查看更多>>摘要：Slip perception based on localized displacement phenomenon (LDP) during incipient slip is a crucial factor in prosthetic/robotic stable manipulation of an object. However, in current LDP-based slip predicting methods, the center point on the contact surface of a fingertip is roughly considered as the latest slipping point which leads to excessive grasping force in some situations. Here, we present a finite element (FE) model of a sliding soft fingertip verified by experiments to investigate the localized displacement and force changing of nodes on the contact surface under different initial grasping forces. Results show that the distance between the latest slipping point and the center point changes linearly with the applied initial normal force, with an R-square of 0.94. Based on these results two slip prediction methods which can be conducted in an unstructured environment with random initial normal grasping force were proposed.
Ivanov, I. I.Baranov, A. M.Spirjakin, D. N.Akbari, S....
9页
查看更多>>摘要：Preventing the explosion of mixtures of combustible gases and vapors is an important task in industry. This research presents an approach for rapid assessment of the explosiveness of combustible gas mixtures of unknown composition. The technique is based on registering the amount of heat released during the combustion of a portion of gases inside the catalytic sensor. The phenomenological theory of the approach for rapid assessment of the explosiveness was also presented. To carry out the measurements, a two-stage heating pulse and an approach to the calibration of the catalytic sensor were developed. The experiments were carried out for various mixtures of methane, propane, butane and hexane within the pre-explosive range (up to 50% Low Explosive Limit). In order to calculate the Lower Explosive Limit (LEL) of a mixture of flammable gases, Le Chatelier's rule was used. Industrial catalytic sensors with additional diaphragm that limits the gas leakage into the sensor were used for measurements. The advanced data processing which is based on integrating the area under the measured dependence of sensor response on time was used to calculate the heat released. The parameters affecting the measurement results were analyzed. The measurement values were in good agreement with the prescribed values. The measurement errors did not exceed 10%. Since in this approach there is no need to identify gases, or their quantity and concentration, it can be used in industry for quick determination of potentially explosive mixtures in the air.
NSTL
Elsevier