Troubleshooting and redesign of a vibration isolator for Space Truss (ESA-ULB-MicroMega)

Dec.2002 – Aug.2003, Research Engineer, Département des constructions mécaniques et robotiques, Active Structure Laboratory, UNIVERSITY OF BRUSSELS (BRUSSELS, Belgium)


For the European Space Agency (ESA), MicroMegaDynamics and ULB were developing an active control vibration isolator based on the so called Stewart Platform: a specific 6 degrees of freedom positioning device.

This vibration isolator is intended to be installed between the structural truss of a satellite and high precision measuring systems, typically laser metrology or telescopes, typically used for inter-satellite optical/laser communication or to observe stellar objects in the deep/early universe.

The noise sources onboard a satellite typically come from reaction positioning wheels, stepping motors, cryocoolers, thermal ‘crinkling’, optics motion, micro-thrusters, Field-Emission Electric Propulsion propellers.

ULB developed and built such Stewart platform BUT some undesired side-effects badly perturbed the expected dynamic isolation behavior of the structure.

I knew the CEO of MicroMegaDynamics, Nicolas Loix, and after some discussions together, I accepted to lead the team trying to get rid of those problems, bringing my knowledge and competences learnt at LMS.


The problem were solved by:

  • building a few experimental test benches to measure with laser beams the real dynamic behavior of each element of the assembly and of the whole assembly,

  • Building an accurate Finite element model (SAMCEF) of each element and of the entire assembly

  • Updating the FEM so that the theoretical behavior perfectly matches the reality

  • Accurately understanding the parasitic behaviors: the lateral stiffness of the membrane of the actuators needed to be improved with a decrease of the axial stiffness, and very important, the joints between the actuators and the platform needed to be stronger and with the least stiffness.


  • by use of the FEM and a matlab program, optimize those critical elements with design for experiment with a fully parametrized calculation chain.


  • proposed a new design for the membrane and for the joints, with a specific super elastic material, the NiTiNol, developed by NASA as as Shape Memory Alloy:
  • Construction of the new membrane and of the new joint,
  • Tested and validated the parasitic behavior disappeared.



  • Technical lead of a 4 people team to resolve the issue, team work coordination within the department and with the client
  • Experimental analysis, FE modelling and FEM updating,
  • Calculation chain and design optimisation
  • Follow-up of suppliers, construction and validation of the modified prototype