Current Issue : October - December Volume : 2015 Issue Number : 4 Articles : 7 Articles
This paper deals with the stability of switched systems with time-varying delay.The time-varying system parameters are assumed\nto be norm-bounded. Based on a novel switched time-varying Lyapunov functional method, some new LMI-based sufficient\nconditions have been obtained to ensure the exponential stability for the uncertain switched delays systems. Finally, the proposed\nmethod is applied to a numerical example and the simulative results are also given...
Joint motion control of a 52-meter-long five-boom system driven by proportional hydraulic system is developed. It has been\nconsidered difficult due to strong nonlinearities and parametric uncertainties, the effect ofwhich increaseswith the size of booms.A\nhuman simulated intelligent control scheme is developed to improve control performance by modifying control mode and control\nparameters. In addition, considering the negative effects caused by frequent and redundant reverse actions of the proportional valve,\na double-direction compensation scheme is proposed to deal with the dead-zone nonlinearity of proportional valve. Sinusoidal\nmotions are implemented on a real boom system.The results indicate that HSIC controller can improve control accuracy, and deadzone\nnonlinearity is effectively compensated by proposed compensation scheme without introducing frequent reverse actions of\nproportional valve....
Due to power-after-launch mode of guided munitions of high rolling speed, initial attitude of munitions cannot be determined\naccurately, and this makes it difficult for navigation and control system to work effectively and validly. An in-flight self-alignment\nmethod aided by geomagnetism that includes a fast in-flight coarse alignment method and an in-flight alignment model based on\nKalman theory is proposed in this paper. Firstly a fast in-flight coarse alignment method is developed by using gyros, magnetic\nsensors, and trajectory angles. Then, an in-flight alignment model is derived by investigation of the measurement errors and\nattitude errors, which regards attitude errors as state variables and geomagnetic components in navigation frame as observed\nvariables. Finally, fight data of a spinning projectile is used to verify the performance of the in-flight self-alignment method. The\nsatisfying results show that (1) the precision of coarse alignment can attain below 5?; (2) the attitude errors by in-flight alignment\nmodel converge to 24???? at early of the latter half of the flight; (3) the in-flight alignment model based on Kalman theory has better\nadaptability, and show satisfying performance....
Model-based methods are used in industry for prototyping concepts based on mathematical models. With our forest industry\npartners, we have established a model-based workflow for rapid development of motion control systems for forestry cranes.\nApplying this working method, we can verify control algorithms, both theoretically and practically. This paper is an example of\nthis workflow and presents four topics related to the application of nonlinear control theory. The first topic presents the system of\ndifferential equations describing the motion dynamics. The second topic presents nonlinear control laws formulated according to\nsliding mode control theory.The third topic presents a procedure for model calibration and control tuning that are a prerequisite to\nrealize experimental tests. The fourth topic presents the results of tests performed on an experimental crane specifically equipped\nfor these tasks. Results of these studies show the advantages and disadvantages of these control algorithms, and they highlight their\nperformance in terms of robustness and smoothness....
The problem of integral sliding mode control (ISMC) with passivity is investigated for a class of uncertain neutral systems with\ntime-varying delay (NTSTD) and external disturbance. The system states are unavailable. An ISMC strategy is proposed based on\nthe state estimate. By employing a novel sliding functional, a new sufficient criterion of robust asymptotic stability and passivity for\nboth the error system and the sliding mode (SM) dynamic system is derived via linear matrix inequality (LMI) technique.Then,\na SM controller is synthesized to guarantee the reachability of the sliding surface predefined in the state estimate space. Finally, a\nnumerical example shows the feasibility and superiority of the obtained result....
Theoretic analysis shows that the output power of the distributed generation system is nonlinear and chaotic. And it is coupled\nwith the microenvironment meteorological data. Chaos is an inherent property of nonlinear dynamic system. A predicator of the\noutput power of the distributed generation system is to establish a nonlinear model of the dynamic system based on real time series\nin the reconstructed phase space. Firstly, chaos should be detected and quantified for the intensive studies of nonlinear systems. If\nthe largest Lyapunov exponent is positive, the dynamical system must be chaotic. Then, the embedding dimension and the delay\ntime are chosen based on the improved C-C method. The attractor of chaotic power time series can be reconstructed based on the\nembedding dimension and delay time in the phase space. By now, the neural network can be trained based on the training samples,\nwhich are observed from the distributed generation system. The neural network model will approximate the curve of output power\nadequately. Experimental results show that the maximum power point of the distributed generation system will be predicted based\non the meteorological data.The system can be controlled effectively based on the prediction....
This paper presents a fault detection and isolation (FDI) approach in order to detect and isolate actuators (thrusters and reaction\nwheels) faults of an autonomous spacecraft involved in the rendez-vous phase of the Mars Sample Return (MSR) mission. The\nprincipal component analysis (PCA) has been adopted to estimate the relationships between the various variables of the process.\nTo ensure the feasibility of the proposed FDI approach, a set of data provided by the industrial ââ?¬Å?high-fidelityââ?¬Â simulator of the MSR\nand representing the opening (resp., the rotation) rates of the spacecraft thrusters (resp., reaction wheels) has been considered.The\ntest results demonstrate that the fault detection and isolation are successfully accomplished....
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