基于PD-滑模耦合算法的压电智能薄板颤振抑制

针对工件柔性主导的薄壁件铣削颤振问题,提出了一种基于PD–滑模耦合算法的压电智能薄板颤振抑制方法。首先设计了只需位移测量的主动控制算法,基于滑模控制理论处理系统参数不确定性和外部扰动,通过动态补偿器对未知切削状态进行在线近似和补偿;为解决传感误差和系统时滞问题,在滑模控制器中进一步耦合了时空依变PD控制模型,借助ABAQUS仿真拟合控制参数时变函数;最后设计了一套薄壁件主动控制装置,试验结果显示采用主动控制可有效抑制薄壁件铣削颤振,验证了控制方法的可行性。

Controllable growth of wafer-scale PdS and PdS_(2) nanofilms via chemical vapor deposition combined with an electron beam evaporation technique

Palladium(Pd)-based sulfides have triggered extensive interest due to their unique properties and potential applications in the fields of electronics and optoelectronics.However,the synthesis of large-scale uniform PdS and PdS_(2)nanofilms(NFs)remains an enormous challenge.In this work,2-inch wafer-scale PdS and PdS_(2) NFs with excellent stability can be controllably prepared via chemical vapor deposition combined with electron beam evaporation technique.The thickness of the pre-deposited Pd film and the sulfurization temperature are critical for the precise synthesis of PdS and PdS_(2) NFs.A corresponding growth mechanism has been proposed based on our experimental results and Gibbs free energy calculations.The electrical transport properties of PdS and PdS_(2) NFs were explored by conductive atomic force microscopy.Our findings have achieved the controllable growth of PdS and PdS_(2) NFs,which may provide a pathway to facilitate PdS and PdS_(2) based applications for next-generation high performance optoelectronic devices.

Fast Ferry Smoothing Motion via Intelligent PD Controller

A novel type of control law was adopted to reduce the vertical acceleration of a fast ferry as well as the motion sickness incidence suffered by the passengers onboard by means of a submerged T-foil.Considering the system changing characteristics under high disturbances,a model-free approach was adopted.In addition,an upgraded proportional-derivative(PD)controller with correction terms resulting from a fast-online estimation of the system dynamics was designed.The overall controller,known as intelligent PD(i-PD)controller,was tested,and the obtained results were compared with those of a classic PD controller.The controllers were also tested in a changing environment and at different operating velocities.The results confirmed the effectiveness of the i-PD controller to smooth the motions with low computational cost control schemes.Furthermore,thanks to ability of the i-PD controller to continually update the estimated dynamics of the system,it showed a better reduction in both vertical motions and the seasickness level of the passengers with the needed robustness under external disturbances and system changing parameters.

欠驱动飞行器横侧向通道的自耦PD控制方法

针对欠驱动高超声速飞行器横侧向通道的姿态控制问题,提出一种基于自耦PD(proportional-differential)控制理论的控制方法.该方法将欠驱动飞行器横侧向姿态模型转换为由速度倾斜角与侧滑角两个通道组成的二阶动态模型,并在速度倾斜角通道中引入一个侧滑角虚拟指令,再对速度倾斜角与侧滑角两个通道的内部动态与外部扰动分别定义两个总扰动,从而将非线性欠驱动扰动系统等价映射为虚拟全驱动线性扰动系统.使用最小速度因子及其自适应速度因子来设计外环速度倾斜角的自耦PD控制器,以便获得侧滑角虚拟指令,并根据该虚拟指令来设计内环侧滑角的自耦PD控制器,从而获得副翼偏角的控制力.分析了自耦PD控制系统的鲁棒稳定性和抗扰动鲁棒性.仿真结果表明,本文设计的自耦PD控制器不仅具有良好的抗扰动鲁棒性,而且具有良好的动态品质和稳态性能.

基于自耦PD的四旋翼无人机轨迹跟踪控制

针对输入受限的四旋翼无人机,为了使其能够快速稳定地跟踪期望轨迹,使用了一种基于自耦PD(SCPD)的轨迹跟踪控制方法。该方法将四旋翼无人机系统不确定性和内外扰动等复杂因素定义为总和扰动,进而将非线性不确定系统映射为未知线性系统。根据自耦PID控制理论,为四旋翼无人机位置环和姿态环各控制通道设计了独立的SCPD控制器,并设计了一种基于误差的速度因子模型。以定点悬停、轨迹跟踪等方式,与基于传统PID和滑模控制的飞行控制系统进行了动态响应性能测试和抗干扰性能对比。仿真结果表明:基于SCPD控制的四旋翼飞行控制系统具有较优的动态响应性能和较强的抗干扰能力,验证了SCPD控制旋翼无人机轨迹跟踪的有效性。

Optimal PD/PID control of smart base isolated buildings equipped with piezoelectric friction dampers

Long-period pulses in near-field earthquakes lead to large displacements in the base of isolated structures.To dissipate energy in isolated structures using semi-active control,piezoelectric friction dampers（PFD） can be employed.The performance of a PFD is highly dependent on the strategy applied to adjust its contact force.In this paper,the seismic control of a benchmark isolated building equipped with PFD using PD/PID controllers is developed.Using genetic algorithms,these controllers are optimized to create a balance between the performance and robustness of the closed-loop structural system.One advantage of this technique is that the controller forces can easily be estimated.In addition,the structure is equipped with only a single sensor at the base floor to measure the base displacement.Considering seven pairs of earthquakes and nine performance indices,the performance of the closed-loop system is evaluated.Then,the results are compared with those given by two well-known methods：the maximum possive operation of piezoelectric friction dampers and LQG controllers.The simulation results show that the proposed controllers perform better than the others in terms of simultaneous reduction of floor acceleration and maximum displacement of the isolator.Moreover,they are able to reduce the displacement of the isolator systems for different earthquakes without losing the advantages of isolation.

Repetitive PD control strategy with inverse transfer function compensation for CVCF inverter

A novel repetitive control strategy for the output waveform of single-phase CVCF inverters is presented. In this scheme, the inverse transfer function of inverter is used as a compensator to obtain stable and satisfy harmonic rejection. Besides, PD controller is adopted to improve transient performance. Simulation and experimental results, which are gotten from a DSP-based 400Hz, 5.5KW inverter, indicate that the proposed control scheme can achieve not only low THD during steady-state operation but also fast transient response during load step change.

Nonlinear observer-controller design for dynamic positioning of ships

The main focus is nonlinear model-based dynamic positioning (DP) control system design. A nonlinear uniform global exponential stability (UGES) observer produces noise-free estimates of the position, the slowly varying environmental disturbances and the velocity, which are used in a proportional-derivative (PD) + feedforward control law. The stability of this observer-controller system is proved by introducing a specific nonlinear cascaded system. The simulation results have successfully demonstrated the performance of designed DP control system.

Decentralized PD Control for Non-uniform Motion of a Hamiltonian Hybrid System

In this paper, a decentralized proportional-derivative （PD） controller design for non-uniform motion of a Hamiltonian hybrid system is considered. A Hamiltonian hybrid system with the capability of producing a non-uniform motion is developed. The structural properties of the system are investigated by means of the theory of Hamiltonian systems. A relationship between the parameters of the system and the parameters of the proposed decentralized PD controller is shown to ensure local stability and tracking performance. Simulation results are included to show the obtained non-uniform motion.

基于改进模糊自适应补偿的柔性关节机器人PD控制

针对柔性关节机器人具有不确定性、轨迹跟踪精度低和抖动的问题,提出一种改进模糊自适应补偿的PD控制方法。该方法在原有模糊自适应控制和PD控制的基础上进行改进,采用改进模糊自适应控制对PD控制进行补偿,以提高存在不确定性条件下的关节轨迹跟踪精度并抑制抖动。通过Lyapunov理论证明了系统的稳定性。仿真结果表明:新型控制器具有良好的自适应能力,与传统PD控制和模糊自适应控制相比,新型控制策略显著提高了关节的轨迹跟踪精度并在一定程度上抑制了关节抖动。

Proportional integral derivative controller design using Legendre orthogonal functions

The Legendre orthogonal functions are employed to design the family of PID controllers for a variety of plants. In the proposed method, the PID controller and the plant model are represented with their corresponding Legendre series. Matching the first three terms of the Legendre series of the loop gain with the desired one gives the PID controller parameters. The closed loop system stability conditions in terms of the Legendre basis function pole(λ) for a wide range of systems including the first order, second order, double integrator, first order plus dead time, and first order unstable plants are obtained. For first order and double integrator plants, the closed loop system stability is preserved for all values of λ and for the other plants, an appropriate range in terms of λ is obtained. The optimum value of λ to attain a minimum integral square error performance index in the presence of the control signal constraints is achieved. The numerical simulations demonstrate the benefits of the Legendre based PID controller.

Analytical Analysis on the Structure of a Typical Fuzzy On - Off Controller

The analytical structure of a typical fuzzy on - off controller that employs three or more triangular Input fuzzy sets, Zadeh fuzzy logic AND operator, fuzzy rules with singleton output fuzzy sets, and the centriod defuzzifier is Investigated in this paper. The analytical expressions of the variable gains of the fuzzy controller are derived. The resulting explicit structure shows that the fuzzy controller is accurately a nonlinear PD - like controller with gains continuously changing with system output in different regions of input space.

Intelligent Dynamic Inversion Controller Design for Ball and Beam System

The Ball and beam system(BBS)is an attractive laboratory experimental tool because of its inherent nonlinear and open-loop unstable properties.Designing an effective ball and beam system controller is a real challenge for researchers and engineers.In this paper,the control design technique is investigated by using Intelligent Dynamic Inversion(IDI)method for this nonlinear and unstable system.The proposed control law is an enhanced version of conventional Dynamic Inversion control incorporating an intelligent control element in it.The Moore-PenroseGeneralized Inverse(MPGI)is used to invert the prescribed constraint dynamics to realize the baseline control law.A sliding mode-based intelligent control element is further augmented with the baseline control to enhance the robustness against uncertainties,nonlinearities,and external disturbances.The semi-global asymptotic stability of IDI control is guaranteed in the sense of Lyapunov.Numerical simulations and laboratory experiments are carried out on this ball and beam physical system to analyze the effectiveness of the controller.In addition to that,comparative analysis of RGDI control with classical Linear Quadratic Regulator and Fractional Order Controller are also presented on the experimental test bench.

全向移动机器人的神经滑模自适应PD跟踪控制

针对四轮全向机器人数学模型中未知因数的干扰,提出了一种基于神经滑模的比例微分(Proportional plus Derivative,PD)自适应跟踪控制策略。首先,对机器人的动力学模型进行分析;其次,利用反步轨迹跟踪控制器得到虚拟速度,基于虚拟输入与实际输入的误差设计PD控制器;接着,采用神经网络来逼近动力学模型中的不确定性,并利用Lyapunov定理证明了系统的稳定性。仿真和实验结果表明,该控制策略具有有效性。

A Parameter Varying PD Control for Fuzzy Servo Mechanism

This paper presents the formulation of novel implementation method based on parameter varying PD controller for fuzzy servo controllers. This formulation uses the approximation of fuzzy nonlinear function including error and error derivation in operation point. Obtained fuzzy control law has been employed to control angular position of servo using digital control technique applied to a typical microcontroller like AVR. The performance and robustness of modified fuzzy controller in comparison with PID controller evaluated in no load, applied external disturbance with different magnitude conditions has been studied. The simulation results showed that the proposed fuzzy controller has a considerable advantage in rise time, settling time and overshoot respect to PID controller when the servo system encounters with nonlinear features like saturation and friction.

On the Comparisons of PID and GI-PD Control

In conjunction with a second order uncertain nonlinear system, this paper makes some comparisons between PID control and general-integral-proportional-derivative (GI-PD) control;that is, by Routh’s stability criterion, we demonstrate that the system matrix under GI-PD control can be stabilized more easily;by linear system theory and Lyapunov method, we demonstrate that GI-PD control can deal with the uncertain nonlinearity more effectively;by analyzing and comparing the integral control action, we demonstrate that GI-PD control has the better control performance. Design example and simulation results verify the justification of our conclusions again. All these mean that GI-PD control has the stronger robustness and higher control performance than PID control. Consequently, GI-PD control has broader application prospects than PID control.

基于双环设计的PD垂直起降飞行器轨迹跟踪控制

论文针对垂直起降飞行器在轨迹跟踪控制过程中存在不确定性和外部扰动的问题,提出了一种基于双环设计的PD轨迹跟踪控制方法。首先,基于前馈补偿对垂直起降飞行器控制器进行PD控制方法设计,其次,将轨迹跟踪系统分为内外两个控制环路,最后进行Matlab/Simulink的仿真实验验证。研究结果表明,基于双环设计的PD控制方法使得垂直起降飞行器性能指标较好,能补偿控制系统所受到的内外干扰,提高控制系统的稳定性。

^(103)Pd核素分离纯化方法研究及质量控制

^(103)Pd通常用于放射性近距离照射治疗,特别在前列腺癌治疗和脉络膜黑色素瘤治疗方面应用较为普遍。目前,^(103)Pd主要的制备方式为加速器辐照铑靶材,经萃取或离子交换树脂分离纯化得到。本研究以非放射性模拟样品对比研究AG 1-X 8和AG MP-1两种阴离子树脂在不同的样品盐酸浓度、淋洗程序、解吸液等条件下对Pd元素的分离纯化效果。经过条件优化,以AG 1-X 8为纯化树脂,通过使用6 mol/L HCl和0.03 mol/L HCl交替淋洗树脂的方式除去Rh基体及其他杂质元素。以1 mol/L氨水与1 mol/L氯化铵1∶1混合溶液解吸Pd时,Pd的回收率约100%,解吸液中Pd/Rh达到最大值,分离效果最佳。以此方法完成3批次加速器辐照铑靶材的分离纯化,^(103)Pd样品的放射性浓度>6 GBq/mL、比活度>800 GBq/mg(分离结束时,EOS)、放射性核纯度>99.9%。依据《中国药典》2020版对检测方法的要求,对放射性核纯度、Pd元素含量分析方法的专属性、检测限和定量限、线性范围、精密度、准确度进行了方法学验证,保证检测结果的准确性及可靠性。