Control System Development and Experimental Study on Ultrasonic Vibration Feeding

Ultrasonic vibration feeding（UVF） method which can quantitatively feed and precisely deposit fine powder is a potential technique for micro feeding.The excitation sources transmit vibration to capillary though the third medium for most UVF devices.The vibrator is directly touched with the capillary can transmit mechanical energy on the capillary as much as possible,and the powder feeding can be controlled more precise.However,there are few reports about it.A direct UVF system which integrates the function of micro feeding,process observing,and powder forming was developed in this work.In order to analyze the effect of the system factors on feeding,a group of L9（3^3） orthogonal experiments are selected to confirm the effect of level change of factors.The three factors are capillary nozzle diameter,amplitude and signal.The flow rate was stable for each combined factors,and the optimum combination for the minimum flow rate are choosing small capillary,small amplitude,and triangular wave orderly.The whole process of feeding includes start point,middle stage and stop stage.Starting of feeding was synchronized to vibration when the amplitude of capillary nozzle is larger than critical amplitude.Then,the feeding process enters the middle stage,the feeding state is observed by the CCD,and it is very stable in the middle stage.Overflow of feeding can＇t be eliminated during the stop stage.The features of the deposited powder lines are analyzed; the overflow can be diminished by choosing small capillary and appropriate ratio of the capillary nozzle diameter to the particle size.Chinese characters lattices were deposited to validate the ability of quantitatively feeding and fixed feeding of UVF.Diameters of all powder dots show normal distribution,and more than 60% dots are concentrated from 550 μm to 650 μm,and the average diameter for all the dots is 597 μm.Most dots positions are well approached to their scheduled positions,and the maximum deviation is 0.27 mm.The new direct UVF system is used to implement experiments,which confirms the precise controllable of feeding.According improve the feeding technique,it suits well for rapid prototyping,chemistry,pharmaceutics and many other fields,which require precise measurement and feed minim powder.

Modified coupled map car-following model and its delayed feedback control scheme

A modified coupled map car-following model is proposed, in which two successive vehicle headways in front of the considering vehicle is incorporated into the optimal velocity function. The steady state under certain conditions is obtained. An error system around the steady state is studied further. Moreover, the condition for the state having no traffic jam is derived. A new control scheme is presented to suppress the traffic jam in the modified coupled map car-following model under the open boundary. A control signal including the velocity differences between the following and the considering vehicles, and between the preceding and the considering vehicles is used. The condition under which the traffic jam can be well suppressed is analysed. The results are compared with that presented by t^onishi et al. （the KKH model）. The simulation results show that the temporal behaviour obtained in our model is better than that in the KKH model. The simulation results are in good agreement with the theoretical analysis.

Adaptive fuzzy integral sliding mode pressure control for cutter feeding system of trench cutter

A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition,the geological condition is time-varying.Due to the complex load characteristics of rock or soil,the feeding velocity of TC is related to geological conditions.What is worse,its dynamic model is subjected to uncertainties and its function is unknown.To deal with the particular characteristics of CFS,a novel adaptive fuzzy integral sliding mode control(AFISMC) was designed for feeding pressure control of CFS,which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller.The AFISMC feeding pressure controller is synthesized using the backstepping technique.The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system,integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory.Experiments are conducted on a TC test bench with the AFISMC under different operating conditions.The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ?0.3 MPa.

Load Shedding Strategy Based on Combined Feed-Forward Plus Feedback Control over Data Streams

In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.

China's Feed Companies Eye Safety Control

China’s feed companies in China are looking to strengthen safety control substantially according to the highest international standard. The first step will be improving the feed safety control in the pre-mixture and compound feed production. The next step will be extending

Automatic control strategy for step feed anoxic/aerobic biological nitrogen removal process

Control of sludge age and mixed liquid suspended solids concentration in the activated sludge process is critical for ensuring effective wastewater treatment. A nonlinear dynamic model for a step-feed activated sludge process was developed in this study. The system is based on the control of the sludge age and mixed liquor suspended solids in the aerator of last stage by adjusting the sludge recycle and wastage flow rates respectively. The simulation results showed that the sludge age remained nearly constant at a value of 16 d in the variation of the influent characteristics. The mixed liquor suspended solids in the aerator of last stage were also maintained to a desired value of 2500 g/m3 by adjusting wastage flow rates.

Real-time Feed-forward Force Compensation for Active Magnetic Bearings System Based on H∞ Controller

There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And the stability of the control system is finally improved.

Research on feed-pulse collaborative control method in micro-electrical discharge machining

Reducing the short-circuit rate and increasing the effective discharge rate are important targets for improving the servo control effect of micro-electrical discharge machining(micro-EDM),as these two indicators are closely related to the machining efficiency and quality.In this study,a feed-pulse collaborative control(FPCC)method is proposed for micro-EDM based on two dimensions(space and time).In the spatial dimension,a feed control strategy with a discharge holding process is adopted.Meanwhile,in the time dimension,a forward-looking pulse control strategy is adopted,in which the pulse interval is adjusted based on a sequence analysis of feed commands and discharge states.Process experiments are carried out to determine the key parameters used in this method,including the discharge holding threshold and pulse interval adjustment value(T_(off_(adj))).The feed smoothness and discharge sufficiency analyses of the experimental results show that compared to the traditional double threshold average voltage method,the FPCC method reduces the number of long-distance retreats by 64%and improves the effective discharge time by 40%.

精密伺服串级进给冲压控制系统的设计与实现

为了提高冲压送料精度,提升冲压件的产品质量,针对当前卷料送料工艺的不足,设计了一种新型线材送料储料架结构,利用两级伺服协调匹配上料,并提出一种卷料储料串级进给速度控制方法。基于三菱PLC和上位机软件设计了一套精密伺服送料控制系统装置,根据精密伺服送料长度和冲压节拍,夹棍伺服控制储料架线材在高限周围波动,实现线材缓冲储料,该方法有效避免了线材在冲压送料时被拉伤的情况出现。可扩展的上位机设计方法,可同时监控多台送料系统,并自动生成报表,实现送料储料及冲压生产的在线管控。改进后的精密伺服自动送料系统的可扩展性和多样化程度更高,该系统装置已经在冲压相关企业中得到应用。

无线电能传输系统最大效率追踪及恒压输出复合控制方法

针对无线电能传输(WPT)系统的传输效率受耦合线圈之间的互感以及负载影响的特点,该文提出一种基于阻抗匹配技术的最大效率追踪及基于前馈PI控制的恒压输出复合控制方法。首先,对双边LCC型WPT系统的参数和传输效率进行分析,通过调整系统参数优化系统的传输效率。其次,在二次侧使用DC-DC变换器采用阻抗匹配的方法实现最大效率追踪,同时在一次侧采用DC-DC变换器利用前馈PI控制器闭环控制负载端电压实现恒压输出。该方法中,效率追踪和电压控制之间相互独立,互不干扰。此外,该方法还通过系统工作时的电路参数来估算线圈间的互感值,并通过线性拟合的方法对该估算互感值进行修正,得到更精确的互感估算值。最后,通过搭建实验平台验证了该方法的可行性和有效性。与PI控制相比,前馈PI控制方法在快速性和抗扰动性上均具有明显优势。

基于PLC的蔬菜移栽机器人输送装置电气控制系统

以蔬菜移栽机器人为研究对象,以准确移栽蔬菜秧苗为目的,采用PLC控制技术设计了一套蔬菜移栽机器人喂苗装置电气控制系统。试验结果表明:蔬菜移栽机器人喂苗装置正确移栽率在96%以上,运行精度满足移栽机定位要求,能够实现蔬菜的无损移栽。

数控皮革裁剪机伺服进给三闭环控制系统PID控制研究

过窗裁剪是皮革机加工过程中的一大特点。本文针对皮革机加工过程中因存在大量过窗裁剪而带来的进给系统控制精度过高、外界工作环境干扰大等问题,构建了一种数控皮革裁剪机伺服进给三闭环控制方案,对该方案的永磁同步电机数学模型、PID控制模型、PID参数整定方案等进行分析,为皮革机加工工艺提升提供借鉴。

现代管理理论下饲料企业的风险成因及控制措施

在市场竞争加剧的背景下,饲料企业面临的风险因素增多,若不加以有效识别和控制,容易对饲料企业的正常运营和发展构成严重影响。可以说,分析饲料企业的风险成因已成为饲料企业的必然选择。对此,本文从现代管理视角出发,深入探讨饲料企业加强风险控制的意义,并提出具有针对性的风险控制措施,旨在为饲料企业的可持续发展提供有益参考。

Feed-Forward-Like Decoupling Control in Coagulation Bath of Carbon Fiber Precursor

The coagulation bath system of carbon fiber precursor is a complicated and multivariable coupling system. Based on the model of industrial production,the full dynamic decoupling control of the coagulation bath system of carbon fiber precursor is achieved in combination with multivariable feed-forward-like decoupling and proportional-integral-differential( PID) control. Compared with the conventional PID decoupling control,the experiment results show that the proposed method has a better control effect. The use of the controller can achieve complete decoupling of three parameters from coagulation bath system. The method should have great applications.

基于分布式协同控制技术的分散式无功补偿技术方案研究

结合实际工程的应用实例从分散式无功补偿方案的提出、分布式协同吸收方案的理论、具体工程方案的设计进行简单的论述。结合线路开通后的实际运行工况,利用设置于正线的能量回馈吸收装置实现了分散式无功补偿,该方案可减少或完全取消设置于主变电所侧的SVG容量,充分开发和利用了能馈吸收装置的能力,节约了工程投资,实现了既定设计目标。

配施硅肥对稻飞虱取食量、田间种群数量及水稻产量的影响

为探明增施硅肥在水稻田稻飞虱绿色防控中的作用,本文采用室内蜜露测定、田间盆拍调查等方法研究了在广西代表性土壤条件下增施硅肥对稻飞虱蜜露量、田间种群数量及水稻产量的影响。结果表明:褐飞虱Nilaparvata lugens St l和白背飞虱Sogatella furcifera Horváth在施硅量为15 kg/hm^(2)和45 kg/hm^(2)水稻上的平均蜜露量均显著低于不施硅对照。在水稻分蘖期,与不施硅对照相比,15 kg/hm^(2)施硅处理下两个试验点稻飞虱发生量均显著减少;45 kg/hm^(2)施硅处理下宾阳试验点的稻飞虱发生量显著减少,而合浦试验点在水稻分蘖盛期稻飞虱发生量虽未显著减少,但水稻分蘖后期稻飞虱发生量极显著低于不施硅对照,减少了51.03%。在水稻灌浆期,与不施硅对照相比,宾阳试验点15 kg/hm^(2)和45 kg/hm^(2)施硅处理稻飞虱的发生量均极显著减少,而合浦试验点稻飞虱发生量没有显著变化。15 kg/hm^(2)和45 kg/hm^(2)施硅处理的稻谷千粒重均显著高于不施硅对照,产量比不施硅对照提高1.88%~9.05%。增施硅肥可明显降低水稻田稻飞虱的取食量和田间种群发生量,同时在一定程度上提高了稻谷产量,因此,水稻增施硅肥有助于广西稻飞虱的绿色防控。

品管圈活动护理应用于预防ICU昏迷患者鼻饲误吸发生的效果

目的:探讨品管圈(QCC)活动护理在应用于预防ICU昏迷患者鼻饲误吸发生的效果.方法:选取2018年6月—2020年5月天津市天津医院ICU收治的301例ICU昏迷鼻饲患者为研究对象,将2019年5月作为我院ICU实施QCC活动护理的分界线,2018年6月—2019年5月收治的135例患者作为对照组,采用常规ICU护理;2019年6月—2020年5月收治的166例患者作为观察组,采用QCC活动护理.由11名ICU护士组成QCC活动组,比较2组的护理效果.结果:实施QCC活动后,ICU昏迷患者鼻饲误吸发生率由活动前的5.32%下降到0.54%,改善幅度为89.8%,目标达成率为184%.结论:品管圈活动能有效提高医院住院部护理质量,大幅降低ICU昏迷鼻饲患者的误吸风险.

可调倾角编程式多功能取苗试验台设计与试验

针对现有取苗试验台不能满足多种型号钵盘和取苗机构进行取苗试验的需求,设计了一种由多个步进电机驱动、可调取苗机构倾角、可编程控制系统的多功能取苗试验台。该试验台通过调节取苗机构安装支架的位姿、改变钵盘驱动鼠笼钢丝间距以及所在圆周直径,可以适应不同型号钵盘和满足多种取苗机构的试验要求;通过编写控制器程序可控制3个步进电机联动并实现送苗装置的横、纵向送苗与取苗机构取苗进程相匹配。在三维软件中对试验台进行了建模、装配和虚拟仿真,在加工制造的物理样机上进行了2种型号钵盘和3种取苗机构的取苗试验。3次试验结果表明:在此试验台上能够顺利完成取苗试验,证明该试验台满足多种型号钵盘和多种类型取苗机构的试验需求。

双闭环控制的三相电压型PWM整流器的研究

针对传统的不控整流电路中网侧电流谐波很大、晶闸管相控整流电路中深控时网侧功率因数低和闭环控制时动态响应慢等问题,设计出一种引入脉冲宽度调制技术的三相电压型整流器。在完成三相电压型整流器的电压外环电流内环的双闭环控制系统设计的基础上,对其进行了仿真实验。仿真结果表明,与不控或相控整流电路相比,该三相电压型PWM整流电路中,不仅输入电流的谐波大大减小,电能可双向流动,能够实现整流和逆变状态下的单位功率因数运行,还可较好地抑制负载突变时直流侧电压的波动,从而显著提高系统的抗扰能力,真正实现绿色环保和高效节能的高度结合。

基于OBE理念的林业“自动控制原理”实践教学改革探索

基于OBE理念,从林业领域对新工科工程技术人员的具体特色需求出发,遵从“电类”专业实践教学培养方案及毕业要求,以“自动控制原理”实验课程为例,以问题为抓手,以成果为导向,探索基于OBE理念的“自动控制原理”实践教学目标,改革实践教学内容及教学方法,建立合理的考核评价体系,通过科研反哺教学,建立基于林业科研项目的案例库,并应用于“自动控制原理”实践教学,促使专业承担起人才培养的任务和基础,为林业生态发展提供高素质的“电类”工程技术人员。