Digital factory technology is an advanced manufacturing technology served as to establish a bridge between the process of product development and manufacturing.In terms of application for digital factory technology in...Digital factory technology is an advanced manufacturing technology served as to establish a bridge between the process of product development and manufacturing.In terms of application for digital factory technology in machining,especially in machining of a complicated part such as a cylinder body part,a concept of digital process planning and its framework are proposed.Its components including machining domain knowledge model,machining knowledge base,machining resource base and process planning system are studied.A machining knowledge model in tree form and an object-driven knowledge reasoning mechanism are used for machining knowledge base.The process planning system is a user interface that leads a planner to finish the planning process.A case about a cylinder head part is given to demonstrate how the platform works.The framework of digital process planning is the foundation of some intelligent CAPP systems and helps to production line planning.展开更多
Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifi...Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifically, in the scenario where the access point （AP） is mobile, a UAV needs to find an efficient path to guarantee the connectivity of the relay link. Motivated by this fact, this paper proposes an optimal design for beamforming （BF） and UAV path planning. First of all, we study a dual-hop amplify-and-forward （AF） wireless relay network, in which a UAV is used as relay between a mobile AP and a fixed base station （BS）. In the network, both of the AP and the BS are equipped with multiple antennas, whereas the UAV has a single antenna. Then, we obtain the output signal^to-noise ratio （SNR） of the dual-hop relay network. Based on the criterion of maximizing the output SNR, we develop an optimal design to obtain the solution of the optimal BF weight vector and the UAV heading angle. Next, we derive the closed-form outage probability （OP） expression to investigate the performance of the dual-hop relay network conveniently. Finally, computer simulations show that the proposed approach can obtain nearly optimal flying path and OP performance, indicating the effectiveness of the proposed algorithm. Furthermore, we find that increasing the antenna number at the BS or the maximal heading angle can significantly improve the performance of the considered relay network.展开更多
巷道断面成形是煤矿掘进过程中的重要工序,但目前的巷道断面成形作业多为人工控制掘进机进行往复式截割,制约了煤矿掘进工作面的智能化发展。为此,针对断面成形轨迹规划未考虑煤岩特征、优化目标单一的问题,提出了一种基于改进灰狼优化(...巷道断面成形是煤矿掘进过程中的重要工序,但目前的巷道断面成形作业多为人工控制掘进机进行往复式截割,制约了煤矿掘进工作面的智能化发展。为此,针对断面成形轨迹规划未考虑煤岩特征、优化目标单一的问题,提出了一种基于改进灰狼优化(grey wolf optimizer, GWO)算法的掘进机断面成形轨迹规划方法。首先,根据夹矸位置将待截割断面环境分为4种情况,对相应断面进行栅格化处理并建立栅格地图,同时采用二值膨胀法对不规则夹矸进行膨胀化处理。然后,对GWO算法进行了改进,以提升其寻优性能和收敛速度。接着,开展了仿真实验,利用改进GWO算法实现了4种环境下掘进机断面成形轨迹的规划。最后,利用掘进机样机开展了断面截割实验。仿真结果表明:相较于传统的GWO算法,改进GWO算法的收敛速度更快且收敛精度更高;在4种断面环境下,基于改进GWO算法规划的断面成形轨迹长度最短,欠挖面积最小,转向次数最少,更容易实现高精度、高效率的轨迹跟踪控制,保证了巷道断面的成形质量。实验结果表明,基于改进GWO算法规划的断面成形轨迹既能提高掘进机的截割效率,又能满足巷道断面成形的质量要求。研究结果可为煤矿井下智能掘进技术的发展提供新的思路和方法。展开更多
The key issues such as vision sensor, sampling planning are studied for reverse engineering. For the developed sensor, the low sensitivity to the incident angle and the high linearity between the output and the input ...The key issues such as vision sensor, sampling planning are studied for reverse engineering. For the developed sensor, the low sensitivity to the incident angle and the high linearity between the output and the input are carried out. During digitizing, the adaptive sampling planning method based on the curvature of surface and the slope of tangent line of measured point is proposed. After integrating the vision sensor, CNC milling and relevant software, the reverse engineering system based on computer vision is developed. The experiment shows that this system is reliable and efficient.展开更多
文摘Digital factory technology is an advanced manufacturing technology served as to establish a bridge between the process of product development and manufacturing.In terms of application for digital factory technology in machining,especially in machining of a complicated part such as a cylinder body part,a concept of digital process planning and its framework are proposed.Its components including machining domain knowledge model,machining knowledge base,machining resource base and process planning system are studied.A machining knowledge model in tree form and an object-driven knowledge reasoning mechanism are used for machining knowledge base.The process planning system is a user interface that leads a planner to finish the planning process.A case about a cylinder head part is given to demonstrate how the platform works.The framework of digital process planning is the foundation of some intelligent CAPP systems and helps to production line planning.
基金supported by the National Natural Science Foundation of China (Nos. 61202351, 61271255)the Natural Science Foundation of Jiangsu Province (No. BK20131068)+2 种基金the Open Research Fund of National Mobile Communications Research Laboratory in Southeast University (No. 2012D15)the Funding of Jiangsu Innovation Program for Graduate Education (No. CXLX11_0202)the Fundamental Research Funds for the Central Universities
文摘Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifically, in the scenario where the access point （AP） is mobile, a UAV needs to find an efficient path to guarantee the connectivity of the relay link. Motivated by this fact, this paper proposes an optimal design for beamforming （BF） and UAV path planning. First of all, we study a dual-hop amplify-and-forward （AF） wireless relay network, in which a UAV is used as relay between a mobile AP and a fixed base station （BS）. In the network, both of the AP and the BS are equipped with multiple antennas, whereas the UAV has a single antenna. Then, we obtain the output signal^to-noise ratio （SNR） of the dual-hop relay network. Based on the criterion of maximizing the output SNR, we develop an optimal design to obtain the solution of the optimal BF weight vector and the UAV heading angle. Next, we derive the closed-form outage probability （OP） expression to investigate the performance of the dual-hop relay network conveniently. Finally, computer simulations show that the proposed approach can obtain nearly optimal flying path and OP performance, indicating the effectiveness of the proposed algorithm. Furthermore, we find that increasing the antenna number at the BS or the maximal heading angle can significantly improve the performance of the considered relay network.
文摘巷道断面成形是煤矿掘进过程中的重要工序,但目前的巷道断面成形作业多为人工控制掘进机进行往复式截割,制约了煤矿掘进工作面的智能化发展。为此,针对断面成形轨迹规划未考虑煤岩特征、优化目标单一的问题,提出了一种基于改进灰狼优化(grey wolf optimizer, GWO)算法的掘进机断面成形轨迹规划方法。首先,根据夹矸位置将待截割断面环境分为4种情况,对相应断面进行栅格化处理并建立栅格地图,同时采用二值膨胀法对不规则夹矸进行膨胀化处理。然后,对GWO算法进行了改进,以提升其寻优性能和收敛速度。接着,开展了仿真实验,利用改进GWO算法实现了4种环境下掘进机断面成形轨迹的规划。最后,利用掘进机样机开展了断面截割实验。仿真结果表明:相较于传统的GWO算法,改进GWO算法的收敛速度更快且收敛精度更高;在4种断面环境下,基于改进GWO算法规划的断面成形轨迹长度最短,欠挖面积最小,转向次数最少,更容易实现高精度、高效率的轨迹跟踪控制,保证了巷道断面的成形质量。实验结果表明,基于改进GWO算法规划的断面成形轨迹既能提高掘进机的截割效率,又能满足巷道断面成形的质量要求。研究结果可为煤矿井下智能掘进技术的发展提供新的思路和方法。
文摘The key issues such as vision sensor, sampling planning are studied for reverse engineering. For the developed sensor, the low sensitivity to the incident angle and the high linearity between the output and the input are carried out. During digitizing, the adaptive sampling planning method based on the curvature of surface and the slope of tangent line of measured point is proposed. After integrating the vision sensor, CNC milling and relevant software, the reverse engineering system based on computer vision is developed. The experiment shows that this system is reliable and efficient.
