Current Issue : July - September Volume : 2016 Issue Number : 3 Articles : 4 Articles
A cheetah model is built to mimic real cheetah and its mechanical and dimensional parameters are derived from the real cheetah.\nIn particular, two joints in spine and four joints in a leg are used to realize the motion of segmented spine and segmented legs which\nare the key properties of the cheetah bounding. For actuating and stabilizing the bounding gait of cheetah, we present a bioinspired\ncontroller based on the state-machine. The controller mainly mimics the function of the cerebellum to plan the locomotion and\nkeep the body balance. The haptic sensor and proprioception system are used to detect the trigger of the phase transition. Besides,\nthe vestibular modulation could perceive the pitching angle of the trunk. At last, the cerebellum acts as the CPU to operate the\ninformation from the biological sensors. In addition, the calculated results are transmitted to the low-level controller to actuate and\nstabilize the cheetah bounding. Moreover, the delay feedback control method is employed to plan the motion of the leg joints to\nstabilize the pitching motion of trunk with the stability criterion. Finally, the cyclic cheetah bounding with biological properties is\nrealized. Meanwhile, the stability and dynamic properties of the cheetah bounding gait are analyzed elaborately....
Possibility for a novel type of sensors for detecting nanosized substances (e.g., macromolecules or molecule clusters) through their\neffects on electron tunneling in a double nanoscale semiconductor heterostructure is discussed.We studied spectral distributions of\nlocalized/delocalized states of a single electron in a double quantum well (DQW) with relation to slight asymmetry perturbations.\nThe asymmetry was modeled by modification of the dot shape and the confinement potential. Electron energy uncertainty is\nrestricted by the differences between energy levels within the spectra of separated QWs. Hence, we established a direct relationship\nbetween the uncertainty of electron localization and the energy uncertainty. We have shown in various instances that a small\nviolation of symmetry drastically affects the electron localization. These phenomena can be utilized to devise new sensing\nfunctionalities. The charge transport in such sensors is highly sensitive to minuscule symmetry violation caused by the detected\nsubstance. The detection of the electron localization constitutes the sensor signal....
Carbon nanotubes (CNTs) are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It\nis evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great\npotential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the\nfield of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques are currently\navailable to enhance the integrity and durability of concrete structures with cracks and spalling, but applicability and/or reliability\nis/are often limited.Therefore, there is always a need for innovative high performing concrete repairmaterials with good mechanical,\nrheological, and durability properties. Considering the mechanical properties of carbon nanotubes (CNTs) and the test results of\nCNT reinforced cement composites, it is apparent that such composites could be used conveniently as concrete repair material.\nWith this end in view, the applicability of multiwalled carbon nanotube (MWNT) reinforced cement composites as concrete repair\nmaterial has been evaluated in this study in terms of setting time, bleeding, and bonding strength (slant shear) tests. It has been\nfound that MWNT reinforced cement mortar has good prospective as concrete repair material since such composites exhibited\ndesirable behavior in setting time, bleeding, and slant shear....
A lower limb assistive exoskeleton is designed to help operators walk or carry payloads. The exoskeleton is required to shadow\nhuman motion intent accurately and compliantly to prevent incoordination. If the user�s intention is estimated accurately, a\nprecise position control strategy will improve collaboration between the user and the exoskeleton. In this paper, a hybrid position\ncontrol scheme, combining sliding mode control (SMC) with a cerebellar model articulation controller (CMAC) neural network,\nis proposed to control the exoskeleton to react appropriately to human motion intent. A genetic algorithm (GA) is utilized to\ndetermine the optimal sliding surface and the sliding control law to improve performance of SMC. The proposed control strategy\n(SMC GA CMAC) is compared with three other types of approaches, that is, conventional SMC without optimization, optimal\nSMC with GA (SMC GA), and SMC with CMAC compensation (SMC CMAC), all of which are employed to track the desired\njoint angular position which is deduced from Clinical Gait Analysis (CGA) data. Position tracking performance is investigated\nwith cosimulation using ADAMS and MATLAB/SIMULINK in two cases, of which the first case is without disturbances while the\nsecond case is with a bounded disturbance. The cosimulation results show the effectiveness of the proposed control strategy which\ncan be employed in similar exoskeleton systems....
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