ESA GNC Conference Papers Repository

In 2011 ESA published the ESA Pointing Error Engineering Handbook as applicable document. The Handbook complements the ECSS control performance standard. It provides guidelines for a step-by-step engineering process from pointing error requirement specification, to systematic pointing error analysis, and the compilation of pointing error budgets. As pointing error engineering is relevant to any space mission, ESA developed the Pointing Error Engineering Tool PEET software to support the user in applying the elements in the Handbook and in the ECSS control performance standard. The prototypes of PEET (v0.X) have been in use by several projects in Airbus Defence & Space. Among others, this is the case for the MetOp-SG project, where PEET is the tool used for pointing error analysis of about 100 instrument and platform budgets. Based on that experience Airbus Defence & Space supported Astos Solutions to further develop PEET from a prototype to a release v1.0 in an ESA GSTP study. This included the verification and benchmarking of the software. This paper demonstrates the capabilities of PEET v1.0 and its verification by means of the PointingSat case study. PointingSat is a fictive but realistic mission that covers almost all use cases for the ESA PEET software v1.0. The mission has demanding pointing error requirements in all possible ECSS error indices. The corresponding PEET model of PointingSat has a high level of detail in the modelling of pointing error sources and system transfers of the pointing errors from their origin to the axis of interest. The paper will show step-by-step how to model and analyse PointingSat in PEET. This includes the pointing error source characterisation, the modelling of the system transfer and the pointing error evaluation w.r.t. the requirements. Finally, the results of the PEET v1.0 verification and benchmarking w.r.t. an equivalent state-of-the-art Monte Carlo simulation in Matlab Simulink will be presented. The verification showed that the PEET v1.0 software produces the same results as the equivalent Monte Carlo simulation for the 'advanced approach', as it is called in the ESA pointing error engineering handbook. PEET v1.0 also produces the same results as the latest PEET prototype v0.6, but for the so called 'simplified approach' as the prototype is limited to this approach. In the benchmarking the achieved computational accuracy is comparable, but the computational speed of PEET v1.0 is >10 times faster than the equivalent Monte Carlo simulation. In addition the gain of accuracy by going from the 'simplified approach' in PEET v0.6 to the 'advanced approach' in PEET v1.0 will be demonstrated. In sum, the conclusion drawn w.r.t. the verification and benchmarking is that the PEET v1.0 software is considered to be an important tool for any future space mission for correctly and efficiently analysing pointing performance and knowledge such that responsive and accurate feedback for system design can be given. The migration from PEET v0.6 to v1.0 is suggested to profit from the higher accuracy in the 'advanced method' and the user friendliness of v1.0 that will save time and thus cost. This is also suggested for running projects already using PEET v0.6 because V1.0 produces the same results in the 'simplified approach', which is currently the standard approach for missions like MetOp-SG.