PRODUCT NEWS

SATELLITE MISSION PLANNING TOOL

Dornier Bases System on ILOG Solver and ILOG Scheduler
System optimizes timelines for earth observation satellites through effective constraint propagation combined with advanced placement techniques

TINA User Interface Example - Mission Editor

By Dr. Jens Eickhoff
Project Manager
Knowledgebased Simulation Systems
Dornier Satellitensysteme GmbH

TINA (Timeline Assistant) is a satellite mission planning tool developed by Dornier Satellitensysteme GmbH (DSS). TINA is neither a pure planning algorithm, nor a pure scheduler like a lot of PC-based tools. In an integrated timeline processing procedure, TINA considers both logical interdependencies of positioned activities and numeric constraints such as resource consumption or interrelations of generated and consumed resources. Due to this hybrid technique, TINA is called a "Timeline Generator."

The foundation of TINA is the ILOG Solver and ILOG Scheduler libraries. The TINA V4.2 system features a program architecture consisting of three separate processes coupled via CORBA interfaces:

• The TINA Console by which the user controls the timeline generation process.
• The Timeline Generator Server, which performs the timeline computation for several consoles connected to it. Different consoles can request timelines for different satellites.
• Orbit Propagation Servers for computing orbital positions, target visibilities, etc., of the satellites.

TINA Timeline Generation is based on user requests. A user request corresponds to a specification data set, a satellite payload the user submits to the space operations for an earth observation. The user-requested specifications include the coordinates of the area of interest, the earliest start of observation and the latest completion, the instrument to be used for the observation, instrument setting parameters, etc.

The TINA software objects are derived from ILOG Scheduler base classes. User request types consist of a key activity and necessary switch-up and switch-down activities, subdivided into state and switch activity types.

• The key activity serves for all operations marking the user request as placed/non-placed.
• The switch activities serve for modeling the logical transitions of modes in the switch-up and -down of equipment.
• The state activities serve for modeling the mode- dependent resource consumption of equipment.

Activities are characterized by the initial constraints, which have to be met for their placement on the timeline, their changes in the system state with respect to time and the resources consumed, produced, required or provided.

For modeling processes that automatically occur and influence onboard resource budgets such as automatic recharging of batteries in the sun TINA provides the efficient and easy-to-use definition of so-called Auto-Activities.

TINA generates highly efficient timelines, including the merging of user requests to minimize switch-up and -down cycles of equipment. Output filters exist for generation of binary formats, which can be directly up-linked to a spacecraft or simulator. TINA is currently available on Sun SPARC platforms under Solaris 2.5.1 or higher.

TINA is expected to be used in the ground segment of a commercial earth observation satellite after its formal qualification. Especially in commercial application fields, the high efficiency of the generated timelines and the high numerical performance achieved through the ILOG libraries provide a significant advantage.