Master Thesis Micro-Vibration Analysis Using Flexible Structural Models

OHB Sweden is a leading Swedish supplier of space systems. We develop build test and commission satellites and subsystems for space missions in for example communication earth observation and space research for institutional and commercial customers within and outside Europe.

The European Space market is becoming more oriented towards very high pointing performance satellites. To ensure high resolution imaging a satellite provider needs to properly assess jittering effects onto the spacecraft mostly caused by the reaction-wheels micro-vibrations. As part of this assessment it is necessary to quantify the propagation of micro-vibration throughout the spacecraft structure up to the optical line of sight in order to fully quantify the impact of the micro-vibrations onto image resolution.

Thesis overview

The focus of this thesis is to investigate methods to incorporate flexibility models from the Finite Element Analysis of the spacecraft structure together with models of the micro vibration of reaction wheels into the AOCS-GNC Simulink simulator. The objective is to assess the impact of jittering onto the payload line of sight. Both analytical proofs and simulation checks will be performed within the thesis work.

The tasks of the Masters thesis topic are as follows:

• State of the art and literature review on the topic.

• Gain familiarity with the current AOCS-GNC simulation tools and software as well as the mathematical descriptions of the spacecraft mechanical structure.

• Create a reaction wheel micro-vibrations simulator model based on supplier data and analytical description.

• Establish analytical proof for flexibility modeling in micro vibration predictions for payload line of sight jitters assessment.

• Test and develop algorithm methods to automate the micro vibration analysis.

• State of the art and literature review on the topic.

The required candidates skills are:

• Strong interest in spacecraft and structural dynamics.

• Relevant undergraduate degree in aerospace engineering mechanical engineering applied mathematics or engineering physics.

  • Knowledge of structural analysis and vibration dynamics is considered a merit.

  • Knowledge of system identification is considered a merit.

• Good knowledge of linear systems theory

• Very good knowledge of Matlab/Simulink.

• Good knowledge of ANSYS or other similar FEM tools.

• Knowledge of model-based design.

• Proactive autonomous can-do attitude with a curious and innovative mindset.

• Strong interpersonal skills as interaction with various internal departments is expected.

• Proficient in English both written and spoken.

• Ability to document work systematically.

What can we offer the student to succeed in their masters thesis

This masters thesis offers an opportunity to contribute directly to build a representative satellite model for OHB Swedens high performance satellite missions. You will gain hands-on experience with satellite structure models micro vibration satellite control systems and high-performance simulators.

You will be assigned a mentor and will receive guidance and technical support from both the AOCS-GNC and the Mechanical team throughout the project.

Successful completion of the thesis may open opportunities for future employment as an AOCS or Structure Engineer within OHB Sweden.

Were looking forward to hearing from you!