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First-order logic
Published in Richard E. Neapolitan, Xia Jiang, Artificial Intelligence, 2018
Richard E. Neapolitan, Xia Jiang
We use a version of Planning Domain Definition Language (PDDL) to address the frame problem. In our version of the language, each state is represented by a conjunction of fluents. For a given action, we list the preconditions (Pre), which are the conditions that must be true for an action to be applied; the add list (Add), which are the fluents that are added when the condition is applied; and the delete list (Del), which are the fluents that are deleted when the action is applied. For example, the unstack(x,y) action is represented as follows:
Hierarchical and parameterized learning of pick-and-place manipulation from under-specified human demonstrations
Published in Advanced Robotics, 2020
Kun Qian, Huan Liu, Jaime Valls Miro, Xingshuo Jing, Bo Zhou
Programming Domain Description Language (PDDL) [45,46] separates the model of the planning problem into domain description and the related problem description, which are eventually the input of a planner. The domain description consists of the definition of requirements, class, predicates, and also actions, which are formulated in the PDDL.Domain file. The class model describes the abstraction of common targets such as object, arm and goal. The predicate model describes the existence of relations or states of classes. In addition, the action model describes a potential action by its action name, parameters, preconditions, effect and duration. An example of the PDDL.Domain file for the , and tasks are shown in Figure 3. As shown in Figure 3, five actions (R, G, M, O, P) and three object-types classes (arm, object, goal) that are necessary for the three tasks are defined. Table 1 is an example of the all possible predicate description for the three tasks. Actions are defined by their parameters, preconditions and effects. Pseudocode 2 and Pseudocode 3 give the description of actions PlaceOnTop(P) and MoveObject(M), respectively. In the action definition, the precondition of a subsequent action should be the same with its former action's effect, so that the two successive actions can be linked in correct order.
Knowledge-based cyber-physical systems for assembly automation
Published in Production & Manufacturing Research, 2019
Munir Merdan, Timon Hoebert, Erhard List, Wilfried Lepuschitz
To generate operation plans, the Planning Domain Definition Language (PDDL) (Mcdermott et al., 1998) is used for decision-making. It is a standard language widely applied in the academic planning community. The PDDL input format consists of two files that specify the domain and the problem. A domain file declares the predicates, functions, and types of objects available on the world and the actions available. In this context, each property of each class in the Semantic Model can be transformed to a PDDL predicate. for describing the states and actions. For example, part locations are specified by the predicates hasLocation pointing on the specific box where the part is located. Another example is the free predicate, which specifies if the concrete gripper is holding something at the particular moment. Actions are the means of how the world state is changed. The statement includes parameters, preconditions, and effects. The preconditions dictate items that must be initially valid for the action to be legal. The effect equation dictates the changes in the world that will occur due to the execution of the action. For example, the following statement is an action that specifies the action of a robot to pick a part from a specific location:
PDDL4J: a planning domain description library for java
Published in Journal of Experimental & Theoretical Artificial Intelligence, 2018
It exists different, but equivalent ways to represent a classical planning problem as a State Transition System. Whatever a representation is adopted, the planning community mainly uses the PDDL language to specify planning problems. However, PDDL is not the only language used in the planning community: see for instance OCL (Object Constraints Language) (Liu & McCluskey, 2001) or OPL (Other Planning Language) (McDermott, 2005). Most of the planners pre-process the PDDL language to encode planning problems in their internal representation. PDDL4J is able to manage two representations that are widely used in the planning community: the logical representation and the Finite Domain Representation (FDR).