1. R&D Attitude Control System in AADL How will complexity and variation in embedded systems be captured? Can system-level design process benefit from system-level tools? AADL is applied to an R&D ESA AOCS concept

2. Introduction Abstract The advanced concept for an attitude control system proposed by ESA special projects group proposes a hardware architecture that boasts improvements in power consumption, mass reduction and cost reduction. These improvements are achieved through adoption of new technologies such as SpaceWire, GPS electronics, Wireless I/F and the constituents of Satellite on a Chip (SOC). A software architecture supporting this attitude control system has been developed written in the Architecture Analysis Design Language (AADL). Preliminary tests results are shown for port connection checking and metrics are presented from the measurement of stream miss rates and flow latency analysis. Diagram of proposed R&D AOCS system This AOCS system, presented by ESA at SDSW 2003, was modeled in AADL and the data flows mapped along 7 data paths through the control system. In this system, AOCS includes data flows to and from the payload system since future attitude control may interact with the payload. The results for the computed Latencies based on the data flows were independently verified.

3. Proposed ESA AOCS Design

4. Results of Latency Analysis

5. Model Preparation Graphic model prepared w/ TNI OpenTool System coded in AADL with OSATE v1.0 Data paths computed with Analysis Plug-in The following slides show the major system components

6. Model Preparation

10. AADL Code Sample

11. Follow-on Work Work on this project continues with plans to update and embellish and the AOCS system model with new design content Advanced analysis plug-ins are planned for spacecraft bus architecture analysis The authors welcome input from ESA to elaborate the model Our contact information: