Aerial Robot Arms (ARAs) enable aerial drones to interact and influence objects in various environments. Traditional ARA controllers need the availability of a high-precision model to avoid high control chattering. Furthermore, in practical applications of aerial object manipulation, the payloads that ARAs can handle vary, depending on the nature of the task. The high uncertainties due to modeling errors and an unknown payload are inversely proportional to the stability of ARAs. To address the issue of stability, a new adaptive robust controller, based on the Radial Basis Function (RBF) neural network, is proposed. A three-tier approach is also followed. Firstly, a detailed new model for the ARA is derived using the Lagrange–d'Alembert principle. Secondly, an adaptive robust controller, based on a sliding mode, is designed to manipulate the problem of uncertainties, including modeling errors. Last, a higher stability controller, based on the RBF neural network, is implemented with the adaptive robust controller to stabilize the ARAs, avoiding modeling errors and unknown payload issues. The novelty of the proposed design is that it takes into account high nonlinearities, coupling control loops, high modeling errors, and disturbances due to payloads and environmental conditions. The model was evaluated by the simulation of a case study that includes the two proposed controllers and ARA trajectory tracking. The simulation results show the validation and notability of the presented control algorithm.
Mode I fracture analysis being employed to study delamination damage in fibre-reinforced composite structures under in-plane and out-of-plane load applications. However, due to the significantly low yield strength of the matrix material and the infinitesimal thickness of the interface matrix layer, the actual delamination process can be assumed as a partially plastic process (elasto-plastic). A simple elasto-plastic model based on the strain field in the vicinity of the crack front was developed for Mode I crack propagation. In this study, a double cantilever beam experiment has been performed to study the proposed process using a 0/90-glass woven cloth sample. A fibre Bragg grating sensor has embedded closer to the delamination to measure the strain at the vicinity of the crack front. Strain energy release rate was calculated according to ASTM D5528. The model predictions were comparable with the calculated values according to ASTM D5528. Subsequently, a finite element analysis on Abaqus was performed using ‘Cohesive Elements’ to study the proposed elasto-plastic behaviour. The finite element analysis results have shown a very good correlation with double cantilever beam experimental results, and therefore, it can be concluded that Mode I delamination process of an fibre-reinforced polymer composite can be monitored successfully using an integral approach of fibre Bragg grating sensors measurements and the prediction of a newly proposed elasto-plastic model for Mode I delamination process.
A field experiment was carried out in one of the plastic houses of the College of Agriculture, University of Kirkuk during the 2018-2019 agricultural season, to study the effect of three cultivation distances and three cucumber hybrids Cucumis sativus L. hybrids and their interaction on some of the characteristics of the cucumber plant using the drip irrigation system under protected cultivation conditions. The experiment included 18 treatments that consisted of matching three hybrids of cucumber (FAEQ F1, DALIA F1, and BARQ F1) with three distances between plants (40, 30, 20) cm. A factorial experiment was carried out according to the design of randomized complete sectors (R.C.B.D) and by the split plates method and with three replications. The significance of differences between the averages was tested according to the least significant difference L.S.D. between the arithmetic means and at a probability level p < 0.01 and p < 0.05. The results showed the significant effect of most of the studied treatments. It gave the highest significant value for the treatment of interaction between cucumber varieties and the interaction between V3D1 and V3D2 in characteristics of plant height and percentage chlorophyll in the plant, which reached (3.197 m plant−1 and 57.283%), respectively.
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