Due to poor predictability of resources and difficulty in perception of task execution status, traditional Automatic Guide Vehicle (AGV) scheduling systems need a lot of extra time in the charging process. To solve this problem, a digital twin-based dynamic AGV scheduling (DTDAS) method is proposed, including four functions, namely the knowledge support system, the scheduling model, the scheduling optimization, and the scheduling simulation. With the features of virtual reality data interaction, symbiosis, and fusion from the digital twin technology, the proposed DTDAS method can solve the AGV charging problem in the AGV scheduling system, effectively improving the operating efficiency of the workshop. An AGV scheduling process in a discrete manufacturing workshop is taken as a case study to verify the effectiveness of the proposed method. The results show that, compared with the traditional AGV scheduling method, the DTDAS method proposed in this article can reduce makespan 10.7% and reduce energy consumption by 1.32%.

In the large-area multidevice linkage-based laser processing, using the traditional control method cannot guarantee the processing accuracy of a permanent magnet linear motor (PMLM) system for a high-speed subject, due to unknown model uncertainties, backlash-like hysteresis, states constraints, and external disturbance. To address this shortcoming, this article develops a disturbance observe-based adaptive neural control for the PMLM system. First, aiming at the problem of unknown and uncertain system parameters, this study uses a radial basis neural network to estimate unknown functions of the system. Then, an adaptive variable is introduced to compensate for the effect of unknown backlash-like hysteresis, and the barrier Lyapunov function is used to restrict the motor from operating in a specified area. In addition, a nonlinear disturbance observer is constructed to adapt to the actual processing to reduce the influence of the external disturbance and the system load change. The proposed control scheme is verified experimentally, and the results indicate that when the proposed method is used, the PMLM system is consistently bounded by using the Lyapunov theorem. Finally, the simulation and experimental results verify the effectiveness of the proposed control strategy. The proposed method could be applied to laser-processing equipment.

Given that signal is weakened to a certain extent in the process of noise suppression using mainstream method, and that new noise is introduced by signal processing system, causing the decrease of detection performance, to improve the performance of detection to BPSK signal under the condition of strong noise and no prior information, the detection algorithm of BPSK signal of bistable stochastic resonance model based on scale change is proposed in this study. Using classical bistable stochastic resonance (BSR) system, only low-amplitude and low-frequency periodic signal can be processed. Scale change is first made to BSR in this study, verifying that BSR can be applied to high-frequency BPSK signal under high sampling frequency condition, and nonlinear threshold detection system is designed following Neyman-Pearson criterion to deduce and quantitatively show error rate of detector. Besides, complete flow for signal detection was built by taking it as feedback quantity to adjust the system parameters adaptively. Scale change feasibility and applicability of algorithm proposed in this study were verified through simulation experiment, which lays the theoretical basis for the detection of weak BPSK signal under low signal-to-noise ratio (SNR).

High-power millisecond laser is an efficient tool to manufacture micro holes, but the laser induced thermal defects, such as recast layer (RL), micro cracks and heat affected zone, are difficult to avoid. However, some important components, like turbine blades, are very sensitive to these defects, therefore, they must be eliminated in the manufacturing process of film cooling holes. We propose a combined processing method which includes high-power laser pre-drilling and electrochemical post-processing. One novelty of this study is that we applied a special back-bonded material (silicate mixture) under the Inconel 718 substrate, which functions as barricade to protect the opposite inner surface of the hollow blade in laser drilling, while in the electrochemical process, it functions as bottom support to form electrolyte back flow. A novel two-step inner streaming electrochemical post-processing technique was designed according to the characteristics of RL distribution in the laser pre-drilled holes. The processing strategy was optimized by a series of experiments. Finally, recast-layer free holes with clear and straight hole walls could be drilled in less than 30 s each, which is much faster than ultrafast laser drilling.

The terminal beam collimation problem of laser processing systems has traditionally been a headache. The deflection of the terminal beam seriously affects the processing accuracy and success. In this article, A novel method for measuring, collimating, and maintaining the spatial pose of the terminal beam in a five-axis laser processing system based on 3-D and 2-D hybrid vision is proposed. The beam pose in the working space of the laser processing system is measured by using a 3D scanner and an alignment sensor. The functional relationship between the galvanometer coordinates and the deflection angles of the terminal beam is established. The coordinates corresponding to the minimum deflection angle are solved to collimate the beam. Moreover, a camera is used to monitor the laser spot and re-collimate the deflected beam. The experimental results show that the method proposed in this article can effectively measure the deflection angle of the terminal beam, collimate the terminal beam and monitor the spot position of the terminal beam. The method can effectively improve the processing accuracy when applied to the laser processing system and has excellent potential application value.