4,968 research outputs found
Correct-by-Construction Approach for Self-Evolvable Robots
The paper presents a new formal way of modeling and designing reconfigurable
robots, in which case the robots are allowed to reconfigure not only
structurally but also functionally. We call such kind of robots
"self-evolvable", which have the potential to be more flexible to be used in a
wider range of tasks, in a wider range of environments, and with a wider range
of users. To accommodate such a concept, i.e., allowing a self-evovable robot
to be configured and reconfigured, we present a series of formal constructs,
e.g., structural reconfigurable grammar and functional reconfigurable grammar.
Furthermore, we present a correct-by-construction strategy, which, given the
description of a workspace, the formula specifying a task, and a set of
available modules, is capable of constructing during the design phase a robot
that is guaranteed to perform the task satisfactorily. We use a planar
multi-link manipulator as an example throughout the paper to demonstrate the
proposed modeling and designing procedures.Comment: The paper has 17 pages and 4 figure
Receding Horizon Temporal Logic Control for Finite Deterministic Systems
This paper considers receding horizon control of finite deterministic
systems, which must satisfy a high level, rich specification expressed as a
linear temporal logic formula. Under the assumption that time-varying rewards
are associated with states of the system and they can be observed in real-time,
the control objective is to maximize the collected reward while satisfying the
high level task specification. In order to properly react to the changing
rewards, a controller synthesis framework inspired by model predictive control
is proposed, where the rewards are locally optimized at each time-step over a
finite horizon, and the immediate optimal control is applied. By enforcing
appropriate constraints, the infinite trajectory produced by the controller is
guaranteed to satisfy the desired temporal logic formula. Simulation results
demonstrate the effectiveness of the approach.Comment: Technical report accompanying a paper to be presented at ACC 201
Time-Constrained Temporal Logic Control of Multi-Affine Systems
In this paper, we consider the problem of controlling a dynamical system such
that its trajectories satisfy a temporal logic property in a given amount of
time. We focus on multi-affine systems and specifications given as
syntactically co-safe linear temporal logic formulas over rectangular regions
in the state space. The proposed algorithm is based on the estimation of time
bounds for facet reachability problems and solving a time optimal reachability
problem on the product between a weighted transition system and an automaton
that enforces the satisfaction of the specification. A random optimization
algorithm is used to iteratively improve the solution
Breaking Dense Structures: Proving Stability of Densely Structured Hybrid Systems
Abstraction and refinement is widely used in software development. Such
techniques are valuable since they allow to handle even more complex systems.
One key point is the ability to decompose a large system into subsystems,
analyze those subsystems and deduce properties of the larger system. As
cyber-physical systems tend to become more and more complex, such techniques
become more appealing.
In 2009, Oehlerking and Theel presented a (de-)composition technique for
hybrid systems. This technique is graph-based and constructs a Lyapunov
function for hybrid systems having a complex discrete state space. The
technique consists of (1) decomposing the underlying graph of the hybrid system
into subgraphs, (2) computing multiple local Lyapunov functions for the
subgraphs, and finally (3) composing the local Lyapunov functions into a
piecewise Lyapunov function. A Lyapunov function can serve multiple purposes,
e.g., it certifies stability or termination of a system or allows to construct
invariant sets, which in turn may be used to certify safety and security.
In this paper, we propose an improvement to the decomposing technique, which
relaxes the graph structure before applying the decomposition technique. Our
relaxation significantly reduces the connectivity of the graph by exploiting
super-dense switching. The relaxation makes the decomposition technique more
efficient on one hand and on the other allows to decompose a wider range of
graph structures.Comment: In Proceedings ESSS 2015, arXiv:1506.0325
Optimality and robustness in multi-robot path planning with temporal logic constraints
In this paper we present a method for automatically generating optimal robot paths satisfying high-level mission specifications. The motion of the robot in the environment is modeled as a weighted transition system. The mission is specified by an arbitrary linear temporal-logic (LTL) formula over propositions satisfied at the regions of a partitioned environment. The mission specification contains an optimizing proposition, which must be repeatedly satisfied. The cost function that we seek to minimize is the maximum time between satisfying instances of the optimizing proposition. For every environment model, and for every formula, our method computes a robot path that minimizes the cost function. The problem is motivated by applications in robotic monitoring and data-gathering. In this setting, the optimizing proposition is satisfied at all locations where data can be uploaded, and the LTL formula specifies a complex data-collection mission. Our method utilizes Büchi automata to produce an automaton (which can be thought of as a graph) whose runs satisfy the temporal-logic specification. We then present a graph algorithm that computes a run corresponding to the optimal robot path. We present an implementation for a robot performing data collection in a road-network platform.This work was supported in part by the Office of Naval Research (grant number MURI N00014-09-1051), Army Research Office (grant number W911NF-09-1-0088), Air Force Office of Scientific Research (grant number YIP FA9550-09-1-020), National Science Foundation (grant number CNS-0834260), Singapore-MIT Alliance for Research and Technology (SMART) Future of Urban Mobility Project and by Natural Sciences and Engineering Research Council of Canada. (MURI N00014-09-1051 - Office of Naval Research; W911NF-09-1-0088 - Army Research Office; YIP FA9550-09-1-020 - Air Force Office of Scientific Research; CNS-0834260 - National Science Foundation; Singapore-MIT Alliance for Research and Technology (SMART); Natural Sciences and Engineering Research Council of Canada
Model Checking One-clock Priced Timed Automata
We consider the model of priced (a.k.a. weighted) timed automata, an
extension of timed automata with cost information on both locations and
transitions, and we study various model-checking problems for that model based
on extensions of classical temporal logics with cost constraints on modalities.
We prove that, under the assumption that the model has only one clock,
model-checking this class of models against the logic WCTL, CTL with
cost-constrained modalities, is PSPACE-complete (while it has been shown
undecidable as soon as the model has three clocks). We also prove that
model-checking WMTL, LTL with cost-constrained modalities, is decidable only if
there is a single clock in the model and a single stopwatch cost variable
(i.e., whose slopes lie in {0,1}).Comment: 28 page
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