For predictive control in industry often very long horizons for control error and manipulated signal are used because of the slow processes which take place in the petrochemical industry. In order to reduce the comput...
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This paper presents the design of a model-based supervision system for the vacuum brake booster of current hydraulic passenger car braking systems. A model is derived, which allows to calculate the pressure in the vac...
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This paper presents the design of a model-based supervision system for the vacuum brake booster of current hydraulic passenger car braking systems. A model is derived, which allows to calculate the pressure in the vacuum chamber and the working chamber of the vacuum brake booster. Based on this model, a real-time supervision system has been implemented. The fidelity of the model has been evaluated by testing the model against experimental data from a braking system test bed. The functioning of the model-based supervision system has also been probed with measurements taken at the aforementioned testbed.
This paper presents an approach to calculate prefilters that are insensitive to parameter deviations. The cost function chosen for this approach is the magnitude of the time-delay filter transfer function. By approxim...
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This paper presents an approach to calculate prefilters that are insensitive to parameter deviations. The cost function chosen for this approach is the magnitude of the time-delay filter transfer function. By approximating the cost function with a polynomial, the effort of calculating minimax robust profiles can be reduced. The resulting control profiles yield a performance similar to the minimax robust controller. This is verified by the numerical results included in this paper.
This paper describes fault detection and diagnosis techniques for a hydraulic passenger car braking system. First, a model of the hydraulic braking system is derived in state space representation. This model is subseq...
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This paper describes fault detection and diagnosis techniques for a hydraulic passenger car braking system. First, a model of the hydraulic braking system is derived in state space representation. This model is subsequentlyemployed for fault detection and diagnosis. Fault detection is based on the calculation of the loss volume, i.e. the amount of brake fluid consumed due to the presence of a fault. The type of fault is determined by means of a correlation analysis approach. Furthermore, the location of the fault can also be determined. This is accomplished by analyzing the master brake cylinder pressure signals. The paper also presents numerical results of data recorded at a braking system testbed which illustrates the feasibility of the proposed approaches.
With predictive control most of the computation time is spent for the simulation of the predicted variables and for the optimization if constraints or nonlinear processes are assumed. In addition to the known blocking...
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With predictive control most of the computation time is spent for the simulation of the predicted variables and for the optimization if constraints or nonlinear processes are assumed. In addition to the known blocking technique for the manipulated variable another possibility is calculating the control error not in each sampling point of the prediction horizon but only in some coincidence points. It will be shown that the best choice is to allocate the coincidence points exponentially thus that with small prediction steps more and with increasing prediction steps less coincidence points are considered. As a practical example the multivariable control of a distillation column model illustrates the benefits of the method presented.
Long-range optimal prediction algorithms use the predicted output for several steps ahead. The prediction based on traditionally estimated model parameters does not result in an optimal prediction if the measurements ...
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Long-range optimal prediction algorithms use the predicted output for several steps ahead. The prediction based on traditionally estimated model parameters does not result in an optimal prediction if the measurements are noisy or/and model structure differs from real process structure. In this paper two different identification schemes are presented and compared: long-range predictive single-model identification and simultaneous multi-step-ahead prediction identification. It is shown that the first method is easier to realize but the second one leads to more accurate results. Both methods are derived for a first-order model in details. Simulation runs and a level control example illustrate the algorithms presented.
For predictive control in industry often very long horizons for control error and manipulated signal are used because of the slow processes which take place in the petrochemical industry. In order to reduce the comput...
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For predictive control in industry often very long horizons for control error and manipulated signal are used because of the slow processes which take place in the petrochemical industry. In order to reduce the computational effort some commercial predictive control program packages offer the ability to reduce the number of points in both horizons but do not recommend how to select the points which have to be considered in the horizon of the control error and manipulated variable. In this work the authors introduce an optimal choice not only of the horizon lengths itself but also for the strategy of reducing the number of points in the horizons. A genetic optimization algorithm was used both for the search for the optimal length of the horizons and for the best allocation of the points in the horizons. The results of the optimization process where used to deduct a simple rule.
Most industrial processes are nonlinear. In such a case only a nonlinear model valid for the whole working area can ensure a good controller design. The nonlinear process is approximated by a multi-model consisting of...
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Most industrial processes are nonlinear. In such a case only a nonlinear model valid for the whole working area can ensure a good controller design. The nonlinear process is approximated by a multi-model consisting of the intelligent combination of some linear sub-models. As a very practical way the following identification strategy was used: independent model parameter estimation in the different working points and the calculation of the global valid model output as the weighted sum of the sub-models. As a weighting function the Gaussian function is used. The parameters of the Gaussian function were chosen either without or with optimization of the identification cost function. The global valid nonlinear model was used for model based predictive control. A heat exchanger example illustrates the method.
This paper investigates the possibility of computing the actual position of a passenger car based on different independent internal signals available in a production car. A new front wheel based dead reckoning approac...
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For many practical applications, a combination of theoretical and experimental modelling appears feasible. Qualitative knowledge about the most significant effects are often known or easily accessible. This contributi...
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