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In this paper, we propose and solve the problem of feedback linearization of single-input control affine time-varying nonlinear systems. Feedback linearizability of time-varying is shown to be equivalent to the orbital feedback linearizability (or feedback linearization by state-dependent time scaling) of an extended version of the time-varying system. Necessary and sufficient conditions for feedback...
The first purpose of this paper is to present shortly an idea of soft variables and evaluating functions as a tool for the unification and generalisation of decision making problems in control systems with a static plant. The random variables, uncertain variables and fuzzy descriptions are considered here as special cases of the descriptions based on the soft variables. The second purpose of the paper...
Traffic dependent speed limits have improved the security of highway traffic considerably. However, on highway sections controlled by variable speed limits large oscillations in speed can still be observed. On the basis of traffic data and a macroscopic traffic model, the influence of decentrally controlled speed limits on the states of highway traffic is analyzed. It is shown that local control of...
In this paper, we develop a discrete-time time-invariant tracking controller for dynamic systems affected by hysteresis. This controller utilizes an approximate model for the inverse hysteresis dynamics, a non-linear discrete-time observer and two linear tracking controllers. The control system is tested on a simulation model of a mechanical translation stage.
The common industrial practice considers static analysis and design for distributed piping system while leaving the solution of problem arising from plant dynamic behaviour to designer experiences and/or to "ad-hoc" developed dynamic simulation models. In this paper, we describe a design methodology which can potentially increase performances, safety and shorten time to market development...
Undesirable time-variable motions of dynamical structures (e.g. scales, balances, vibratory platforms, bridges and buildings) are mainly caused by unknown or uncertain excitations. In a variety of applications it is desirable or even necessary to attenuate these disturbances in an effective way and with moderate effort. Hence, several passive as well as active methods and techniques have been developed...
This paper describes an interactive tool focused on teaching and learning basic concepts on multivariable control systems. Most industrial processes are represented by multivariable systems and thus the teaching and learning of basic concepts on multivariable control is a key factor in control engineering education. In this sense, the interactive tool presented in this paper is aimed to introduce...
We are considering the problem of controlling wind turbine synchronous generators driven through AC/DC rectifiers and DC/AC inverters. The control objectives are threefold: (i) forcing the turbine speed to track a reference signal, (ii) regulating the DC Link voltage, (iii) enforcing power factor correction (PFC) with respect to the power network. First, a nonlinear model of the whole controlled system...
The paper proposes an alternative way to solve robust reference tracking problem. Instead of rejecting the effect of the disturbance directly, an intermediate step is built into the state estimation problem. The advantage of the methodology is to elaborate a modified optimal state estimation problem taking the unbiased estimate of the disturbance into account. Henceforward, the solution of the discrete...
This paper deals with the controller design for the lateral motion of automatic steering of vehicles. The nonlinear models without and with uncertainties are considered. Sliding mode controllers with first order sliding surfaces are proposed for the control of lateral velocity and yaw rate. These controllers are designed directly based on the second order differential equation model which simplifies...
Kuipers' QSIM algorithm for tracking the monotonicity properties of solutions to differential equations has been revisited by Dordan by placing it in a rigorous mathematical framework. The Dordan QSIM algorithm provides the transition laws from one qualitative cell to the others. We take up this idea and revisit it at the light of recent advances in the field of "hybrid systems" and, more...
In the paper the role of anti-aliasing filters is revised based on control quality assessment of PID controllers when using average sampling versus instantaneous sampling without any analog filter. Numerical results show that contrary to common belief possible benefits gained from anti-aliasing devices are very restricted.
In this paper, a new IMC-based PID controller design is proposed. The model reduction is employed to find the best PID controller approximation to the IMC controller. Compared with the existing IMC-based methods, the proposed design is applicable to a wider range of processes, and yields a control system with performance closer to the more sophisticated IMC counterpart. Furthermore, it can be made...
This paper focuses on the problem of adaptively controlling nonlinear systems with time-varying and unknown parameters. Both state feedback and output feedback systems are considered. We seek plant stabilization and output reference tracking. The control problem is dealt with using a back-stepping adaptive controller including a switching a modification. In the case of state feedback systems, all...
The paper presents a Rapid Control Prototyping (RCP) toolbox for Scilab/Scicos, which can be used to generate real-time C code using RTAI-Lab. The toolbox contains three main blocks: PID controller, Fractional Order PID controller and Least Mean Square (LMS) adaptive filter. Once the coefficients of the PID or fractional PID controller are determined the PID control blocks can be used to easily test...
Typical digital implementations of feedback controllers periodically measure the state, compute the control law, and update the actuators. Although periodicity simplifies the analysis and implementation, it results in a conservative usage of resources. In this paper we drop the periodicity assumption in favor of self-trigger strategies that decide when to measure the state, execute the controller,...
Macro-Micro bilateral manipulation is a remote control with scaling factor of position/force between master (macro) and slave (micro) system. Normally, bilateral control based on acceleration control can realize not only high performance of force transmission because of the utilization of reaction force observer (RFOB), but also accurate tracking of position because of disturbance observer (DOB)....
Nature inspired algorithms are among the most potent and robust algorithms for optimization for solving the real life problems. This paper introduces the Bat algorithm for the optimization based design of the PID controllers. The optimized PID controller has been implemented for liquid level control system which finds a wide application in petrochemical, food processing, and water treatment industries...
In this paper, a control strategy for switched reluctance motor(SRM) based variable speed drives is proposed. The phase inductance profile for an SRM being nonlinear, a small signal model based method is applied in a restricted way to design and then implement the controllers based on a linearised model. Two control loops — a Pi-controller based speed loop and and a hysteresis controller current loop...
Differential equations with fractional-order derivatives, e.g., the "one-half" derivative, have a long history in mathematics, but have not yet attained mainstream use in engineering and applied science. While applications do exist in modeling specific phenomena such as visco-elasticity and other types of difficult-to-model phenomena, and extensions to control such as in fractional-order...
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