662 research outputs found
Animal-Inspired Agile Flight Using Optical Flow Sensing
There is evidence that flying animals such as pigeons, goshawks, and bats use
optical flow sensing to enable high-speed flight through forest clutter. This
paper discusses the elements of a theory of controlled flight through obstacle
fields in which motion control laws are based on optical flow sensing.
Performance comparison is made with feedback laws that use distance and bearing
measurements, and practical challenges of implementation on an actual robotic
air vehicle are described. The related question of fundamental performance
limits due to clutter density is addressed.Comment: 20 pages, 7 figure
Saliency Based Control in Random Feature Networks
The ability to rapidly focus attention and react to salient environmental
features enables animals to move agiley through their habitats. To replicate
this kind of high-performance control of movement in synthetic systems, we
propose a new approach to feedback control that bases control actions on
randomly perceived features. Connections will be made with recent work
incorporating communication protocols into networked control systems. The
concepts of {\em random channel controllability} and {\em random channel
observability} for LTI control systems are introduced and studied.Comment: 9 pages, 2 figure
A two level feedback system design to provide regulation reserve
Demand side management has gained increasing importance as the penetration of renewable energy grows. Based on a Markov jump process modelling of a group of thermostatic loads, this paper proposes a two level feedback system design be- tween the independent system operator (ISO) and the regulation service provider such that two objectives are achieved: (1) the ISO can optimally dispatch regulation signals to multiple providers in real time in order to reduce the requirement for expensive spinning reserves, and (2) each regulation provider can control its thermostatic loads to respond the ISO signal. It is also shown that the amount of regulation service that can be provided is implicitly restricted by a few fundamental parameters of the provider itself, such as the allowable set point choice and its thermal constant. An interesting finding is that the regulation provider’s ability to provide a large amount of long term accumulated regulation and short term signal tracking restrict each other. Simulation results are presented to verify and illustrate the performance of the proposed framework
A Packetized Direct Load Control Mechanism for Demand Side Management
Electricity peaks can be harmful to grid stability and result in additional
generation costs to balance supply with demand. By developing a network of
smart appliances together with a quasi-decentralized control protocol, direct
load control (DLC) provides an opportunity to reduce peak consumption by
directly controlling the on/off switch of the networked appliances. This paper
proposes a packetized DLC (PDLC) solution that is illustrated by an application
to air conditioning temperature control. Here the term packetized refers to a
fixed time energy usage authorization. The consumers in each room choose their
preferred set point, and then an operator of the local appliance pool will
determine the comfort band around the set point. We use a thermal dynamic model
to investigate the duty cycle of thermostatic appliances. Three theorems are
proposed in this paper. The first two theorems evaluate the performance of the
PDLC in both transient and steady state operation. The first theorem proves
that the average room temperature would converge to the average room set point
with fixed number of packets applied in each discrete interval. The second
theorem proves that the PDLC solution guarantees to control the temperature of
all the rooms within their individual comfort bands. The third theorem proposes
an allocation method to link the results in theorem 1 and assumptions in
theorem 2 such that the overall PDLC solution works. The direct result of the
theorems is that we can reduce the consumption oscillation that occurs when no
control is applied. Simulation is provided to verify theoretical results.Comment: the 51st IEEE Conference on Decision and Control,December 10-13,
Maui, 201
Paradigm and Paradox in Topology Control of Power Grids
Corrective Transmission Switching can be used by the grid operator to relieve
line overloading and voltage violations, improve system reliability, and reduce
system losses. Power grid optimization by means of line switching is typically
formulated as a mixed integer programming problem (MIP). Such problems are
known to be computationally intractable, and accordingly, a number of heuristic
approaches to grid topology reconfiguration have been proposed in the power
systems literature. By means of some low order examples (3-bus systems), it is
shown that within a reasonably large class of greedy heuristics, none can be
found that perform better than the others across all grid topologies. Despite
this cautionary tale, statistical evidence based on a large number of
simulations using using IEEE 118- bus systems indicates that among three
heuristics, a globally greedy heuristic is the most computationally intensive,
but has the best chance of reducing generation costs while enforcing N-1
connectivity. It is argued that, among all iterative methods, the locally
optimal switches at each stage have a better chance in not only approximating a
global optimal solution but also greatly limiting the number of lines that are
switched
The control theory of motion-based communication: problems in teaching robots to dance
The paper describes results on two components of a research program focused on motion-based communication mediated by the dynamics of a control system. Specifically we are interested in how mobile agents engaged in a shared activity such as dance can use motion as a medium for transmitting certain types of messages. The first part of the paper adopts the terminology of motion description languages and deconstructs an elementary form of the well-known popular dance, Salsa, in terms of four motion primitives (dance steps). Several notions of dance complexity are introduced. We describe an experiment in which ten performances by an actual pair of dancers are evaluated by judges and then compared in terms of proposed complexity metrics. An energy metric is also defined. Values of this metric are obtained by summing the lengths of motion segments executed by wheeled robots replicating the movements of the human dancers in each of the ten dance performances. Of all the metrics that are considered in this experiment, energy is the most closely correlated with the human judges' assessments of performance quality. The second part of the paper poses a general class of dual objective motion control problems in which a primary objective (artistic execution of a dance step or efficient movement toward a specified terminal state) is combined with a communication objective. Solutions of varying degrees of explicitness can be given in several classes of problems of communicating through the dynamics of finite dimensional linear control systems. In this setting it is shown that the cost of adding a communication component to motions that steer a system between prescribed pairs of states is independent of those states. At the same time, the optimal encoding problem itself is shown to be a problem of packing geometric objects, and it remains open. Current research is aimed at solving such communication-through-action problems in the context of the motion control of mobile robots.Support for this work is gratefully acknowledged to ODDR&E MURI07 Program Grant Number FA9550-07-1-0528, the National Science Founda tion ITR Program Grant Number DMI-0330171, and the Office of Naval Research, and by ODDR&E MURI10 Program Grant Number N00014-10- 1-0952. (FA9550-07-1-0528 - ODDRE MURI07; DMI-0330171 - National Science Foundation ITR Program; Office of Naval Research; N00014-10-1-0952 - ODDRE MURI10
Decision Making for Rapid Information Acquisition in the Reconnaissance of Random Fields
Research into several aspects of robot-enabled reconnaissance of random
fields is reported. The work has two major components: the underlying theory of
information acquisition in the exploration of unknown fields and the results of
experiments on how humans use sensor-equipped robots to perform a simulated
reconnaissance exercise.
The theoretical framework reported herein extends work on robotic exploration
that has been reported by ourselves and others. Several new figures of merit
for evaluating exploration strategies are proposed and compared. Using concepts
from differential topology and information theory, we develop the theoretical
foundation of search strategies aimed at rapid discovery of topological
features (locations of critical points and critical level sets) of a priori
unknown differentiable random fields. The theory enables study of efficient
reconnaissance strategies in which the tradeoff between speed and accuracy can
be understood. The proposed approach to rapid discovery of topological features
has led in a natural way to to the creation of parsimonious reconnaissance
routines that do not rely on any prior knowledge of the environment. The design
of topology-guided search protocols uses a mathematical framework that
quantifies the relationship between what is discovered and what remains to be
discovered. The quantification rests on an information theory inspired model
whose properties allow us to treat search as a problem in optimal information
acquisition. A central theme in this approach is that "conservative" and
"aggressive" search strategies can be precisely defined, and search decisions
regarding "exploration" vs. "exploitation" choices are informed by the rate at
which the information metric is changing.Comment: 34 pages, 20 figure
Control and Communication Protocols that Enable Smart Building Microgrids
Recent communication, computation, and technology advances coupled with
climate change concerns have transformed the near future prospects of
electricity transmission, and, more notably, distribution systems and
microgrids. Distributed resources (wind and solar generation, combined heat and
power) and flexible loads (storage, computing, EV, HVAC) make it imperative to
increase investment and improve operational efficiency. Commercial and
residential buildings, being the largest energy consumption group among
flexible loads in microgrids, have the largest potential and flexibility to
provide demand side management. Recent advances in networked systems and the
anticipated breakthroughs of the Internet of Things will enable significant
advances in demand response capabilities of intelligent load network of
power-consuming devices such as HVAC components, water heaters, and buildings.
In this paper, a new operating framework, called packetized direct load control
(PDLC), is proposed based on the notion of quantization of energy demand. This
control protocol is built on top of two communication protocols that carry
either complete or binary information regarding the operation status of the
appliances. We discuss the optimal demand side operation for both protocols and
analytically derive the performance differences between the protocols. We
propose an optimal reservation strategy for traditional and renewable energy
for the PDLC in both day-ahead and real time markets. In the end we discuss the
fundamental trade-off between achieving controllability and endowing
flexibility
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