The discrete-time version of the continuous-time sliding mode control approach requires the redefinition of the sliding mode concept. In previous papers the authors have introduced an alternative definition of discret...
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The discrete-time version of the continuous-time sliding mode control approach requires the redefinition of the sliding mode concept. In previous papers the authors have introduced an alternative definition of discrete-time 'equivalent control' as the control signal causing the dead-beat zeroing of the distance from the sliding manifold. Within this paper, the problem of discrete-time zero dynamics is expressly addressed, and what is shown is that with the proposed approach, as long as the sampling interval is small, non minimum phase behaviours cannot occur.
This paper deals with the problem of the adaptivecontrol of discrete-time linear SISO plants with unknown time delay. In this context, a new control scheme is presented which does not require the explicit identificat...
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This paper deals with the problem of the adaptivecontrol of discrete-time linear SISO plants with unknown time delay. In this context, a new control scheme is presented which does not require the explicit identification of the unknown time delay and is characterized by a complexity which is comparable with that of the undelayed discrete-time plant, i.e., that obtained by sampling the continuous-time plant neglecting the time delay. Moreover, the order of the resulting controller is known and independent of the sampling interval.
This paper presents real-time application adaptivecontrol concept of a typical industrial plant whose performance is severely affected by disturbances and in particular by changes in the operating point. This is typi...
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This paper presents real-time application adaptivecontrol concept of a typical industrial plant whose performance is severely affected by disturbances and in particular by changes in the operating point. This is typically the case for large coal fired power plants which canbe treated as multivariable dynamic system. A short description of the power plant is given. For this power plant, a reduced mathematical model is developed. The results of experimental modelling will be shortly discussed. The conventional control of this power plant is investigated and described. The design of the adaptivemodel-refence controller used in the power plant for real-time control is presented in theory. Realization of the use of the adaptivecontrol is shown and the results of a three-month installation of a decentralized adaptivecontrol algorithm for electrical power and enthalpy control of a 750 MW power plant are discussed and compared with those of the conventional PID control.
The problem of MRAC system design for stable SISO contin-uous-time plants with amplitude constraints on the inputs is dealt with. A modification is made on the basic adaptive law based on the a prior information about...
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The problem of MRAC system design for stable SISO contin-uous-time plants with amplitude constraints on the inputs is dealt with. A modification is made on the basic adaptive law based on the a prior information about the desired vector. It is shown that an adaptivecontroller with the modified adaptive law proposed can guarantee the asymptotical convergence of the output of the plant to that of the referencemodel and the boundedness of all signals involved in the closed-loop control systeM for any bounded initial conditions, if some assumption which is very reasonable holds.
This paper presents an indirect adaptive continuous-time periodic control system for single-input single-output continuous-time systems that may have unstable zeros (i.e., nonminimum phase systems) with a priori knowl...
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This paper presents an indirect adaptive continuous-time periodic control system for single-input single-output continuous-time systems that may have unstable zeros (i.e., nonminimum phase systems) with a priori knowledge of the system order. By using the benefits of the continuous-time periodic control design, the proposed control system has a desirable feature that it is applicable to open-loop zeros placement asymptotically. The averaging method is applied for an analysis of the closed-loop system in the non-adaptive case. So the system can adaptively match to an arbitrary desired referencemodel. The numerical simulations are given to illustrate the effectiveness of the proposed method.
This paper is concerned with the design of a discrete time model reference adaptive control System (WACS) for motion control under unknown nonlinear friction. Static and Coulomb friction forces are represented by a de...
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This paper is concerned with the design of a discrete time model reference adaptive control System (WACS) for motion control under unknown nonlinear friction. Static and Coulomb friction forces are represented by a deadzone element for the input, which is active at low velocities. and disturbance. which may take different values depending on the motion direction. respectively. Then, the WAes for the nonlinear friction is a cascade combination of a nonlinear block which contains the deadzone and the disturbance term and a linear dynamic block. Experimental results from a rotary servo system demonstrate the effectiveness of the proposed WAeS
Although previous case studies rigorously investigated the feasibility of implementing passivity-based inner loop adaptation on an industrial manipulator, an unanswered question was the general validity of those resul...
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Although previous case studies rigorously investigated the feasibility of implementing passivity-based inner loop adaptation on an industrial manipulator, an unanswered question was the general validity of those results. That issue is addressed by repeating the analysis on a small serial robot with a pneumatic tendon drive system. Experimental analysis reverified the algorithm's adaptation/learning capabilities and provided insight into how the implementation issues of tuning and parameter convergence depend on specific manipulator structure. Direct adaptivecontrol enhances trajectory efficacy for a wide range of manipulators.< >
A design method for an exact model matching control (EMMC) system which reduces the effect of measurement noise on the plant output is presented. This method uses the freedom of controller parameters achieved by incre...
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A design method for an exact model matching control (EMMC) system which reduces the effect of measurement noise on the plant output is presented. This method uses the freedom of controller parameters achieved by increasing the degree of the observer polynomial. For some fixed degree of the observer polynomial, the controller for this EMMC is obtained as a solution of a simple optimization problem. It is shown that the effect of the measurement noise on the plant output becomes smaller as the degree of the observer polynomial is increased. This method is applied to a MRACS for a plant with measurement noise.< >
Based on an extended modelreferencecontrol (MRC) theory developed here, a model reference adaptive control (MRAC) algorithm is proposed for not necessarily minimum phase digital or sampled plants. It is shown that t...
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Based on an extended modelreferencecontrol (MRC) theory developed here, a model reference adaptive control (MRAC) algorithm is proposed for not necessarily minimum phase digital or sampled plants. It is shown that the algorithm is capable of globally stabilizing the plants as well as achieving asymptotical model matching in a suitable sense without making a richness assumption on the reference signal. The only assumptions made on the plant are minimality and known order, and hence the delay in the plant is unknown, and moreever may be larger than the delay in the referencemodel.
The problem of overparameterization of the plant in model reference adaptive control (MRAC) is analyzed. Overparametrization may arise when an upper bound for the order of the plant is used in the design of the MRAC o...
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The problem of overparameterization of the plant in model reference adaptive control (MRAC) is analyzed. Overparametrization may arise when an upper bound for the order of the plant is used in the design of the MRAC or when the transfer function of the modeled part of the plant has common zeros and poles. It is shown that under parametrization the parameters for model-plant transfer function matching lie in a linear variety. If the reference input signal has enough frequencies, the estimated parameters will converge to this variety. In the presence of modeling errors such as bounded disturbances, the parameters may drift to infinity along the linear variety independently of the number of frequencies in the reference input signal. In the case of exact parameterization but close zero-pole cancellation, the signal vector is shown to be persistently exciting with a low level of excitation. Such a low level of excitation may lead to poor rate of convergence and to loss of robustness with respect to modeling errors.
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