For the welding cell in the manufacturing process of large excavation motor arm workpieces, a system framework, based on a digital twin welding robot cell, is proposed and constructed in order to optimize the robotic collaboration process of the welding workstation with digital twin technology. For the automated welding cell, combined with the actual robotic welding process, the physical entity was digitally modeled in 3D, and the twin welding robot operating posture process beats and other data were updated in real time, through real-time interactive data drive, to achieve real-time synchronization and faithful mapping of the virtual twin as well as 3D visualization and monitoring of the system. For the robot welding process in the arc welding operation process, a mathematical model of the kinematics of the welding robot was established, and an optimization method for the placement planning of the initial welding position of the robot base was proposed, with the goal of smooth operation of the robot arm joints, which assist in the process simulation verification of the welding process through the virtual twin scenario. The implementation and validation process of welding process optimization, based on this digital twin framework, is introduced with a moving arm robot welding example.

Achieving high throughput in input-queued switches has been found to be difficult, especially when traffic is nonuniform in the sense that different inputs have very different cell generation rates. We show that for general arrival processes, 100% throughput can be achieved with a simple algorithm that is very easy to implement.We consider a switch in which in each time slot, at most one cell may be transmitted from each input, and at most one cell may be received at each output. Cells that are destined for output j arrive at input i according to a stationary and ergodic process, and arrivals are queued at the input. The problem is to decide which inputs are to transmit to which outputs in each time slot in order to maximize throughput. Necessary conditions for stability are that the total arrival rate to each input must be less than 1, and the total arrival rate destined to each output must be less than 1. We propose a simple scheduling algorithm and show that with this algorithm the necessary conditions for stability are also sufficient.