Modelling of a Cable-driven Ankle Rehabilitation Robot

Ankle injury is one of physical injury that commonly occurs in sports or domestic-related activities. Presently, there are various established treatments for ankle rehabilitation in hospital or rehabilitation clinic. This involves a range of motion treatment exercise and endurance treatment exercise. However, current treatment requires patients to frequently visit to the hospital which is tedious and also repetitive. One of the solutions to deal with the repetitiveness of the treatment is to introduce an automated device such as a robot that can help the therapist to perform this repetitive task on the patients. A concept design for a cable driven ankle rehabilitation robot has been proposed for this task. The reason for selecting cable-based design is the design is lighter than a rigidly based robot. This adds up its potential for mobility and portability which allows convenience to the users. The focus of this paper is to present inverse kinematics analysis and modelling of the proposed concept design of the robot which aimed to determine the feasibility of the concept design. Overall, the modelling of the cable-based ankle rehabilitation robot using inverse kinematics is feasible to project or to predict the trajectory paths of the moving platform of the robot. This will be useful for planning suitable dimension for fabrication of the robot

Structural stability and electronic properties of graphene/germanene heterobilayer

In this work, the structural and electronic properties of graphene/germanene heterobilayer is investigated by using density functional theory. We find that the graphene and germanene are bounded together mainly by weak van der Waal forces. This is supported by small interlayer binding energy of graphene/germanene heterobilayer. In the heterobilayer, the Dirac cone characteristics of both graphene and germanene layers are well preserved. The band gap opening is found due to the unsaturated pz-orbital of germanene layer. Further variation of compressive strain along the normal of the heterobilayer increases the band gap opening in the heterobilayer. Inhomogeneous charge redistribution is found in between graphene and germanene layer, where small charge accumulation region is found in germanene layer while charge depletion region in graphene layer. The total charge accumulations in between graphene and germanene sheets is 5.645 × 10−4

The effect of erbium oxide in physical and structural properties of zinc tellurite glass system

In this research, the melt-quenching method was used to synthesize a series of zinc tellurite glass systems doped with erbium oxide with the chemical composition of [(TeO2)0.7 (ZnO)0.3]1−x (Er2O3)x at different molar fraction, x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05. X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, density, molar volume, elastic and optical measurements were used to characterize the prepared glass samples. At room temperature, the result of the XRD, FTIR, density, elastic and optical properties were all recorded. An amorphous nature of glass samples is proven by the XRD spectra. The analysis of FTIR spectra shows the presence of functional vibration of tellurite network. It is observed that the density of the glass system increase with the molar fraction of Er2O3. The value of molar volume is found to be directly proportional to the density. Thus, the increment in the density value causes the increment of the molar volume due to the increase of erbium concentration. This in turn results in the creation of excess free volume due to the difference of atomic radius between erbium and tellurite. On the other hand, ultrasonic velocity was used to determine the elastic moduli of the glass systems. The elastic moduli such as longitudinal modulus, shear modulus, bulk modulus and Young's modulus give a fluctuating trend against the concentration of Er2O3. The increase of the elastic moduli is due to the mix former effect. In contrast, the decrease of the elastic moduli is due to the breakdown of Er2O3 in the zinc tellurite glass system which weakens the glass structure of the ternary tellurite system. The optical properties of the prepared glasses were determined by UV–vis analysis. The optical absorption was recorded at room temperature in the wavelength ranging from 220 nm to 800 nm. The optical absorption spectra reveal that fundamental absorption edge shifts to higher wavelength as the content of erbium oxide increase. The values of direct and indirect band gap have been calculated and are observed to decrease with the increase content of erbium oxide. However, the Urbach energy, refractive index, molar refraction and electronic polarizability are shown to be increased with an addition content of erbium oxides