59 research outputs found
Timed Automata Approach for Motion Planning Using Metric Interval Temporal Logic
In this paper, we consider the robot motion (or task) planning problem under
some given time bounded high level specifications. We use metric interval
temporal logic (MITL), a member of the temporal logic family, to represent the
task specification and then we provide a constructive way to generate a timed
automaton and methods to look for accepting runs on the automaton to find a
feasible motion (or path) sequence for the robot to complete the task.Comment: Full Version for ECC 201
An Efficient Algorithm for Monitoring Practical TPTL Specifications
We provide a dynamic programming algorithm for the monitoring of a fragment
of Timed Propositional Temporal Logic (TPTL) specifications. This fragment of
TPTL, which is more expressive than Metric Temporal Logic, is characterized by
independent time variables which enable the elicitation of complex real-time
requirements. For this fragment, we provide an efficient polynomial time
algorithm for off-line monitoring of finite traces. Finally, we provide
experimental results on a prototype implementation of our tool in order to
demonstrate the feasibility of using our tool in practical applications
Algebraic foundations for qualitative calculi and networks
A qualitative representation is like an ordinary representation of a
relation algebra, but instead of requiring , as
we do for ordinary representations, we only require that , for each in the algebra. A constraint
network is qualitatively satisfiable if its nodes can be mapped to elements of
a qualitative representation, preserving the constraints. If a constraint
network is satisfiable then it is clearly qualitatively satisfiable, but the
converse can fail. However, for a wide range of relation algebras including the
point algebra, the Allen Interval Algebra, RCC8 and many others, a network is
satisfiable if and only if it is qualitatively satisfiable.
Unlike ordinary composition, the weak composition arising from qualitative
representations need not be associative, so we can generalise by considering
network satisfaction problems over non-associative algebras. We prove that
computationally, qualitative representations have many advantages over ordinary
representations: whereas many finite relation algebras have only infinite
representations, every finite qualitatively representable algebra has a finite
qualitative representation; the representability problem for (the atom
structures of) finite non-associative algebras is NP-complete; the network
satisfaction problem over a finite qualitatively representable algebra is
always in NP; the validity of equations over qualitative representations is
co-NP-complete. On the other hand we prove that there is no finite
axiomatisation of the class of qualitatively representable algebras.Comment: 22 page
An Analysis Tool for Models of Virtualized Systems
This paper gives an example-driven introduction to modelling and analyzing virtualized systems in, e.g., cloud computing, using virtually timed ambients, a process algebra developed to study timing aspects of resource management for (nested) virtual machines. The calculus supports nested virtualization and virtual machines compete with other processes for the resources of their host environment. Resource provisioning in virtually timed ambients extends the capabilities of mobile ambients to model the dynamic creation, migration, and destruction of virtual machines. Quality of service properties for virtually timed ambients can be formally expressed using modal contracts describing aspects of resource provisioning and verified using a model checker for virtually timed ambients, implemented in the rewriting system Maude
Weak Alternating Timed Automata
Alternating timed automata on infinite words are considered. The main result
is a characterization of acceptance conditions for which the emptiness problem
for these automata is decidable. This result implies new decidability results
for fragments of timed temporal logics. It is also shown that, unlike for MITL,
the characterisation remains the same even if no punctual constraints are
allowed
Formal Synthesis of Control Strategies for Positive Monotone Systems
We design controllers from formal specifications for positive discrete-time
monotone systems that are subject to bounded disturbances. Such systems are
widely used to model the dynamics of transportation and biological networks.
The specifications are described using signal temporal logic (STL), which can
express a broad range of temporal properties. We formulate the problem as a
mixed-integer linear program (MILP) and show that under the assumptions made in
this paper, which are not restrictive for traffic applications, the existence
of open-loop control policies is sufficient and almost necessary to ensure the
satisfaction of STL formulas. We establish a relation between satisfaction of
STL formulas in infinite time and set-invariance theories and provide an
efficient method to compute robust control invariant sets in high dimensions.
We also develop a robust model predictive framework to plan controls optimally
while ensuring the satisfaction of the specification. Illustrative examples and
a traffic management case study are included.Comment: To appear in IEEE Transactions on Automatic Control (TAC) (2018), 16
pages, double colum
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