A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the mode...A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the modeling of interaction between hydraulic circuit and flexible manipulator mechanism. Furthermore, a new robust controller based on mentioned above dynamic model was also considered to regulate both flexural vibrations and rigid body motion. The proposed controller combined sliding mode and backstepping techniques to deal with the nonlinear system with uncertainties. The sliding mode control was used to achieve an asymptotic joint angle and vibration regulation by providing a virtual force while the backstepping technique was used to regulate the spool position of a hydraulic valve to provide the required control force. Simulation results are presented to show the stabilizing effect and robustness of this control strategy.展开更多
This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model error...This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.展开更多
Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Part...Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.展开更多
Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub- micrometer precision under low-strength rotating magnetic fields （〈 10 rer）. Since magnetic fields with low strengths ...Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub- micrometer precision under low-strength rotating magnetic fields （〈 10 rer）. Since magnetic fields with low strengths are harmless to cells and tissues, magnetic helical micro/ nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.展开更多
Parallel manipulator systems as promising precision devices are used widely in current researches. A novel large workspace flexure parallel manipulator system utilizing wide-range flexure hinges as passive joints is p...Parallel manipulator systems as promising precision devices are used widely in current researches. A novel large workspace flexure parallel manipulator system utilizing wide-range flexure hinges as passive joints is proposed in this paper, which can attain sub-micron-seale precision over the cubic centimeter motion range. This paper introduces the mechanical system architecture based on the wide-range flexure hinges, analyzes the kinematics via stiffness matrices, presents the control system configuration and control strategy, and finally gives the system performance test results.展开更多
Acupuncture is an important component part of Traditional Chinese Medicine(TCM). The therapeutic effects may be influenced by a variety of factors.Stimulation quantity is one of the factors for achieving good therapeu...Acupuncture is an important component part of Traditional Chinese Medicine(TCM). The therapeutic effects may be influenced by a variety of factors.Stimulation quantity is one of the factors for achieving good therapeutic effects in acupuncture practice. With the development of science and technology, besides the influence of manual manipulations, the parameters adopted for electroacupuncture have become the benchmark of stimulation quantity. This study, by referring to the related literatures, is designed to explore the influence of manual manipulations and electrical parameters on therapeutic effects of acupuncture. The results from the present study show that different manualmanipulations and electrical parameters may exert different therapeutic effects of acupuncture, which are closely related to the characteristics of diseases.Different manual manipulations and electrical parameters should be adopted according to syndrome differentiation of TCM. This is very important in acupuncture treatment.展开更多
文摘A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the modeling of interaction between hydraulic circuit and flexible manipulator mechanism. Furthermore, a new robust controller based on mentioned above dynamic model was also considered to regulate both flexural vibrations and rigid body motion. The proposed controller combined sliding mode and backstepping techniques to deal with the nonlinear system with uncertainties. The sliding mode control was used to achieve an asymptotic joint angle and vibration regulation by providing a virtual force while the backstepping technique was used to regulate the spool position of a hydraulic valve to provide the required control force. Simulation results are presented to show the stabilizing effect and robustness of this control strategy.
基金Project (No.50775200) supported by the National Natural Science Foundation of China
文摘This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.
文摘Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.
文摘Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub- micrometer precision under low-strength rotating magnetic fields （〈 10 rer）. Since magnetic fields with low strengths are harmless to cells and tissues, magnetic helical micro/ nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.
文摘Parallel manipulator systems as promising precision devices are used widely in current researches. A novel large workspace flexure parallel manipulator system utilizing wide-range flexure hinges as passive joints is proposed in this paper, which can attain sub-micron-seale precision over the cubic centimeter motion range. This paper introduces the mechanical system architecture based on the wide-range flexure hinges, analyzes the kinematics via stiffness matrices, presents the control system configuration and control strategy, and finally gives the system performance test results.
基金National Basic Research Program of China(973 Program No.2012CB518500)the Major Program of the National Natural Science Foundation of China(A PET-CTStudy on Acupuncture for Migraine at Acupoints on Involved Meridian,NSFC,No.30930112)
文摘Acupuncture is an important component part of Traditional Chinese Medicine(TCM). The therapeutic effects may be influenced by a variety of factors.Stimulation quantity is one of the factors for achieving good therapeutic effects in acupuncture practice. With the development of science and technology, besides the influence of manual manipulations, the parameters adopted for electroacupuncture have become the benchmark of stimulation quantity. This study, by referring to the related literatures, is designed to explore the influence of manual manipulations and electrical parameters on therapeutic effects of acupuncture. The results from the present study show that different manualmanipulations and electrical parameters may exert different therapeutic effects of acupuncture, which are closely related to the characteristics of diseases.Different manual manipulations and electrical parameters should be adopted according to syndrome differentiation of TCM. This is very important in acupuncture treatment.
