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Physical systems typically evolve continuously whereas modern controllers and signal processing devices invariably operate in discrete time. Hence sampling arises as a cornerstone problem in essentially all aspects of modern systems science. This paper reviews various aspects of sampling of signals and systems. We argue that careful consideration must be given to sampling to obtain meaningful results...
The world's first robotic insect capable of vertical takeoff was developed and demonstrated by the Harvard Microrobotics Lab. This vehicle consisted of a single power actuator that drove both wings symmetrically. In this case, there was no method to generate body torques, only lift could be modulated. The Harvard Microrobotics Lab has modified this configuration to include not only a single power...
In this paper, we present a mathematical model of near-hover attitude dynamics and control in flapping flight. Then we apply this model to fruit fly (Drosophila) as an example. The attitude dynamics are derived from the complete 6-DOF equations of motion. Stability derivatives are estimated based on quasi-steady aerodynamic models of Flapping counter-torques (FCTs). Control derivatives are derived...
This paper details the flight dynamics and control of a prototype mono-wing rotorcraft that mimics the passive transit of the species of samara (winged seed), Acer diabolicum Blume. The asymmetric and all-rotating platform requires the development of a novel sensing and control framework. The general rigid body dynamics are separated into rotor dynamics and particle navigation, which are derived for...
This paper describes the Samarai - a rotating mono-wing nano air vehicle (NAV) designed at Lockheed Martin Advanced Technology Laboratories. Challenges uniquely associated with developing this type of vehicle are identified and a dynamic modeling and control synthesis procedure is described for tackling them. It is shown that, by modeling the rotating wing as a lower-complexity spinning disk, and...
In this work, we study the collective behavior of fish shoals in annular domains. Shoal mates are modeled as self-propelled particles moving on a discrete lattice. Collective decision making is determined by information exchange among neighbors. Topological distances are used to specify neighborhoods within the fish shoal. We employ random variables to model fish self-propulsion and obedience to group...
This paper presents modification of the conventional model reference adaptive control (MRAC) architecture in order to achieve guaranteed transient performance both in the output and input signals of an uncertain system. The proposed modification is based on the tracking error feedback to the reference model. It is shown that approach guarantees tracking of a given command and the ideal control signal...
Adaptive control using multiple identification models is currently well established. Switching, tuning, and switching and tuning in such systems have been extensively investigated, and their stability properties have been established [1]. If the number of models is sufficiently large, and is uniformly distributed in parameter space, the method results in fast and accurate response. In practice, even...
In this paper, we develop an output feedback adaptive control framework for continuous-time nonminimum phase multivariable systems for output stabilization and command following. The approach is based on a nonminimal state space realization that generates an expanded set of states using the filtered inputs and filtered outputs of the original system. Specifically, a direct adaptive controller for...
In this paper, we study the output synchronization problem of networked Euler-Lagrange(EL) systems subject to nonholonomic constraints. An EL system subject to nonholonomic constraints can be input-output linearized if a proper decoupling matrix can be found, and the linearized form is equivalent to a double integrator. Although a double integrator is not a passive system, with proper design of the...
An enhancement to the CSMA p-persistent protocol family is proposed, based on a fully decentralized control that adjusts the message transmission rate of each node to the estimated density of surrounding transmitting nodes. The system does not require enumeration of nodes nor control messages, the only input to the control coming from the physical medium occupation. Stability conditions are given...
Cognitive radio systems are currently a popular topic and are a good prospect for research when combined with control technology. In this paper, we consider the control and estimation via a two switch model which can represent a cognitive radio system. We provide an optimal estimator for this model and demonstrate that the optimal LQG controller is not a linear gain of the estimate of the states,...
This paper considers the problem of time-domain assessment of the Phase Margin (PM) of a Single Input Single Output (SISO) Linear Time-Invariant (LTI) system using a singular perturbation approach, where a SISO LTI fast loop system, whose phase lag increases monotonically with frequency, is introduced into the loop as a singular perturbation with a singular perturbation (time-scale separation) parameter...
Dynamic Systems & Control is one of the most difficult courses to teach in the mechanical engineering curriculum. The subject is very mathematical and the mathematical framework is unfamiliar to novice students. Recently we began using a video game to demonstrate and teach content of the course. The game provides a natural way to align instruction with constructivist theories on how people learn...
A wooden game board named Shoot-the-Moon has interesting dynamics properties despite its simple structure of one steel ball rolling on two cylindrical rods. In this paper, we derive the equations of motion for Shoot-the-moon using an Eular-Lagrangian approach and explore its underactuated, nonlinear, nonholonomic dynamics. Two positon controllers are designed, one for a local linearization and another...
The straight beam in the ball and beam control experiment was replaced by a curved beam mounted away from its center of rotation. The resulting system is much harder to understand, model and control than the ball and straight beam. Nonetheless, the apparatus was constructed, a model was derived using Lagrangian mechanics, and a controller was designed using a linearized model and the LQR. This controller...
Combining solid oxide fuel cell and gas turbine (SOFC/GT) system is a promising concept for future clean and efficient power generation. An SOFC/GT system exploits the complementary features of the two power plants, where the GT recuperates the energy in the SOFC exhaust stream and thereby boosting the overall system efficiency. Through model based transient analysis, however, it is shown that the...
We demonstrate an alternative approach for the hedging of flexible energy conversion networks appropriate for use in campus scale and municipal scale utilities with complex energy requirements, fuel sources, and operational flexibility. This new approach utilizes empirical modeling of price models for alternative commodity fuels coupled with a previously reported class of bilinear models for estimating...
A decision-theoretic approach to modeling the response of multi-strain pathogens to humoral defense is investigated in this paper. The reported theory of language-measure theoretic optimal control is used to compute the optimal response of the invading pathogen. The model is validated by comparison of simulation results with in-vivo observations and contrasted with prominent existing modeling approaches.
Deep brain stimulation (DBS) is a clinically recognized electrical therapy for the treatment of several neural disorders, e.g., Parkinson's disease (PD), essential tremor, and compulsive disorders. High frequency (HF) STN DBS (Deep Brain Stimulation in SubThalamic Nucleus) is currently used to reduce the motor symptoms of PD, but the actual procedures for the selection of the stimulation parameters...
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