490 research outputs found
Symmetry Reduction Enables Model Checking of More Complex Emergent Behaviours of Swarm Navigation Algorithms
The emergent global behaviours of robotic swarms are important to achieve
their navigation task goals. These emergent behaviours can be verified to
assess their correctness, through techniques like model checking. Model
checking exhaustively explores all possible behaviours, based on a discrete
model of the system, such as a swarm in a grid. A common problem in model
checking is the state-space explosion that arises when the states of the model
are numerous. We propose a novel implementation of symmetry reduction, in the
form of encoding navigation algorithms relatively with respect to a reference,
based on the symmetrical properties of swarms in grids. We applied the relative
encoding to a swarm navigation algorithm, Alpha, modelled for the NuSMV model
checker. A comparison of the state-space and verification results with an
absolute (or global) and a relative encoding of the Alpha algorithm highlights
the advantages of our approach, allowing model checking larger grid sizes and
number of robots, and consequently, verifying more complex emergent behaviours.
For example, a property was verified for a grid with 3 robots and a maximum
allowed size of 8x8 cells in a global encoding, whereas this size was increased
to 16x16 using a relative encoding. Also, the time to verify a property for a
swarm of 3 robots in a 6x6 grid was reduced from almost 10 hours to only 7
minutes. Our approach is transferable to other swarm navigation algorithms.Comment: Accepted for presentation in Towards Autonomous Robotic Systems
(TAROS) 2015, Liverpool, U
Towards a Formal Verification Methodology for Collective Robotic Systems
We introduce a UML-based notation for graphically modeling
systemsā security aspects in a simple and intuitive
way and a model-driven process that transforms graphical
specifications of access control policies in XACML. These
XACML policies are then translated in FACPL, a policy
language with a formal semantics, and the resulting policies
are evaluated by means of a Java-based software tool
Towards temporal verification of swarm robotic systems
A robot swarm is a collection of simple robots designed to work together to carry out some task. Such swarms rely on the simplicity of the individual robots; the fault tolerance inherent in having a large population of identical robots; and the self-organised behaviour of the swarm as a whole. Although robot swarms present an attractive solution to demanding real-world applications, designing individual control algorithms that can guarantee the required global behaviour is a difficult problem. In this paper we assess and apply the use of formal verification techniques for analysing the emergent behaviours of robotic swarms. These techniques, based on the automated analysis of systems using temporal logics, allow us to analyse whether all possible behaviours within the robot swarm conform to some required specification. In particular, we apply model-checking, an automated and exhaustive algorithmic technique, to check whether temporal properties are satisfied on all the possible behaviours of the system. We target a particular swarm control algorithm that has been tested in real robotic swarms, and show how automated temporal analysis can help to refine and analyse such an algorithm. Ā© 2012 Elsevier B.V. All rights reserved
Distributed Monitoring of Robot Swarms with Swarm Signal Temporal Logic
In this paper, we develop a distributed monitoring framework for robot swarms
so that the agents can monitor whether the executions of robot swarms satisfy
Swarm Signal Temporal Logic (SwarmSTL) formulas. We define generalized moments
(GMs) to represent swarm features. A dynamic generalized moments consensus
algorithm (GMCA) with Kalman filter (KF) is proposed so that each agent can
estimate the GMs. Also, we obtain an upper bound for the error between an
agent's estimate and the actual GMs. This bound is independent of the motion of
the agents. We also propose rules for monitoring SwarmSTL temporal and logical
operators. As a result, the agents can monitor whether the swarm satisfies
SwarmSTL formulas with a certain confidence level using these rules and the
bound of the estimation error. The distributed monitoring framework is applied
to a swarm transporting supplies example, where we also show the efficacy of
the Kalman filter in the dynamic generalized moments consensus process
Towards formal models and languages for verifiable Multi-Robot Systems
Incorrect operations of a Multi-Robot System (MRS) may not only lead to
unsatisfactory results, but can also cause economic losses and threats to
safety. These threats may not always be apparent, since they may arise as
unforeseen consequences of the interactions between elements of the system.
This call for tools and techniques that can help in providing guarantees about
MRSs behaviour. We think that, whenever possible, these guarantees should be
backed up by formal proofs to complement traditional approaches based on
testing and simulation.
We believe that tailored linguistic support to specify MRSs is a major step
towards this goal. In particular, reducing the gap between typical features of
an MRS and the level of abstraction of the linguistic primitives would simplify
both the specification of these systems and the verification of their
properties. In this work, we review different agent-oriented languages and
their features; we then consider a selection of case studies of interest and
implement them useing the surveyed languages. We also evaluate and compare
effectiveness of the proposed solution, considering, in particular, easiness of
expressing non-trivial behaviour.Comment: Changed formattin
On formal specification of emergent behaviours in swarm robotic systems
It is a characteristic of swarm robotics that specifying overall emergent swarm behaviours in terms of the low-level behaviours of individual robots is very difficult. Yet if swarm robotics is to make the transition from the laboratory to real-world engineering realisation we need such specifications. This paper explores the use of temporal logic to formally specify, and possibly also prove, the emergent behaviours of a robotic swarm. The paper makes use of a simplified wireless connected swarm as a case study with which to illustrate the approach. Such a formal approach could be an important step toward a disciplined design methodology for swarm robotics
Modelling and analyzing adaptive self-assembling strategies with Maude
Building adaptive systems with predictable emergent behavior is a challenging task and it is becoming a critical need. The research community has accepted the challenge by introducing approaches of various nature: from software architectures, to programming paradigms, to analysis techniques. We recently proposed a conceptual framework for adaptation centered around the role of control data. In this paper we show that it can be naturally realized in a reflective logical language like Maude by using the Reflective Russian Dolls model. Moreover, we exploit this model to specify, validate and analyse a prominent example of adaptive system: robot swarms equipped with self-assembly strategies. The analysis exploits the statistical model checker PVeStA
Morphogen diffusion algorithms for tracking and herding using a swarm of kilobots
Ā© 2016 Springer-Verlag Berlin Heidelberg This paper investigates self-organised collective formation control using swarm robots. In particular, we focus on collective tracking and herding using a large number of very simple robots. To this end, we choose kilobots as our swarm robot test bed due to its low cost and attractive operational scalability. Note, however, that kilobots have extremely limited locomotion, sensing and communication capabilities. To handle these limitations, a number of new control algorithms based on morphogen diffusion and network connectivity preservation have been suggested for collective object tracking and herding. Numerical simulations of large-scale swarm systems as well as preliminary physical experiments with a relatively small number of kilobots have been performed to verify the effectiveness of the proposed algorithms
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