9,573 research outputs found
Stability and Equilibrium Analysis of Laneless Traffic with Local Control Laws
In this paper, a new model for traffic on roads with multiple lanes is
developed, where the vehicles do not adhere to a lane discipline. Assuming
identical vehicles, the dynamics is split along two independent directions: the
Y-axis representing the direction of motion and the X-axis representing the
lateral or the direction perpendicular to the direction of motion. Different
influence graphs are used to model the interaction between the vehicles in
these two directions. The instantaneous accelerations of each car, in both X
and Y directions, are functions of the measurements from the neighbouring cars
according to these influence graphs. The stability and equilibrium spacings of
the car formation is analyzed for usual traffic situations such as steady flow,
obstacles, lane changing and rogue drivers arbitrarily changing positions
inside the formation. Conditions are derived under which the formation
maintains stability and the desired intercar spacing for each of these traffic
events. Simulations for some of these scenarios are included.Comment: 8 page
Social issues of power harvesting as key enables of WSN in pervasive computing
Pervasive systems have gained popularity and open the door to new applications that will improve the quality of life of the users. Additionally, the implementation of such systems over an infrastructure of Wireless Sensor Networks has been proven to be very powerful. To deal with the WSN problems related to the battery of the elements or nodes that constitute the WSN, Power Harvesting techniques arise as good candidates. With PH each node can extract the energy from the surrounding environment. However, this energy source could not be constant, affecting the continuity and quality of the services provided. This behavior can have a negative impact on the user's perception about the system, which could be perceived as unreliable or faulty. In the current paper, some related works regarding pervasive systems within the home environment are referenced to extrapolate the conclusions and problems to the paradigm of Power Harvesting Pervasive Systems from the user perspective. Besides, the paper speculates about the approach and methods to overcome these potential problems and presents the design trends that could be followed.<br/
Vehicle platoons through ring coupling
In this paper, a novel strategy for the control of a string of vehicles is designed. The vehicles are coupled in a unidirectional ring at the interaction level: each vehicle is influenced by the position of its immediate forward neighbor; the first vehicle in the platoon is influenced by the position of the last vehicle. Through these interactions a cooperative behavior emerges and a platoon of vehicles moving at a constant velocity with constant inter-vehicle spacings is formed. This contrasts with more traditional control schemes where an independent leader vehicle is followed by the remaining vehicles. For this control structure, stability properties are established. The concept of string stability of a platoon is discussed and applied to the ring interconnection. Design rules are presented, showing how an appropriate choice of parameter values leads to a constant spacing or constant time headway policy. Furthermore, the scheme has a characteristic property: it maintains the platoon structure when subject to malfunctioning vehicles
Stability Margin Scaling Laws for Distributed Formation Control as a Function of Network Structure
We consider the problem of distributed formation control of a large number of
vehicles. An individual vehicle in the formation is assumed to be a fully
actuated point mass. A distributed control law is examined: the control action
on an individual vehicle depends on (i) its own velocity and (ii) the relative
position measurements with a small subset of vehicles (neighbors) in the
formation. The neighbors are defined according to an information graph.
In this paper we describe a methodology for modeling, analysis, and
distributed control design of such vehicular formations whose information graph
is a D-dimensional lattice. The modeling relies on an approximation based on a
partial differential equation (PDE) that describes the spatio-temporal
evolution of position errors in the formation. The analysis and control design
is based on the PDE model. We deduce asymptotic formulae for the closed-loop
stability margin (absolute value of the real part of the least stable
eigenvalue) of the controlled formation. The stability margin is shown to
approach 0 as the number of vehicles N goes to infinity. The exponent on the
scaling law for the stability margin is influenced by the dimension and the
structure of the information graph. We show that the scaling law can be
improved by employing a higher dimensional information graph.
Apart from analysis, the PDE model is used for a mistuning-based design of
control gains to maximize the stability margin. Mistuning here refers to small
perturbation of control gains from their nominal symmetric values. We show that
the mistuned design can have a significantly better stability margin even with
a small amount of perturbation. The results of the analysis with the PDE model
are corroborated with numerical computation of eigenvalues with the state-space
model of the formation.Comment: This paper is the expanded version of the paper with the same name
which is accepted by the IEEE Transactions on Automatic Control. The final
version is updated on Oct. 12, 201
Transients in the Synchronization of Oscillator Arrays
The purpose of this note is threefold. First we state a few conjectures that
allow us to rigorously derive a theory which is asymptotic in N (the number of
agents) that describes transients in large arrays of (identical) linear damped
harmonic oscillators in R with completely decentralized nearest neighbor
interaction. We then use the theory to establish that in a certain range of the
parameters transients grow linearly in the number of agents (and faster outside
that range). Finally, in the regime where this linear growth occurs we give the
constant of proportionality as a function of the signal velocities (see [3]) in
each of the two directions. As corollaries we show that symmetric interactions
are far from optimal and that all these results independent of (reasonable)
boundary conditions.Comment: 11 pages, 4 figure
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