Planning & Scheduling
Task Sequencing for Remote Laser Welding in the Automotive Industry
Kovács, András (Computer and Automation Research Institute)
This paper proposes a new model and algorithm for task sequencing in remote laser welding in the automotive industry. It is shown that task sequencing (in which order to weld the seams) is strongly related to path planning (how the welding robot should move), therefore the two problems must be solved together, in an integrated way. The problem is modeled as a direct product of a traveling salesman and a path planning problem, and a tabu search algorithm is proposed for solving it. Computational experiments show that the proposed method leads to a substantial reduction in the cycle time of the welding operation compared to an earlier approach.
Behavior Composition as Fully Observable Non-Deterministic Planning
Ramirez, Miquel (RMIT University) | Yadav, Nitin (RMIT University) | Sardina, Sebastian (RMIT University)
The behavior composition problem involves the automatic synthesis of a controller able to “realize” (i.e., implement) a target behavior module by suitably coordinating a collection of partially controllable available behaviors. In this paper, we show that the existence of a composition solution amounts to finding a strong cyclic plan for a special non-deterministic planning problem, thus establishing the formal link between the two synthesis tasks. Importantly, our results support the use of non-deterministic planing systemsfor solving composition problems in an off-the-shelf manner. We then empirically evaluate three state-of-the-art synthesis systems (a domain-independent automated planner and two game solvers based on model checking techniques) on various non-trivial composition instances. Our experiments show that while behavior composition is EXPTIME-complete, the current technology is already able to handle instances of significant complexity. Our work is, as far as we know, the first serious experimental work on behavior composition.
Compiling Conformant Probabilistic Planning Problems into Classical Planning
Taig, Ran (Ben Gurion University of the Negev) | Brafman, Ronen I. (Ben Gurion University of the Negev)
In CPP, we are given a set of actions (assumed deterministic in this paper), a distribution over initial states, a goal condition, and a real value 0 < θ ≤1. We seek a plan π such that following its execution, the goal probability is at least θ. Motivated by the success of the translation-based approach for conformant planning, introduced by Palacios and Geffner, we suggest a new compilation scheme from CPP to classical planning. Our compilation scheme maps CPP into cost-bounded classical planning, where the cost-bound represents the maximum allowed probability of failure. Empirically, this technique shows mixed, but promising results, performing very well on some domains, and less so on others when compared to the state of the art PFF planner. It is also very flexible due to its generic nature, allowing us to experiment with diverse search strategies developed for classical planning. Our results show that compilation-based technique offer a new viable approach to CPP and, possibly, more general probabilistic planning problems.
Challenge: Modelling Unit Commitment as a Planning Problem
Campion, Joshua (University of Durham) | Dent, Chris (University of Durham) | Fox, Maria (King's College London) | Long, Derek (King's College London) | Magazzeni, Daniele (King's College London)
Unit Commitment is a fundamental problem in power systems engineering, deciding which generating units to switch on, and when to switch them on, in order to efficiently meet anticipated demand. It has traditionally been solved as a Mixed Integer Programming (MIP) problem but upcoming changes to the power system drastically increase the MIP solution time. In this paper, we discuss the benefits that using planning may have over the established methods.We provide a formal description of Unit Commitment, and we present its formulation as MIP and as a planning problem. This is a novel and interesting application area for planning, with features that make the domain challenging for current planners.
Planning Solar Array Operations on the International Space Station
Flight controllers manage the orientation and modes of eight large solar arrays that power the International Space Station (ISS). The task requires generating plans that balance complex constraints and preferences. These considerations include context-dependent constraints on viable solar array configurations, temporal limits on transitions between configurations, and preferences on which considerations have priority. The Solar Array Constraint Engine (SACE) treats this operations planning problem as a sequence of tractable constrained optimization problems. SACE uses constraint management and automated planning capabilities to reason about the constraints, to find optimal array configurations subject to these constraints and solution preferences, and to automatically generate solar array operations plans.
New Encoding Methods for SAT-Based Temporal Planning
Rankooh, Masood Feyzbakhsh (Sharif University of Technology) | Ghassem-Sani, Gholamreza (Sharif University of Technology)
Although satisfiability checking is known to be an effective approach in classical planning, it has scarcely been investigated in the field of temporal planning. Most notably, the usage of E-step semantics for encoding the problem into a SAT formula, while being demonstrably quite efficient for decreasing the size of the encodings in classical planning, has not yet been employed to tackle temporal planning problems. In this paper, we define temporal versions of classical A-step and E-step plans. We show that when the casual and temporal reasoning phases of a SAT-based temporal planner are separated, these semantics can be used to translate a given temporal planning problem into a SAT formula. We introduce two different types of E-step encodings in temporal planning. The first encoding method is a temporal version of the classical E-step encoding. Like its classical counterpart, in the new encoding we suppose a few restrictive simplifying assumptions. On the other hand, by relaxing one of these assumptions, the second type of E-step encodings, which is often more compact than the first one, is introduced. However, if a temporal planning problem possesses the property that we call required causal simultaneity, neither of our proposed encodings will be expressive enough to represent a valid temporal plan. Nevertheless, we show that this property is rather rare and can be detected in polynomial time. Our experiments indicate that by embedding the proposed encodings into ITSAT, a SAT-based temporal planner based on the A-step encoding, a considerable improvement is achieved in terms of both speed and memory usage of the planner. The resulting planner significantly outperforms POPF, which is currently the state-of-the-art of temporally expressive planners.
A Constraint-Based Approach for Proactive, Context-Aware Human Support
Pecora, Federico (Örebro University) | Cirillo, Marcello (Örebro University) | Dell' (Örebro University) | Osa, Francesca (Örebro University) | Ullberg, Jonas (Örebro University) | Saffiotti, Alessandro
She has (which includes a human user), while planning determines equipped the apartment with a series of service robots, the concrete actions that should be carried out in order to sensors and actuators which help her manage some of best support the perceived context. The domain description the physical and cognitive difficulties she has due to formalism used by SAM is based on metric temporal constraints; her age. Her home alerts her if she appears to be overcooking such domains model both the criteria for context inference her meals, and autonomously organizes when and the planning operators used for plan synthesis. The of the user and to contextually synthesize action plans for home recognizes when Malin is sleeping, eating and actuators in the intelligent environment. The knowledge representation scheme used in SAM is based State of the art robotic and sensor systems can be leveraged on Allen's Interval Relations (Allen 1984), augmented with to achieve intelligent functionalities that are useful in a number temporal bounds.
A Constraint-Based Approach for Proactive, Context-Aware Human Support
Pecora, Federico (Örebro University) | Cirillo, Marcello (Örebro University) | Dell' (Örebro University) | Osa, Francesca (Örebro University) | Ullberg, Jonas (Örebro University) | Saffiotti, Alessandro
She has (which includes a human user), while planning determines equipped the apartment with a series of service robots, the concrete actions that should be carried out in order to sensors and actuators which help her manage some of best support the perceived context. The domain description the physical and cognitive difficulties she has due to formalism used by SAM is based on metric temporal constraints; her age. Her home alerts her if she appears to be overcooking such domains model both the criteria for context inference her meals, and autonomously organizes when and the planning operators used for plan synthesis. The of the user and to contextually synthesize action plans for home recognizes when Malin is sleeping, eating and actuators in the intelligent environment. The knowledge representation scheme used in SAM is based State of the art robotic and sensor systems can be leveraged on Allen's Interval Relations (Allen 1984), augmented with to achieve intelligent functionalities that are useful in a number temporal bounds.
A Constraint-Based Approach for Proactive, Context-Aware Human Support
Pecora, Federico (Örebro University) | Cirillo, Marcello (Örebro University) | Dell' (Örebro University) | Osa, Francesca (Örebro University) | Ullberg, Jonas (Örebro University) | Saffiotti, Alessandro
She has (which includes a human user), while planning determines equipped the apartment with a series of service robots, the concrete actions that should be carried out in order to sensors and actuators which help her manage some of best support the perceived context. The domain description the physical and cognitive difficulties she has due to formalism used by SAM is based on metric temporal constraints; her age. Her home alerts her if she appears to be overcooking such domains model both the criteria for context inference her meals, and autonomously organizes when and the planning operators used for plan synthesis. The of the user and to contextually synthesize action plans for home recognizes when Malin is sleeping, eating and actuators in the intelligent environment. The knowledge representation scheme used in SAM is based State of the art robotic and sensor systems can be leveraged on Allen's Interval Relations (Allen 1984), augmented with to achieve intelligent functionalities that are useful in a number temporal bounds.
A Constraint-Based Approach for Proactive, Context-Aware Human Support
Pecora, Federico (Örebro University) | Cirillo, Marcello (Örebro University) | Dell' (Örebro University) | Osa, Francesca (Örebro University) | Ullberg, Jonas (Örebro University) | Saffiotti, Alessandro
She has (which includes a human user), while planning determines equipped the apartment with a series of service robots, the concrete actions that should be carried out in order to sensors and actuators which help her manage some of best support the perceived context. The domain description the physical and cognitive difficulties she has due to formalism used by SAM is based on metric temporal constraints; her age. Her home alerts her if she appears to be overcooking such domains model both the criteria for context inference her meals, and autonomously organizes when and the planning operators used for plan synthesis. The of the user and to contextually synthesize action plans for home recognizes when Malin is sleeping, eating and actuators in the intelligent environment. The knowledge representation scheme used in SAM is based State of the art robotic and sensor systems can be leveraged on Allen's Interval Relations (Allen 1984), augmented with to achieve intelligent functionalities that are useful in a number temporal bounds.