Showing papers by "Edward J. Davison published in 2006"
TL;DR: The characteristic equations of time delay systems are quasipolynomials, whose roots determine the stability of such systems, and the root-locus of these equations in specified desired regions is investigated.
46 citations
14 Jun 2006
TL;DR: In this article, a multi-link inverted pendulum with an arbitrary number of v links and controlled by a single torque input is considered and it is conjectured that the primary reason for such an increase of difficulty is due to the poor stabilizability robustness properties of the pendulum's linearized model as additional links are added.
Abstract: A multi-link inverted pendulum with an arbitrary number of v links and controlled by a single torque input is considered in this paper. It is well known that as the number of pendulum links increases, an experimental pendulum system becomes more difficult to stabilize, and this is demonstrated in this paper for a nonlinear model of a multi-link inverted pendulum system. It is conjectured that the primary reason for such an increase of difficulty is due to the poor stabilizability robustness properties of the pendulum's linearized model as additional links are added. Using the real stability and stabilizability radius, this conjecture is confirmed.
33 citations
TL;DR: This paper investigates the decentralized control of LTI continuous-time plants using generalized sampled-data hold functions (GSHF) to modify the structure of the digraph of the resultant discrete plant, by removing certain interconnections in the discrete-time equivalent model to form a hierarchical system model of the plant.
27 citations
14 Jun 2006
TL;DR: In this article, the authors studied the decentralized control of a platoon of identical vehicles which are moving on a plane, where each vehicle is assumed to have steering dynamics; each vehicle in this case is described by a 6/sup th/order model and has two inputs: traction force and steering angle.
Abstract: This paper studies the decentralized control of a platoon of identical vehicles which are moving on a plane, where each vehicle is assumed to have steering dynamics; each vehicle in this case is assumed to be described by a 6/sup th/ order model and has two inputs: traction force and steering angle. Special cases such as a "side-tracking" formation with decentralized coordinated lateral-longitudinal control is studied. An example of a 10-vehicle platoon which is controlled to "sweep a field" is included to illustrate the results which can be obtained.
18 citations
01 Dec 2006
TL;DR: It is shown that generalized sampled-data hold functions (GSHF) instead of a simple zero-order hold (ZOH), in the implementation of the digital controllers, can significantly improve the overall performance of the resultant closed-loop system.
Abstract: In this paper, the digital control of decentralized continuous-time systems, which have approximate decentralized fixed modes, is studied. It is shown that under some conditions, discrete-time controllers can improve the overall performance of the decentralized control system, when a linear time-invariant continuous-time controller is ineffective. In order to obtain these conditions, a quantitative measure for different types of fixed modes in a decentralized system is given. In this case, it is shown that generalized sampled-data hold functions (GSHF) instead of a simple zero-order hold (ZOH), in the implementation of the digital controllers, can significantly improve the overall performance of the resultant closed-loop system. The proposed sampled-data controller is, in fact, a linear time-varying controller for the continuous-time system.
5 citations
14 Jun 2006
TL;DR: This note outlines enhancements to previously developed switching controllers in an effort to improve output transient behavior and results are presented that characterize limits on the rate at which the system may change.
Abstract: Linear jump parameter systems, which are characterized by sudden changes in dynamics, are ready candidates for the application of switching control. This note outlines enhancements to previously developed switching controllers in an effort to improve output transient behavior. As well, results are presented that characterize limits on the rate at which the system may change, and a condition for stability in the presence of rapid changes is presented.
4 citations
TL;DR: In this paper, the authors considered linear time invariant (LTI) systems with parameter uncertainty and presented global optimization techniques to determine permissible perturbations of the parameters of the system that maintain stability.
Abstract: In this paper, we consider linear time invariant (LTI) systems with parameter uncertainty. For such systems, we present global optimization techniques to determine permissible perturbations of the parameters of the system that maintain stability (the so-called parameter stability margins), for cases in which the coefficients of the characteristic equation of the system are polynomial functions of the uncertain parameters. The parameter uncertainty domains for maintaining stability are characterized as hypersolids, defined with respect to lp -norms for various values of p ∊ (1, ∞). Algorithms are devised based on the reformulation–linearization/convexification technique (RLT) in concert with branch-and-bound methods to solve the underlying parametric non-convex subproblems for computing the stability margins. Several illustrative examples are solved to demonstrate the efficacy of the proposed approach towards producing global optimal solutions. We also present comparative computational experience with the ...
2 citations