651 research outputs found
Quantization effects and convergence properties of rigid formation control systems with quantized distance measurements
In this paper, we discuss quantization effects in rigid formation control
systems when target formations are described by inter-agent distances. Because
of practical sensing and measurement constraints, we consider in this paper
distance measurements in their quantized forms. We show that under
gradient-based formation control, in the case of uniform quantization, the
distance errors converge locally to a bounded set whose size depends on the
quantization error, while in the case of logarithmic quantization, all distance
errors converge locally to zero. A special quantizer involving the signum
function is then considered with which all agents can only measure coarse
distances in terms of binary information. In this case, the formation converges
locally to a target formation within a finite time. Lastly, we discuss the
effect of asymmetric uniform quantization on rigid formation control.Comment: 29 pages, International Journal of Robust and Nonlinear Control 201
An Overview of Recent Progress in the Study of Distributed Multi-agent Coordination
This article reviews some main results and progress in distributed
multi-agent coordination, focusing on papers published in major control systems
and robotics journals since 2006. Distributed coordination of multiple
vehicles, including unmanned aerial vehicles, unmanned ground vehicles and
unmanned underwater vehicles, has been a very active research subject studied
extensively by the systems and control community. The recent results in this
area are categorized into several directions, such as consensus, formation
control, optimization, task assignment, and estimation. After the review, a
short discussion section is included to summarize the existing research and to
propose several promising research directions along with some open problems
that are deemed important for further investigations
Coordination of passive systems under quantized measurements
In this paper we investigate a passivity approach to collective coordination
and synchronization problems in the presence of quantized measurements and show
that coordination tasks can be achieved in a practical sense for a large class
of passive systems.Comment: 40 pages, 1 figure, submitted to journal, second round of revie
Adaptive Control of Systems with Quantization and Time Delays
This thesis addresses problems relating to tracking control of nonlinear systems in the presence of quantization and time delays. Motivated by the importance in areas such as networked control systems (NCSs) and digital systems, where the use of a communication network in NCS introduces several constraints to the control system, such as the occurrence of quantization and time delays. Quantization and time delays are of both practical and theoretical importance, and the study of systems where these issues arises is thus of great importance. If the system also has parameters that vary or are uncertain, this will make the control problem more complicated. Adaptive control is one tool to handle such system uncertainty. In this thesis, adaptive backstepping control schemes are proposed to handle uncertainties in the system, and to reduce the effects of quantization. Different control problems are considered where quantization is introduced in the control loop, either at the input, the state or both the input and the state. The quantization introduces difficulties in the controller design and stability analysis due to the limited information and nonlinear characteristics, such as discontinuous phenomena. In the thesis, it is analytically shown how the choice of quantization level affects the tracking performance, and how the stability of the closed-loop system equilibrium can be achieved by choosing proper design parameters. In addition, a predictor feedback control scheme is proposed to compensate for a time delay in the system, where the inputs are quantized at the same time. Experiments on a 2-degrees of freedom (DOF) helicopter system demonstrate the different developed control schemes.publishedVersio
On the passivity approach to quantized coordination problems
We investigate a passivity approach to collective coordination problems in the presence of quantized measurements and show that coordination tasks can be achieved in a practical sense for a large class of passive systems. Both static and time-varying graphs are considered. The results are then specialized to some particular coordination problems and compared with existing results.</p
Cooperative Nearest-Neighbor Control of Multi-Agent Systems: Consensus and Formation Control Problems
This letter studies the problem of cooperative nearest-neighbor control of
multi-agent systems where each agent can only realize a finite set of control
points. Under the assumption that the underlying graph representing the
communication network between agents is connected and the interior of the
convex hull of all finite actions of each agent contains the zero element,
consensus or distance-based formation problems can practically be stabilized by
means of nearest-neighbor control approach combined with the well-known
consensus control or distributed formation control laws, respectively.
Furthermore, we provide the convergence bound for each corresponding error
vector which can be computed based on the information of individual agent's
finite control points. Finally, we show Monte Carlo numerical simulations that
confirm our analysis
- …