4,842 research outputs found
A macroscopic analytical model of collaboration in distributed robotic systems
In this article, we present a macroscopic analytical model of collaboration in a group of reactive robots. The model consists of a series of coupled differential equations that describe the dynamics of group behavior. After presenting the general model, we analyze in detail a case study of collaboration, the stick-pulling experiment, studied experimentally and in simulation by Ijspeert et al. [Autonomous Robots, 11, 149-171]. The robots' task is to pull sticks out of their holes, and it can be successfully achieved only through the collaboration of two robots. There is no explicit communication or coordination between the robots. Unlike microscopic simulations (sensor-based or using a probabilistic numerical model), in which computational time scales with the robot group size, the macroscopic model is computationally efficient, because its solutions are independent of robot group size. Analysis reproduces several qualitative conclusions of Ijspeert et al.: namely, the different dynamical regimes for different values of the ratio of robots to sticks, the existence of optimal control parameters that maximize system performance as a function of group size, and the transition from superlinear to sublinear performance as the number of robots is increased
Multi-robot team formation control in the GUARDIANS project
Purpose
The GUARDIANS multi-robot team is to be deployed in a large warehouse in smoke. The team is to assist firefighters search the warehouse in the event or danger of a fire. The large dimensions of the environment together with development of smoke which drastically reduces visibility, represent major challenges for search and rescue operations. The GUARDIANS robots guide and accompany
the firefighters on site whilst indicating possible obstacles and the locations of danger and maintaining communications links.
Design/methodology/approach
In order to fulfill the aforementioned tasks the robots need to exhibit certain behaviours. Among the basic behaviours are capabilities to stay together as a
group, that is, generate a formation and navigate while keeping this formation.
The control model used to generate these behaviours is based on the so-called social potential field framework, which we adapt to the specific tasks required for the GUARDIANS scenario. All tasks can be achieved without central control, and some of the behaviours can be performed without explicit communication between the robots.
Findings
The GUARDIANS environment requires flexible formations of the robot team: the formation has to adapt itself to the circumstances. Thus the application has forced us to redefine the concept of a formation. Using the graph-theoretic terminology, we can say that a formation may be stretched out as a path or be compact as a star or wheel. We have implemented the developed behaviours in simulation environments as well as on real ERA-MOBI robots commonly referred to as Erratics. We discuss advantages and shortcomings of our model, based on the simulations as
well as on the implementation with a team of Erratics.</p
Integrated Robotic and Network Simulation Method
The increasing use of mobile cooperative robots in a variety of applications also implies an
increasing research effort on cooperative strategies solutions, typically involving communications
and control. For such research, simulation is a powerful tool to quickly test algorithms, allowing
to do more exhaustive tests before implementation in a real application. However, the transition
from an initial simulation environment to a real application may imply substantial rework if early
implementation results do not match the ones obtained by simulation, meaning the simulation was not
accurate enough. One way to improve accuracy is to incorporate network and control strategies in the
same simulation and to use a systematic procedure to assess how different techniques perform. In this
paper, we propose a set of procedures called Integrated Robotic and Network Simulation Method
(IRoNS Method), which guide developers in building a simulation study for cooperative robots and
communication networks applications. We exemplify the use of the improved methodology in a
case-study of cooperative control comparison with and without message losses. This case is simulated
with the OMNET++/INET framework, using a group of robots in a rendezvous task with topology
control. The methodology led to more realistic simulations while improving the results presentation
and analysis.info:eu-repo/semantics/publishedVersio
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