In order to improve the pointing accuracy of a small satellite, the attitude control system is controlled with pitch-axis momentum and three-axis magnetic torquerods. The satellite dynamics equation and kinematic equa...
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In order to improve the pointing accuracy of a small satellite, the attitude control system is controlled with pitch-axis momentum and three-axis magnetic torquerods. The satellite dynamics equation and kinematic equation are built with the method of quaternion. For each of the three body axes, well-known PD control torque equations are adopted. Three position, three rate, and a dumping control gains are optimally found by building up the optimal attitude control model. In the model, two single objectives: the minimum of the transient time and the minimum of the sum of both the square sum of the attitude angle error and the square sum of the angle rate error are integrated into the multi objectives with multiobjective optimization method. The constraints require that the attitude angle, the angle rate, the three-axis dipole moment and the pitch wheel momentum should not exceed the required value. Finally, an application to the attitude control of a small satellite is presented as an example. Results show that the optimal control algorithm is feasible, effective, and reliable, and attitude control performance is also significantly improved after optimization, compared to the traditional PD control.
Most of iterative learning control (ILC) methods requires that the relative degree of the plant is less than 2 for a linear system or the plant is passive for a non-linear system. A new model reference parametric adap...
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Most of iterative learning control (ILC) methods requires that the relative degree of the plant is less than 2 for a linear system or the plant is passive for a non-linear system. A new model reference parametric adaptive iterative learning control using the command generator tracker (CGT) theory is proposed in this paper. The method can be applied to control a plant with a higher relative degree and it only requires to iteratively adjust n m + 2 parameters for an SISO plant. Therefore, the ILC control system is very simple. The proposed method is in the spirit of simple adaptive control which has received intensive researches during past two decades. Simulation results show the effectiveness and usefulness of the proposed method.
The paper investigates the closed-loop stability issue of finite-precision realizations for digital controllers implemented in floating-point arithmetic. Unlike the existing methods which only address the effect of th...
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ISBN:
(纸本)0780375165
The paper investigates the closed-loop stability issue of finite-precision realizations for digital controllers implemented in floating-point arithmetic. Unlike the existing methods which only address the effect of the mantissa bits in floating-point format to the sensitivity of closed-loop stability, the sensitivity of closed-loop stability is analyzed with respect to both the mantissa and exponent bits of floating-point format. A computationally tractable finite word length (FWL) closed-loop stability measure is defined, and the optimal controller realization problem is posed as searching for a floating-point realization that maximizes the proposed measure. A numerical optimization approach is adopted to solve for the resulting optimization problem. Simulation results show that the proposed design procedure yields computationally efficient controller realizations with enhanced FWL closed-loop stability performance.
The paper analyzes global solutions to the optimal digital controller realization problem based on maximizing a finite word length (FWL) closed-loop stability measure. For each closed-loop eigenvalue, a single-pole FW...
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ISBN:
(纸本)0780375165
The paper analyzes global solutions to the optimal digital controller realization problem based on maximizing a finite word length (FWL) closed-loop stability measure. For each closed-loop eigenvalue, a single-pole FWL stability function is first introduced, and a single-pole FWL stability measure is then defined as the maximum of the corresponding single-pole stability function over all the controller realizations. It is shown that the minimum of the single-pole stability measures for all the closed-loop eigenvalues is an upper bound of the optimal value for the optimal realization problem. An analytical method to compute a single-pole stability measure is developed, and an expression for all the realizations which achieve a given single-pole measure is derived. When a realization, which is a solution of the minimum single-pole measure, further satisfies the condition that the values of all its single-pole stability functions are not less than the minimum single-pole measure, the minimum single-pole measure is the optimal value of the optimal realization problem and this realization is the solution for the optimal realization problem. A computationally simple algorithm is presented.
In this paper we present a new technique to face the so-called constrained Model Predictive control. The main advantage of this new approach with respect to other well-known techniques is represented by the reduced co...
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Fault detection is increasingly an essential part of vehicle development. Integrating such fault detection subsystems raises the reliability, maintainability, and safety of automobile components. Until now, the suspen...
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Fault detection is increasingly an essential part of vehicle development. Integrating such fault detection subsystems raises the reliability, maintainability, and safety of automobile components. Until now, the suspension system was not a safety-critical component, but with the introduction of global chassis control systems this system is getting more important. Therefore, the paper presents fault detection algorithms for the suspension system. Real measurements of a vehicle are made to compare the advantages of the different fault detection algorithms.
In dynamically changing environments, the performance of a standard evolutionary algorithm deteriorates. This is due to the fact that the population, which is considered to contain the history of the evolutionary proc...
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In this paper we present a new technique to face the so-called constrained Model Predictive control. The main advantage of this new approach with respect to other well-known techniques is represented by the reduced co...
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In this paper we present a new technique to face the so-called constrained Model Predictive control. The main advantage of this new approach with respect to other well-known techniques is represented by the reduced conservativeness. More precisely, the technique described in this paper can be applied to polytopic uncertain systems and is based on the use of several Lyapunov functions each one corresponding to a different vertex of the uncertainty's polytope.
In the paper,we exhibit the usefulness of nonlinearity in two aspects:analysis of nonlinear dynamics and nonsmooth feedback *** illustrative examples are given to show how the new bifurcation p
In the paper,we exhibit the usefulness of nonlinearity in two aspects:analysis of nonlinear dynamics and nonsmooth feedback *** illustrative examples are given to show how the new bifurcation p
Bluetooth is currently emerging as one of the most promising personal wireless network technologies. The automation industry is also showing interest in using Bluetooth for more industrial applications. However, probl...
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Bluetooth is currently emerging as one of the most promising personal wireless network technologies. The automation industry is also showing interest in using Bluetooth for more industrial applications. However, problems with unreliable links and time delays must be explicitly addressed in any wireless control application. This paper discusses two specific problems that may occur when using Bluetooth in a control loop: long random delays and bit errors. Simple solutions to these problems are presented. The ideas have been tried out, both in simulations and in experiments, on a rotating inverted pendulum controlled over a Bluetooth network.
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