Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinem...Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot＇s base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product- of-exponential （POE） formula. In the first step the robot＇s base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot＇s reference configuration and the base coordinate frame＇s pose are equivalently transformed to the zero-position errors of the robot＇s joints. The simplified model of the robot＇s positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot＇ s 39 kinematic parameters are finished in the second step. It＇s proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot＇s base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.展开更多
Steel-making areas are harsh operation environments that involve many highly dangerous manual operations.The use of robotic equipment technology is a key step toward intelligent manufacturing in steel-making areas.The...Steel-making areas are harsh operation environments that involve many highly dangerous manual operations.The use of robotic equipment technology is a key step toward intelligent manufacturing in steel-making areas.The steel-making environment is not suitable for long-term debugging work,so in order to reduce the debugging workload,it is an important method to improve the absolute position accuracy of the robot.This paper addresses the identification of kinematic parameters of the 7-DOF robotic equipment used in a continuous casting area at Baosteel.The purpose of this work is to apply compensation measures during the application process of the robotic equipment to improve its accuracy and stability,while shortening the on-site debugging time.展开更多
Computer-assisted sperm class analyser (CASA) analysis of avian semen following cryopreservation indicates that their semen motility and viability parameters become compromised, due in part to oxidative stress. To mim...Computer-assisted sperm class analyser (CASA) analysis of avian semen following cryopreservation indicates that their semen motility and viability parameters become compromised, due in part to oxidative stress. To mimic these observations we have treated cockerel semen with an oxidative stress inducing agent, namely hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and monitored the motility, kinematic and viability parameters over time. Briefly, five healthy and fertile South African Venda cockerels were selected and their semen was collected using the abdominal massage technique. The semen was then treated with H<sub>2</sub>O<sub>2</sub> at 0 µM, 5 µM, 50 µM and 200 µM concentrations for 0, 3, 16 and 24 hrs. The semen motility, kinematic and viability parameters were then determined using the CASA system while the viability was determined using the SYBR-14/PI staining. The Pearson’s correlation coefficient was determined to test the relationships between the levels of induced oxidative stress, period of exposure to oxidative stress inducing agent and the motility plus kinematic parameters. Our data revealed that in raw cockerel semen, there was high and positive correlations between total motility (TM), progressive motility (PM), rapid (RAP), curvilinear velocity (VCL), straight line velocity (VSL) and average path velocity (VAP) while the kinematic parameters LIN, STR, WOB, ALH and BCF had low or negative correlations with them. Furthermore, TM, PM, RAP, VCL and VSL remained highly and positively correlated with the induced oxidative stress and also, linearity (LIN), straightness (STR), wobble (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) remained negatively correlated with the induced oxidative stress, after 3 hrs. After 24 hrs, TM, PM, RAP, VCL, VSL, VAP and ALH, became negatively correlated with the induced oxidative stress while LIN, STR, WOB and BCF became positively correlated with the induced oxidative stress. Conversely, when the H<sub>2</sub>O<sub>2</sub> concentration used was correlated with motility and kinematic parameters over time, TM, PM, RAP, VCL, VSL, VAP became negatively correlated with oxidative stress while LIN, STR, WOB, ALH and BCF show negative or low correlations with the induced oxidative stress. This data indicates that LIN, STR, WOB, BCF and to some extend ALH, reveal the least correlations with the induced oxidative stress under persistent oxidative stress conditions in cockerel semen. In conclusion, cockerel semen, like buck semen, does not easily succumb to oxidative stress since the raw semen correlations of CASA analysed parameters are comparable to these observed after 3 hrs of H<sub>2</sub>O<sub>2</sub> treatment. In addition, the oxidative stress levels tolerated by cockerel semen should not 5 µM H<sub>2</sub>O<sub>2</sub> oxidative stress levels. Lastly, lack of correlation between LIN, STR, WOB, BCF and ALH and induced oxidative stress can be used in cockerel semen to show intolerable cryopreservation conditions.展开更多
The accurate measurement of kinematic parameters in satellite separation tests has great significance in evaluating separation performance. A novel study is made on the measuring accuracy of monocular and binocular, w...The accurate measurement of kinematic parameters in satellite separation tests has great significance in evaluating separation performance. A novel study is made on the measuring accuracy of monocular and binocular, which are the two main vision measurement methods used for kinematic parameters. As satellite separation process is transient and high-dynamic, it will bring more extraction errors to the binocular. Based on the design approach of intersection measure and variance ratio, the monocular method reflects higher precision, simpler structure and easier calibration for level satellite separation. In ground separation tests, a high-speed monocular system is developed to gain and analyze twelve kinematic parameters of a small satellite. Research shows that this monocular method can be widely applied for its high precision, with position accuracy of 0.5 mm, speed accuracy of 5 mm/s, and angular velocity accuracy of 1 (°)/s.展开更多
The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic...The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic parameters of internal solitary waves in the Andaman Sea(AS).The kinematic parameters include phase speed,dispersion parameter,quadratic and cubic nonlinear parameters.It shows that the phase speed and dispersion parameter are mainly determined by the topographic feature and have limited seasonal variation.The maximum phase speed is 2.6 m/s,which occurs in the cool season(November)in the middle of the AS,while the phase speed in the cool season is slightly larger than those in other seasons,up to 11.4%larger than that in the rainy season(July)in the southern AS.The dispersion parameter in the cool season can be 22.3%larger than that in the hot season.The nonlinear parameters have significant seasonal variation,and they can even change their signs at the continental slope in the north of the AS,from season to season.Meanwhile,the algebraic solitons dominate in the AS with minimum amplitudes(aal)ranging from 0.1 m to 102 m,and the maximum aal occurs in the cool season in the southern AS.The effect of the background flow on the parameters is also studied.The background flow has a great influence on the nonlinear parameters,e.g.,the value of cubic nonlinear parameter can be reduced by 1/3 when the background flow is not considered.展开更多
Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters ...Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters of rockfall movement is critical for understanding motion patterns and effectively preventing and controlling rockfall hazards.In this study,a monitoring system consisting of selfdeveloped inertial navigation equipment,high-speed cameras,and an unmanned aerial vehicle was used to conduct onsite motion tests involving four differently shaped rock specimens on three types of slopes(bedrock,detritus,and clast bedding).The selfdeveloped inertial navigation system integrated a highdynamic-range accelerometer(±400 g)and a shockresistant gyroscope(±4000°/s),capable of robustly collecting data during the test.The data collected from these tests were processed to extract key kinematic parameters such as velocity,trajectory,restitution coefficients,and friction coefficients.The test results demonstrated that the inertial navigation system accurately recorded the acceleration and angular velocity of the rocks during motion,with these measurements closely aligning with the field data.The normal and tangential restitution coefficients were found to be influenced primarily by the slope material and impact angle,with higher normal restitution coefficients observed for low-angle impacts.The normal restitution coefficients ranged from 0.35 to 0.86,whereas the tangential restitution coefficients ranged from 0.46 to 0.91,depending on the slope materials.Additionally,the sliding friction coefficient was calculated to be between 0.66 and 0.78,whereas the rolling friction coefficient for the slab-shaped specimen was determined to be 0.53.These findings provide valuable data for improving the accuracy of rockfall trajectory predictions and the design of protective structures.展开更多
A rigorous back analysis of shear strength parameters of landslide slip was presented. Kinematical element method was adopted to determine factor of safety and critical failure surface, which overcomes the disadvantag...A rigorous back analysis of shear strength parameters of landslide slip was presented. Kinematical element method was adopted to determine factor of safety and critical failure surface, which overcomes the disadvantage of limit equilibrium method. The theoretical relationship between the combination of shear strength parameters and stability state was studied. The results show that the location of critical slip surface, F/tan f and F/c depend only on the value of c/tan f. The failure surface moves towards the inside of slope as c/tan f increases. According to the information involving factor of safety and critical failure surface in a specific cross-section, strength parameters can be back calculated based on the above findings. Three examples were given for demonstrating the validity of the present method. The shear strength parameters obtained by back analysis are almost consistent with their correct solutions or test results.展开更多
With advanced communication technologies,cyberphysical systems such as networked industrial control systems can be monitored and controlled by a remote control center via communication networks.While lots of benefits ...With advanced communication technologies,cyberphysical systems such as networked industrial control systems can be monitored and controlled by a remote control center via communication networks.While lots of benefits can be achieved with such a configuration,it also brings the concern of cyber attacks to the industrial control systems,such as networked manipulators that are widely adopted in industrial automation.For such systems,a false data injection attack on a control-center-to-manipulator(CC-M)communication channel is undesirable,and has negative effects on the manufacture quality.In this paper,we propose a resilient remote kinematic control method for serial manipulators undergoing a false data injection attack by leveraging the kinematic model.Theoretical analysis shows that the proposed method can guarantee asymptotic convergence of the regulation error to zero in the presence of a type of false data injection attack.The efficacy of the proposed method is validated via simulations.展开更多
Based on the study of passive articulated rover,a complete suspension kinematics model from wheel to inertial reference frame is presented,which uses D-H method of manipulator and presentation with Euler angle of pitc...Based on the study of passive articulated rover,a complete suspension kinematics model from wheel to inertial reference frame is presented,which uses D-H method of manipulator and presentation with Euler angle of pitch,roll and yaw.An improved contact model is adopted aimed at the loose and rough lunar terrain.Using this kinematics model and numerical continuous and discrete Newton's method with iterative factor,the numerical method for estimation of kinematical parameters of articulated rovers on loose and rough terrain is constructed.To demonstrate this numerical method,an example of two torsion bar rocker-bogie lunar rover with eight wheels is presented.Simulation results show that the numerical method for estimation of kinematical parameters of articulated rovers based on improved contact model can improve the precision of kinematical estimation on loose and rough terrain and decrease errors caused by contact models established based on general hypothesis.展开更多
A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning...A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning between angular velocity and linear velocity.In the processing of pivot turning,the slippage parameters could be obtained by measuring the end point in a square path.In the process of coupled turning,the slippage parameters could be calculated by measuring the perimeter of a circular path and the linear distance between the start and end points.The identification results showed that slippage parameters were affected by velocity.Therefore,a fuzzy rule base was established with the basis on the identification data,and a fuzzy controller was applied to motion control and dead reckoning.This method effectively compensated for errors resulting in unequal tension between the left and right tracks,structural dimensions and slippage.The results demonstrated that the accuracy of robot positioning and control could be substantially improved on a rigid floor.展开更多
Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present ...Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task.A high-speed video camera has been employed to visually record the movement of index finger,and miniaturized(5-mm diameter) reflective markers have affixed to the subject's index finger on the side close to thumb and dorsum of thumb at different joint landmarks.Captured images have been reviewed frame by frame to get the coordinate values of each joint,and the angular displacements,angular velocities and angular acceleration can be obtained with triangle function.The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving,and can be a valid route to study the motor function of index finger.展开更多
The kinematic equivalent model of an existing ankle-rehabilitation robot is inconsistent with the anatomical structure of the human ankle,which influences the rehabilitation effect.Therefore,this study equates the hum...The kinematic equivalent model of an existing ankle-rehabilitation robot is inconsistent with the anatomical structure of the human ankle,which influences the rehabilitation effect.Therefore,this study equates the human ankle to the UR model and proposes a novel three degrees of freedom(3-DOF)generalized spherical parallel mechanism for ankle rehabilitation.The parallel mechanism has two spherical centers corresponding to the rotation centers of tibiotalar and subtalar joints.Using screw theory,the mobility of the parallel mechanism,which meets the requirements of the human ankle,is analyzed.The inverse kinematics are presented,and singularities are identified based on the Jacobian matrix.The workspaces of the parallel mechanism are obtained through the search method and compared with the motion range of the human ankle,which shows that the parallel mechanism can meet the motion demand of ankle rehabilitation.Additionally,based on the motion-force transmissibility,the performance atlases are plotted in the parameter optimal design space,and the optimum parameter is obtained according to the demands of practical applications.The results show that the parallel mechanism can meet the motion requirements of ankle rehabilitation and has excellent kinematic performance in its rehabilitation range,which provides a theoretical basis for the prototype design and experimental verification.展开更多
基金Supported by State Key Lab of Digital Manufacturing Equipment & Technology(Grant No.DMETKF2015013)National Natural Science Foundation of China(Grant No.51305008)
文摘Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot＇s base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product- of-exponential （POE） formula. In the first step the robot＇s base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot＇s reference configuration and the base coordinate frame＇s pose are equivalently transformed to the zero-position errors of the robot＇s joints. The simplified model of the robot＇s positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot＇ s 39 kinematic parameters are finished in the second step. It＇s proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot＇s base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.
基金supported by the National Key R& D Program of China( No. 2017YFB1303600)
文摘Steel-making areas are harsh operation environments that involve many highly dangerous manual operations.The use of robotic equipment technology is a key step toward intelligent manufacturing in steel-making areas.The steel-making environment is not suitable for long-term debugging work,so in order to reduce the debugging workload,it is an important method to improve the absolute position accuracy of the robot.This paper addresses the identification of kinematic parameters of the 7-DOF robotic equipment used in a continuous casting area at Baosteel.The purpose of this work is to apply compensation measures during the application process of the robotic equipment to improve its accuracy and stability,while shortening the on-site debugging time.
文摘Computer-assisted sperm class analyser (CASA) analysis of avian semen following cryopreservation indicates that their semen motility and viability parameters become compromised, due in part to oxidative stress. To mimic these observations we have treated cockerel semen with an oxidative stress inducing agent, namely hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and monitored the motility, kinematic and viability parameters over time. Briefly, five healthy and fertile South African Venda cockerels were selected and their semen was collected using the abdominal massage technique. The semen was then treated with H<sub>2</sub>O<sub>2</sub> at 0 µM, 5 µM, 50 µM and 200 µM concentrations for 0, 3, 16 and 24 hrs. The semen motility, kinematic and viability parameters were then determined using the CASA system while the viability was determined using the SYBR-14/PI staining. The Pearson’s correlation coefficient was determined to test the relationships between the levels of induced oxidative stress, period of exposure to oxidative stress inducing agent and the motility plus kinematic parameters. Our data revealed that in raw cockerel semen, there was high and positive correlations between total motility (TM), progressive motility (PM), rapid (RAP), curvilinear velocity (VCL), straight line velocity (VSL) and average path velocity (VAP) while the kinematic parameters LIN, STR, WOB, ALH and BCF had low or negative correlations with them. Furthermore, TM, PM, RAP, VCL and VSL remained highly and positively correlated with the induced oxidative stress and also, linearity (LIN), straightness (STR), wobble (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) remained negatively correlated with the induced oxidative stress, after 3 hrs. After 24 hrs, TM, PM, RAP, VCL, VSL, VAP and ALH, became negatively correlated with the induced oxidative stress while LIN, STR, WOB and BCF became positively correlated with the induced oxidative stress. Conversely, when the H<sub>2</sub>O<sub>2</sub> concentration used was correlated with motility and kinematic parameters over time, TM, PM, RAP, VCL, VSL, VAP became negatively correlated with oxidative stress while LIN, STR, WOB, ALH and BCF show negative or low correlations with the induced oxidative stress. This data indicates that LIN, STR, WOB, BCF and to some extend ALH, reveal the least correlations with the induced oxidative stress under persistent oxidative stress conditions in cockerel semen. In conclusion, cockerel semen, like buck semen, does not easily succumb to oxidative stress since the raw semen correlations of CASA analysed parameters are comparable to these observed after 3 hrs of H<sub>2</sub>O<sub>2</sub> treatment. In addition, the oxidative stress levels tolerated by cockerel semen should not 5 µM H<sub>2</sub>O<sub>2</sub> oxidative stress levels. Lastly, lack of correlation between LIN, STR, WOB, BCF and ALH and induced oxidative stress can be used in cockerel semen to show intolerable cryopreservation conditions.
基金Project(50975280)supported by the National Natural Science Foundation of ChinaProject(NCET-08-0149)supported by Program for New Century Excellent Talents in Universities of China
文摘The accurate measurement of kinematic parameters in satellite separation tests has great significance in evaluating separation performance. A novel study is made on the measuring accuracy of monocular and binocular, which are the two main vision measurement methods used for kinematic parameters. As satellite separation process is transient and high-dynamic, it will bring more extraction errors to the binocular. Based on the design approach of intersection measure and variance ratio, the monocular method reflects higher precision, simpler structure and easier calibration for level satellite separation. In ground separation tests, a high-speed monocular system is developed to gain and analyze twelve kinematic parameters of a small satellite. Research shows that this monocular method can be widely applied for its high precision, with position accuracy of 0.5 mm, speed accuracy of 5 mm/s, and angular velocity accuracy of 1 (°)/s.
基金The Key Research Program of Frontier SciencesChinese Academy of Sciences under contract No.QYZDJ-SSWDQC034+9 种基金the Grant from Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0304the National Natural Science Foundation of China under contract Nos 41521005,41776007 and 41776008the Guangdong Natural Science Foundation under contract No.2020A1515010495the Grant from Chinese Academy of Sciences under contract No.ISEE2021PY01the Guangzhou Science and Technology Program under contract No.201804010373the Youth Science and Technology Innovation Talent of Guangdong Te Zhi Plan under contract No.2019TQ05H519the Pearl River S&T Nova Program of Guangzhou under contract No.201806010091the Rising Star Foundation of South China Sea Institute of Oceanology under contract No.NHXX2019WL0201the Youth Innovation Promotion Association of Chinese Academy of Sciences under contract No.2018378the State Key Laboratory of Tropical Oceanolography Independent Research Program under contract No.LTOZZ2001。
文摘The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic parameters of internal solitary waves in the Andaman Sea(AS).The kinematic parameters include phase speed,dispersion parameter,quadratic and cubic nonlinear parameters.It shows that the phase speed and dispersion parameter are mainly determined by the topographic feature and have limited seasonal variation.The maximum phase speed is 2.6 m/s,which occurs in the cool season(November)in the middle of the AS,while the phase speed in the cool season is slightly larger than those in other seasons,up to 11.4%larger than that in the rainy season(July)in the southern AS.The dispersion parameter in the cool season can be 22.3%larger than that in the hot season.The nonlinear parameters have significant seasonal variation,and they can even change their signs at the continental slope in the north of the AS,from season to season.Meanwhile,the algebraic solitons dominate in the AS with minimum amplitudes(aal)ranging from 0.1 m to 102 m,and the maximum aal occurs in the cool season in the southern AS.The effect of the background flow on the parameters is also studied.The background flow has a great influence on the nonlinear parameters,e.g.,the value of cubic nonlinear parameter can be reduced by 1/3 when the background flow is not considered.
基金supported by Guizhou Provincial Basic Research Program(Natural Science,Grant No.QKHJC-ZK[2022]YB075)the National Natural Science Foundation of China(Grant No.42067046)+2 种基金the Guizhou Provincial Program on Commercialization of Scientific and Technological Achievements(N0.QKHCG-LH2024-ZD025)the Science and Technology Planning Project of Guiyang City(Grant No.ZKHT[2023]13-10)Undergraduate Training Program for Innovation and Entrepreneurship of Guizhou Province(Project No.S202110657053)。
文摘Rockfall kinematic characteristics exhibit significant randomness and are influenced by factors such as rock mass properties,slope morphology,impact angle,and slope materials.Accurately determining the key parameters of rockfall movement is critical for understanding motion patterns and effectively preventing and controlling rockfall hazards.In this study,a monitoring system consisting of selfdeveloped inertial navigation equipment,high-speed cameras,and an unmanned aerial vehicle was used to conduct onsite motion tests involving four differently shaped rock specimens on three types of slopes(bedrock,detritus,and clast bedding).The selfdeveloped inertial navigation system integrated a highdynamic-range accelerometer(±400 g)and a shockresistant gyroscope(±4000°/s),capable of robustly collecting data during the test.The data collected from these tests were processed to extract key kinematic parameters such as velocity,trajectory,restitution coefficients,and friction coefficients.The test results demonstrated that the inertial navigation system accurately recorded the acceleration and angular velocity of the rocks during motion,with these measurements closely aligning with the field data.The normal and tangential restitution coefficients were found to be influenced primarily by the slope material and impact angle,with higher normal restitution coefficients observed for low-angle impacts.The normal restitution coefficients ranged from 0.35 to 0.86,whereas the tangential restitution coefficients ranged from 0.46 to 0.91,depending on the slope materials.Additionally,the sliding friction coefficient was calculated to be between 0.66 and 0.78,whereas the rolling friction coefficient for the slab-shaped specimen was determined to be 0.53.These findings provide valuable data for improving the accuracy of rockfall trajectory predictions and the design of protective structures.
基金Project(51174228)supported by the National Natural Science Foundation of ChinaProject(CX2012B069)supported by Hunan Provincial Innovation Foundation for PostgraduateProject(201003)supported by Transportation Science and Technology Projects of Hunan Province,China
文摘A rigorous back analysis of shear strength parameters of landslide slip was presented. Kinematical element method was adopted to determine factor of safety and critical failure surface, which overcomes the disadvantage of limit equilibrium method. The theoretical relationship between the combination of shear strength parameters and stability state was studied. The results show that the location of critical slip surface, F/tan f and F/c depend only on the value of c/tan f. The failure surface moves towards the inside of slope as c/tan f increases. According to the information involving factor of safety and critical failure surface in a specific cross-section, strength parameters can be back calculated based on the above findings. Three examples were given for demonstrating the validity of the present method. The shear strength parameters obtained by back analysis are almost consistent with their correct solutions or test results.
基金This work was supported in part by the National Natural Science Foundation of China(62206109)the Fundamental Research Funds for the Central Universities(21620346)。
文摘With advanced communication technologies,cyberphysical systems such as networked industrial control systems can be monitored and controlled by a remote control center via communication networks.While lots of benefits can be achieved with such a configuration,it also brings the concern of cyber attacks to the industrial control systems,such as networked manipulators that are widely adopted in industrial automation.For such systems,a false data injection attack on a control-center-to-manipulator(CC-M)communication channel is undesirable,and has negative effects on the manufacture quality.In this paper,we propose a resilient remote kinematic control method for serial manipulators undergoing a false data injection attack by leveraging the kinematic model.Theoretical analysis shows that the proposed method can guarantee asymptotic convergence of the regulation error to zero in the presence of a type of false data injection attack.The efficacy of the proposed method is validated via simulations.
基金Sponsored by the National High Technology Research and Development Program of China(863 Program)(Grant No.2006AA04Z231)the National Science Foundation of Heilongjiang Province(Grant No.ZJG0709)"The 111 Project"(Grant No.B07018)
文摘Based on the study of passive articulated rover,a complete suspension kinematics model from wheel to inertial reference frame is presented,which uses D-H method of manipulator and presentation with Euler angle of pitch,roll and yaw.An improved contact model is adopted aimed at the loose and rough lunar terrain.Using this kinematics model and numerical continuous and discrete Newton's method with iterative factor,the numerical method for estimation of kinematical parameters of articulated rovers on loose and rough terrain is constructed.To demonstrate this numerical method,an example of two torsion bar rocker-bogie lunar rover with eight wheels is presented.Simulation results show that the numerical method for estimation of kinematical parameters of articulated rovers based on improved contact model can improve the precision of kinematical estimation on loose and rough terrain and decrease errors caused by contact models established based on general hypothesis.
文摘A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning between angular velocity and linear velocity.In the processing of pivot turning,the slippage parameters could be obtained by measuring the end point in a square path.In the process of coupled turning,the slippage parameters could be calculated by measuring the perimeter of a circular path and the linear distance between the start and end points.The identification results showed that slippage parameters were affected by velocity.Therefore,a fuzzy rule base was established with the basis on the identification data,and a fuzzy controller was applied to motion control and dead reckoning.This method effectively compensated for errors resulting in unequal tension between the left and right tracks,structural dimensions and slippage.The results demonstrated that the accuracy of robot positioning and control could be substantially improved on a rigid floor.
基金Supported by the National Natural Science Foundation of China (30770546 )Natural Science Foundation of Chongqing(2006BB2043,2007BB5148)
文摘Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task.A high-speed video camera has been employed to visually record the movement of index finger,and miniaturized(5-mm diameter) reflective markers have affixed to the subject's index finger on the side close to thumb and dorsum of thumb at different joint landmarks.Captured images have been reviewed frame by frame to get the coordinate values of each joint,and the angular displacements,angular velocities and angular acceleration can be obtained with triangle function.The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving,and can be a valid route to study the motor function of index finger.
基金Supported by National Natural Science Foundation of China(Grant No.52075145)S&T Program of Hebei Province of China(Grant Nos.20281805Z,E2020103001)Central Government Guides Basic Research Projects of Local Science and Technology Development Funds of China(Grant No.206Z1801G).
文摘The kinematic equivalent model of an existing ankle-rehabilitation robot is inconsistent with the anatomical structure of the human ankle,which influences the rehabilitation effect.Therefore,this study equates the human ankle to the UR model and proposes a novel three degrees of freedom(3-DOF)generalized spherical parallel mechanism for ankle rehabilitation.The parallel mechanism has two spherical centers corresponding to the rotation centers of tibiotalar and subtalar joints.Using screw theory,the mobility of the parallel mechanism,which meets the requirements of the human ankle,is analyzed.The inverse kinematics are presented,and singularities are identified based on the Jacobian matrix.The workspaces of the parallel mechanism are obtained through the search method and compared with the motion range of the human ankle,which shows that the parallel mechanism can meet the motion demand of ankle rehabilitation.Additionally,based on the motion-force transmissibility,the performance atlases are plotted in the parameter optimal design space,and the optimum parameter is obtained according to the demands of practical applications.The results show that the parallel mechanism can meet the motion requirements of ankle rehabilitation and has excellent kinematic performance in its rehabilitation range,which provides a theoretical basis for the prototype design and experimental verification.
