93 research outputs found
Trajectory Planning on Grids: Considering Speed Limit Constraints
Trajectory (path) planning is a well known and thoroughly studied field
of automated planning. It is usually used in computer games, robotics or autonomous
agent simulations. Grids are often used for regular discretization of continuous
space. Many methods exist for trajectory (path) planning on grids, we
address the well known A* algorithm and the state-of-the-art Theta* algorithm.
Theta* algorithm, as opposed to A*, provides âany-angleâ paths that look more realistic.
In this paper, we provide an extension of both these algorithms to enable
support for speed limit constraints.We experimentally evaluate and thoroughly discuss
how the extensions affect the planning process showing reasonability and justification
of our approach
On Applicability of Automated Planning for Incident Management
Incident management aims to save human lives, mitigate the effect of accidents, prevent damages, to mention a few of their benefits. Efficient coordination of rescue team members, allocation of available resources, and appropriate responses to the realtime unfolding of events is critical for managing incidents successfully.
Coordination involves a series of decisions and event monitoring, usually made by human coordinators, for instance task definition, task assignment, risk assessment, etc. Each elementary decision can be described by a named action (e.g. boarding an ambulance, assigning a task). Taken as a whole, the team coordinating an incident
response can be seen as a decision-making system.
In this paper, we discuss how invaluable assistance can be brought to such a system using automated planning.
In consultation with experts we have derived a set of requirements from which we provide a formal specification of the domain. Following the specification, we have developed a prototype domain model and evaluated it empirically. Here we present the results of this evaluation, along with several challenges (e.g uncertainty) that
we have identifie
Exploiting Block Deordering for Improving Planners Efficiency
Capturing and exploiting structural knowledge of
planning problems has shown to be a successful
strategy for making the planning process more ef-
ficient. Plans can be decomposed into its constituent
coherent subplans, called blocks, that encapsulate
some effects and preconditions, reducing
interference and thus allowing more deordering
of plans. According to the nature of blocks, they
can be straightforwardly transformed into useful
macro-operators (shortly, âmacrosâ). Macros are
well known and widely studied kind of structural
knowledge because they can be easily encoded in
the domain model and thus exploited by standard
planning engines.
In this paper, we introduce a method, called
BLOMA, that learns domain-specific macros from
plans, decomposed into âmacro-blocksâ which are
extensions of blocks, utilising structural knowledge
they capture. In contrast to existing macro learning
techniques, macro-blocks are often able to capture
high-level activities that form a basis for useful
longer macros (i.e. those consisting of more original
operators). Our method is evaluated by using
the IPC benchmarks with state-of-the-art planning
engines, and shows considerable improvement in
many cases
On Different Strategies for Eliminating Redundant Actions from Plans
Satisficing planning engines are often able to generate plans in a reasonable time, however, plans are often far from optimal. Such plans often contain a high number of redundant actions, that are actions, which can be removed without affecting the validity of the plans. Existing approaches for determining and eliminating redundant actions work in polynomial time, however, do not guarantee eliminating the "best" set of redundant actions, since such a problem is NP-complete. We introduce an approach which encodes the problem of determining the "best" set of redundant actions (i.e. having the maximum total-cost) as a weighted MaxSAT problem. Moreover, we adapt the existing polynomial technique which greedily tries to eliminate an action and its dependants from the plan in order to eliminate more expensive redundant actions. The proposed approaches are empirically compared to existing approaches on plans generated by state-of-the-art planning engines on standard planning benchmark
ASAP: An Automatic Algorithm Selection Approach for Planning
Despite the advances made in the last decade in automated planning, no planner out-
performs all the others in every known benchmark domain. This observation motivates
the idea of selecting different planning algorithms for different domains. Moreover, the
plannersâ performances are affected by the structure of the search space, which depends
on the encoding of the considered domain. In many domains, the performance of a plan-
ner can be improved by exploiting additional knowledge, for instance, in the form of
macro-operators or entanglements.
In this paper we propose ASAP, an automatic Algorithm Selection Approach for
Planning that: (i) for a given domain initially learns additional knowledge, in the form
of macro-operators and entanglements, which is used for creating different encodings
of the given planning domain and problems, and (ii) explores the 2 dimensional space
of available algorithms, defined as encodingsâplanners couples, and then (iii) selects the
most promising algorithm for optimising either the runtimes or the quality of the solution
plans
On the Online Generation of Effective Macro-operators
Macro-operator (âmacroâ, for short) generation is a
well-known technique that is used to speed-up the
planning process. Most published work on using
macros in automated planning relies on an offline
learning phase where training plans, that is, solutions
of simple problems, are used to generate the
macros. However, there might not always be a place
to accommodate training.
In this paper we propose OMA, an efficient method
for generating useful macros without an offline
learning phase, by utilising lessons learnt from existing
macro learning techniques. Empirical evaluation
with IPC benchmarks demonstrates performance
improvement in a range of state-of-the-art
planning engines, and provides insights into what
macros can be generated without training
An Automatic Algorithm Selection Approach for Planning
Despite the advances made in the last decade in automated planning, no planner outperforms all the others in every known benchmark domain. This observation motivates the idea of selecting different planning algorithms for different domains. Moreover, the planners' performances are affected by the structure of the search space, which depends on the encoding of the considered domain. In many domains, the performance of a planner can be improved by exploiting additional knowledge, extracted in the form of macro-operators or entanglements.
In this paper we propose ASAP, an automatic Algorithm Selection Approach for Planning that: (i) for a given domain initially learns additional knowledge, in the form of macro-operators and entanglements, which is used for creating different encodings of the given planning domain and problems, and (ii) explores the 2 dimensional space of available algorithms, defined as encodings--planners couples, and then (iii) selects the most promising algorithm for optimising either the runtimes or the quality of the solution plans
Towards a Reformulation Based Approach for Efficient Numeric Planning: Numeric Outer Entanglements
Restricting the search space has shown to be an effective approach for improving the performance of automated planning systems. A planner-independent technique for pruning the search space is domain and problem reformulation. Recently, Outer Entanglements, which are relations between planning operators and initial or goal predicates, have been introduced as a reformulation technique for eliminating potential undesirable instances of planning operators, and thus restricting the search space. Reformulation techniques, however,
have been mainly applied in classical planning, although many real-world planning applications require to deal with numerical information.
In this paper, we investigate the usefulness of reformulation approaches in planning with numerical fluents. In particular, we propose and extension of the notion of outer entanglements for handling numeric fluents. An empirical evaluation, which involves 150 instances from 5 domains, shows promising results
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