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Optimum-AIV Kielce 2006. Space Vehicles. Ariane 5. Space Vehicles. Space Shuttle Columbia. Space Vehicles. Soyuz. Space Vehicles. Shuttle Buran with a Energiya rocket. Space Vehicles. Voyager. Space Vehicles. cargo ISS Progress. Introduction.
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Optimum-AIV Kielce 2006
Space Vehicles Ariane 5
Space Vehicles Space Shuttle Columbia
Space Vehicles Soyuz
Space Vehicles Shuttle Buran with a Energiya rocket
Space Vehicles Voyager
Space Vehicles cargo ISS Progress
Introduction • Due to AIV (Assembly, Integration and Verification) complexity in spacecrafts the European Space Agency (ESA) ordered: • A system for planning and scheduling based in the knowledge for the AIV in spacecrafts.
Introduction • The consortium formed for CRI, MMS, AIAI e Progespace supplied the project: Optimum-AIV.
Optimum-AIVObjectives • To develop an operational tool of planning, scheduling and of repairing plans that consisted of a set of functionalities of software for the assistance of:
Optimum-AIVObjectives • Specifications in the initial plan of the AIV. • Generation of valid plans and schedules for some activities AIV. • Interactive monitoring of the execution of AIV plans. • Identification of immediate effect of problems and repairing of plans.
Optimum-AIVObjectives • To adapt external interfaces that allow the integration with alternative systems of scheduling and databases of projects.
Optimum-AIVObjectives • To supply easinesses that allow the readjustment of the system so that it serves other individual projects.
Domain of planning AIV in spacecraft The projects of development of spacecrafts are constituted typically by the following phases:
Domain of planning AIV in spacecraft • Previous studies: • of the based objectives of the mission in operational constraints, • to define the characteristics of the system, • to establish a preliminary philosophy model,
Domain of planning AIV in spacecraft • to identify the aspects of design and its influence in the spacecrafts • as well as making a previous identification of the verification tools • and a general plan of AIV program.
Domain of planning AIV in spacecraft • Specification phase: • The characteristics of the system are extracted from top to bottom, starting from the total system and finishing in subsystems • Detailed plans are produced on a different level base
Domain of planning AIV in spacecraft • General AIV plans, test hardware requirements, ground support requirements, development plans at lower levels are produced
Domain of planning AIV in spacecraft C/D Development and integration phase. • Design stops and starts the manufacturing • Exists an activity from bottom-up where the primitive units are gathered in assemblies, that are part of a subsystem that is integrated in a level system
Domain of planning AIV in spacecraft • The phase is complete with the integration, verification and qualification of the spacecraft systems • Implementation of the plans created in B and produces detailed AIV plans in different levels • This involves the propagation of logical restrictions, verification of stocks and monitoring of the execution.
Domain of planning AIV in spacecraft • Operational phase: • This phase covers the period from launching until the o end of the mission of the spacecraft
System Knowledge An important aspect of the Optimum-AIV and that it makes the difference of the other traditional tools is the inclusion of explicit knowledge:
System Knowledge Entity knowledge – defines and represents the entities that must be manipulated in the domain, that are: • The models and spacecraft systems, generic, past and current plans. • The AIV activities • The resources • The global constraints
System Knowledge Knowledge of the processes – represents the knowledge stating how the entity knowledge manipulation can be done: • For the AIV planning domain, the process knowledge is the general planning and scheduling knowledge • Adding heuristics and knowledge of the rationality behind the structure plan
System Knowledge A project consists of a plan of activities that can be divided in sub plans to any level of detail, so that each one can be worked on independently. Each activity can have a classification according to its function in the AIV process; reception, preparation, assembly, functional test, etc.
System Knowledge The descriptions of the individual activities contain information on: • Pre conditions that must be connected to the activities to be correct and to be set in motion; for example house.keeping.module CONNECTED.TO data.handling.subassembly
System Knowledge • effects (and side effects) of using the activity; for example tm-tc-lock INTEGRATED.IN house.keeping.module • constraints, including target dates and resources requests; for example: the activity requires two electricians for 3 days • Objectives, documentation, experiences, etc.
System Knowledge The resources have been categorized in two dimensions: • In accordance with the predefined resource classes; ground support equipment, manpower, test facilities, money, etc. • In accordance with the origin of the resource; shared or consumable.
System Knowledge Resource descriptions contain information about: • The availability profile; for example the resource is available during the 3rd week of May. • Alternative and indirect resources. • Documentation, experiences, etc.
System Knowledge Activity global constraints can be associated to a plan. They express the temporal relations between activities in a certain context. For example:
System Knowledge IF ACTIVITY acoustic.and.vibration.test of.Class enviroment.test works.on.System ?s AND ACTIVITY ?x of.Class integration works.on.System ?e AND SYSTEM ?e SUBELEMENT.OF ?s AND ?x power.supply.subsystem.integration THEN acoustic.and.vibration.test AFTER ?x
System process stages • Knowledge edition and specification of the plan • Definition and input of general domain of knowledge: spacecraft system, activity, resource, global constraint classes and instances. • Specification of the actual planning problem.
System process stages • Plan and schedule generation • Constraint satisfaction: Precedence, precondition, temporal, resource usage, global activity constraints. • Planning: to find a logically valid plan in enough details • Scheduling: to include times and resources in the plan
System process stages • Project monitoring and plan repair • Monitoring of the execution of schedule: recording the progress, reminding the user of activities to be started soon. • Detection of problems and its immediate impacts: deriving local inconsistencies
System process stages • Schedule repair: rescheduling or editing the current schedule locally • Plan repair: more serious problems interfering plan logic
Plan editing and specification • In this initial stage, most of the work relies on the user entering and specifying of AIV activities, there required components, resources and its decomposition that will eventually build a plan for the project.
Plan and schedule generation • Constraint satisfaction: 5 kinds of activity and restrictions exist: • Precedence These predecessor and successor constraints specify explicit user defined orderings on the activities. • Precondition These are more general constraints, which can specify that certain results have been obtained or some equipment be available before the activity can be undertaken.
Plan and schedule generation • Temporal Time is one of the major constraining factors in the spacecraft AIV planning. • Resource usage This type of activity constraints specifies which and how much of various resources an activity demands.
Plan and schedule generation • Global activity constraints Express overall temporal relations that must hold between activities satisfying the IF part of the global constraint.
Plan and schedule generation • Planning It is based on the logical plan verification, assistance in conflict resolution and construction of new precedence relations based on preconditions and effects of activities.
Plan and schedule generation • Scheduling Scheduling generation involves not only management of temporal resource usage constraints but also conflict detection and collection. The time table for the activities are calculated by a forward and a backward pass of the logical plan.
Plan and schedule generation • Knowledge about plans and schedules The Optimum-AIV holds a large amount of information associated with its domain elements: activities, resources, calendars and constraints And is able to use this information in an active way in the planning and scheduling process to reason about the plan.
Project monitoring and plan repair • The major use of the Optimum-AIV will be on the plan execution phase. This phase covers the period from the time that AIV plan starts to be executed until the planned process is completed. • It can have an imperfection of a test
External interfaces • Artemis interface It is a used interface to the import of space project data, to export and display of plans, report writings and graphics and agregations.
External interfaces • Database Interface It is practically the same that the previous one • Programming the interface It allows to write programs externally to develop its own documentation (Lisp, C, Pascal).
IA techniques applied • The Optimum-AIV adopts the non-linear planning paradigm. • Another characteristic is the hierarchical planning
IA techniques applied • The scheduling task is considered a constraint satisfaction problem solved by the constraint-based reasoning. The constrains are propagated throughout the plan, gradually transforming it into a realizable schedule. • After planning/scheduling has ben performed the system checks the global activity constraints (IF/THEN).
References Arentoft, M. M., Parrod, and J. Stader. 1990. OPTMUM-AIV: Software requirements document. Arentoft, M. M., Parrod, and J. Stader. 1991. OPTIMUM-AIV: Architectural design document. Currie, K. W., and A. Tate. 1991. “O-plan: the open planning architecture” Funchs, J. J., G. S. Pedersen, and A. Gasket. 1989. EPS-AIT: Final report. Parrod, Y., and I. Stokes. 1990. OPTIMUM-AIV: AIV Knowledge acquired. Swartout, W. 1987. DARPA Santa Cruz workshop on planning. Tate, A. 1984. “Goal structure: Capturing the intent of plans” Wilkins, D. E. 1984. “Domain independent planning: Representation and plan representation”.