for the external target facility of the Cooler Storage Ring is reported in this paper. The active areas of the MWPCs are 518 mm 9400 mm, 582 mm 9 450 mm, and 710 mm 9 500 mm Each MWPC consists of a series of alternately placed cathode and anode wire planes and can measure position along the directions of-30°, 0°, and 30° relative to horizontal. The construction and operation of the detectors are described, and a method for track reconstruction is introduced. A track-finding efficiency of about 62% and a spatial resolution of 1.21 mm have been achieved. The pion and proton can be identified clearly with the tracking system combined with a time-of-flight system.
基金the Ministerial Level Advanced Research Foundation (061103)
文摘Grey modeling can be used to predict the behavioral development of a system and find out the lead control values of the system. By using fuzzy inference, PID parameters can be adjusted on line by the fuzzy controller with PID parameters self-tuning. According to the characteristics of target tracking system in a robot weapon, grey prediction theory and fuzzy PID control ideas are combined. A grey prediction mathematical model is constructed and a fuzzy PID controller with grey prediction was developed. Simulation result shows fuzzy PID control algorithm with grey prediction is an efficient method that can improve the control equality and robustness of traditional PID control and fuzzy PID control, and has much better performance for target tracking.
基金The work was supported by National Natural Science Foundation of China （No. 50975195）.
文摘Seam image processing is the basis of the realization of automatic laser vision seam tracking system, and it has become one of the important research directions. Adding windows processing, gray processing, fast median filtering, binary processing and image edge extraction are used to pretreat the seam image. In the post-processing of seam image, the feature points of the target image are succesfully detected by using center line extraction and feature points detection algorithm based on slope analysis. The whole processing time is less than 150 ms, and the real-time processing of seam image can be implemented.
