Nowadays, a highly integrated valve?controlled cylinder(HIVC) is applied to drive the joints of legged robots. Although the adoption of HIVC has resulted in high?performance robot control, the hydraulic force system s...Nowadays, a highly integrated valve?controlled cylinder(HIVC) is applied to drive the joints of legged robots. Although the adoption of HIVC has resulted in high?performance robot control, the hydraulic force system still has problems, such as strong nonlinearity, and time?varying parameters. This makes HIVC force control very diffcult and complex. How to improve the control performance of the HIVC force control system and find the influence rule of the system parameters on the control performance is very significant. Firstly, the mathematical model of HIVC force control system is established. Then the mathematical expression for parameter sensitivity matrix is obtained by applying matrix sensitivity analysis(PSM). Then, aimed at the sinusoidal response under(three factors and three levels) working conditions, the simulation and the experiment are conducted. While the error between the simulation and experiment can’t be avoided. Therefore, combined with the range analysis, the error in the two performance indexes of sinusoidal response under the whole working condition is analyzed. Besides, the sensitivity variation pattern for each system parameter under the whole working condition is figured out. Then the two sensitivity indexes for the three system parameters, which are supply pressure, proportional gain and initial displacement of piston, are proved experimentally. The proposed method significantly reveals the sensitivity characteristics of HIVC force control system, which can make the contribution to improve the control performance.展开更多
SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanow...SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanowire in a temperature range in which both surface and bulk states contribute to the total conductance. Under a magnetic field parallel to the SmB6 nanowire, the resistance suddenly increases at the turning point from up-sweep to down-sweep of the magnetic field. The magnetoresistance hysteresis loops are well consistent with the magnetocaloric effect. Our results suggest that the SmB6 nanowires possess potential applications in the magnetic cooling technology.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51605417)Key Project of Hebei Provincial Natural Science Foundation,China(Grant No.E2016203264)State Key Laboratory of Fluid Power and Mechatronic Systems(Zhejiang University)Open Fund Project(Grant No.GZKF-201502)
文摘Nowadays, a highly integrated valve?controlled cylinder(HIVC) is applied to drive the joints of legged robots. Although the adoption of HIVC has resulted in high?performance robot control, the hydraulic force system still has problems, such as strong nonlinearity, and time?varying parameters. This makes HIVC force control very diffcult and complex. How to improve the control performance of the HIVC force control system and find the influence rule of the system parameters on the control performance is very significant. Firstly, the mathematical model of HIVC force control system is established. Then the mathematical expression for parameter sensitivity matrix is obtained by applying matrix sensitivity analysis(PSM). Then, aimed at the sinusoidal response under(three factors and three levels) working conditions, the simulation and the experiment are conducted. While the error between the simulation and experiment can’t be avoided. Therefore, combined with the range analysis, the error in the two performance indexes of sinusoidal response under the whole working condition is analyzed. Besides, the sensitivity variation pattern for each system parameter under the whole working condition is figured out. Then the two sensitivity indexes for the three system parameters, which are supply pressure, proportional gain and initial displacement of piston, are proved experimentally. The proposed method significantly reveals the sensitivity characteristics of HIVC force control system, which can make the contribution to improve the control performance.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0300802)the National Natural Science Foundation of China(Grant Nos.61825401 and 11774004)
文摘SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanowire in a temperature range in which both surface and bulk states contribute to the total conductance. Under a magnetic field parallel to the SmB6 nanowire, the resistance suddenly increases at the turning point from up-sweep to down-sweep of the magnetic field. The magnetoresistance hysteresis loops are well consistent with the magnetocaloric effect. Our results suggest that the SmB6 nanowires possess potential applications in the magnetic cooling technology.
