As a typical rhythmic movement, human being's rhythmic gait movement can be generated by a central pattern generator (CPG) located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by g...As a typical rhythmic movement, human being's rhythmic gait movement can be generated by a central pattern generator (CPG) located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by gait frequency and amplitude variances. As an important property of human being's motion vision, the attention selection mechanism plays a vital part in the regulation of gait movement. In this paper, the CPG model is amended under the condition of attention selection on the theoretical basis of Matsuoka neural oscillators. Regulation of attention selection signal for the CPG model parameters and structure is studied, which consequentially causes the frequency and amplitude changes of gait movement output. Further, the control strategy of the CPG model gait movement under the condition of attention selection is discussed, showing that the attention selection model can regulate the output model of CPG gait movement in three different ways. The realization of regulation on the gait movement frequency and amplitude shows a variety of regulation on the CPG gait movement made by attention selection and enriches the controllability of CPG gait movement, which demonstrates potential influence in engineering applications.展开更多
The modulation and control of gecko's foot movements were studied electrophysiologically in order to design the motor control system of a gecko-mimic robot. In this study (1) the anatomy of the peripheral nerves co...The modulation and control of gecko's foot movements were studied electrophysiologically in order to design the motor control system of a gecko-mimic robot. In this study (1) the anatomy of the peripheral nerves controlling the gecko's foot movements was determined; (2) the relationship between the limb nerves of the gecko and its foot motor patterns was studied; (3) the afferent impulses of the nerves evoked by rubbing the gecko's toes and palm were recorded; (4) copying the natural patterns of movement of the gecko's foot (abduction, adduction, flexion, and revolution) and its limb nerve modulation and control mechanism, the nerves were stimulated under computer control, and the results recorded by CCD. Results suggest that gecko's foot movements can be successfully controlled by artificial electrical signals.展开更多
In this paper, we propose a new formula of the real-time minimum safety headway based on the relative velocity of consecutive trains and present a dynamic model of high-speed passenger train movements in the rail line...In this paper, we propose a new formula of the real-time minimum safety headway based on the relative velocity of consecutive trains and present a dynamic model of high-speed passenger train movements in the rail line based on the proposed formula of the minimum safety headway. Moreover, we provide the control strategies of the high-speed passenger train operations based on the proposed formula of the real-time minimum safety headway and the dynamic model of highspeed passenger train movements. The simulation results demonstrate that the proposed control strategies of the passenger train operations can greatly reduce the delay propagation in the high-speed rail line when a random delay occurs.展开更多
Structural superlubricity(SSL)refers to a state where the friction and wear between two directly contacted solid surfaces are virtually zero.The realization of microscale SSL in 2012 rapidly explored SSL technologies ...Structural superlubricity(SSL)refers to a state where the friction and wear between two directly contacted solid surfaces are virtually zero.The realization of microscale SSL in 2012 rapidly explored SSL technologies which hold great potential in the development of reliable and energy⁃efficient micro devices.A key to a successful superlubric device is to control the movements of the superlubric slider.To solve this challenge,here two general principles are shown to guide and control the motion of the slider,i.e.,by minimization of interfacial energy and minimization of electrostatic energy.When the shapes of the slider and substrate are designed appropriately,the excess interfacial energy of the contact⁃pair provides restoring and constraining forces to the slider.Similarly,tunable driving and constraining forces are enabled by the electric fields induced by the electrodes buried in the substrate.These concepts are demonstrated on the design of a superlubric resonator whose natural frequency of the lateral translational mode is well⁃defined and unfavorable rotation is constrained.The above design principles should be applicable to superlubric devices in general and help the development of future applications of structural superlubricity.展开更多
Rebuilding the damaged motor function caused by spinal cord injury is one of the most serious challenges in clinical neuroscience.The function of the neural pathway under the damaged sites can be rebuilt using functio...Rebuilding the damaged motor function caused by spinal cord injury is one of the most serious challenges in clinical neuroscience.The function of the neural pathway under the damaged sites can be rebuilt using functional electrical stimulation technology.In this study,the locations of motor function sites in the lumbosacral spinal cord were determined with functional electrical stimulation technology.A three-dimensional map of the lumbosacral spinal cord comprising the relationship between the motor function sites and the corresponding muscle was drawn.Based on the individual experimental parameters and normalized coordinates of the motor function sites,the motor function sites that control a certain muscle were calculated.Phasing pulse sequences were delivered to the determined motor function sites in the spinal cord and hip extension,hip flexion,ankle plantarflexion,and ankle dorsiflexion movements were successfully achieved.The results show that the map of the spinal cord motor function sites was valid.This map can provide guidance for the selection of electrical stimulation sites during the rebuilding of motor function after spinal cord injury.展开更多
In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrica...In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrical framework.In particular,in a first approach,a piece-wise affine transformation based on subdomains division has been implemented for modelling the movement of one control rod.In the second approach,a“staircase”strategy has been adopted for simulating themovement of all the three rods featured by the nuclear reactor chosen as case study.The neutron kinetics has been modelled according to the so-called multi-group neutron diffusion,which,in the present case,is a set of ten coupled parametrized parabolic equations(two energy groups for the neutron flux,and eight for the precursors).Both the reduced order models,developed according to the two approaches,provided a very good accuracy comparedwith high-fidelity results,assumed as“truth”solutions.At the same time,the computational speed-up in the Online phase,with respect to the fine“truth”finite element discretization,achievable by both the proposed approaches is at least of three orders of magnitude,allowing a real-time simulation of the rod movement and control.展开更多
Micro/nanomotors(MNMs)are small-scale devices that can effectively convert various forms of energy into mechanical motion.Their controllable motility and good permeability have attracted the interest of researchers as...Micro/nanomotors(MNMs)are small-scale devices that can effectively convert various forms of energy into mechanical motion.Their controllable motility and good permeability have attracted the interest of researchers as promising drug carriers in cancer therapy.Compared with traditional formulations,micro/nanomotor drug delivery systems can greatly improve therapeutic efficiency and reduce the side effects of antitumor drugs.This review mainly discusses the advantages of micro/nanomotor drug delivery systems and the applications of MNMs propelled by exogenous,endogenous,and biohybrid power in cancer therapy.Finally,the main challenges of the applications of micro/nanomotor drug delivery systems,as well as future development trends and opportunities are discussed.展开更多
A position/force hybrid control system based on impedance control scheme is designed to align a small gripper to a special ring object. The vision information provided by microscope vision system is used as the feedba...A position/force hybrid control system based on impedance control scheme is designed to align a small gripper to a special ring object. The vision information provided by microscope vision system is used as the feedback to indicate the position relationship between the gripper and the ring object. Multiple image features of the gripper and the ring object are extracted to estimate the relative positions between them. The end-effector of the gripper is tracked using the extracted features to keep the gripper moving in the field of view. The force information from the force sensor serves as the feedback to ensure that the contact force between the gripper and the ring object is limited in a small safe range. Experimental results verify the effectiveness of the proposed control strategy.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11232005 and11472104)the Doctoral Fund of Ministry of Education of China(No.20120074110020)
文摘As a typical rhythmic movement, human being's rhythmic gait movement can be generated by a central pattern generator (CPG) located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by gait frequency and amplitude variances. As an important property of human being's motion vision, the attention selection mechanism plays a vital part in the regulation of gait movement. In this paper, the CPG model is amended under the condition of attention selection on the theoretical basis of Matsuoka neural oscillators. Regulation of attention selection signal for the CPG model parameters and structure is studied, which consequentially causes the frequency and amplitude changes of gait movement output. Further, the control strategy of the CPG model gait movement under the condition of attention selection is discussed, showing that the attention selection model can regulate the output model of CPG gait movement in three different ways. The realization of regulation on the gait movement frequency and amplitude shows a variety of regulation on the CPG gait movement made by attention selection and enriches the controllability of CPG gait movement, which demonstrates potential influence in engineering applications.
基金This work was funded by Hi-tech Research and Development Program of China(2002AA 423230)National Natural Science Foundation of China(90205014,30400086).
文摘The modulation and control of gecko's foot movements were studied electrophysiologically in order to design the motor control system of a gecko-mimic robot. In this study (1) the anatomy of the peripheral nerves controlling the gecko's foot movements was determined; (2) the relationship between the limb nerves of the gecko and its foot motor patterns was studied; (3) the afferent impulses of the nerves evoked by rubbing the gecko's toes and palm were recorded; (4) copying the natural patterns of movement of the gecko's foot (abduction, adduction, flexion, and revolution) and its limb nerve modulation and control mechanism, the nerves were stimulated under computer control, and the results recorded by CCD. Results suggest that gecko's foot movements can be successfully controlled by artificial electrical signals.
基金supported by the National Basic Research Program of China (Grant No. 2012CB725400)the National Natural Science Foundation of China (Grant No. 71131001-1)the Research Foundation of State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University,China (Grant Nos. RCS2012ZZ001 and RCS2012ZT001)
文摘In this paper, we propose a new formula of the real-time minimum safety headway based on the relative velocity of consecutive trains and present a dynamic model of high-speed passenger train movements in the rail line based on the proposed formula of the minimum safety headway. Moreover, we provide the control strategies of the high-speed passenger train operations based on the proposed formula of the real-time minimum safety headway and the dynamic model of highspeed passenger train movements. The simulation results demonstrate that the proposed control strategies of the passenger train operations can greatly reduce the delay propagation in the high-speed rail line when a random delay occurs.
基金National Natural Science Foundation of China(Grant Nos.11572173,11890671,51961145304 and 11921002)the National Key Basic Research Program of China(Grant No.2013CB934200)+3 种基金the Cyrus Tang Foundation(Grant No.202003)the Beijing Municipal Science&Technology Commission(Grant No.Z151100003315008)the Tsinghua University Initiative Scientific Research(Grant Nos.2014Z01007 and 2012Z01015)the State Key Laboratory of Tribology Tsinghua University Initiative Scientific Research(Grant No.SKLT2019D02).
文摘Structural superlubricity(SSL)refers to a state where the friction and wear between two directly contacted solid surfaces are virtually zero.The realization of microscale SSL in 2012 rapidly explored SSL technologies which hold great potential in the development of reliable and energy⁃efficient micro devices.A key to a successful superlubric device is to control the movements of the superlubric slider.To solve this challenge,here two general principles are shown to guide and control the motion of the slider,i.e.,by minimization of interfacial energy and minimization of electrostatic energy.When the shapes of the slider and substrate are designed appropriately,the excess interfacial energy of the contact⁃pair provides restoring and constraining forces to the slider.Similarly,tunable driving and constraining forces are enabled by the electric fields induced by the electrodes buried in the substrate.These concepts are demonstrated on the design of a superlubric resonator whose natural frequency of the lateral translational mode is well⁃defined and unfavorable rotation is constrained.The above design principles should be applicable to superlubric devices in general and help the development of future applications of structural superlubricity.
基金supported by the National Natural Science Foundation of China,No.81371663,61534003the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions of China,No.PPZY2015B135
文摘Rebuilding the damaged motor function caused by spinal cord injury is one of the most serious challenges in clinical neuroscience.The function of the neural pathway under the damaged sites can be rebuilt using functional electrical stimulation technology.In this study,the locations of motor function sites in the lumbosacral spinal cord were determined with functional electrical stimulation technology.A three-dimensional map of the lumbosacral spinal cord comprising the relationship between the motor function sites and the corresponding muscle was drawn.Based on the individual experimental parameters and normalized coordinates of the motor function sites,the motor function sites that control a certain muscle were calculated.Phasing pulse sequences were delivered to the determined motor function sites in the spinal cord and hip extension,hip flexion,ankle plantarflexion,and ankle dorsiflexion movements were successfully achieved.The results show that the map of the spinal cord motor function sites was valid.This map can provide guidance for the selection of electrical stimulation sites during the rebuilding of motor function after spinal cord injury.
基金We acknowledge CINECA and Regione Lombardia LISA computational initiative,for the availability of high performance computing resources and support.G.Rozza acknowledges INDAM-GNCS national activity group and NOFYSAS program of SISSA.
文摘In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrical framework.In particular,in a first approach,a piece-wise affine transformation based on subdomains division has been implemented for modelling the movement of one control rod.In the second approach,a“staircase”strategy has been adopted for simulating themovement of all the three rods featured by the nuclear reactor chosen as case study.The neutron kinetics has been modelled according to the so-called multi-group neutron diffusion,which,in the present case,is a set of ten coupled parametrized parabolic equations(two energy groups for the neutron flux,and eight for the precursors).Both the reduced order models,developed according to the two approaches,provided a very good accuracy comparedwith high-fidelity results,assumed as“truth”solutions.At the same time,the computational speed-up in the Online phase,with respect to the fine“truth”finite element discretization,achievable by both the proposed approaches is at least of three orders of magnitude,allowing a real-time simulation of the rod movement and control.
基金supported by the National Natural Science Founda-tion of China(82173757)the Young Scholar Program of Shandong University(YSPSDU,2017WLJH40)。
文摘Micro/nanomotors(MNMs)are small-scale devices that can effectively convert various forms of energy into mechanical motion.Their controllable motility and good permeability have attracted the interest of researchers as promising drug carriers in cancer therapy.Compared with traditional formulations,micro/nanomotor drug delivery systems can greatly improve therapeutic efficiency and reduce the side effects of antitumor drugs.This review mainly discusses the advantages of micro/nanomotor drug delivery systems and the applications of MNMs propelled by exogenous,endogenous,and biohybrid power in cancer therapy.Finally,the main challenges of the applications of micro/nanomotor drug delivery systems,as well as future development trends and opportunities are discussed.
基金supported by National Natural Science Foundation of China(No.61105036 and 61227804)
文摘A position/force hybrid control system based on impedance control scheme is designed to align a small gripper to a special ring object. The vision information provided by microscope vision system is used as the feedback to indicate the position relationship between the gripper and the ring object. Multiple image features of the gripper and the ring object are extracted to estimate the relative positions between them. The end-effector of the gripper is tracked using the extracted features to keep the gripper moving in the field of view. The force information from the force sensor serves as the feedback to ensure that the contact force between the gripper and the ring object is limited in a small safe range. Experimental results verify the effectiveness of the proposed control strategy.