76 normal lab. The IFPM performance for very low frequencies will therefore be validated in future  environmental tests to be carried out by Airbus DS  in their IFP breadboard setup.  

Conclusions  

In this paper we have presented the design and realization  of the In- Field Pointing Mechanism for the  eLISA mission.  This mechanism encompasses a tilt mirror guided by Haberland hinges, which is actuated  by walking piezo actuators. The redesign of the actuator unit to a planar  configuration has improved the  open- loop behavior significantly,  resulting in local velocity variations of just a factor 3 and nearly constant  dynamics over a full actuator  cycle.    The open- loop measurements have been taken into account  in a robust high- performance controller  design. This controller has been combined with both interferometer  and encoder feedback; the latter has  demonstrated that  IFPM can be operated stand- alone with high accuracy. In both cases the resulting  ASDs suggest compliance with the maximum allowed pointing jitter.    However, in our unconditioned laboratory the performance could only be guaranteed for frequencies  above 2 Hz. For a real validation of the low -frequent performance a better conditioned environment is  required. This  validation will be carried out by Airbus DS in their environmental  tests. In these tests the  piston jitter of the IFPM will also be assessed.  

Acknowledgments    The authors would like to thank Dennis Weise, Ewan  Fitzsimons and Christina Brugger (Airbus Defence &   Space) for the fruitful c ollaboration within the IFPM project, Per Bendixen (Piezomotor) for his help on  improving the actuator module, and former colleagues Joep Pijnenburg, Niek Rijnveld and Martijn te Voert for their contributions to the IFPM development . 

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