Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. T...Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. This experimental method needn't special experiment equipments. Experiment's dynamic repeatability is good. So wrist force sensor's dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn't require that wavelet primary function be orthogonal and needn't wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor's dynamic characteristics are identified by the frequency response function.展开更多
Lorentz force electrical impedance tomography(LFEIT) inherits the merit of high resolution by ultrasound stimulation and the merit of high contrast through electromagnetic field detection. To reduce the instantaneou...Lorentz force electrical impedance tomography(LFEIT) inherits the merit of high resolution by ultrasound stimulation and the merit of high contrast through electromagnetic field detection. To reduce the instantaneous peak power of the stimulating signal to the transducer, the sinusoidal pulse and step-frequency technique is investigated in LFEIT. The theory of application of step-frequency technique in LFEIT is formulated with the direct demodulation method and the in-phase quadrature demodulation method. Compared with the in-phase quadrature demodulation method, the direct demodulation method has simple experimental setup but could only detect half of the range. Experiments carried out with copper foils confirmed that LFEIT using the step-frequency technique could detect the electrical conductivity variations precisely, which suggests an alternative method of realization of LFEIT.展开更多
Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force(WSF) that is 23 times their body weight.Aiming at a full understanding of the origins of this ext...Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force(WSF) that is 23 times their body weight.Aiming at a full understanding of the origins of this extremely large force,in this study,we concentrate on two aspects of it:the intrinsic properties of the leg surface and the active control of the initial stepping angle of the whole leg.Using a measurement system that we developed ourselves,the WSFs for the original leg samples are compared with those whose surface wax and microstructures have been removed and with those of a different stiffness.The results show that leg f exibility plays a dominant role over surface wax and microstructures on the leg surface in creating the supporting force.Moreover,we discuss the dependence relationship between the maximum WSF and the initial stepping angle,which indicates that the mosquito can regulate this angle to increase or decrease the WSF during landing or takeoff.These finding are helpful for uncovering the locomotion mechanism of aquatic insects and for providing inspiration for the design of microfluids miniature boats,biomimetic robots,and microsensors.展开更多
基金National Hi-tech Research and Development Program of China(863 Program,No.2001AA42330).
文摘Negative step response experimental method is used in wrist force sensor's dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor's load in working. This experimental method needn't special experiment equipments. Experiment's dynamic repeatability is good. So wrist force sensor's dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn't require that wavelet primary function be orthogonal and needn't wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor's dynamic characteristics are identified by the frequency response function.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51137004 and 61427806the Scientific Instrument and Equipment Development Project of Chinese Academy of Sciences under Grant No YZ201507the China Scholarship Council Program under Grant No 201604910849
文摘Lorentz force electrical impedance tomography(LFEIT) inherits the merit of high resolution by ultrasound stimulation and the merit of high contrast through electromagnetic field detection. To reduce the instantaneous peak power of the stimulating signal to the transducer, the sinusoidal pulse and step-frequency technique is investigated in LFEIT. The theory of application of step-frequency technique in LFEIT is formulated with the direct demodulation method and the in-phase quadrature demodulation method. Compared with the in-phase quadrature demodulation method, the direct demodulation method has simple experimental setup but could only detect half of the range. Experiments carried out with copper foils confirmed that LFEIT using the step-frequency technique could detect the electrical conductivity variations precisely, which suggests an alternative method of realization of LFEIT.
基金supported by the National Natural Science Foundation of China (Grants 11302093,11302094 and 11272357)the Natural Science Fund for Distinguished Young Scholars of Shandong Province (JQ201302)
文摘Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force(WSF) that is 23 times their body weight.Aiming at a full understanding of the origins of this extremely large force,in this study,we concentrate on two aspects of it:the intrinsic properties of the leg surface and the active control of the initial stepping angle of the whole leg.Using a measurement system that we developed ourselves,the WSFs for the original leg samples are compared with those whose surface wax and microstructures have been removed and with those of a different stiffness.The results show that leg f exibility plays a dominant role over surface wax and microstructures on the leg surface in creating the supporting force.Moreover,we discuss the dependence relationship between the maximum WSF and the initial stepping angle,which indicates that the mosquito can regulate this angle to increase or decrease the WSF during landing or takeoff.These finding are helpful for uncovering the locomotion mechanism of aquatic insects and for providing inspiration for the design of microfluids miniature boats,biomimetic robots,and microsensors.