OSEK/VDX嵌入式实时操作系统在汽车稳定性控制器中的应用

根据OSEK/VDX标准设计嵌入式实时操作系统,侧重于任务管理,资源管理部分的实现。并在自主开发的汽车稳定性控制器硬件在环仿真平台上进行验证。实验结果表明,在该操作系统上开发系统可以有效地提高实时性和稳定性,能够满足汽车稳定性控制器的要求。

基于非线性MPC方法的车辆稳定性控制

针对非线性模型预测控制(NMPC)在车辆操纵控制过程中的实时性问题,提出了显式NMPC的解决方法,然后在显式NMPC中将优化问题进行离线求解,并通过在线评估得到满足要求的次优解。最后基于显式NMPC方法设计了一种车辆横摆和侧向稳定控制器,该控制器通过车辆的制动系统发挥作用。为验证控制器的有效性,进行了相关的仿真试验,分析了代价函数公式中权值的影响,并对最优控制问题的不同设置方案进行了比较分析。

高速铁道车辆的主动稳定性系统

介绍了高速铁道车辆的主动稳定性控制系统。利用整车滚动试验台对稳定性控制器的性能进行了试验。

单相高频隔离双向DC/AC变换器谐振控制

对带阻性负载的双功率方向单相高频链(HFL)DC/AC变换器的谐振控制方法进行了探讨。谐振控制器与结合钳位电路的调制方法相配合,消除了内部的电压过冲现象,实现了对输出电压的快速、精确控制。对该高频链变换器在连续时间域进行了建模,并根据该模型设计实现了该变换器的谐振控制方法,分析了该控制器的稳定范围,与该变换器的调制方法相配合,实现了在负载变化、输入电压变化等干扰下对输出电压的零误差控制。实验验证了所设计谐振控制方法的有效性。

基于恒定开关频率的内置式永磁同步电机直接转矩控制方法

针对常规直接转矩控制方法存在开关频率不恒定和转矩脉动较大的问题,采用了一种基于恒定开关频率的内置式永磁同步电机直接转矩控制方法,该方法由一个PI调节器和一个三角波载波器组成,通过比较PI转矩调节器的输出与固定频率载波信号,实现了逆变器开关频率恒定,从而使电机的转矩脉动明显降低并改善了电流波形畸变;并对所提出的转矩调节器提供了详细的数学建模过程和小信号稳定性分析。仿真结果表明该算法在保持快速动态响应的前提下,可有效改善内置式永磁同步电机直接转矩控制系统的稳定运行特性,同时开关频率几乎处于恒定状态。

新型光伏并网逆变器的建模与控制方法

将由对称Z源逆变器和三相对称LCL滤波器组成的光伏并网逆变器作为研究对象,对Z源网络和一相LCL滤波器建立数学模型。将模型参数看作系统参数,模型输入信号的变化看作扰动,根据模型的固有缺陷,结合前期成果,重点研究两种情况的系统改进策略:(1)系统参数未变化且扰动可测;(2)系统参数变化或扰动不可测。针对第1种情况,改进时主要采取加入"模拟模块"和"开关切换"的策略;针对第2种情况,改进策略是对系统加入稳定性鲁棒控制器。通过仿真实验验证,结果表明Z源网络和一相LCL滤波器的数学模型正确,在此基础上针对第1种情况采取的改进策略比改进前暂态性能得到提高,稳态性能与原系统一致;针对第2种情况采取的改进策略比改进前稳定性得到提高。

一类磁性刚体航天器的混沌控制研究

采用基于误差线性系统稳定性准则的混沌控制方法,控制具有结构内阻尼的磁性刚体航天器在重力场与磁场共同作用下在圆形轨道的混沌姿态运动.讨论了航天器姿态运动方程中部分参数的取值对于运动姿态的影响,给出了这些参数通过倍周期分岔或逆倍周期分岔通往混沌的途径.当参数使系统做混沌姿态运动时,采用上述方法将混沌运动控制至周期-4轨道,并实现周期-1、2、4轨道之间转换的灵活控制.此外,分析了控制参数的变化对于控制效果的影响,并分别给出了控制至不同轨道时的输入扰动范围及控制参数范围.仿真结果表明,该方法能够实现混沌姿态运动在预定周期轨道间的灵活控制,且输入扰动量小、控制速度快、具有高精度,从而验证了该方法在航天器混沌姿态运动控制方面的有效性.

Active Vibration Control and Stability Analysis of Cantilever Plate

Active vibration control and stability analysis of cantilever plate are discussed. Based on the analysis of characteristic equation of the closed loop control system, it is shown that such an active control may increase damping properties of the system, meanwhile it may result in instability of the system. It is stable when the feedback only occurs between the collocated sensors and actuators, but it may be unstable when there exists the feedback between sensors and actuators, which mainly depends on the property of the gain matrix of feedback. If the gain matrix is symmetric and definitely positive, the system is stable.

Disturbance Observer Based Control for Four Wheel Steering Vehicles With Model Reference

This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front and rear wheel steering angles are controlled simultaneously to follow both the desired sideslip angle and the yaw rate of the reference vehicle model.A nonlinear three degree-of-freedom four wheel steering vehicle model containing lateral, yaw and roll motions is built up, which also takes the dynamic effects of crosswind into consideration.The disturbance observer based control method is provided to cope with ignored nonlinear dynamics and to handle exogenous disturbances. Finally, a simulation experiment is carried out,which shows that the proposed four wheel steering vehicle can guarantee handling stability and present strong robustness against external disturbances.

Design of an optimal active stabilizer mechanism for enhancing vehicle rolling resistance

Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes.The main objective of this work is to develop active control mechanism based on fuzzy logic controller(FLC) and linear quadratic regulator(LQR) for improving vehicle path following,roll and handling performances simultaneously.3-DOF vehicle model including yaw rate,lateral velocity(lateral dynamic) and roll angle(roll dynamic) were developed.The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal.The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers.Simulation results demonstrate that in both cases(FLC and LQR controllers) by reducing roll angle,lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver,which ensures vehicle stability and handling properties.Finally,the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.

Development of Linearizing Feedback Control with a Variable Structure Observer for Continuous Stirred Tank Reactors

This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors(CSTR).A variable structure observer is constructed to estimate the whole process state variables.This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors.The observer is coupled with a nonlinear controller,designed based on input-output linearization for controlling the reactor temperature.The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem.Finally,computer simulations are developed for showing the performance of the proposed approach.

Design of novel sliding-mode controller for high-velocity AUV with consideration of residual dead load

This work focuses on motion control of high-velocity autonomous underwater vehicle(AUV).Conventional methods are effective solutions to motion control of low-and-medium-velocity AUV.Usually not taken into consideration in the control model,the residual dead load and damping force which vary with the AUV’s velocity tend to result in difficulties in motion control or even failure in convergence in the case of high-velocity movement.With full consideration given to the influence of residual dead load and changing damping force upon AUV motion control,a novel sliding-mode controller(SMC)is proposed in this work.The stability analysis of the proposed controller is carried out on the basis of Lyapunov function.The sea trials results proved the superiority of the sliding-mode controller over sigmoid-function-based controller(SFC).The novel controller demonstrated its effectiveness by achieving admirable control results in the case of high-velocity movement.

A multi-objective gravitational search algorithm based approach of power system stability enhancement with UPFC

On the basis of the theoretical analysis of a single-machine infinite-bus （SMIB）, using the modified linearized Phil- lips-Heffron model installed with unified power flow controller （UPFC）, the potential of the UPFC supplementary controller to enhance the dynamic stability of a power system is evaluated by measuring the electromechanical controllability through singular value decomposition （SVD） analysis. This controller is tuned to simultaneously shift the undamped electromeehanical modes to a prescribed zone in the s-plane. The problem of robust UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multi-objective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using gravitational search algorithm （GSA） that has a strong ability to find the most optimistic results. The different loading conditions are simulated on a SMIB system and the rotor speed deviation, internal voltage deviation, DC voltage deviation and electrical power deviation responses are studied with the effect of this flexible AC transmission systems （FACTS） controller. The results reveal that the tuned GSA based UPFC controller using the proposed multi-objective function has an excellent capability in damping power system with low frequency oscillations and greatly enhances the dynamic stability of the power systems.

State feedback control for Lurie networked control systems

The problem of the stability analysis and controller design which the network-induced delays and data dropout problems network-induced delays are assumed to be time-varying and bounded, for Lurie networked control systems （NCSs） is investigated, in are simultaneously considered. By considering that the and analyzing the relationship between the delay and its upper bound, employing a Lyapunov-Krasovskii function and an integral inequality approach, an improved stability criterion for NCSs is proposed. Furthermore, the resulting condition is extended to design a less conservative state feedback controller by employing an improved cone complementary linearization （ICCL） algorithm. Numerical examples are provided to show the effectiveness of the method.

Chatter free sliding mode control of a chaotic coal mine power grid with small energy inputs

An augmented proportional-integral sliding surface was designed for a sliding mode controller. A chatter free sliding mode control strategy for a chaotic coal mine power grid was developed. The stability of the control strategy was proven by Lyapunov stability theorem. The proposed sliding mode control strategy eliminated the chattering phenomenon by replacing the sign function with a saturation function, and by replacing the constant coefficients in the reaching law with adaptive ones. An immune genetic algorithm was used to optimize the parameters in the improved reaching law. The cut-in time of the controllers was optimized to reduce the peak energy of their output. Simulations showed that the proposed sliding mode controller has good, chatter flee performance.

Stability Analysis and Design of Impulsive Control Lorenz Systems Family

Lorenz systems family unifying Lorenz system, Chen system and Lü system is a typical chaotic family. In this paper, we consider impulsive control Lorenz chaotic systems family with time-varying impulse intervals. By establishing an effective tool of a set of inequalities, we analyze the asymptotic stability of impulsive control Lorenz systems family and obtain some new less conservative conditions. Based on the stability analysis, we design a novel impulsive controller with time-varying impulse intervals. Illustrative examples are provided to show the feasibility and effectiveness of our method. The obtained results not only can be used to design impulsive control for Lorenz systems family, but also can be extended to other chaotic systems.

TSM control of the delayed input system

The paper proposed a terminal sliding mode control method for the delayed input system with uncertainties. Firstly, through the state transformation, the original system was transformed into the non-delayed controllabte canonical form system. Then the paper designed a terminal sliding mode and terminal sliding control law with Lyapunov method for the transformed system. Through the method, the reaching time of the any initial state and the convergencing time to the equilibrium points are constrained in finite time. The simulation results show the validation of the method.

Adaptive trajectory tracking control of two-wheeled self-balance robot

Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.

Optimization of block-floating-point realizations for digital controllers with finite-word-length considerations

The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.

Analysis and implementation of FURLS algorithm for active vibration control system with positive feedback

While positive feedback exists in an active vibration control system, it may cause instability of the whole system. To solve this problem, a feedforward adaptive controller is proposed based on the Fihered-U recursive least square （FURLS） algorithm. Algorithm development process is presented in this paper. Real time active vibration control experimental tests were done. The experiment resuits show that the active control algorithm proposed in this paper has good control performance for both narrow band disturbances and broad band disturbances.