This technical note outlines an approach to the problem of synthesizing fixed-structure low-order controllers for systems whose mathematical models are unknown, but their frequency responses are available. Stability o...
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ISBN:
(纸本)9783902823182
This technical note outlines an approach to the problem of synthesizing fixed-structure low-order controllers for systems whose mathematical models are unknown, but their frequency responses are available. Stability of the closed-loop system is guaranteed if the frequency response of the plant and the controller satisfy certain conditions at specific frequencies. It is shown that the relation between the rate of change of phase of the plant and the controller, at specific frequencies, characterizes the closed-loop system stability. We use this characterization in a systematic way to design fixed-structure low-order controllers such as PI and PID-controllers.
In this paper, we provide a new method of the PID parameter tuning for time-delay systems by utilizing the fictitious reference iterative tuning (FRIT), which is a controller tuning method enabling us to obtain the de...
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ISBN:
(纸本)9783902823182
In this paper, we provide a new method of the PID parameter tuning for time-delay systems by utilizing the fictitious reference iterative tuning (FRIT), which is a controller tuning method enabling us to obtain the desired parameter with only one-shot experimental data. Here, by relating the conventional PID controller to the internal model controller (IMC), we show that PID parameters obtained as the result of the FRIT yield not only a desired controller but also a mathematical model of the controlled time delay system. In order to show the validity of the proposed method, we give an illustrative example.
The human-machine symbiotics, in its wider conception extends beyond the production game. It is about the symbiosis of hand and brain, a productive interplay between the user and the machine, and an interactive interp...
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ISBN:
(纸本)9783902823205
The human-machine symbiotics, in its wider conception extends beyond the production game. It is about the symbiosis of hand and brain, a productive interplay between the user and the machine, and an interactive interplay between the objective knowledge and the tacit dimension. Central to this conception is the design of 'machines with purpose', an alternative vision to that of the instrumental rationality embedded in the computer. The paper reflects back upon the 1970s conception of symbiotics, exploring its evolution over the last four decades. As we now enter the world of cyber realities and fragmented selves on the one hand, and the world of cultural diversities and pluralities on the other, we ponder on whether neuroscience offers a route to a holistic symbiotics, which is even more relevant to the digitally mediated world we live in.
In this work we focus on the development of a software tool, which allows users to perform experiments with event-based PI controllers in a multivariable system composed of four coupled tanks. The quadruple tank plant...
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ISBN:
(纸本)9783902823182
In this work we focus on the development of a software tool, which allows users to perform experiments with event-based PI controllers in a multivariable system composed of four coupled tanks. The quadruple tank plant allows the student of control engineering to experiment and obtain an intuitive knowledge about multivariable systems (systems with more than one inputs and more than one outputs), to study the differences between the minimum phase and non-minimum phase behaviours and the difficulties in control that arise in the latter case, and all this with the motivation that the experiments can be done not only in simulation but with a real plant. The control system provides the possibility of using a decoupling net between the controllers and the actuators, which can have a direct or inverse scheme, and which can be used to reduce the effect of the interactions between inputs and outputs. Finally, we present a set of results illustrating the possibilities of the application to investigate the performance of the event-based controller together with a decoupling strategy.
Recent advances in data-driven (or model-free) control have permitted to enhance the closed loop behavior of linear and especially nonlinear systems using very simple control structures. As a result, unknown or badly ...
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ISBN:
(纸本)9783902823182
Recent advances in data-driven (or model-free) control have permitted to enhance the closed loop behavior of linear and especially nonlinear systems using very simple control structures. As a result, unknown or badly known dynamics are compensated and disturbances are rejected without any learning or on-line identification procedure. However, the ultra-local phenomenological models on which this control technique rely have not yet exploited the fractional nature of many processes and the nonlocal nature of the fractional integrodifferential operators. In this paper, fractional derivatives are used in the so called model free control structure in order to explore the advantages they provide in terms of robustness and dynamic response. Fractional and integer order data driven PIDs will be compared for a DC motor in a robot flexible joint control application in a simulation environment.
For several decades Proportional-Integral-Derivative control (PID) has been successfully used for a wide variety of industrial processes and remains the most used method. Recent work concerning the tuning of PID contr...
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ISBN:
(纸本)9783902823182
For several decades Proportional-Integral-Derivative control (PID) has been successfully used for a wide variety of industrial processes and remains the most used method. Recent work concerning the tuning of PID control coefficients has been proven to provide both robust and near-optimal performance using a Frequency Loop Shaping (FLS) procedure. The FLS tuning method minimizes the difference between the actual and the desired target loop transfer function. Such a controldesign procedure is ideal for problems in which the desired closed loop frequency response is predetermined over a specific frequency band. This paper explores the possibilities and trade-offs of applying the FLS control strategy in Active Noise control (ANC) problems. The use of the FLS design is ideal for the problem of noise suppression in ducts, because the required acoustic impedance for the elimination of reflecting sound waves in the one-dimensional case is well defined. Hence, by controlling locally the reflecting boundary structure, a global cancelation of the undesired noise can be accomplished.
This paper presents a method for tuning simple controllers for distributed parameter systems in the process industry. These systems are usually described by partial differential equations (PDE), which are then simplif...
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ISBN:
(纸本)9783902823182
This paper presents a method for tuning simple controllers for distributed parameter systems in the process industry. These systems are usually described by partial differential equations (PDE), which are then simplified into lumped parameter systems represented by ordinary differential equations (ODE), providing low order transfer functions used for PID controldesign. The drawback of this approach is that the control system only performs well at low bandwidths and without disturbances, as relevant system dynamics, such as resonances lying at medium-high frequencies, are not taken into account, limiting the performance of the closed-loop system. This work proposes a method for SISO systems which uses a transfer function that models the resonances (obtained directly from the PDE) to tune a PID controller that incorporates a filter that is designed to fulfill control requirements.
PID controllers are indisputably the most common controller type encountered in process control applications. They are used for regulating processes with diverse dynamics in industrial applications. Especially, proces...
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ISBN:
(纸本)9783902823182
PID controllers are indisputably the most common controller type encountered in process control applications. They are used for regulating processes with diverse dynamics in industrial applications. Especially, processes with long dead times should require special attention as they are difficult to handle with conventional PID controllers. Al of of different dead time compensating control methods have been introduced in theory. This paper presents another modification of a predicitive PI controller contributing to its inventor and, also hereby, Smith predictor. The proposed method has resemblance with a PID controller and, therefore, is rather applicable for industrial implementations for dead time dominating processes. The introduced method has an additional tuning parameter which is, however, intuitively rather appealing.
This paper presents a library of (PID) controller models adopting the object-oriented approach, and written in Modelica. Peculiar to this work is that controllers are represented both as dynamic continuous-time and di...
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ISBN:
(纸本)9783902823182
This paper presents a library of (PID) controller models adopting the object-oriented approach, and written in Modelica. Peculiar to this work is that controllers are represented both as dynamic continuous-time and digital models, achieving consistence between the two and accounting for the functionalities of typical industrial implementations. This allows the designer to use realistic controllers, maintaining the possibility of choosing the continuous-time or digital (event based) representation. The former allows for example for variable-step simulation, to the advantage of efficiency, while the latter represents very realistically the actual control system's operation, clearly at the cost of more simulation time. Beside standard PI and PID controls, in this work also autotuning is (initially) considered, and some application examples are reported to show how the presented library can ease system studies involving (PID) controls.
Some design schemes of model-free controllers which do not require any system models have been considered in the last decade. FRIT(Fictitious Reference Iterative Tuning) method that directly computes the control param...
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ISBN:
(纸本)9783902823182
Some design schemes of model-free controllers which do not require any system models have been considered in the last decade. FRIT(Fictitious Reference Iterative Tuning) method that directly computes the control parameters from the operating data have been proposed as the one of model-free controllers. FRIT has some useful practical features. One is that it does not require system identification. Another is that the control parameters can be directly computed using only a set of closed loop input/output data and the desired output signal. The calculations of the control parameters needs the optimization of the cost functions. The ordinary approach is the gradient method. However, this calculations derives only linear parameters. Therefore, the applications of FRIT are limited for linear systems. In this paper, a new approach to the discrete FRIT-based nonlinear PID control is proposed. The neural network is utilized for the optimization of FRIT. PID parameters are adequately adjusted corresponding to the nonlinear properties. The conventional schemes by using the neural networks require the information of system Jacobian to update weighting factors. This proposed method can calculate the control parameters without the information of system Jacobian or system parameters except for the information about the time-delay.
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