The Design and Its Application of Cross-Coupled Controller in X-Y Table

In conventional cross-coupled controller design,the method usually ignored the inherent characteristic of time-vary- ing parameters and model uncertainties in system.In this paper,a cross-coupled controller(CCC)using an H~∞control scheme has been proposed to reduce the contouring error for an X-Y table.Furthermore,the proposed CCC design,which is a typical Multi- Input Multi-Output(MIMO)system with linear time varying(LTV)characteristics,has been verified as being internally stable. The simulations are carried on Matlab simulink to verify the proposed method,and the results showed that the proposed method can reduce the contouring error significantly compared with the conventional one.     

Combined Control Allocation and Sliding Mode Control in the Dynamic Control of a Vehicle with Eight In-Wheel Motors

An eight wheel independently driving steering (8WIDBS) electric vehicle is studied in this paper. The vehicle is equipped with eight in-wheel motors and a steer-by-wire system. A hierarchically coordinated vehicle dynamic control (HCVDC) system, including a high-level vehicle motion controller, a control allocation, an inverse tire model and a lower-level slip/slip angle controller, is proposed for the over-actuated vehicle system. The high-level sliding mode vehicle motion controller is designed to produce desired total forces and yaw moment, distributed to longitudinal and lateral forces of each tire by an advanced control allocation method. And the slip controller is designed to use a sliding mode control method to follow the desired slip ratios by manipulating the corresponding in-wheel motor torques. Evaluation of the overall system is accomplished by sine maneuver simulation. Simulation results confirm that the proposed control system can coordinate among the redundant and constrained actuators to achieve the vehicle dynamic control task and improve the vehicle stability.     

STATE SPACE METHODS FOR DECENTRALIZED H_∞ CONTROL

ＳＴＡＴＥＳＰＡＣＥＭＥＴＨＯＤＳＦＯＲＤＥＣＥＮＴＲＡＬＩＺＥＤＨ＿∞ＣＯＮＴＲＯＬＳＴＡＴＥＳＰＡＣＥＭＥＴＨＯＤＳＦＯＲＤＥＣＥＮＴＲＡＬＩＺＥＤＨ＿∞ＣＯＮＴＲＯＬ￥ＷｕＭｉｎ；ＧｕｔＷｅｉｈｕａ；ＣｈｅｎＮｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡ...     

基于零和竞争理论的雷达网干扰功率分配方法

在海水泵的线谱振动自适应控制中,由于环境等条件因素的影响,获取的参考信号频与线谱振源信号频率往往存在着偏差。该频率偏差的存在往往造成自适应主动控制算法性能下降。针对这个问题,通过结合一种自适应更新参考信号的方法,提出了基于FXLMS的反馈式线谱振动自适应主动控制算法。在参考信号生成中,通过一种几何关系来进行参考信号的相位更新,并基于最小均方误差方法,来实现参考信号频率对应的相关系数的更新;为验证该方法的有效性,进行了仿真和试验。仿真结果表明,该方法能够在参考信号频率与振源信号频率存在偏差的情况下,通过自适应调节参考信号频率,取得良好的线谱振动自适应控制效果。进行了基于水泵试验台架的主动控制试验研究,检验该自适应算法控制性能。试验结果表明,该方法能够在参考信号频率与线谱振动频率存在偏差的情况下,进行有效的线谱振动自适应控制。     

New model reference adaptive control with input constraints

A new scheme of adaptive control is proposed for a class of linear time-invariant( LTI) dynamical systems,especially in aerospace,with matched parametric uncertainties and input constraints. Based on a typical and conventional direct model reference adaptive control scheme,various modifications have been employed to achieve the goal. "C omposite model reference adaptive control"of higher performance is seam-lessly combined with "positive μ-mod",which consequently results in a smooth tracking trajectory despite of the input constraints. In addition,bounded-gain forgetting is utilized to facilitate faster convergence of parameter estimates. The stability of the closed-loop systemcan be guaranteed by using Lyapunov theory.The merits and effectiveness of the proposed method are illustrated by a numerical example of the longitudinal dynamical systems of a fixed-wing airplane.     

Energy-Based Current Control for Stabilizing a Flexible Electrodynamic Tether System

An energy-based controller of electric current is synthesized for the libration stabilization of an electrodynamic tether system, which consists of a relatively large main-satellite and a sub-satellite of much smaller size. Two dynamic models with different levels of accuracy are considered in this work. First, a dumbbell model of the system is used for the controller design, which aims at damping injection on the libration motions via the real-time regulation of the electric current. Furthermore, the efficacy and performance of the proposed scheme are numerically verified by using a more complex multi-body model which accounts for not only the tether flexibility but also the attitude of the main-satellite.     

Longitudinal speed control algorithm to improve the vehicle stability and mobility on a sharp curve

A new longitudinal speed control strategy is proposed. It used the lateral jerk information as the feedback to predict the longitudinal acceleration and deceleration, which is especially beneficial to a sharp curve turning at a high driving speed. The performance of the controller is validated with Matlab/Simulink. The simulation results indicate that compared with the traditional vehicle, the G-vector controller can reduce the turning radius and improve the vehicle stability and agility obviously. And the proposed longitudinal speed control strategy could trade-off the longitudinal and lateral acceleration by using the tire force during the turning.     

Robust H~∞ controller design for a class of uncertain systems

Ｈ∞ｃｏｎｔｒｏｌｔｈｅｏｒｙｈａｓｍａｄｅｓｉｇｎｉｆｉｃａｎｔａｄｖａｎｃｅｍｅｎｔｆｏｒｂｏｔｈｌｉｎｅａｒａｎｄｎｏｎｌｉｎｅａｒｓｙｓｔｅｍｓ.ＴｈｅｓｏｌｖａｂｉｌｉｔｙｃｏｎｄｉｔｉｏｎｓｆｏｒｎｏｎｌｉｎｅａｒｓｙｓｔｅｍｓｗｅｒｅｐｒｅｓｅｎｔｅｄｉｎｔｅｒｍｓｏｆＨａｍｉｌｔｏｎＪａｃｃｏｂｉｅｑｕａｔｉｏｎｓ(ＨＪＥ)ｏｒｉｎｅｑｕａｌｉｔｉｅｓ(ＨＪＩ)[1,2].Ｈｏｗｅｖｅｒ,ｔｈｅｓｅＨＪＥｓｏｒＨＪＩｓａｒｅｄｉｆｆｉｃｕｌｔｔｏｓｏｌｖｅｇｅｎｅｒａｌｌｙ.Ｔｈｕｓ,ａｇｒｅ…     

H∞ Theory and its Application to the Position of Rolling Mill Control System

The controller designed according to classical or modern control theory will not satisfy the performance requirements when the controlled object in industrial field can not be described by exact mathematical model or the disturbance of the controlled system. In order to make the controlled system stable and having good performance, H∞ control theory was put forward to solve this practical problem. Taking the position of a rolling mill as the controlled object, it was rectified by optimal engineering way. Then, three different plans were put forward according to Bang-Bang control, LQ control and H∞ control, respectively. The result of the simulation shows that the controller designed according to H∞ method whose robust performance and ability to restrain colors disturbance is satisfactory.     

The Design and Its Application of Cross-Coupled Controller in X-Y Table

In conventional cross-coupled controller design,the method usually ignored the inherent characteristic of time-varying parameters and model uncertainties in system.In this paper,a cross-coupled controller (CCC) using an H∞ control scheme has been proposed to reduce the contouring error for an X-Y table. Furthermore, the proposed CCC design, which is a typical Multi-Input Multi-Output (MIMO) system with linear time varying (LTV) characteristics, has been verified as being internally stable.The simulations are carried on Matlab simulink to verify the proposed method, and the results showed that the proposed method can reduce the contouring error significantly compared with the conventional one.     

Stability analysis of tactical missile autopilots based on vector margin

A novel stability computation approach for tactical missile autopilots is detailed. The limi- tations of traditional stability margins are exhibited. Then the vector margin is introduced and com- pared with sensitivity function to show their essential relationship. The longitudinal three-loop auto- pilot for tactical missiles is presented and used as the baseline for all the available linear autopilots. Ten linear autopilot topologies using all the measurable feedback components are given with the iden- tical closed-loop characteristic equation and time-domain step response. However, the stability of the ten autopilots differs when considering the actuator dynamics, which limits their application. Then vector margin method is adopted to compute and evaluate the stability of all available autopi- lots. The analysis and computation results show that the vector margin method could better evaluate autopilot stability.     

Investigation on full vehicle height control algorithm using feedback linearization method

Aiming to improve the control accuracy of the vehicle height for the air suspension system, deeply analyzing the processes of variable mass gas thermodynamics and vehicle dynamics, a nonlinear height control model of the air suspension vehicle was built. To deal with the nonlinear characteristic existing in the lifting and lowering processes, the nonlinear model of vehicle height control was linearized by using a feedback linearization method. Then, based on the linear full vehicle model, the sliding model controller was designed to achieve the control variables. Finally, the nonlinear control algorithm in the original coordinates can be achieved by the inverse transformation of coordinates. To validate the accuracy and effectiveness of the sliding mode controller, the height control processes were simulated in Matlab, i.e., the lifting and lowering processes of the air suspension vehicle were taken when vehicle was in stationary and driving at a constant speed. The simulation results show that, compared to other controllers, the designed sliding model controller based on the feedback linearization can effectively solve the "overshoot" problem, existing in the height control process, and force the vehicle height to reach the desired value, so as to greatly improve the speed and accuracy of the height control process. Besides, the sliding mode controller can well regulate the roll and pitch motions of the vehicle body, thereby improving the vehicle''s ride comfort.     

A novel current vector decomposition controller design for six-phase permanent magnet synchronous motor

The vector control algorithm based on vector space decomposition(VSD) transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor(PMSM) is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current(DC) component, only using the traditional proportional integral(PI) controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing internal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.     

Research on nonlinear attitude control algorithm for upper stage during multi-satellite disposing

For the issues of attitude strong coupling and the increments of attitude errors of upper stage during multi-satellite disposing,a three-axis stability nonlinear attitude control algorithm via feedback linearization is presented.By the definitions of coordinates and the attitude angle during multi-satellite disposing,the attitude dynamics and kinematics equations with Euler angles described are built.And the equations are equivalently linearized based on feedback linearization theory.A three-axis nonlinear predictive control algorithm is designed and the system robustness is analyzed.An example of mathematical simulation is completed using the Matlab/Simulink environment.Simulation results showed that the control algorithm has good disturbance rejection,rapidity,stability and robustness.     

Dynamic Characteristics of Single-frequency Signal after Modulated by Feedback Control System

In order to study the dynamic characteristics of the single-frequency signal through the nonlinear control system, the system control mode, the outer excitation patterns of the model and the amplitude are investigated by using the methods of the nonlinear dynamical analysis. The time-domain diagram, power spectrum, phase diagram and the largest Lyapunov exponent obtained from the process of the signal propagate through different control module are given. The researches on different control systems demonstrate that： after single-frequency signal goes through the nonlinear controller, it is still non-chaotic although the output contains more frequency components; but with the feedback and the external perturbation, the output is a continuous broadband spectrum and the result shows that there is chaos. The energy of the input signal reduces with some appropriate parameters. Therefore, the control system of the nonlinear feedback is a good way to broaden the spectrum of output with inputting a single-frequency signal.     

Bifurcation analysis for Hindmarsh-Rose neuronal model with time-delayed feedback control and application to chaos control

This paper is concerned with bifurcations and chaos control of the Hindmarsh-Rose(HR)neuronal model with the time-delayed feedback control.By stability and bifurcation analysis,we find that the excitable neuron can emit spikes via the subcritical Hopf bifurcation,and exhibits periodic or chaotic spiking/bursting behaviors with the increase of external current.For the purpose of control of chaos,we adopt the time-delayed feedback control,and convert chaos control to the Hopf bifurcation of the delayed feedback system.Then the analytical conditions under which the Hopf bifurcation occurs are given with an explicit formula.Based on this,we show the Hopf bifurcation curves in the two-parameter plane.Finally,some numerical simulations are carried out to support the theoretical results.It is shown that by appropriate choice of feedback gain and time delay,the chaotic orbit can be controlled to be stable.The adopted method in this paper is general and can be applied to other neuronal models.It may help us better understand the bifurcation mechanisms of neural behaviors.     

Research on Directly Adaptive Fuzzy Algorithm Based ACC Controller

A directly adaptive fuzzy algorithm is applied in vehicle adaptive cruise control system. The basic principle of the adaptive fuzzy algorithm is analyzed. The initial value of the fuzzy based vector is given by the traditional fuzzy membership. Adaptive law of the adjustable parameters θ is also determined. The directly adaptive fuzzy ACC controller is designed based on Matlab fuzzy toolbox. Matlab-Simulink is adopted to test the function of the adaptive fuzzy ACC controller. The control system is established using a 7 DOF vehicle dynamics model. Simulation results indicate that the principle of the method is correct and it performs well both in cruise and distance keeping.     

Nonlinear hierarchy-structured predictive control design for a generic hypersonic vehicle

A hierarchy-structured predictive controller is designed and analyzed for rotation motion dynamics of a generic hypersonic vehicle(GHV).This vehicle model has fast variability,is highly nonlinear,and includes uncertain parameters.The controller contains two subsystems,the inner-fast-loop nonlinear generable predictive controller(NGPC)and the outer-slow-loop NGPC,both of which are designed by the closed-form optimal generable predictive control method.Thus,the heavy on-line computational burden in the classical predictive control method is avoided.The hierarchy structure of the control system decreases the relative degree of each subsystem and helps increase the dynamic response speed of the attitude controller.In order to improve the robustness of the control system,a feedback correction algorithm is proposed that corrects the calculation error between the predictive model and the real dynamic model.Simulation studies are conducted for the trimmed cruise conditions of an altitude of 33.5 km and Mach 15 to investigate the responses of the vehicle to the step commands of angle of attack,sideslip angle,and bank angle.The simulation studies demonstrate that the proposed controller is robust with respect to the parametric uncertainties and atmospheric disturbance,and meets the performance requirements of GHV with acceptable control inputs.     

Neigborhood state dynamic update algorithm for MANET

The effect of too much overhead caused by fixed neighborhood state update cycle on the whole network performance has been greatly alleviated by a neighborhood state dynamic update ( NSDU ) algorithm pr...     

Delay-independent decentralized H∞ control for multi-channel discrete-time systems with uncertainties

A robust decentralized H∞ control problem was considered for uncertain multi-channel discrete-time systems with time-delay. The uncertainties were assumed to be time-invariant, norm-bounded, and exist in the system, the time-delay and the output matrices. Dynamic output feedback was focused on. A sufficient condition for the multi-channel uncertain discrete time-delay system to be robustly stabilizable with a specified disturbance attenuation level was derived based on the theorem of Lyapunov stability theory. By setting the Lyapunov matrix as block diagonal appropriately according to the desired order of the controller, the problem was reduced to a linear matrix inequality (LMI) which is sufficient to existence condition but much more tractable. An example was given to show the efficiency of this method.