A novel methodology for a walk-assisting balance system of the exoskeleton robot for dis-abled people is presented. The experiment on the walk-assisting balance system is implemented using amini-type ropewalker robot....A novel methodology for a walk-assisting balance system of the exoskeleton robot for dis-abled people is presented. The experiment on the walk-assisting balance system is implemented using amini-type ropewalker robot. The mechanism of the ropewalker robot is designed, its dynamic model isbuilt, and its control system based on PWM is developed. The emulations in Matlab and the results ofexperiments prove that this methodology is effective.展开更多
A motion planning strategy for the assembly task of inserting a dissymmetrical T-shaped part into a C-shaped slot is presented. The coarse motion planning strategy is expounded by geometric reasoning. A medial axis di...A motion planning strategy for the assembly task of inserting a dissymmetrical T-shaped part into a C-shaped slot is presented. The coarse motion planning strategy is expounded by geometric reasoning. A medial axis diagram decreases the unnecessary configuration states and optimizes the planning strategy. Due to the uncertainties, force sensing and force control is indispensable for motion planning. Combining the coarse motion planning strategy with fine motion planning strategy, the task of assembling a dissymmetrical T-shaped part can be completed successfully.展开更多
This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers.The control mechanism of muscle contract...This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers.The control mechanism of muscle contraction generated by collective motion of molecular motors is elucidated from the perspective of variable-frequency regulation,and action potential with variable frequency is proposed as the control signal to directly regulate Ca2+ concentration and indirectly control isometric tension.Furthermore,the transfer function between stimulation frequency and Ca2+ concentration is deduced,and the frequency domain properties of muscle contraction are analyzed.Moreover the conception of "electro-muscular time constant" is defined to denote the minimum delay time from electric stimulation to muscle contraction.Finally,the experimental research aiming at the relation between tension and stimulation frequency of action potential is implemented to verify the proposed variable-frequency control mechanism,whose effectiveness is proved by good consistence between experimental and theoretical results.展开更多
A dynamic model of skeletal muscle is developed to describe its activation kinetics and contraction dynamics based on the collective working mechanism of myosin II motors with a statistical mechanics method.According ...A dynamic model of skeletal muscle is developed to describe its activation kinetics and contraction dynamics based on the collective working mechanism of myosin II motors with a statistical mechanics method.According to the structure of sarcomeres arranged in series and in parallel,the mechanical properties of skeletal muscle are studied.This model reveals the relations between action potential and muscle characteristics.It is shown that calcium concentration in sarcoplasmic(SP) increases linearly with the increasing stimulation frequency and gradually reaches saturation.Active force and contraction velocity follow the trend of calcium concentration and reach a peak value at the maximum stimulation frequency.Contraction velocity is inversely proportional to the load while the contraction power increases to maximum and then reduces to zero with the increasing load.These properties are consistent with published physiological experimental results of skeletal muscle.展开更多
Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet...Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet the high stiffness requirement for grinding large mirror, especially with a diameter over 2 m. Meanwhile, the use of fewer-axis grinding solves this problem, as it reduces the number of the grinder's axes to improve the rigidity of the system and minimize deformation for hard and brittle materials. But its characteristic of unfixed grinding point which changes with workpiece surface curvature increases geometric complexity and requires a higher geometric shape accuracy of grinding wheel. This paper parameterizes grinding wheel's geometric shape, reveals the relationship between fewer-axis and five-axis grinding methods from the point of view of the differential geometry, and establishes virtual-axis equivalence principium of feweraxis grinding. A quantitative method to determine grinding wheel's geometric parameters and its shaft inclination angle is proposed based on the requirements of geometric properties of optical mirror, grinder features and grinding process. Moreover, according to the properties of Gauss curvature of curved surface, the wear law of the toric grinding wheel is found and the surface geometric error distribution due to wear is achieved for fewer-axis grinding. The correctness of the principium and method above are verified through simulations.展开更多
Motoneuron is the control unit of skeletal muscles,and the dynamic frequency-regulating feedback from the afferent nerve of receptors like muscle spindles forms the physical basis of its closed-loop regulation.Focused...Motoneuron is the control unit of skeletal muscles,and the dynamic frequency-regulating feedback from the afferent nerve of receptors like muscle spindles forms the physical basis of its closed-loop regulation.Focused on the synapses of muscle spindle afferents,this paper established a dynamical system-Markov model starting from presynaptic stimulations to postsynaptic responses,and further verified the model via comparisons between theoretical results and relevant experimental data.With the purpose of describing the active features of dendritic membrane,we employed the methods of dynamical systems rather than the traditional passive cable theory,and identified the physical meaning of parameters involved.For the dynamic behavior of postsynaptic currents,we adopted simplified Markov models so that the analytical solutions for the open dynamics of postsynaptic receptors can be obtained.The model in this paper is capable of simulating the actual non-uniformity of channel density,and is suitable for complex finite element analysis of neurons;thus it facilitates the exploration of the frequency-regulating feedback and control mechanisms of motoneurons.展开更多
基金This project is supported by National Natural Science Foundation of China (No.60205006) and International Cooperation Foundation (Germany).
文摘A novel methodology for a walk-assisting balance system of the exoskeleton robot for dis-abled people is presented. The experiment on the walk-assisting balance system is implemented using amini-type ropewalker robot. The mechanism of the ropewalker robot is designed, its dynamic model isbuilt, and its control system based on PWM is developed. The emulations in Matlab and the results ofexperiments prove that this methodology is effective.
文摘A motion planning strategy for the assembly task of inserting a dissymmetrical T-shaped part into a C-shaped slot is presented. The coarse motion planning strategy is expounded by geometric reasoning. A medial axis diagram decreases the unnecessary configuration states and optimizes the planning strategy. Due to the uncertainties, force sensing and force control is indispensable for motion planning. Combining the coarse motion planning strategy with fine motion planning strategy, the task of assembling a dissymmetrical T-shaped part can be completed successfully.
基金supported by the National Natural Science Foundation of China (Grant No. 61075101)the Research Fund of State Key Laboratory of MSV,China (Grant No. MSV-2010-01)+1 种基金the Medical and Technology Intercrossing Research Foundation (Grant No. YG2010ZD101)the Science and Technology Intercrossing Research Foundation of Shanghai Jiaotong University
文摘This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers.The control mechanism of muscle contraction generated by collective motion of molecular motors is elucidated from the perspective of variable-frequency regulation,and action potential with variable frequency is proposed as the control signal to directly regulate Ca2+ concentration and indirectly control isometric tension.Furthermore,the transfer function between stimulation frequency and Ca2+ concentration is deduced,and the frequency domain properties of muscle contraction are analyzed.Moreover the conception of "electro-muscular time constant" is defined to denote the minimum delay time from electric stimulation to muscle contraction.Finally,the experimental research aiming at the relation between tension and stimulation frequency of action potential is implemented to verify the proposed variable-frequency control mechanism,whose effectiveness is proved by good consistence between experimental and theoretical results.
基金supported by the National Natural Science Foundation of China (Grant No. 61075101/60643002)the Research Fund of State Key Lab of MSV,China (Grant No. MSV-2010-1)+1 种基金the Science and Technology Intercrossingthe Medical and Technology Intercrossing Research Foundation of Shanghai Jiao Tong University (Grant No. YG2010ZD101)
文摘A dynamic model of skeletal muscle is developed to describe its activation kinetics and contraction dynamics based on the collective working mechanism of myosin II motors with a statistical mechanics method.According to the structure of sarcomeres arranged in series and in parallel,the mechanical properties of skeletal muscle are studied.This model reveals the relations between action potential and muscle characteristics.It is shown that calcium concentration in sarcoplasmic(SP) increases linearly with the increasing stimulation frequency and gradually reaches saturation.Active force and contraction velocity follow the trend of calcium concentration and reach a peak value at the maximum stimulation frequency.Contraction velocity is inversely proportional to the load while the contraction power increases to maximum and then reduces to zero with the increasing load.These properties are consistent with published physiological experimental results of skeletal muscle.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2011CB013203)
文摘Ultraprecision grinding is an important approach to efficiently fabricate large complex optical mirrors, and five-axis grinding method is commonly used for ultraprecision grinding. However, this method can hardly meet the high stiffness requirement for grinding large mirror, especially with a diameter over 2 m. Meanwhile, the use of fewer-axis grinding solves this problem, as it reduces the number of the grinder's axes to improve the rigidity of the system and minimize deformation for hard and brittle materials. But its characteristic of unfixed grinding point which changes with workpiece surface curvature increases geometric complexity and requires a higher geometric shape accuracy of grinding wheel. This paper parameterizes grinding wheel's geometric shape, reveals the relationship between fewer-axis and five-axis grinding methods from the point of view of the differential geometry, and establishes virtual-axis equivalence principium of feweraxis grinding. A quantitative method to determine grinding wheel's geometric parameters and its shaft inclination angle is proposed based on the requirements of geometric properties of optical mirror, grinder features and grinding process. Moreover, according to the properties of Gauss curvature of curved surface, the wear law of the toric grinding wheel is found and the surface geometric error distribution due to wear is achieved for fewer-axis grinding. The correctness of the principium and method above are verified through simulations.
基金supported by the National Natural Science Foundation of China (61075101)the National Basic Research Program of China(2011CB013203)the Science and Technology Intercrossing Research Foundation of Shanghai Jiao Tong University (LG2011ZD106)
文摘Motoneuron is the control unit of skeletal muscles,and the dynamic frequency-regulating feedback from the afferent nerve of receptors like muscle spindles forms the physical basis of its closed-loop regulation.Focused on the synapses of muscle spindle afferents,this paper established a dynamical system-Markov model starting from presynaptic stimulations to postsynaptic responses,and further verified the model via comparisons between theoretical results and relevant experimental data.With the purpose of describing the active features of dendritic membrane,we employed the methods of dynamical systems rather than the traditional passive cable theory,and identified the physical meaning of parameters involved.For the dynamic behavior of postsynaptic currents,we adopted simplified Markov models so that the analytical solutions for the open dynamics of postsynaptic receptors can be obtained.The model in this paper is capable of simulating the actual non-uniformity of channel density,and is suitable for complex finite element analysis of neurons;thus it facilitates the exploration of the frequency-regulating feedback and control mechanisms of motoneurons.