Based on Lyapunov stability theorem, a MRAC system was researched to solve that differential value of plant output is unknown. Meanwhile an improved design for MRAC system aimed on the factor of restricting convergenc...
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The application of model reference adaptive control (MRAC) for train dynamic braking is investigated in order to control dynamic braking forces while remaining within the allowable adhesion and coupler forces. This co...
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The application of model reference adaptive control (MRAC) for train dynamic braking is investigated in order to control dynamic braking forces while remaining within the allowable adhesion and coupler forces. This control method can accurately determine the train braking distance. One of the critical factors in Positive Train control (PTC) is accurately estimating train braking distance under different operating conditions. Accurate estimation of the braking distance will allow trains to be spaced closer together, with reasonable confidence that they will stop without causing a collision. This study develops a dynamic model of a train consist based on a multibody formulation of railcars, trucks (bogies), and suspensions. The study includes the derivation of the mathematical model and the results of a numerical study in Matlab. A three-railcar model is used for performing a parametric study to evaluate how various elements will affect the train stopping distance from an initial speed. Parameters that can be varied in the model include initial train speed, railcar weight, wheel-rail interface condition, and dynamic braking force. Other parameters included in the model are aerodynamic drag forces and air brake forces. An MRAC system is developed to control the amount of current through traction motors under various wheel/rail adhesion conditions while braking. Minimizing the braking distance of a train requires the dynamic braking forces to be maximized within the available wheel/rail adhesion. Excessively large dynamic braking can cause wheel lockup that can damage the wheels and rail. Excessive braking forces can also cause large buff loads at the couplers. For DC traction motors, an MRAC system is used to control the current supplied to the traction motors. This motor current is directly proportional to the dynamic braking force. In addition, the MRAC system is also used to control the train speed by controlling the synchronous speed of the AC traction motors. The
This paper presents the optimal control modification for linear uncertain plants. The Lyapunov analysis shows that the modification parameter has a limiting value depending on the nature of the uncertainty. The optima...
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ISBN:
(纸本)9781624102240
This paper presents the optimal control modification for linear uncertain plants. The Lyapunov analysis shows that the modification parameter has a limiting value depending on the nature of the uncertainty. The optimal control modification exhibits a linear asymptotic property that enables it to be analyzed in a linear time invariant framework for linear uncertain plants. The linear asymptotic property shows that the closedloop plants in the limit possess a scaled input-output mapping. Using this property, we can derive an analytical closed-loop transfer function in the limit as the adaptive gain tends to infinity. The paper revisits the Rohrs counterexample problem that illustrates the nature of non-robustness of model-referenceadaptivecontrol in the presence of unmodeled dynamics. An analytical approach is developed to compute exactly the modification parameter for the optimal control modification that stabilizes the plant in the Rohrs counterexample. The linear asymptotic property is also used to address output feedback adaptivecontrol for non-minimum phase plants with a relative degree 1.
Recently, a class of adaptivecontrol schemes called L1 adaptivecontrol (L1-AC) has been proposed and widely advertised in aerospace control for achieving fast and robust adaptation and better performance than the ex...
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ISBN:
(数字)9781624102240
ISBN:
(纸本)9781624102240
Recently, a class of adaptivecontrol schemes called L1 adaptivecontrol (L1-AC) has been proposed and widely advertised in aerospace control for achieving fast and robust adaptation and better performance than the existing model reference adaptive control (MRAC) Schemes. The L1-AC scheme is designed mainly for plants with full state measurement even though the name L1-AC has been used as an umbrella name for more general classes of plants. In this paper, we show that the L1-AC for plants with measured states is simply a standard MRAC with a low pass filter inserted in front of the control input. The analysis of the scheme is almost identical to that of MRAC as the same Lyapunov function is used to establish stability. The motivation for using the filter is the fact that for this class of adaptive schemes i.e. MRAC for plants with full state measurement the tracking error can be made arbitrarily small during transient by increasing the adaptive gain. A high adaptive gain however makes the differential equation of the adaptive law or estimator very stiff and leads to numerical problems that cause high oscillations in the estimated parameters leading to loss of adaptivity and deviations from what the theoretical properties dictate. The L1-AC approach mistook these numerical oscillations as properties of the adaptive scheme and inserted an input low pass filter in order to filter them out. While the filter helps reduce the frequency of these oscillations in the control law the price paid is high. First the numerical instability does not go away and the estimated parameters continue to oscillate without converging to the true parameters even in the presence of suffciently rich signals. Second, due to the filter the tracking error is no longer guaranteed to converge to zero and the transient bounds for the tracking error also depend on the filter. As a result, the tracking properties of the L1-AC scheme are worse than what a simple MRAC scheme can generate with adaptive
A Fault Tolerant control (FTC) reconfigurable structure for a second order nonlinear process is developed. This structure is based on a model reference adaptive control (MRAC) with a H∞, Gain Scheduling controller de...
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In structural behavior, the analysis of civil buildings by seismic tests has been generalized by the use of shaking tables. This method requires advanced control systems. In our research we show the implementation of ...
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This paper proposes a digital Robust model reference adaptive control (RMRAC) applied to control the output current (by the grid side) of a three-phase LCL-filter to applications in static converters connected to elec...
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This paper presents a multiple-input Concurrent Learning model reference adaptive control (CL-MRAC) approach applied to longitudinal dynamics of the generic transport model (GTM) aircraft. A reduced order model of the...
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This paper presents a multiple-input Concurrent Learning model reference adaptive control (CL-MRAC) approach applied to longitudinal dynamics of the generic transport model (GTM) aircraft. A reduced order model of the short period flight dynamics coupled with structural bending and torsion is used. This aeroelastic model of the commercial passenger aircraft incorporates parametric uncertainties for mass and structural stiffness affecting both the structural dynamics and coupling. CL-MRAC with nonparametric Budgeted Kernel Restructuring (BKR) assigns centers and regressor vectors dynamically. The CL controller is used alongside an optimal tracking controller to enforce performance criteria on the rigid body dynamics. Results from this method demonstrate new insights into the application of large scale CL-MRAC implementations that arise from multiple-input multiple-output (MIMO) models.
Zeta converters are the fourth-order DC-DC converters capable of operating in both step-up and step-down modes and do not suffer from the polarity reversal problem. There are many applications which require a variable...
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This paper presents some experimental results on actuator fault-tolerant control (FTC) for a quadrotor Unmanned Aerial Vehicle (UAV) system. The strategy is based on model reference adaptive control (MRAC) where three...
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