Based on the results of similar material simulation, the laws of slope movementdue to mining under a gully were analyzed. Selected a slope rock as objective, the mechanisms of slope movement influence upon underground...Based on the results of similar material simulation, the laws of slope movementdue to mining under a gully were analyzed. Selected a slope rock as objective, the mechanisms of slope movement influence upon underground mining were proposed, and respective structural models were built by means of numerical modeling and physical simulation.It holds the point that the influence of slope movement on underground mining could becontrolled to some extent by appropriate measures. The results indicate that, forgully-ward mining, which mines toward a gully, the slope rock slides horizontally and rotates in layers; for gully-away mining, which mines away from the gully, the slope rock rotates in a reversed polygon. The slope movement associated with mining under a gully isattributed to pre-existing free faces in the ground gully and underground mining-inducedfree faces.展开更多
To control movement,the brain has to integrate proprioceptive information from a variety of mechanoreceptors.The role of proprioception in daily activities,exercise,and sports has been extensively investigated,using d...To control movement,the brain has to integrate proprioceptive information from a variety of mechanoreceptors.The role of proprioception in daily activities,exercise,and sports has been extensively investigated,using different techniques,yet the proprioceptive mechanisms underlying human movement control are still unclear.In the current work we have reviewed understanding of proprioception and the three testing methods:threshold to detection of passive motion,joint position reproduction,and active movement extent discrimination,all of which have been used for assessing proprioception.The origin of the methods,the different testing apparatus,and the procedures and protocols used in each approach are compared and discussed.Recommendations are made for choosing an appropriate technique when assessing proprioceptive mechanisms in different contexts.展开更多
Vestibulo-ocular reflex(VOR) is an important biological reflex that controls eye movement to ensure clear vision while the head is in motion.Nowadays,VOR measurement is commonly done with a video head impulse test bas...Vestibulo-ocular reflex(VOR) is an important biological reflex that controls eye movement to ensure clear vision while the head is in motion.Nowadays,VOR measurement is commonly done with a video head impulse test based on a velocity gain algorithm or a position gain algorithm,in which velocity gain is a VOR calculation on head and eye velocity,whereas position gain is calculated from head and eye position.The aim of this work is first to compare the two algorithms' performance and to detect covert catch-up saccade,then to propose a stand-alone recommendation application for the patient's diagnosis.In the first experiment,for ipsilesional and contralesional sides,the calculated position gain(0.94±0.17) is higher than velocity gain(0.84±0.19).Moreover,gain asymmetry of both lesion and intact sides using velocity gain is mostly higher than that from using position gain(four out of five subjects).Consequently,for subjects who have unilateral vestibular neuritis diagnosed from clinical symptoms and a vestibular function test,vestibular weakness is depicted by velocity gain much better than by position gain.Covert catch-up saccade and position gain then are used as inputs for recommendation applications.展开更多
Good understanding of relationship between parameters of vehicle, terrain and interaction at the interface is required to develop effective navigation and motion control algorithms for autonomous wheeled mobile robots...Good understanding of relationship between parameters of vehicle, terrain and interaction at the interface is required to develop effective navigation and motion control algorithms for autonomous wheeled mobile robots (AWMR) in rough terrain. A model and analysis of relationship among wheel slippage (S), rotation angle (0), sinkage (z) and wheel radius (r) are presented. It is found that wheel rotation angle, sinkage and radius have some influence on wheel slippage. A multi-objective optimization problem with slippage as utility function was formulated and solved in MATLAB. The results reveal the optimal values of wheel-terrain parameters required to achieve optimum slippage on dry sandy terrain. A method of slippage estimation for a five-wheeled mobile robot was presented through comparing the odometric measurements of the powered wheels with those of the fifth non-powered wheel. The experimental result shows that this method is feasible and can be used for online slippage estimation in a sandy terrain.展开更多
Hybrid mecihanism is a new type of planar controllable mechanism. Position control acouracy of system determines the output aconracy of the mechanism. In order to achieve the desired high acowacy, nonlinear factors as...Hybrid mecihanism is a new type of planar controllable mechanism. Position control acouracy of system determines the output aconracy of the mechanism. In order to achieve the desired high acowacy, nonlinear factors as friction nmst be accurately compensated in the real-time servo control algoritinn. In this paper, the model of a hybrid five-bar mechanism is introduced. In terms of the characteristics of the hybrid mechanism, a hybrid intelligent control algorithm based on proportional-integral-derivative (PID) control and cerebellar model articulation control techniques was presented and used to perform control of hybrid five-bar mechanism for the lust time. The sinmulation results show that the hybrid control method can improve the control effect remarkably, compared with the traditional PID control strategy.展开更多
As a new sort of mobile ad hoc network(MANET), aeronautical ad hoc network(AANET) has fleet-moving airborne nodes(ANs) and suffers from frequent network partitioning due to the rapid-changing topology. In this work, t...As a new sort of mobile ad hoc network(MANET), aeronautical ad hoc network(AANET) has fleet-moving airborne nodes(ANs) and suffers from frequent network partitioning due to the rapid-changing topology. In this work, the additional relay nodes(RNs) is employed to repair the network and maintain connectivity in AANET. As ANs move, RNs need to move as well in order to re-establish the topology as quickly as possible. The network model and problem definition are firstly given, and then an online approach for RNs' movement control is presented to make ANs achieve certain connectivity requirement during run time. By defining the minimum cost feasible moving matrix(MCFM), a fast algorithm is proposed for RNs' movement control problem. Simulations demonstrate that the proposed algorithm outperforms other control approaches in the highly-dynamic environment and is of great potential to be applied in AANET.展开更多
The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames ar...The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames are selected according to the motion activity of each frame and the motion accumulation of successive frames. The motion activity analysis is based on the statistics of motion vectors and with consider- ation of the characteristics of H. 264 coding standard. A prediction model of motion accumulation is pro- posed to reduce complex computation of motion estimation. The dynamic encoding frame rate control algorithm is applied to both the frame level and the GOB (Group of Macroblocks ) level. Simulation is done to compare the performance of JM76 with the proposed frame level scheme and GOB level scheme.展开更多
Motion simulator usually appears the phenomenon of false cues and the workspace is limited in the process of washout. The proposed washout algorithm combines fuzzy logic control with the vestibular system to design th...Motion simulator usually appears the phenomenon of false cues and the workspace is limited in the process of washout. The proposed washout algorithm combines fuzzy logic control with the vestibular system to design the tilt coordination fuzzy adaptive filter, in order to minimize the vestibular sensory error below the human perception threshold. Owing to tilt coordination angular velocity limiter, the loss of low-pass acceleration must be compensated by the acceleration transform model. The translational channel decreases the possibility of the workspace beyond limitation and expands the scope of motion platform simulating input acceleration by using third-order filter. The simulation results show that the proposed algorithm can effectively overcome the phase retardation of classical washout algorithm, and then prevent the produce of false cues, decrease the displacement of motion platform simultaneously; in addition, white Gaussian noise simulates large variations in acceleration. The proposed washout algorithm can have maximal extreme value of acceleration and accurate simulating performance in general. It also proves that the proposed washout algorithm has a strong adaptability and reliability, which can effectively improve the dynamic fidelity for motion simulator.展开更多
The permutation flow shop scheduling problems with deteriorating jobs and rejection on dominant machines were studied.The objectives are to minimize the makespan of scheduled jobs plus the total rejection penalty and ...The permutation flow shop scheduling problems with deteriorating jobs and rejection on dominant machines were studied.The objectives are to minimize the makespan of scheduled jobs plus the total rejection penalty and the total completion time of scheduled jobs plus the total rejection penalty.For each objective, polynomial time algorithms based on dynamic programming were presented.展开更多
Behavior-based flocking has got remarkable attention in the recent past. The flocking algorithms can have inherent properties like organizing,healing and re-configuring for a distributed system. In this research we pr...Behavior-based flocking has got remarkable attention in the recent past. The flocking algorithms can have inherent properties like organizing,healing and re-configuring for a distributed system. In this research we presented the emergent flocking behavior-based control. We defined the basis behavior and with variety of combination, and obtained a complex group behavior flocking. Unlike classical flocking, we implemented additional rules obstacle avoidance,formation and seek target which results in V-formation flocking while avoiding obstacles. We performed the visual simulation of our flocking algorithm using MATLAB. The results concluded that the multi-boid flock could successfully navigate to the target while avoiding collisions. This can be applied to areas where we need to maximize the coverage of sensors or minimize the risk of combative attack,both in military and civilian scenarios.展开更多
A moving-mass control method is introduced to stratospheric airship for its special working condition of low atmospheric density and low speed.The dynamic equation of airship is derived by using the Newton-Euler metho...A moving-mass control method is introduced to stratospheric airship for its special working condition of low atmospheric density and low speed.The dynamic equation of airship is derived by using the Newton-Euler method and the mechanism of attitude control by moving masses is studied.Then the passive gliding of airship by the moving masses is given based on the theory of glider,and attitude control capability between moving mass and elevator is compared at different airspeed.Analysis results show that the motion of masses changes the gravity center of the airship system,which makes the inertia tensor and the gravity moment vary.Meanwhile,the aerodynamic angles are generated,which results in the change of aerodynamic moment.Control efficiency of moving masses is independent of airspeed.Thus the moving-mass control has the advantage over the aerodynamic surfaces at low airspeed.展开更多
The article presents multi-pattern formation exchange of mobile robots according to the image signals, programs motion paths using A* searching algorithm, and avoids the collision points of motion paths. The system c...The article presents multi-pattern formation exchange of mobile robots according to the image signals, programs motion paths using A* searching algorithm, and avoids the collision points of motion paths. The system contains an image system, a grid based motion platform, some wireless Radio Frequency (RF) modules and five mobile robots. We use image recognition algorithm to classify variety pattern formation according to variety Quick Response (QR) code symbols on the user interface of the supervised computer. The supervised computer controls five mobile robots to execute formation exchange and presents the movement scenario on the grid based motion platform. We have been developed some pattern formations according to game applications, such as long snake pattern formation, phalanx pattern formation, crane wing pattern formation, sword pattern formation, cone pattern formation, sward pattern tbrmation, T pattern formation, rectangle pattern formation and so on. We develop the user interface of the multi-robot system to program motion paths for variety pattern formation exchange according to the minimum displacement. In the experimental results, the supervised computer recognizes the various QR-code symbols using image system and decides which pattern formation to be selected on real-time. Mobile robots can receive the pattern formation command from the supervised computer, present the movement scenario from the original pattern formation to the assigned pattern formation on the motion platform, and avoid other mobile robots on real-time.展开更多
To guarantee the accuracy of error analysis and evaluate the manufacturing tolerance s influence,anumerical error analysis method for parallel kinematic machines (PKMs) is presented in this paper.Quasi-Newton method a...To guarantee the accuracy of error analysis and evaluate the manufacturing tolerance s influence,anumerical error analysis method for parallel kinematic machines (PKMs) is presented in this paper.Quasi-Newton method and genetic algorithm are introduced for the forward kinematic solution.Based onthe inverse and forward kinematic solutions,the end-effector s error calculation procedure is developed.To solve the accuracy problem caused by the length and angular parameters' different units,a normalizationmethod is proposed based on the manufacturing tolerance.Comparison between the error analysis resultscalculated by the traditional method and the numerical method for a 4RRR PKM shows that,this numericalerror analysis method is more accurate,simpler,and can evaluate the machine s real error basedon the manufacturing tolerance.展开更多
Based on the good time-frequency localization of the wavelet packet modulation (WPM) system and the analysis of the muhitone (MT) interference, an improved WPM narrow band interference (NBI) rejection system usi...Based on the good time-frequency localization of the wavelet packet modulation (WPM) system and the analysis of the muhitone (MT) interference, an improved WPM narrow band interference (NBI) rejection system using an adaptive least mean square (LMS) algorithm is discussed in this paper. In the WPM interference rejection system, according to the structure of the wavelet packet tree (WFF) and the characteristic of the MT interference, the demodulated WPM signal which contains the interference component is filtered using an adaptive LMS filtering implementation. Theoretical analysis and simulation resuits show that the proposed method improves the bit error rate (BER) performance of the WPM system in the presence of MT interference.展开更多
In this paper,Waish functions are applied to dynamical system analysis. An operational matrix for differential is developed first and compared with M. S. Corrington's method vis a simple example. Then this operati...In this paper,Waish functions are applied to dynamical system analysis. An operational matrix for differential is developed first and compared with M. S. Corrington's method vis a simple example. Then this operational matrix is used to analyze both time-invariant and time-variant systems ,and examples are presented respectively.展开更多
Based on the structure of Elman and Jordan neural networks, a new dynamic neural network is constructed. The network can remember the past state of the hidden layer and adjust the effect of the past signal to the curr...Based on the structure of Elman and Jordan neural networks, a new dynamic neural network is constructed. The network can remember the past state of the hidden layer and adjust the effect of the past signal to the current value in real-time. And in order to enhance the signal processing capabilities, the feedback of output layer nodes is increased. A hybrid learning algorithm based on genetic algorithm (GA) and error back propagation algorithm (BP) is used to adjust the weight values of the network, which can accelerate the rate of convergence and avoid getting into local optimum. Finally, the improved neural network is utilized to identify underwater vehicle (UV) ' s hydrodynamic model, and the simulation results show that the neural network based on hybrid learning algorithm can improve the learning rate of convergence and identification nrecision.展开更多
In this paper, we study the kinematic mechanism and path planning for a two-caster nonholonomic vehicle (the Essboard) which is a recent variant of skateboard. Different from the most studied Snakeboard, the Essboard ...In this paper, we study the kinematic mechanism and path planning for a two-caster nonholonomic vehicle (the Essboard) which is a recent variant of skateboard. Different from the most studied Snakeboard, the Essboard consists of a torsion bar and two platforms, each of which contains a pedal and a caster. We first investigate the relationship between the tilt angles of the pedals and the wheel directions of the casters. This relationship reveals how to control the wheel directions by adjusting the tilt angles. Next, the rotational radius of the Essboard is derived for a given pair of tilt angles of both pedals. The rotational radius of the Essboard is much different than that of the Snakeboard. Then we develop a path-planning algorithm for the Essboard to move from a start position to the goal, using a series of consecutively connected arcs, which are tangent to each other at the connected points. It is shown from a kinematic point of view that the path planning of the Essboard can be solved by a series of pairs of pedals' tilt angles. Three experiments are conducted to confirm the correctness of the main results. The results in this paper are a foundation for further study of the Essboard.展开更多
基金Supported by the Program for New Century Excellent Talents in University (NCET-05-0480)Gradute Student Scientific Research Innovation in University of Jiangsu Province
文摘Based on the results of similar material simulation, the laws of slope movementdue to mining under a gully were analyzed. Selected a slope rock as objective, the mechanisms of slope movement influence upon underground mining were proposed, and respective structural models were built by means of numerical modeling and physical simulation.It holds the point that the influence of slope movement on underground mining could becontrolled to some extent by appropriate measures. The results indicate that, forgully-ward mining, which mines toward a gully, the slope rock slides horizontally and rotates in layers; for gully-away mining, which mines away from the gully, the slope rock rotates in a reversed polygon. The slope movement associated with mining under a gully isattributed to pre-existing free faces in the ground gully and underground mining-inducedfree faces.
基金the University of Canberra,Key Laboratory of Exercise and Health Sciences of Ministry of Education,Shanghai University of Sport and Shanghai Municipal Science and Technology Commission (No.13490503800)supported by Shanghai Pujiang Program (No.15PJ1407600)
文摘To control movement,the brain has to integrate proprioceptive information from a variety of mechanoreceptors.The role of proprioception in daily activities,exercise,and sports has been extensively investigated,using different techniques,yet the proprioceptive mechanisms underlying human movement control are still unclear.In the current work we have reviewed understanding of proprioception and the three testing methods:threshold to detection of passive motion,joint position reproduction,and active movement extent discrimination,all of which have been used for assessing proprioception.The origin of the methods,the different testing apparatus,and the procedures and protocols used in each approach are compared and discussed.Recommendations are made for choosing an appropriate technique when assessing proprioceptive mechanisms in different contexts.
基金supported by the MSIP (Ministry of Science,ICT and Future Planning),Korea,under the ITRC (Information Technology Research Center)support program (IITP-2016-H8501-16-1019) supervised by the IITP (Institute for Information & Communications Technology Promotion) and Inha University Research Grantsupported by the Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education (2010-0020163)
文摘Vestibulo-ocular reflex(VOR) is an important biological reflex that controls eye movement to ensure clear vision while the head is in motion.Nowadays,VOR measurement is commonly done with a video head impulse test based on a velocity gain algorithm or a position gain algorithm,in which velocity gain is a VOR calculation on head and eye velocity,whereas position gain is calculated from head and eye position.The aim of this work is first to compare the two algorithms' performance and to detect covert catch-up saccade,then to propose a stand-alone recommendation application for the patient's diagnosis.In the first experiment,for ipsilesional and contralesional sides,the calculated position gain(0.94±0.17) is higher than velocity gain(0.84±0.19).Moreover,gain asymmetry of both lesion and intact sides using velocity gain is mostly higher than that from using position gain(four out of five subjects).Consequently,for subjects who have unilateral vestibular neuritis diagnosed from clinical symptoms and a vestibular function test,vestibular weakness is depicted by velocity gain much better than by position gain.Covert catch-up saccade and position gain then are used as inputs for recommendation applications.
基金Project(60775060) supported by the National Natural Science Foundation of ChinaProject(F200801) supported by the Natural Science Foundation of Heilongjiang Province,China+1 种基金Project(200802171053,20102304110006) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(2012RFXXG059) supported by Harbin Science and Technology Innovation Talents Special Fund,China
文摘Good understanding of relationship between parameters of vehicle, terrain and interaction at the interface is required to develop effective navigation and motion control algorithms for autonomous wheeled mobile robots (AWMR) in rough terrain. A model and analysis of relationship among wheel slippage (S), rotation angle (0), sinkage (z) and wheel radius (r) are presented. It is found that wheel rotation angle, sinkage and radius have some influence on wheel slippage. A multi-objective optimization problem with slippage as utility function was formulated and solved in MATLAB. The results reveal the optimal values of wheel-terrain parameters required to achieve optimum slippage on dry sandy terrain. A method of slippage estimation for a five-wheeled mobile robot was presented through comparing the odometric measurements of the powered wheels with those of the fifth non-powered wheel. The experimental result shows that this method is feasible and can be used for online slippage estimation in a sandy terrain.
文摘Hybrid mecihanism is a new type of planar controllable mechanism. Position control acouracy of system determines the output aconracy of the mechanism. In order to achieve the desired high acowacy, nonlinear factors as friction nmst be accurately compensated in the real-time servo control algoritinn. In this paper, the model of a hybrid five-bar mechanism is introduced. In terms of the characteristics of the hybrid mechanism, a hybrid intelligent control algorithm based on proportional-integral-derivative (PID) control and cerebellar model articulation control techniques was presented and used to perform control of hybrid five-bar mechanism for the lust time. The sinmulation results show that the hybrid control method can improve the control effect remarkably, compared with the traditional PID control strategy.
文摘As a new sort of mobile ad hoc network(MANET), aeronautical ad hoc network(AANET) has fleet-moving airborne nodes(ANs) and suffers from frequent network partitioning due to the rapid-changing topology. In this work, the additional relay nodes(RNs) is employed to repair the network and maintain connectivity in AANET. As ANs move, RNs need to move as well in order to re-establish the topology as quickly as possible. The network model and problem definition are firstly given, and then an online approach for RNs' movement control is presented to make ANs achieve certain connectivity requirement during run time. By defining the minimum cost feasible moving matrix(MCFM), a fast algorithm is proposed for RNs' movement control problem. Simulations demonstrate that the proposed algorithm outperforms other control approaches in the highly-dynamic environment and is of great potential to be applied in AANET.
基金Supported by the High Technology. Research and Development Program of China (No. 2005AA103310) and the National Natural Science Foundation of China (No. 60202006).
文摘The goal of this paper is to improve human visual perceptual quality as well as coding efficiency of H. 264 video at low bit rate conditions by adaptively adjusting the number of skipped frames. The encoding frames are selected according to the motion activity of each frame and the motion accumulation of successive frames. The motion activity analysis is based on the statistics of motion vectors and with consider- ation of the characteristics of H. 264 coding standard. A prediction model of motion accumulation is pro- posed to reduce complex computation of motion estimation. The dynamic encoding frame rate control algorithm is applied to both the frame level and the GOB (Group of Macroblocks ) level. Simulation is done to compare the performance of JM76 with the proposed frame level scheme and GOB level scheme.
基金Funded by the National Natural Science Foundation of China(U1233107)Civil Aviation Science and Technology Innovation Project of China(MHRD20140210)
文摘Motion simulator usually appears the phenomenon of false cues and the workspace is limited in the process of washout. The proposed washout algorithm combines fuzzy logic control with the vestibular system to design the tilt coordination fuzzy adaptive filter, in order to minimize the vestibular sensory error below the human perception threshold. Owing to tilt coordination angular velocity limiter, the loss of low-pass acceleration must be compensated by the acceleration transform model. The translational channel decreases the possibility of the workspace beyond limitation and expands the scope of motion platform simulating input acceleration by using third-order filter. The simulation results show that the proposed algorithm can effectively overcome the phase retardation of classical washout algorithm, and then prevent the produce of false cues, decrease the displacement of motion platform simultaneously; in addition, white Gaussian noise simulates large variations in acceleration. The proposed washout algorithm can have maximal extreme value of acceleration and accurate simulating performance in general. It also proves that the proposed washout algorithm has a strong adaptability and reliability, which can effectively improve the dynamic fidelity for motion simulator.
文摘The permutation flow shop scheduling problems with deteriorating jobs and rejection on dominant machines were studied.The objectives are to minimize the makespan of scheduled jobs plus the total rejection penalty and the total completion time of scheduled jobs plus the total rejection penalty.For each objective, polynomial time algorithms based on dynamic programming were presented.
文摘Behavior-based flocking has got remarkable attention in the recent past. The flocking algorithms can have inherent properties like organizing,healing and re-configuring for a distributed system. In this research we presented the emergent flocking behavior-based control. We defined the basis behavior and with variety of combination, and obtained a complex group behavior flocking. Unlike classical flocking, we implemented additional rules obstacle avoidance,formation and seek target which results in V-formation flocking while avoiding obstacles. We performed the visual simulation of our flocking algorithm using MATLAB. The results concluded that the multi-boid flock could successfully navigate to the target while avoiding collisions. This can be applied to areas where we need to maximize the coverage of sensors or minimize the risk of combative attack,both in military and civilian scenarios.
基金Supported by the National Natural Science Foundation of China(No.61175074,11272205)
文摘A moving-mass control method is introduced to stratospheric airship for its special working condition of low atmospheric density and low speed.The dynamic equation of airship is derived by using the Newton-Euler method and the mechanism of attitude control by moving masses is studied.Then the passive gliding of airship by the moving masses is given based on the theory of glider,and attitude control capability between moving mass and elevator is compared at different airspeed.Analysis results show that the motion of masses changes the gravity center of the airship system,which makes the inertia tensor and the gravity moment vary.Meanwhile,the aerodynamic angles are generated,which results in the change of aerodynamic moment.Control efficiency of moving masses is independent of airspeed.Thus the moving-mass control has the advantage over the aerodynamic surfaces at low airspeed.
文摘The article presents multi-pattern formation exchange of mobile robots according to the image signals, programs motion paths using A* searching algorithm, and avoids the collision points of motion paths. The system contains an image system, a grid based motion platform, some wireless Radio Frequency (RF) modules and five mobile robots. We use image recognition algorithm to classify variety pattern formation according to variety Quick Response (QR) code symbols on the user interface of the supervised computer. The supervised computer controls five mobile robots to execute formation exchange and presents the movement scenario on the grid based motion platform. We have been developed some pattern formations according to game applications, such as long snake pattern formation, phalanx pattern formation, crane wing pattern formation, sword pattern formation, cone pattern formation, sward pattern tbrmation, T pattern formation, rectangle pattern formation and so on. We develop the user interface of the multi-robot system to program motion paths for variety pattern formation exchange according to the minimum displacement. In the experimental results, the supervised computer recognizes the various QR-code symbols using image system and decides which pattern formation to be selected on real-time. Mobile robots can receive the pattern formation command from the supervised computer, present the movement scenario from the original pattern formation to the assigned pattern formation on the motion platform, and avoid other mobile robots on real-time.
基金Supported by the National High Technology Research and Development Programme of China ( No. 2007AA041901 )the National Natural Science Foundation of China ( No. 50775117 )+1 种基金the National S&T Major Project ( No. 2009XZ04001-025 )the Technology Innovation Fund of AVIC ( No.2009E 13224 )
文摘To guarantee the accuracy of error analysis and evaluate the manufacturing tolerance s influence,anumerical error analysis method for parallel kinematic machines (PKMs) is presented in this paper.Quasi-Newton method and genetic algorithm are introduced for the forward kinematic solution.Based onthe inverse and forward kinematic solutions,the end-effector s error calculation procedure is developed.To solve the accuracy problem caused by the length and angular parameters' different units,a normalizationmethod is proposed based on the manufacturing tolerance.Comparison between the error analysis resultscalculated by the traditional method and the numerical method for a 4RRR PKM shows that,this numericalerror analysis method is more accurate,simpler,and can evaluate the machine s real error basedon the manufacturing tolerance.
基金Supported by the National Natural Science Foundation of China (No. 60532030).
文摘Based on the good time-frequency localization of the wavelet packet modulation (WPM) system and the analysis of the muhitone (MT) interference, an improved WPM narrow band interference (NBI) rejection system using an adaptive least mean square (LMS) algorithm is discussed in this paper. In the WPM interference rejection system, according to the structure of the wavelet packet tree (WFF) and the characteristic of the MT interference, the demodulated WPM signal which contains the interference component is filtered using an adaptive LMS filtering implementation. Theoretical analysis and simulation resuits show that the proposed method improves the bit error rate (BER) performance of the WPM system in the presence of MT interference.
文摘In this paper,Waish functions are applied to dynamical system analysis. An operational matrix for differential is developed first and compared with M. S. Corrington's method vis a simple example. Then this operational matrix is used to analyze both time-invariant and time-variant systems ,and examples are presented respectively.
基金Supported by the Postdoctoral Science Foundation of China( No. 20100480964 ) , the Basic Research Foundation of Central University ( No. HEUCF100104) and the National Natural Science Foundation of China (No. 50909025/E091002).
文摘Based on the structure of Elman and Jordan neural networks, a new dynamic neural network is constructed. The network can remember the past state of the hidden layer and adjust the effect of the past signal to the current value in real-time. And in order to enhance the signal processing capabilities, the feedback of output layer nodes is increased. A hybrid learning algorithm based on genetic algorithm (GA) and error back propagation algorithm (BP) is used to adjust the weight values of the network, which can accelerate the rate of convergence and avoid getting into local optimum. Finally, the improved neural network is utilized to identify underwater vehicle (UV) ' s hydrodynamic model, and the simulation results show that the neural network based on hybrid learning algorithm can improve the learning rate of convergence and identification nrecision.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51105012 and 61175079)
文摘In this paper, we study the kinematic mechanism and path planning for a two-caster nonholonomic vehicle (the Essboard) which is a recent variant of skateboard. Different from the most studied Snakeboard, the Essboard consists of a torsion bar and two platforms, each of which contains a pedal and a caster. We first investigate the relationship between the tilt angles of the pedals and the wheel directions of the casters. This relationship reveals how to control the wheel directions by adjusting the tilt angles. Next, the rotational radius of the Essboard is derived for a given pair of tilt angles of both pedals. The rotational radius of the Essboard is much different than that of the Snakeboard. Then we develop a path-planning algorithm for the Essboard to move from a start position to the goal, using a series of consecutively connected arcs, which are tangent to each other at the connected points. It is shown from a kinematic point of view that the path planning of the Essboard can be solved by a series of pairs of pedals' tilt angles. Three experiments are conducted to confirm the correctness of the main results. The results in this paper are a foundation for further study of the Essboard.