Consensus disturbance rejection control of directed multi-agent networks with extended state observer

This paper investigates the consensus disturbance rejection problem among multiple high-order agents with directed graphs. Based on disturbance observers, distributed consensus disturbance rejection protocols are constructed in leaderless and leader-follower consensus setups. Different from the previous related papers, the consensus protocols in this paper are developed in a fully distributed fashion, relying on only the state information of each agent and its neighbors. Sufficient conditions are provided to guarantee that the asymptotic stability of high-order multi-agent systems can be reached with matched disturbances.     

Adaptive double chain quantum genetic algorithm for constrained optimization problems

Optimization problems are often highly constrained and evolutionary algorithms(EAs)are effective methods to tackle this kind of problems. To further improve search efficiency and convergence rate of EAs, this paper presents an adaptive double chain quantum genetic algorithm(ADCQGA) for solving constrained optimization problems. ADCQGA makes use of doubleindividuals to represent solutions that are classified as feasible and infeasible solutions. Fitness(or evaluation) functions are defined for both types of solutions. Based on the fitness function, three types of step evolution(SE) are defined and utilized for judging evolutionary individuals. An adaptive rotation is proposed and used to facilitate updating individuals in different solutions.To further improve the search capability and convergence rate, ADCQGA utilizes an adaptive evolution process(AEP), adaptive mutation and replacement techniques. ADCQGA was first tested on a widely used benchmark function to illustrate the relationship between initial parameter values and the convergence rate/search capability. Then the proposed ADCQGA is successfully applied to solve other twelve benchmark functions and five well-known constrained engineering design problems. Multi-aircraft cooperative target allocation problem is a typical constrained optimization problem and requires efficient methods to tackle. Finally, ADCQGA is successfully applied to solving the target allocation problem.     

GPS姿态测量中模糊度函数法的适应度函数研究

基于全球卫星定位系统（GPS）双差整周模糊度的统计特性,对模糊度函数法（AFM）中的适应度函数进行了改进。分析了传统余弦适应度函数的不足,论证了适应度函数在AFM算法中的重要性。提出了设计适应度函数应满足的五条标准,在此基础上给出了一类适应度函数公式,并对性能进行测试。结果表明：该适应度函数的性能明显优于传统的余弦函数,有效提高了GPS姿态解算的成功率。     

A novel target detection approach based on adaptive radar waveform design

To resolve problems of complicated clutter, fast-varying scenes, and low signal-clutterratio (SCR) in application of target detection on sea for space-based radar (SBR), a target detection approach based on adaptive waveform design is proposed in this paper. Firstly, complicated sea clutter is modeled as compound Gaussian process, and a target is modeled as some scatterers with Gaussian reflectivity. Secondly, every dwell duration of radar is divided into several sub-dwells. Regular linear frequency modulated pulses are transmitted at Sub-dwell 1, and the received signal at this sub-dwell is used to estimate clutter covariance matrices and pre-detection. Estimated matrices are updated at every following sub-dwell by multiple particle filtering to cope with fast-varying clutter scenes of SBR. Furthermore, waveform of every following sub-dwell is designed adaptively according to mean square optimization technique. Finally, principal component analysis and generalized likelihood ratio test is used for mitigation of colored interference and property of constant false alarm rate, respectively. Simulation results show that, considering configuration of SBR and condition of complicated clutter, 9 dB is reduced for SCR which reliable detection requires by this target detection approach. Therefore, the work in this paper can markedly improve radar detection performance for weak targets.     

Aircraft-on-ground path following control by dynamical adaptive backstepping

The necessity of improving the air traffic and reducing the aviation emissions drives to investigate automatic steering for aircraft to effectively roll on the ground. This paper addresses the path following control problem of aircraft-on-ground and focuses on the task that the aircraft is required to follow the desired path on the runway by nose wheel automatic steering. The proposed approach is based on dynamical adaptive backstepping so that the system model does not have to be transformed into a canonical triangular form which is necessary in conventional backstepping design. This adaptive controller performs well despite the lack of information on the aerodynamic load and the tire cornering stiffness parameters. Simulation results clearly demonstrate the advantages and effectiveness of the proposed approach.     

Fault tolerant small satellite attitude control using adaptive non-singular terminal sliding mode

The Attitude Control System (ACS) plays a pivotal role in the whole performance of the spacecraft on the orbit; therefore, it is vitally important to design the control system with the performance of rapid response, high control precision and insensitive to external perturbations. In the first place, this paper proposes two adaptive nonlinear control algorithms based on the sliding mode control (SMC), which are designed for small satellite attitude control system. The nonlinear dynamics describing the attitude of small satellite is considered in a circle reference orbit, and the stability of the closed-loop system in the presence of external perturbations is investigated. Then, in order to account for accidental or degradation fault in satellite actuators, the fault-tolerant control schemes are presented. Hence, two adaptive fault-tolerant control laws (continuous sliding mode control and non-singular terminal sliding mode control) are developed by adopting the nonlinear analytical model to describe the system, which can guarantee global asymptotic convergence of the attitude control error with the existence of unknown external perturbations. The nonlinear hyperplane based Terminal sliding mode is introduced into the control law design; therefore, the system convergence performance improves and the control error is convergent in “finite time”. As a result, the study on the non-singular terminal sliding mode control is the emphasis and the continuous sliding mode control is used to compare with the non-singular terminal sliding mode control. Meanwhile, an adaptive fuzzy algorithm has been proposed to suppress the chattering phenomenon. Moreover, several numerical examples are presented to demonstrate the efficacy of the proposed controllers by correcting for the external perturbations. Simulation results confirm that the suggested methodologies yield high control precision in control. In addition, actuator degradation, actuator stuck and actuator failure for a period of time are simulated to demonstrate the fault recovery capability of the fault tolerant controllers. The numerical results clearly demonstrate the good performance of the adaptive non-singular terminal control in the event of actuator fault compare with the continuous sliding mode control.     

卫星姿态系统执行器故障的自适应控制设计

针对带冗余执行器的卫星姿态控制系统,考虑部分执行器发生未知故障(故障模式、大小、时间均未知)的情况,结合Backstepping方法设计了自适应容错控制器,使得当一个甚至多个飞轮出现未知故障时,系统能调整正常执行器的输入,补偿故障执行器的影响,保证系统闭环稳定及输出信号对参考输出量的渐近跟踪.对该算法进行仿真验证,得到了较理想的控制效果.     

基于相似理论的航空发动机转速自适应PID控制

根据航空发动机在相似坐标系中特性不变的特点，提出一种基于相似理论的航空发动机转速自适应PID控制。该方案采用衰减曲线法进行换算PID参数整定，获得自适应调节律。仿真结果表明控制器具有良好的动静态性能，自适应性和鲁俸性。所得参数变化规律对数控系统全包线内PID控制器的参数选择具有一定的指导意义。     

体积成形过程的模型跟随自适应控制

为控制热锻的生产过程和锻件的产品质量 ,应用体积成形过程的有限元数值仿真离线训练人工神经网络 (ANN) ,采用电学模拟方法 ,通过简单的模拟电路构造出复杂的ANN模型 ,完成了从体积成形过程到模拟电路之间的映射。模拟电路与自适应控制系统并联 ,构成了模型跟踪的自适应控制系统