Browsing by Author "Afaghani, Jamal Eldeen"

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On-Line Deadlock-Free Planning of N-Industrial Arms With Independent Controllers Using Advanced Escaping Method
(inst Control Robotics & Systems, Korean inst Electrical Engineers, 2023) Afaghani, Ahmad Yasser; Afaghani, Jamal Eldeen; Aiyama, Yasumichi
This work presents an on-line deadlock avoidance system for N-industrial-robot arms utilizing an advanced escaping method. Robots within the same workspace are controlled via independent controllers using point-to-point commands. Besides, the robots have no preceding information about the commands that will be sent to the controllers after starting the system of robots up. In practice, the deadlock situations, in which the robot becomes an obstacle in front of another in the collision avoidance process, are an industrially common problem in on-line planning. Therefore, to make the proposed on-line collision avoidance system more functional in industrial applications, a deadlock avoidance method is integrated into the system. We have previously proposed a simple escaping method to avoid the deadlocks among the end-effectors of two robots, thereafter, an escaping method for the whole bodies of two robots has been proposed. In this work, an advanced escaping method using our previously devised advanced collision map is developed to avoid the deadlocks of N-industrial-robot arms. The advanced collision map has been designed to detect potential collisions between all body parts of robots and to represent collisions as collision areas on the map. The map is created for the robot that has acquired the command and is going to execute it and other robots in the workspace. Thus, the robot treats other robots as either static or dynamic obstacles. Hence, for generating a collision-free trajectory of the robots, time scheduling of command execution time is applied to avoid any collision areas on the map. The effectiveness of the proposed collision and deadlock avoidance system is demonstrated by testing the system on an OpenGL-based simulator. In addition, the system is evaluated by analyzing the results of many simulations with different robot arrangement patterns in the workspace as well as by comparing the system with the most relevant work to this article.
Tear-off Wear Mechanism of Sintered Diamond Tool in Cutting SiC Particle-strengthened Epoxy Composite
(Elsevier Science Pub., 1997) Afaghani, Jamal Eldeen; Yamaguchi, Katsumi; Nakamoto, T.
This study concerns the wear of sintered diamond tools in the cutting of SiC-particle–epoxy composites. The effects of the SiC particle size, volume ratio in the composite and diamond grain size of the cutting tool on tool wear were investigated. The experimental work has shown that a coarse-grained diamond tool exhibits higher wear resistance than a corresponding fine-grained tool. Greater tool wear was obtained in cutting the composites that had coarser particles and a higher volume ratio of SiC. Moreover, it was found that the tool wear increases drastically when the SiC particles are larger than the tool grains. A wear model of the tool was proposed, in which the tool is worn mainly by the ‘tear-off’ mechanism of the diamond grains. This model could explain the experimental results by comparing the pushing force of an SiC particle with the tear-off resistance of the diamond grains of the tool. Finally, a fatigue-like empirical curve was established. This curve can be used to predict the wear of the tool during cutting of the composite. q 1997 Elsevier Science S.