<span>Model based adaptive controllers (MBACs) are considered one of the most common adaptive controllers that are used with robotic systems due to their ensuring nonlinear robust scheme with global asymptotic stability for controlling nonlinear systems. However, this controller requires precise mathematical models of the controlled systems. In this paper, an optimal model-based adaptive controller (OMBAC) is suggested for controlling a two-link upper limb rehabilitation robot. This controller, in the presence of model uncertainties, can guarantee the robustness of the rehabilitation robot. Although the OMBAC is an adaptive and model-based controller, some of its parameters need to be determined precisely. In this paper, these parameters are determined by the grasshopper optimization algorithm (GOA). The Lyapunov method is used to analyze the stability assurance of controlled rehabilitation. The results of the simulation for two tested trajectories (linear and nonlinear trajectories) demonstrate the efficiency of the suggested OMBAC with fast settling time, minimum error steady state, and very small overshoot.</span>
A Human Leg Robot (HLR) is a type of manipulator robot that has non-linear, quality, time-varying behaviors and uncertainty in parameters. Therefore, it must be controlled. The purpose of this work is to design an optimal Improved Proportional-Integral-Derivative (IPID) controller for this robot to improve its performance in tracking the desired path. Two schemes of IPID controllers are suggested to enhance the performance of the traditional PID in controlling the human leg robot and following the desired path. The Grasshopper Optimization Algorithm (GOA) is considered to optimize the IPID parameters. The performance of the suggested IPID structures has been compared to traditional PID methods. The simulation results show that the efficiency of these schemes was enough to handle the tracking problems of the HLR.
Numerical and experimental study is carried out to investigate flow structure and heat transfer of air jet normally impinging on a flat plate. Three orifices of 5, 10 and 20 mm diameters and Z/d ratios in the range of 2 to 8 were used. The numerical simulations were performed with the ANSYS FLUENT for steady, three-dimensional, incompressible, and turbulent flow from the jet. The comparison of CFD predictions with experimental results show that a good agreement of the average Nusselt number, the pressure coefficients distributions, radial velocity distributions of the fee jet.
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