Design of speed controller for electronic fuel injection gasoline generator based on feed-forward PID control

As for the application of electronic fuel injection （EFI） system to small gasoline generator set, mechanical speed controller cannot be coupled with EFI system and has the shortcomings of lagged regulation and poor accuracy, a feed-forward control strategy based on load combined with proportional-integral-differential （PID） control strategy was proposed, and a digital speed controller applied to the electrical control system was designed. The detailed control strategy of the controller was intro- duced. The hardware design for the controller and the key circuits of motor driving, current sampling and angular signal captu- ring were given, and software architecture was discussed. Combined with a gasoline generator set mounted with EFI system, the controller parameters were tuned and optimized empirically by hardware in loop and bench test methods. Test results show that the speed deviation of generator set is low and the control system is stable in steady state; In transient state the control system responses quickly, has high stability under mutation loads especially when suddenly apply and remove 100% load, the speed deviation is within 8% of reference speed and the transient time is less than 5 s, satisfying the ISO standard.

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.

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.

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.

Behavioral modeling of RF power amplifiers with time-delay feed-forward neural networks

A novel behavioral model using three-layer time-delay feed-forward neural networks （TDFFNN）is adopted to model radio frequency （RF）power amplifiers exhibiting memory nonlinearities. In order to extract the parameters, the back- propagation algorithm is applied to train the proposed neural networks. The proposed model is verified by the typical odd- order-only memory polynomial model in simulation, and the performance is compared with different numbers of taped delay lines（TDLs） and perceptrons of the hidden layer. For validating the TDFFNN model by experiments, a digital test bench is set up to collect input and output data of power amplifiers at a 60 × 10^6 sample/s sampling rate. The 3.75 MHz 16-QAM signal generated in the vector signal generator（VSG） is chosen as the input signal, when measuring the dynamic AM/AM and AM/PM characteristics of power amplifiers. By comparisons and analyses, the presented model provides a good performance in convergence, accuracy and efficiency, which is approved by simulation results and experimental results in the time domain and frequency domain.

Stabilization control of a bumblebee in hovering and forward flight

Our previous study shows that the hovering and forward flight of a bumblebee do not have inherent stability （passive stability）. But the bumblebees are observed to fly stably. Stabilization control must have been applied. In this study, we investigate the longitudinal stabilization control of the bumblebee. The method of computational fluid dynamics is used to compute the control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of motion. Controllability analysis shows that at all flight speeds considered, although inherently unstable, the flight is controllable. By feedbacking the state variables, i.e. vertical and horizontal velocities, pitching rate and pitch angle （which can be measured by the sensory system of the insect）, to produce changes in stroke angle and angle of attack of the wings, the flight can be stabilized, explaining why the bumblebees can fly stably even if they are passively unstable.

The Maximum Principle for Fully Coupled Forward-backward Stochastic Control System

The maximum principle for fully coupled forward-backward stochastic control system in the global form is proved, under the assumption that the forward diffusion coefficient does not contain the control variable, but the control domain is not necessarily convex.

Improved forwarding control design method and its application

Integrator forwarding is a recursive nonlinear design technique for the stabilization of feed-forward systems. However, this method still has some limitation. An improved design method is proposed to extend the field of application of this technique. This method is used to design a stabilizer for the inertia wheel pendulum system. Moreover, it is shown that the control Lyapunov function which is obtained from this method can also be used to design a globally asymptotically stabilizing controller with optimality.

FORWARD LINK PARTIAL-BALANCE POWER CONTROL ALGORITHM FOR W-CDMA COMMUNICATION

Balance power control is based on the idea of balancing Carrier to Interference Ratio (CIR) of all wireless links. Unbalance power control means that different traffics can achieve different CIR at receivers. This paper proposes a forward link partial-balance power control algorithm, which can provide necessary Quality of Service (QoS) for multimedia traffics in Wideband CDMA(W-CDMA) systems. The proposed algorithm is the integration of grading traffics priority and allocating and adjusting forward link power levels. For higher priority traffics, the unbalance power control is used. Whereas for lower priority traffics, balance power control is adopted. Computer simulation results show that the proposed algorithm can guarantee the special QoS requirements of the traffics with higher priority orders and maximize the CIR of the traffics with lower priority orders.

Laser-induced forward transferred silver nanomembrane with controllable light absorption

Laser processing provides highly-controlled modification and on-demand fabrication of plasmon metal nanostructures for light absorption and photothermal convention.We present the laser-induced forward tansfer(LIFT)fabrication of silver nanomembranes in control of light absorption.By varying the hatch distance,different morphologies of randomly distributed plasmon silver nanostructures were produced,leading to well-controlled light absorption levels from 11%to 81%over broadband.The anti-reflection features were maintained below 17%.Equilibrated and plain absorptions were obtained throughout all absorption levels with a maximum intensity fluctuation of±8.5%for the 225μJ cases.The 45μJ pulse energy can offer a highly equilibrated absorption at a 60%absorption level with an intensity fluctuation of±1%.Pattern transfer was also achieved on a thin tape surface.The laser-transferred characters and patterns demonstrate a localized temperature rise.A rapid temperature rising of roughly 15℃can be achieved within 1 s.The LIFT process is highly efficiently fabricated with a typical speed value of 10^(3)to 10^(5)cm^(2)/h.The results indicated that LIFT is a well-controlled and efficient method for the production of optical films with specific absorption levels.

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。

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。

基于变前视距离的四轮同步转向农机改进纯跟踪控制

路径跟踪控制是提高自主导航系统控制精度的关键。针对在复杂农田作业环境下转弯时纯跟踪算法跟踪精度不高的问题,本文提出了一种基于改进纯追踪模型的四轮同步转向农机路径跟踪控制算法。建立了基于四轮同步转向农机的运动学模型和纯跟踪模型,在此基础上考虑航向误差得到改进纯跟踪模型,进行RTK定位坐标修正,根据量化误差的评价函数搜索前视区域最优目标点,得到最优前视距离。本文算法能实时确定四轮同步转向农机改进纯跟踪模型中的前视距离,使航向误差和横向误差最小化,实现目标点的自适应优化。仿真结果表明,本文方法转弯时平均绝对横向误差减至0.035 m,平均绝对航向误差减至0.212°;水田实验结果表明,当四轮同步转向农机作业速度为3.6 km/h时,四轮转向农机轨迹跟踪平均绝对横向误差减至0.109 m,平均绝对航向误差减至2.799°,转弯跟踪精度显著提高。

基于DTN路由的多通路精准灌溉系统布局设计

为进一步提升我国智能灌溉装备的综合作业效率,从多通路实施与精准化控制角度展开布局设计。以灌溉系统的作业原理及田间信息获取特征为出发点,建立灌溉网络的DTN路由算法模型,实施网络节点的规划分配与通道布置,形成精准性的逻辑控制流程及节点网络相互执行关系。进行系统性的灌溉试验,结果表明:基于DTN路由算法的多通路精准灌溉系统布局正确可行,信息投递成功率可达94.13%,节点转发率可达96.07%,各信息传递的实时准确,各阀门组件的动作协调,综合灌溉效率实现了高于90%的优化目标,是DTN路由控制理念在灌溉装备领域的应用创新思路之一,具有较好的推广意义。

单相级联H桥整流器平方电压反馈控制算法

以单相级联H桥整流器为研究对象,对其控制策略进行了研究。首先在采用双闭环控制策略的基础上,构建了dq前馈解耦模型,并通过二阶广义积分算法改善了虚拟交流分量对系统的影响,实现了网侧电流对电压相位、频率的快速精确追踪。其次,对传统电压平衡控制算法进行了改进,通过对功率平衡关系的定义,将输出电压平方作为控制信号,增强了系统自适应能力,提高了系统在投切载时的动态性能。最后,基于MATLAB/Simulink软件进行仿真,验证了所提策略的正确性和有效性。

一种新型3-RRPU并联机构的运动学及鲁棒控制研究

针对现有的三平移并联机构大多正解不唯一、较难实现精确稳定运动控制的问题,提出了一种新的3-RRPU型三平移并联机构,同时研究了机构的运动学、动力学及轨迹跟踪控制方法。首先,运用螺旋理论分析了该机构三平移的原理,进行了驱动输入的选取与论证,对机构平台奇异性、驱动奇异性和支链奇异性进行了分析;其次,运用运动学理论建立了运动学模型,推导了位置正、逆解析解;再次,运用拉格朗日动力学理论建立了机构操作空间的刚体动力学模型;最后,提出了一种基于非线性反馈解耦的自适应滑模轨迹跟踪控制方法,以证明其控制稳定性,并基于动力学模型对空间轨迹跟踪精度和控制力矩进行了仿真分析。研究结果表明:3-RRPU并联机构的位置正解在一般位形下具有唯一性,机构的平台奇异位形和驱动奇异位形少且无支链奇异。该轨迹控制方法可使机构在载荷20 kg、速度0.18 m/s、加速度0.12 m/s 2下,实现0.002 m以内的高精度复杂轨迹跟踪;基于Sigmoid函数的轨迹控制方法还能有效削弱控制力矩的抖振,为实现工业领域高速、高精度、高性能的三平移运动提供了新方法。

滑移转向无人车轨迹跟踪控制策略研究

针对滑移转向车辆构型的无人车,通过建立车辆动力学和运动学模型,对LQR(linear quadratic regulator)最优控制算法进行改进,在速度环采用一种自抗滑移的前馈控制,设计了一种轨迹跟踪控制策略。前馈控制有效提高了横摆角速度响应速度,可进一步优化LQR估计器的参数矩阵,保证车辆在提高轨迹跟踪控制精度的同时不影响跟随稳定性。采用Trucksim与Simulink联合仿真进行验证,结果表明:在双移线测试工况下,使用该控制策略的无人车最大横向误差比在双PID控制下小0.086 m,误差收敛速度2.1 s,稳态误差振荡幅值比滑模控制小约0.05 m;不同车速和不同附着系数路面下,无人车最大横向误差浮动小于0.02 m,误差收敛速度不变,设计算法控制效果稳定,验证了其鲁棒性。

南水北调中线渠首前馈控制方案快速计算分析

明渠调水工程中为适时适量的满足下游用水需求,需要提前制定控制方案。前馈控制方案的设计往往较为复杂,且影响因素众多,调度人员难以快速做出决策。基于蓄量补偿法对南水北调中线工程刁河节制闸至十二里河节制闸段作前馈控制,基于蓄量补偿计算结果,分析了初始流量、分水流量与前馈控制时间的关系,构建了单、双变量的前馈控制时间快速计算公式。探究了不同因素对蓄量补偿控制下游水位偏差的影响,得到初始流量、分水流量与下游水位最大偏差之间的函数关系式。针对工程运行中的极端工况,原蓄量补偿控制的下游水位偏差过大的问题,采用二次蓄量补偿规则对渠池进行前馈控制,有效减小了下游水位偏差。

基于双估计强化学习结合前向预测控制的自动驾驶运动控制研究

运动控制研究是实现自动驾驶目标的重要组成部分,针对传统强化学习算法在求解中因单步决策局限而导致控制序列次优的问题,提出了一种基于双估计强化学习算法及前向预测控制方法结合的运动控制框架(DEQL-FPC)。在该框架中引入双估计器以解决传统强化学习方法动作值过估计问题并提高训练优化的速度,设计前向预测多步决策方法替代传统强化学习的单步决策,以有效提高全局控制策略的性能。通过虚拟驾驶环境仿真,证明了该控制框架应用在自动驾驶汽车的路径跟踪以及安全避障的优越性,保证了运动控制中的精确性、安全性、快速性以及舒适性。

基于前馈非线性模型预测控制的类车机器人路径跟踪

类车机器人由于零件标准化程度低,侧偏刚度等轮胎力学参数难以准确获得,存在动力学建模十分困难的问题,因此现有研究工作通常以运动学模型作为类车机器人的控制模型,但由于其运动学模型存在模型失配,导致类车机器人与参考路径之间的误差、类车机器人的前轮转角和前轮转角速度出现剧烈振荡现象.针对前述问题,本文基于非线性模型预测控制(Nonlinear model predictive control,NMPC)的滚动优化原理,引入基于逆运动学模型的前馈转角信息,将前轮转向角作为预测模型的第四维,提出了一种基于前馈非线性模型预测控制(Feedforward NMPC,FNMPC)的类车机器人路径跟踪控制算法.并通过Simulink和CarSim进行了联合仿真,结果表明FNMPC有效减小了模型失配导致的振荡现象,同时具有较高的跟踪精度.其中前馈非线性模型预测控制器的位移误差幅值不超过0.1106 m,航向误差幅值不超过0.1253 rad.在相同工况下,线性模型预测控制、前馈线性模型预测控制、纯跟踪控制和Stanley控制误差发散,而本文提出的FNMPC相比已有NMPC跟踪精度更高,且控制增量绝对累计值相比NMPC控制器减小67.53%.通过线控类车机器人底盘作为实验平台完成的测试结果表明,NMPC系统在进入弯道时出现控制失控现象,在相同工况下,FNMPC系统能够有效完成对参考路径的跟踪,同时将位移误差幅值控制在0.1624 m以内,航向误差幅值控制在0.1138 rad以内.