Few study gives guidance to design weighting filters according to the frequency weighting factors,and the additional evaluation method of automotive ride comfort is not made good use of in some countries.Based on the ...Few study gives guidance to design weighting filters according to the frequency weighting factors,and the additional evaluation method of automotive ride comfort is not made good use of in some countries.Based on the regularities of the weighting factors,a method is proposed and the vertical and horizontal weighting filters are developed.The whole frequency range is divided several times into two parts with respective regularity.For each division,a parallel filter constituted by a low-and a high-pass filter with the same cutoff frequency and the quality factor is utilized to achieve section factors.The cascading of these parallel filters obtains entire factors.These filters own a high order.But,low order filters are preferred in some applications.The bilinear transformation method and the least P-norm optimal infinite impulse response（IIR） filter design method are employed to develop low order filters to approximate the weightings in the standard.In addition,with the window method,the linear phase finite impulse response（FIR） filter is designed to keep the signal from distorting and to obtain the staircase weighting.For the same case,the traditional method produces 0.330 7 m · s^–2 weighted root mean square（r.m.s.） acceleration and the filtering method gives 0.311 9 m · s^–2 r.m.s.The fourth order filter for approximation of vertical weighting obtains 0.313 9 m · s^–2 r.m.s.Crest factors of the acceleration signal weighted by the weighting filter and the fourth order filter are 3.002 7 and 3.011 1,respectively.This paper proposes several methods to design frequency weighting filters for automotive ride comfort evaluation,and these developed weighting filters are effective.展开更多
Wearable exoskeleton is a wearable device to enhance human ability,however,it is too heavy because of some constraints,such as material,structure and energy storage battery. Thus it brings fatigue to people after a lo...Wearable exoskeleton is a wearable device to enhance human ability,however,it is too heavy because of some constraints,such as material,structure and energy storage battery. Thus it brings fatigue to people after a long period of wearing. The research aims at optimizing shoulder fatigue and improving wearing comfort by means of changing the device-body contact material. After analyzing the current wearable exoskeletons ' weight, a standard load was set and a wearable exoskeleton was designed that could switch the weight. The experiment chose movement stability and change of cumulative pressure upon shoulder as the indexes of fatigue. The indexes were measured and analyzed before and after changing the contact material to memory foam with the standard load. The results showed promotion in action stability and obvious decrease in cumulative pressure upon shoulder.The experiment proves that the using of memory foam in wearable exoskeleton has evident effects on optimizing shoulder fatigue with load,promoting movement stability and wearing comfort.展开更多
文摘Few study gives guidance to design weighting filters according to the frequency weighting factors,and the additional evaluation method of automotive ride comfort is not made good use of in some countries.Based on the regularities of the weighting factors,a method is proposed and the vertical and horizontal weighting filters are developed.The whole frequency range is divided several times into two parts with respective regularity.For each division,a parallel filter constituted by a low-and a high-pass filter with the same cutoff frequency and the quality factor is utilized to achieve section factors.The cascading of these parallel filters obtains entire factors.These filters own a high order.But,low order filters are preferred in some applications.The bilinear transformation method and the least P-norm optimal infinite impulse response（IIR） filter design method are employed to develop low order filters to approximate the weightings in the standard.In addition,with the window method,the linear phase finite impulse response（FIR） filter is designed to keep the signal from distorting and to obtain the staircase weighting.For the same case,the traditional method produces 0.330 7 m · s^–2 weighted root mean square（r.m.s.） acceleration and the filtering method gives 0.311 9 m · s^–2 r.m.s.The fourth order filter for approximation of vertical weighting obtains 0.313 9 m · s^–2 r.m.s.Crest factors of the acceleration signal weighted by the weighting filter and the fourth order filter are 3.002 7 and 3.011 1,respectively.This paper proposes several methods to design frequency weighting filters for automotive ride comfort evaluation,and these developed weighting filters are effective.
基金the Fundamental Research Funds for the Central Universities,China(No.16D110301)Research Innovation Project of Shanghai Municipal Education Commission,China(No.201506000008)Science and Technology Guidance Project of Chinese Textile Industry Association(No.2015109)
文摘Wearable exoskeleton is a wearable device to enhance human ability,however,it is too heavy because of some constraints,such as material,structure and energy storage battery. Thus it brings fatigue to people after a long period of wearing. The research aims at optimizing shoulder fatigue and improving wearing comfort by means of changing the device-body contact material. After analyzing the current wearable exoskeletons ' weight, a standard load was set and a wearable exoskeleton was designed that could switch the weight. The experiment chose movement stability and change of cumulative pressure upon shoulder as the indexes of fatigue. The indexes were measured and analyzed before and after changing the contact material to memory foam with the standard load. The results showed promotion in action stability and obvious decrease in cumulative pressure upon shoulder.The experiment proves that the using of memory foam in wearable exoskeleton has evident effects on optimizing shoulder fatigue with load,promoting movement stability and wearing comfort.
