This paper presents some initial solutions to the problem of accuracy and repeatability of the arm position placement in applied kinematics by solving the inverse kinematics problem of a serial jointed manipulator who...This paper presents some initial solutions to the problem of accuracy and repeatability of the arm position placement in applied kinematics by solving the inverse kinematics problem of a serial jointed manipulator whose forward kinematics solution was earlier presented to solve the position placement problem of a mobile manipulator for Lunar Oxygen production. The problem herein is that of identifying a combination of joint angles to effectively position the end-effecter at a specified location in space. The reverse solution as presented in this paper is predicated on DH＇s （Denavit-Hartenberg＇s） technique for robot arm position analysis. The generalized solution for the 5-degrees of freedom DOF （degree of freedom） revolute joint variables which comprises 2-1inks and a spade-like 3-DOF end-effecter was obtained by solving a set of algebraic equations emerging from series of transformation matrices. The proposed solution herein has a high degree of accuracy and repeatability for workspace reachable domains where joint combination is analytic.展开更多
A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking ...A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H_∞ robustness controller suppresses the disturbances well within the close loop(including the load and the end effect force of linear motor etc.) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.展开更多
The changes of stress and strain around the shaft under the non-axial symmetrical loads during the excavation are analyzed with the finite element semi-analytical method based on the separated variable method. The cha...The changes of stress and strain around the shaft under the non-axial symmetrical loads during the excavation are analyzed with the finite element semi-analytical method based on the separated variable method. The change laws of deformation and stress of surrounding rocks are obtaied. Moreover, an optimum method of the design and construction of the shaft lining is de veloped. which presents a new train of thought of the design and costruction of the shaft and has important theoretical value and extensive application prospects.展开更多
The permanent-magnet(PM) spherical motor has special configuration and complicated distribution of electromagnetic field.The spatial distribution of the effective flux density produced by permanent magnets is obtained...The permanent-magnet(PM) spherical motor has special configuration and complicated distribution of electromagnetic field.The spatial distribution of the effective flux density produced by permanent magnets is obtained,and the end-effect of the permanent magnets is analyzed.In the 3-dimensional(3-D) finite element(FE) analysis,the calculation of Back-EMF charac-teristics of the PM spherical motor needs to be conducted by steps,which leads to large computational burden.A novel ana-lyzing method to quantize the end-effect of the PM spherical motor is proposed,that is,the end-effect coefficient of the PM spherical motor is calculated to revise the back-EMF waveform obtained from the 2-D FE model.Under different outer radii of the stator coil and different pole arc coefficients of the PM spherical motor,the revised 2-D results are validated by the results obtained from the 3-D FE model and the experimental results.With this method,the special structural feature of the PM spherical motor is fully considered;the pure 3-D calculation of electromagnetic field is conducted only once;higher precision and less computational burden can be achieved.The method provides a new approach to investigating the back-EMF charac-teristic of the PM spherical motor.展开更多
文摘This paper presents some initial solutions to the problem of accuracy and repeatability of the arm position placement in applied kinematics by solving the inverse kinematics problem of a serial jointed manipulator whose forward kinematics solution was earlier presented to solve the position placement problem of a mobile manipulator for Lunar Oxygen production. The problem herein is that of identifying a combination of joint angles to effectively position the end-effecter at a specified location in space. The reverse solution as presented in this paper is predicated on DH＇s （Denavit-Hartenberg＇s） technique for robot arm position analysis. The generalized solution for the 5-degrees of freedom DOF （degree of freedom） revolute joint variables which comprises 2-1inks and a spade-like 3-DOF end-effecter was obtained by solving a set of algebraic equations emerging from series of transformation matrices. The proposed solution herein has a high degree of accuracy and repeatability for workspace reachable domains where joint combination is analytic.
文摘A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H_∞ robustness controller suppresses the disturbances well within the close loop(including the load and the end effect force of linear motor etc.) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.
文摘The changes of stress and strain around the shaft under the non-axial symmetrical loads during the excavation are analyzed with the finite element semi-analytical method based on the separated variable method. The change laws of deformation and stress of surrounding rocks are obtaied. Moreover, an optimum method of the design and construction of the shaft lining is de veloped. which presents a new train of thought of the design and costruction of the shaft and has important theoretical value and extensive application prospects.
基金supported by the National Scientific Fund for Distinguished Young Scholars (Grant NO.50825701) the Key Program of National Natural Science Foundation of China (Grant NO.51037004)+1 种基金the National Natural Science Foundation of China (Grant NO.51077097)the Key Technologies Research and Development Program of Tianjin (Grant Nos:10ZCKFGX02300,10ZCKFGX02800)
文摘The permanent-magnet(PM) spherical motor has special configuration and complicated distribution of electromagnetic field.The spatial distribution of the effective flux density produced by permanent magnets is obtained,and the end-effect of the permanent magnets is analyzed.In the 3-dimensional(3-D) finite element(FE) analysis,the calculation of Back-EMF charac-teristics of the PM spherical motor needs to be conducted by steps,which leads to large computational burden.A novel ana-lyzing method to quantize the end-effect of the PM spherical motor is proposed,that is,the end-effect coefficient of the PM spherical motor is calculated to revise the back-EMF waveform obtained from the 2-D FE model.Under different outer radii of the stator coil and different pole arc coefficients of the PM spherical motor,the revised 2-D results are validated by the results obtained from the 3-D FE model and the experimental results.With this method,the special structural feature of the PM spherical motor is fully considered;the pure 3-D calculation of electromagnetic field is conducted only once;higher precision and less computational burden can be achieved.The method provides a new approach to investigating the back-EMF charac-teristic of the PM spherical motor.
