Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 5 Articles
This paper presents a dynamic study of sandwich functionally graded beam with\npiezoelectric layers that are used as sensors and actuators. This study is exploited later in the\nformulation of the active control laws, while using the optimal control Linear Quadratic Gaussian\n(LQG), accompanied by the Kalman filter. The mathematical formulation is based on Timoshenkoâ??s\nassumptions and the finite element method, which is applied to a flexible beam divided into a finite\nnumber of elements. By applying the Hamilton principle, the equations of motion are obtained. The\nvibration frequencies are found by solving the eigenvalue problem. The structure is analytically then\nnumerically modeled and the results of the simulations are presented in order to visualize the states\nof their dynamics without and with active control....
The ionic liquid gel (ILG), a new type of soft actuator material, is a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate\n(BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP), and ZrO2 polymerized into a gel state under\nultraviolet (UV) light irradiation. The soft actuator structure consists of a layer of ionic liquid polymer gel sandwiched between\ntwo layers of activated carbon capped with gold foil. The volume of the cationic BMIM +in the ionic liquid BMIMBF4 is much\nlarger than that of the anionic BF4-. When voltages are applied to both sides of the actuator, the anions and cations move toward\nthe anode and cathode of the electrode, respectively, under the electric field. The volume of the ILG cathode side therefore\nexpands, and the volume of the ILG anode side shrinks, hence bending the entire actuator toward the anode side. The Ogden\nmodel was selected as the hyperelastic constitutive model to study the mechanical properties of the ILG by nonlinear analysis. As\nthe ILG is an ideal material for the preparation of a supercapacitor, the equivalent circuit of the ILG can be modeled by the\nsupercapacitor theory to identify the transfer function of the soft actuator. The central pattern generator (CPG) control is widely\nused in the area of biology, and CPGs based on bioinspired control methods have attracted great attention from researchers\nworldwide. After the continuum soft actuator is discretized, the CPG-based bioinspired method can be used to control the soft\nrobot drivers. According to the simulation analysis results, the soft actuator can be smooth enough to reach the specified location....
Magnetic springs are a fatigue-free alternative to mechanical springs that could enable\ncompliant actuation concepts in highly dynamic industrial applications. The goals of this article are:\n(1) to develop and validate a methodology for the optimal design of a magnetic spring and (2) to\nbenchmark the magnetic springs at the component level against conventional solutions, namely,\nmechanical springs and highly dynamic servo motors. We present an extensive exploration of the\nmagnetic spring design space both with respect to topology and geometry sizing, using a 2D finite\nelement magnetostatics software combined with a multi-objective genetic algorithm, as a part of a\nMagOpt design environment. The resulting Pareto-optima are used for benchmarking rotational\nmagnetic springs back-to-back with classical industrial solutions. The design methodology has been\nextensively validated using a combination of one physical prototype and multiple virtual designs.\nThe findings show that magnetic springs possess an energy density 50% higher than that of stateof-\nthe-art reported mechanical springs for the gigacycle regime and accordingly a torque density\nsignificantly higher than that of state-of-the-practice permanently magnetic synchronous motors....
Herein, we report the application of a chemometric tool for the optimisation of\nelectrochemical biosensor performances. The experimental design was performed based on the\nresponses of an amperometric biosensor developed for metal ions detection using the flow injection\nanalysis. The electrode preparation and the working conditions were selected as experimental\nparameters, and thus, were modelled by a response surface methodology (RSM). In particular,\nenzyme concentration, flow rates, and number of cycles were reported as continuous factors, while\nthe sensitivities of the biosensor......
Objective. To quantify the concurrent accuracy and the test-retest reliability of a Kinect V2-based upper limb functional assessment\nsystem. Approach. Ten healthy males performed a series of upper limb movements, which were measured concurrently with Kinect\nV2 and the Vicon motion capture system (gold standard). Each participant attended two testing sessions, seven days apart. Four\ntasks were performed including hand to contralateral shoulder, hand to mouth, combing hair, and hand to back pocket. Upper\nlimb kinematics were calculated using our developed kinematic model and the UWA model for Kinect V2 and Vicon. The\ninterdevice coefficient of multiple correlation (CMC) and the root mean squared error (RMSE) were used to evaluate the\nvalidity of the kinematic waveforms. Mean absolute bias and Pearsonâ??s r correlation were used to evaluate the validity of the\nangles at the points of target achieved (PTA) and the range of motion (ROM). The intersession CMC and RMSE and the\nintraclass correlation coefficient (ICC) were used to assess the test-retest reliability of Kinect V2. Main Results. Both validity and\nreliability are found to be task-dependent and plane-dependent. Kinect V2 had good accuracy in measuring shoulder and elbow\nflexion/extension angular waveforms (CMC> 0 87),moderate accuracy of measuring shoulder adduction/abduction angular\nwaveforms (CMC = 0 69-0.82), and poor accuracy of measuring shoulder internal/external angles (CMC < 0 6).We also found\nhigh test-retest reliability of Kinect V2 in most of the upper limb angular waveforms (CMC = 0 75-0.99), angles at the PTA\n(ICC = 0 65-0.91), and the ROM (ICC = 0 68-0.96). Significance. Kinect V2 has great potential as a low-cost, easy implemented\ndevice for assessing upper limb angular waveforms when performing functional tasks. The system is suitable for assessing\nrelative within-person change in upper limb motions over time, such as disease progression or improvement due to intervention....
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