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Simulation analysis for optimal design of pneumatic bellow actuators for soft-robotic glove

Guo Ning, Sun Zhidao, Wang Xiaojun, Yeung Eric Hiu Kwong, To Michael Kai Tsun, Li Xiaodong, Hu Yong

Biocybernetics and Biomedical Engineering

2020

Vol. 40, no. 4

1359--1368

Soft actuators that have a bellows structure are favorable candidates for robots designed to interact with humans. However, a weak point in the actuator can occur as a result of deformation from the driving pressure. In this study, a simulation analysis of a soft bellows actuator composed of ethylene-vinyl acetate copolymer molding was conducted. The mechanical characteristics along different latitudes of the bellows in the soft actuator were evaluated using finite element modeling and analysis. Functional performance was studied during both compression and inflation using two driving methods (constant pumping rate-driven and constant displacement-driven). To validate the simulation, experimental tests were performed on a version of the soft bellows actuator that was constructed according to the same specifications as the model version; simulation and experimental displacements in relation to air pressure were compared. The results showed points near the trough were more likely to experience the largest stress during inflation and may suffer critical structural damage. During compression, points near the crest were more easily damaged. Stress variation showed good symmetry at points of interest on either side of the trough, during both inflation and compression. These findings provide a basis for precise control of and design improvements to soft bellows actuators for human-friendly usage.

Full waveform inversion based on a local traveltime correction and zero-mean cross-correlation-based misft function

Dong Shiqi, Han Liguo, Hu Yong, Yin Yuchen

Acta Geophysica

2020

Vol. 68, no. 1

29--50

Full waveform inversion (FWI) sufers from the cycle skipping problem, because the observed data usually lack low-frequency components or due to errors in the wavelet estimation. In addition, the strong low-frequency non-zero-mean noise can have a large impact on FWI results. Thus, we propose a local waveform traveltime correction scheme to solve the situations when the observed data lack low-frequency components or when the estimation for the wavelet is incorrect. We use a sliding time window, which is used to decrease the traveltime diferences between the calculated and observed data to increase the cross-correlation between them. Besides, we propose a zero-mean normalized cross-correlation misft function to reduce the interference of the low-frequency non-zero-mean noise. Therefore, we propose new approaches to improve FWI results whether the observed data lack low-frequency components or the observed data are contaminated by the non-zero-mean lowfrequency noise. Numerical examples on Marmousi model show the feasibility of a FWI based on the zero-mean normalized cross-correlation misft function and a FWI based on the local traveltime correction method.

Stair-like multivariable generalized predictive control of pulverizing system in thermal power plants

Zhang Jiansheng, Zhang Gang, Gao Yaokui, Hu Yong

Transactions on Environment and Electrical Engineering

2019

Vol. 3, No. 1

21--25

Pulverizing system is an important part in the clean and efficient utilization of coal in thermal power plant, and the optimal control of the system is an important way to achieve this goal. This paper presents a stair-like multivariable generalized predictive control scheme for a pulverizing system. This control scheme focuses on the problem of predictive control algorithm in practical application, and integrates the feedforward experience in traditional control schemes of pulverizing system. Simulation results showed that the scheme are able to realize the decoupling control of the pulverizing system, avoid the problem of matrix inversion, reduce the amount of calculation, and has certain engineering application value.