Research on key control technologies of all-position automatic welding machine

The pipeline all-position automatic welding machine system is a special welding system for automatically welding circumferential joint of pipeline on site, which has been widely used to the long-distance pipeline construction projects due to the advantages of automatic control for welding parameters at all-position, moving speed of bugs and operating. In this paper, the key control technologies of PAWM all-position automatic welding machine （ developed by Pipeline Research Institute of CNPC） such us the automatic control system, control software, personal digital assistant （PDA） software and complex programmable logic device （ CPLD ） program as well us the control method of welding parameter have been described detailedly. With the higher welding quality, higher welding effwiency and lower labor intensity, PA WM all-position automatic welding machine has been successfully applied in many famous pipeline construction projects.

Fuzzy control on automatic frequency tracking of ultrasonic vibration system with high power and high quality factor Q

In order to realize automatic tracking drift of resonance frequency of ultrasonic vibration system with high power and high quality factor Q, adaptive fuzzy control was studied with a self-fabricated ultrasonic plastic welding machine. At first, relations between amplitude of vibration and frequency as well as main loop current and amplitude of vibration were analyzed. From this analysis, we deduced that frequency tracking process of the vibration system can be concluded as an optimizing problem of one dimensional fluctuant extremum of main loop current in vibration system. Then a method of self-optimizing fuzzy control, used for the realization of automatic frequency tracking in vibration system, is presented on the basis of serf-optimizing adaptive control approach and fuzzy control approach. The result of experiments shows that the fuzzy self-optimizing method can solve the problem of tracking frequency drift very well. Response time of tracking in the system is less than 50 ms, which basically meets the requirements of frequency tracking in ultrasonic plastic welding machine.

A computer control system for automatic TIG welding of aluminium alloy sheets

Aimed at the welding ttechnological requirements of foe missile shell,a computer control system for automatic TIG welding of aluminium alloy sheets has been developed in this paper.The hardware of the system is composed of the four sub-systems,i.e.weldingpower source,arc length controller,welding wire feeder and welding head traveller.The software of the system comprises the on-line executing program and the off-line serving program.The operating principle,specifications and control of the system are introduced.The experiments indicate that the system possesses rational hardware structure and practical software function,and has solved the problem of high frequency interference to the computer control system. Therefore,the control system can satisfy the requirements of automatic TIG welding of the missile shell.

Design and test of flexible chassis automatic tracking steering system

In order to develop an innovative omnidirectional non-homonymic flexible chassis(FC),the four-wheel steering control method of FC was designed by a new concept called off-centered steering(OCS)and the automatic tracking steering system was analyzed.Novelty of this wheel concept lies in the non-conventional positioning of the steering axis and wheel axis.Additionally,the steering axis of steerable wheel was motorized with an on/off electrometrical brake to overcome a hyper-motorization issue inherent to the wheel’s geometrical properties and hold the steering position.Based on the off-centered steering characteristics of FC,the Wheatstone bridge was applied in the steering control system.The bridge resistances are used to track target steering angles and the actual steering angle,respectively.The output voltage of the bridge is exploited to adjust the wheel’s speed so that steering and automatic tracking could be achieved.Experiments at different speeds,loadings,and target steering angles were conducted.Results showed that the chassis can indeed be controlled independently and its steering range is from-90°to 90°,which indicated the automatic tracking steering system was effective.The electromagnetic lock(EL)can significantly improve the stability of the chassis and reduce the vibration.Loading has no significant effect on the accuracy of the steering angle and the time it takes to complete steering tasks.The time taken to complete a forward steering task showed a linear relationship with the required angles,but was independent of rotation speed;for backward steering,time was related to both target angles and rotation speed.The results presented in this research may provide a reference for the steering control strategies of the four-wheel individual drive and four-wheel(4WID/4WIS)vehicle in the future.

Optimal tracking control for automatic transmission shift process

In order to improve the shift quality, a linear quadratic optimal tracking control algorithm for automatic transmission shift process is proposed. The dynamic equations of the shift process are derived using a Lagrange method. And a powertrain model is built in the Matlab/Simulink and veri- fied by the measurements. Considering the shift jerk and friction loss during the shift process, the tracking trajectories of the turbine speed and output shaft speed are defined. Furthermore, the linear quadratic optimal tracking control performance index is proposed. Based on the Pontryagin＇ s mini- mum principle, the optimal control law of the shift process is presented. Finally, the simulation study of the 1 - 2 upshift process under different load conditions is carried out with the powertrain model. The simulation results demonstrate that the shift jerk and friction loss can be significantly re- duced by applying the proposed optimal tracking control method.

An Automatic Synchronization Method for Distributed Power Electronics System

Currently, the high-speed serial fiber-optic ring net communication is a main method for performing the distributed control network topology and control mode. Because of a network transmission delay inherent in the topology, synchronization between nodes has become a critical issue which needs to be studied. The existing synchronization methods largely depend on the complex communication protocol. Therefore, this paper has proposed a method of automatic measurement and compensation of synchronization delay, and analyzed its operating principle and implementation procedure in detail. The results obtained from the experiments prove the proposed method to be correct, effective and practicable.

Research on Fuzzy Control for Automatic Transmission of Tracked Vehicles

A principle of fuzzy control for tracked vehicles is proposed to make its automatic transmission system be able to adapt complex running conditions, and a model of its power train is established to be used in simulation. Based on the fuzzy control method, a fuzzy shift control system composed of a basic shift strategy and a fuzzy modification module is developed to improve the dynamic characteristics and cross-country maneuverability. Simulation results show that the fuzzy shift strategy can improve the shift quality under manifold driving conditions and avoid cycled shift effectively.Therefore, the proposed fuzzy shift strategies are proved to be feasible and practicable.

Robotic Knee Tracking Control to Mimic the Intact Human Knee Profile Based on Actor-Critic Reinforcement Learning

We address a state-of-the-art reinforcement learning(RL)control approach to automatically configure robotic pros-thesis impedance parameters to enable end-to-end,continuous locomotion intended for transfemoral amputee subjects.Specifically,our actor-critic based RL provides tracking control of a robotic knee prosthesis to mimic the intact knee profile.This is a significant advance from our previous RL based automatic tuning of prosthesis control parameters which have centered on regulation control with a designer prescribed robotic knee profile as the target.In addition to presenting the tracking control algorithm based on direct heuristic dynamic programming(dHDP),we provide a control performance guarantee including the case of constrained inputs.We show that our proposed tracking control possesses several important properties,such as weight convergence of the learning networks,Bellman(sub)optimality of the cost-to-go value function and control input,and practical stability of the human-robot system.We further provide a systematic simulation of the proposed tracking control using a realistic human-robot system simulator,the OpenSim,to emulate how the dHDP enables level ground walking,walking on different terrains and at different paces.These results show that our proposed dHDP based tracking control is not only theoretically suitable,but also practically useful.

Research and engineering application of the arc welding pulsed controller technology

The tenacity of heat-affected zone （HAZ） will decline and the size of grains will increase, because of the overheating on HAZ when submerged are welding （SAW） is ased to thick plate with high heat input. The shaping will worsen when SAW is used to thin plate with high current at high speed. A new SAW technology, the pulsed direct current （DC） automatic SAW, will be put forward in this paper in order to overcome the above shortcomings. And a pulsed controller with micro-controller unit （MCU） as the core, nixie tube （NT） and keyboard as the man-machine conversation interface is developed. The main functions of the pulsed controller include the output of pulsed welding current and the working with twinwire. The research has widely prospects in application with significant meanings in theory and practical engineering.

Research and Development of Engine-Generator Set Control System for Tracked Vehicle Electric Transmission System

As an energy generating equipment, the engine-generator set supplies power to the electric transmission. Therefore, its control is one of the key technologies of electric vehicles. Based on the discussion about the demands to the engine-generator set in tracked vehicles, the detailed function of engine-generator and the control strategy are determined. The hardware and software of the control system are also developed and tested in a prototype vehicle. The experiment results show that the control system has good reliability and can satisfy the power requirements of vehicles under all operating conditions.

Automatic Generation Control in a Distributed Power Grid Based on Multi-step Reinforcement Learning

The increasing use of renewable energy in the power system results in strong stochastic disturbances and degrades the control performance of the distributed power grids.In this paper,a novel multi-agent collaborative reinforcement learning algorithm is proposed with automatic optimization,namely,Dyna-DQL,to quickly achieve an optimal coordination solution for the multi-area distributed power grids.The proposed Dyna framework is combined with double Q-learning to collect and store the environmental samples.This can iteratively update the agents through buffer replay and real-time data.Thus the environmental data can be fully used to enhance the learning speed of the agents.This mitigates the negative impact of heavy stochastic disturbances caused by the integration of renewable energy on the control performance.Simulations are conducted on two different models to validate the effectiveness of the proposed algorithm.The results demonstrate that the proposed Dyna-DQL algorithm exhibits superior stability and robustness compared to other reinforcement learning algorithms.

BASIC THEORY AND APPLICATIONS OF WELDING ARC SPECTRAL INFORMATION

Welding arc spectral information is a rising welding information source. In some occasion, it can reflect many physical phenomena of welding process and solve many problems that cannot be done with arc electric information, acoustic information and other arc information. It is of important significance in developing automatic control technique of welding process and other similar process. Many years study work on welding arc spectral information of the anthor are discussed from three aspects of theory, method and application. Basic theory, view and testing methods of welding arc spectral information has been put forward. In application aspects, many applied examples, for example, monitoring of harmful gases in arc （such as hydrogen and nitrogen） with the method of welding arc spectral information; welding arc spectral imaging of the welding pool which is used in automatic seam tracking; controlling of welding droplet transfer with welding arc spectral information and so on, are introduced. Especially, the successful application in real time controlling of welding droplet transfer in pulsed GMAW is introduced too. These application examples show that the welding arc spectral information has great applied significance and development potentialities. These .content will play an important role in applying and spreading welding arc spectral informarion technology.

Automatic Generation Control of Multi-area Power System with Network Constraints and Communication Delays

Newly proposed power system control methodologies combine economic dispatch(ED) and automatic generation control(AGC) to achieve the steady-state cost-optimal solution under stochastic operation conditions. However, a real power system is subjected to continuous demand disturbance and system constraints due to the input saturation, communication delays and unmeasurable feed-forward load disturbances. Therefore, optimizing the dynamic response under practical conditions is equally important. This paper proposes a state constrained distributed model predictive control(SCDMPC)scheme for the optimal frequency regulation of an interconnected power system under actual operation conditions, which exist due to the governor saturation, generation rate constraints(GRCs), communication delays, and unmeasured feed-forward load disturbances. In addition, it proposes an algorithm to handle the solution infeasibility within the SCDMPC scheme, when the input and state constraints are conflicting. The proposed SCDMPC scheme is then tested with numerical studies on a three-area interconnected network. The results show that the proposed scheme gives better control and cost performance for both steady state and dynamic state in comparison to the traditional distributed model predictive control(MPC) schemes.

Study on Modeling and Control Strategy for Electric Drive Motor of Tracked Vehicles

Aimed at the requirements for electric transmission system of a military tracked vehicle, the motor's design indexes were analysed and calculated. A model based on saturate inductance parameter of interior permanent magnet (IPM) synchronous motor was brought forward by using finite element analysis. And its control strategy based on the largest running capability was studied also. The experiment results for a scale model show that the modelling method improves the model's accuracy, and the motor's control strategy is effective.

BASIC THEORY AND METHOD OF WELDING ARC SPECTRAL INFORMATION

Arc spectral information is a rising information source which can solve manyproblems that can not be done with arc electric information and other arc information. It is ofimportant significance to develop automatic control technique of welding process. The basic theoryand methods on it play an important role in expounding and applying arc spectral information. Usingconcerned equation in plasma physics and spectrum theory, a system of equations including 12equations which serve as basic theory of arc spectral information is set up. Through analyzing ofthe 12 equations, a basic view that arc spectral information is the reflection of arc state andstate variation, and is the most abundant information resource reflecting welding arc process isdrawn. Furthermore, based on the basic theory, the basic methods of test and control of arc spectralinformation and points out some applications of it are discussesed.

Impact of Islanding on Governor Signal of Distributed Resources

Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develop these units is islanding situation. Expert diagnosis system is needed to distinguish network cut off from normal occurrences. It should detect islanding in time to disconnect the unit and prevent any additional failures in equipment. An important part of synchronous generator is automatic load-frequency controller (ALFC). This controller is designed properly to respond to load variations and to fix frequency at constant value when working alone as an islanding system and to control output power when operating in parallel with the main. In this paper, a new approach based on monitoring ALFC re-sponse with regard to input signal to governor is introduced. Numbers of initial crossing value are introduced as an index for islanding detection. Simulation results show that input signal to governor has different characteristics in common disturbances.

Research and Implementation of Multi-Point Automatic Synchronization Based on Active Frequency Tracking Control

Reliable connection of turbine generators in complex main wiring structures to the power grid through a plurality of switches is a new key problem,referred to as multipoint automatic synchronization(MPAS),in automatic control systems(ACS).In this paper,different methods of voltage-frequency and phase-difference control are analyzed,and a control methodology based on active frequency tracking(AFT)is presented.Through the establishment of the multi-point automatic synchronization model and the analysis of the governor transfer function with this control method,the important control parameters and automatic process control sequence are summarized.The correctness and effectiveness of the designed methodology are inspected through on-site testing,and the importance of the function and selection of parameters are also explored.

自动泊车前轮转角闭环的分层控制方案

为提高自动泊车系统中控制器的抗扰动能力,优化控制律执行效果,提出了前轮转角闭环的分层控制方案.设计了以行驶距离为非时间参考量的fal函数非光滑控制律,输出前轮转角控制量.以阿克曼转向模型为基础,建立了前轮转角观测器,并使用模糊滑模控制器实现前轮转角闭环的横向控制.搭建Carsim/Simulink联合仿真系统,在典型泊车场景下验证所设计控制器的有效性、跟踪效果及鲁棒性.使用实车测试平台开展了试验.结果表明:所设计的前轮转角闭环分层控制方案能够快速准确地跟踪目标路径,提高了泊车系统的横向控制精度,并在未知转向非线性扰动下也具有良好的跟踪控制效果.

烧碱浓度在线检测与自动配碱控制系统的研究

为了解决印染丝光加工过程中,烧碱浓度不稳定对织物染色加工质量的影响,开发一种浓碱浓度在线检测与自动配碱控制系统,解决了传统印染丝光人工配碱、浓度滴定控制方式存在的弊端。

基于视觉传感的焊接电流及电压检测控制方法

焊接电流及电压是影响焊接质量的重要参数,为了提高焊接质量,研究了一种基于视觉传感技术的焊接电流及电压在线检测及精确控制方法.首先,分析焊接电流及电压图像的预处理,分割出了焊接电流及电压对应的字符图像;然后,使用了一种基于投影特征的焊接电流及电压对应字符的识别方法,并进一步实现了焊接电流及电压的识别;最后,研究了基于专家控制的焊接电流及电压自动控制方法,可提高焊接电流及电压自动调节的稳定性、准确性和快速性.结果表明,利用文中的方法,在线识别焊接电流及电压的准确度高于99.75%,可实现焊接前及焊接过程中焊接电流及电压的自动检测控制,而且焊道尺寸根据需要在线调整,有助于提高焊接的自动化程度及焊接质量.创新点:(1)研究了焊接电流电压在线检测方法,可实现电流电压的监测及识别.(2)实现了焊接前及焊接过程中电流电压的控制,可在线调整焊道尺寸.