A generalized Udwadia-Kalaba control design for uncertain belt conveyor systems with inequality constraints.

Uncertainty can lead to jitter or overshoot in mechanical systems, necessitating the design of multiple constraints to stabilize them. This paper proposes a control structure based on the generalized Udwadia-Kalaba equation to address these constraints simultaneously. An uncertain dynamical model is developed, incorporating both equality and inequality constraints. By integrating diffeomorphism theory, a robust control strategy is designed to ensure compliance with these constraints. Utilizing the Lyapunov approach, the uniform boundedness and uniform ultimate boundedness of the dynamical system are demonstrated. Finally, the feasibility of the proposed control method is validated through its application to a belt conveyor system.

Experimental study on the deterioration of mechanical properties of sandy mudstone under different water-gas interactions.

Based on the water-rock-gas coupling test system, the work combined the scanning electron microscope and XTDIC 3D full-field strain measurement system. The Brazilian splitting test was performed on four groups of sandy mudstone specimens under contrast (CO), mash-gas soaking (MS), water-mash gas soaking (WM), and water-soaking (WS) conditions. The tensile strength, deformation failure, and microscopic characteristics of fractures were studied to reveal the deterioration mechanism of the tensile properties of sandy mudstone under water-gas coupling. The results showed that the uniaxial tensile strength of sandy mudstone specimens under the three soaking conditions was less than that of the contrast conditions. Compared with specimens in the CO group, the tensile strength of specimens in MS-WS groups was reduced; the WS group decreased the most. Specimens changed from brittle failure to plastic failure after soaking. The decrease rate in strength after the peak was consistent with the change trend in tensile strength. It led to a larger localized deformation zone of specimens and more obvious displacement. The deformation localization zone of the WS group was the broadest, with the most intense displacement. Besides, stress concentration first occurred in the submerged part of the WM group. Fractures expanded in the direction of maximum principal strain. The internal pore structure of sandy mudstone specimens in each group changed after soaking. The average porosity, maximum pore area, and probability entropy of specimens in WS-MS groups increased compared to the CO group. The WS group had the largest reduction and the MS group had the smallest. The pre-peak energy storage capacity of sandy mudstone specimens was gradually weakened. Compared with the CO group, that in the WS-MS groups was reduced. The WS group had the greatest reduction, and the MS group had the smallest. The deterioration effect of water on the interior of sandy mudstone was stronger than that of gas. The work is of great significance for understanding the stability of coal and rocks in closed-pit high-gas mines.

Prediction of Fusion Hole Perforation Based on Arc Characteristics of Front Image in Backing Welding.

In one-side welding with back-formation, the weld is penetrated after the fusion hole is perforated. Therefore, judging whether the fusion hole is perforated is very important to realize autocontrol of penetration in one-side welding with back-formation process. Previous researches mainly focused on the morphological characteristics of the molten pool and fusion hole to judge the weld penetration state. Sometimes it is difficult to obtain the morphological characteristics of the molten pool, keyhole and fusion hole and image processing is complex. In this paper, a visual detection system of fusion holes based on visual sensing is constructed to obtain the real-time fusion hole images in backing welding. It is found that the arc characteristics in the front images contain abundant information about the perforation of fusion hole. An image processing program is developed based on MATLAB software, and the arc characteristic parameters in front images are obtained. Taking the arc characteristic parameters as the input, obtaining the penalty function and the kernel function parameters through the cross validation and grid search method, a prediction model of fusion hole perforation based on the support vector machine is put forward. The accuracy for prediction samples is 88%. By analyzing the misidentified samples, it is found that some of the newly perforated images are predicted as nonperforated ones, which has little influence on the penetration control of the weld.