In recent years, Unmanned Aerial Vehicles (UAVs) are increasingly becoming flight-based communicative and computing platforms, but the scarcity of communication resources can significantly hinder their performance and...
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This paper presents a novel compensator segmentation scheme for rule-based control of a linear system characterized by structured uncertainties. To start with, it is assumed that the design of a segmented compensator ...
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This paper presents a novel compensator segmentation scheme for rule-based control of a linear system characterized by structured uncertainties. To start with, it is assumed that the design of a segmented compensator becomes necessary because the parameter variation region is too wide to be handled by a single robust compensator. The segmentation scheme is based on the simulated annealing technique. Starting with an initial estimate of the number of segments, the off-line segmentation scheme attempts to minimize it while assuring coverage of the entire parameter variation region. The information about the segment boundaries and the appropriate compensators is then utilized as the database of a rule-based switching controller. The paper includes the results of simulation studies that demonstrate the performance of the proposed scheme.
The theory of optimal output feedback control is extended to a class of quadratic performance measures whose weighting matrices are functions of frequency. The incorporation of frequency-dependent weighting matrices a...
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The theory of optimal output feedback control is extended to a class of quadratic performance measures whose weighting matrices are functions of frequency. The incorporation of frequency-dependent weighting matrices allows one to emphasise or de-emphasise the importance of the variables being penalised over specific bands of frequencies. Optimization of the frequency-shaped performance measure yields optimal compensators that can be more meaningful for certain minimisation problems. Results are presented for different configurations of frequency-shaping feedback control. An example is presented to illustrate the usefulness of the design technique.
The linear quadratic design of an optimal robust servo–controller for a continuous–time control system is described. It introduces a servo–control performance measure which accommodates the internal model principle...
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The linear quadratic design of an optimal robust servo–controller for a continuous–time control system is described. It introduces a servo–control performance measure which accommodates the internal model principle. The measure selectively discounts penalties on control effort of desirable frequencies and provides complete flexibility in the selection of weighting matrices. The proposed servo–controller uses plant state feedback, signal state feedforward and a servo–compensator for ensuring robust asymptotic command tracking and disturbance rejection. An informal alternate proof of the internal model principle in the state variable domain is presented using an operator-transformation technique. Where necessary, observers are used to complement the servo-controller. The proposed optimal robust servo–controller yields the expected superior performance in terms of response and error minimization. An illustrative example is given.
The state estimation problem is considered for linear time-varying continuous systems with non-lexicographic-fixed observability basis. A two-stage design strategy is presented for constructing observers for this clas...
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The state estimation problem is considered for linear time-varying continuous systems with non-lexicographic-fixed observability basis. A two-stage design strategy is presented for constructing observers for this class of systems. At the first stage, by augmenting the given system with an auxiliary system, the original system is transformed to a new augmented model whose observability indices are lexicographic-fixed. A specific augmentation scheme is proposed in order to find this auxiliary system. At the second stage, a design procedure is given to construct minimum-order observers for the augmented system by utilizing the new input and output information. The canonical transformation technique is also employed to simplify the design procedure. Finally, with the help of a simple reverse transformation, solutions to the original problem are obtained. An example is also given to illustrate the design techniques.
The design of minimal-order state observers is considered for linear time-varying multivariable continuous systems. Employing the observable block companion canonical transformation technique, a simple and straightfor...
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The design of minimal-order state observers is considered for linear time-varying multivariable continuous systems. Employing the observable block companion canonical transformation technique, a simple and straightforward design procedure is given for constructing the minimal-order state observers. This design technique also allows all eigenvalues of the observer to be arbitrarily assigned. Compared with existing observer design techniques for time-varying systems, the method developed has the advantage of being applicable to a more general class of systems and reducing the design complexity in the sense that various observer matrices can be determined as constant matrices. An example is also presented to illustrate the design technique.
This paper presents the kinematic and dynamic analysis of an n -link manipulator with flexible members. The deformation of a link from its rigid body position is modeled by a homogeneous transformation. The dynamic eq...
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This paper presents the kinematic and dynamic analysis of an n -link manipulator with flexible members. The deformation of a link from its rigid body position is modeled by a homogeneous transformation. The dynamic equations are obtained using Euler-Lagrange formulation. These equations are compared to those describing a rigid link mechanism.
For an optimal parametric linear quadratic (LQ) control problem, a design objective is to determine a controller of constrained structure such that the closed-loop system is asymptotically stable and an associated per...
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For an optimal parametric linear quadratic (LQ) control problem, a design objective is to determine a controller of constrained structure such that the closed-loop system is asymptotically stable and an associated performance measure is optimized. In the presence of system uncertainty, the system via a parametric LQ design is further required to be robust in terms of maintaining the closed-loop stability with a guaranteed cost bound. This problem is referred to as ‘robust optimal parametric LQ control with a guaranteed cost bound’ and is addressed in this work. A new design method is proposed to find an optimal controller for simultaneously guaranteeing robust stability and performance over a specified range of parameter variations. The results presented generalize some previous work in this area. A versatile numerical algorithm is also given for computing the robust optimal gains. The usefulness of the design method is demonstrated by numerical examples and a design of the robust control of a VTOL helicopter.
A new technique for the digital control of continuous time systems is presented. This technique is based on a table look-up algorithm. To minimize the number of entries in the table, a grid embedding process is propos...
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A new technique for the digital control of continuous time systems is presented. This technique is based on a table look-up algorithm. To minimize the number of entries in the table, a grid embedding process is proposed. Using this process, an accurate, fast, and low-cost controller can be constructed using a table of a few thousand entries. The paper derives the control strategy and proposes a digital circuit to implement the controller. An example is presented in which the performance of a closed-loop digital controller is compared with that of an optimal regulator. The comparison shows that the performance of the new controller is very close to that of an equivalent optimal controller
A dynamic model that represents an exact linearization scheme with a simplified nonlinear feedback is presented. To realize this model for robotic systems, the output functions should be chosen so that a special decom...
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A dynamic model that represents an exact linearization scheme with a simplified nonlinear feedback is presented. To realize this model for robotic systems, the output functions should be chosen so that a special decomposition of the total inertial matrix is satisfied. The concept of an imaginary robot is utilized to achieve the formulation and to solve the realization problem. Two illustrative examples are given in the paper, one for the Stanford arm and the other for a PUMA type of robot. An optimal robotic physical design and a control system design based on the new model are also discussed.
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