Development challenges of a focus mechanism for EXOMARS mission submitted to the harsh Martian environment

For the development of the Focus Mechanism of the CLUPI instrument of the ExoMars 2020 mission, the CSEM implemented a design based on flexible structure technology and the use of Commercial Off-The-Shelf (COTS) components. This choice was essentially motivated by the availability of the miniature sensor and actuator components. Such approach presents many challenges such as: the qualification of the OTS voice-coil motor and Linear Variable Differential Transformer (LVDT), the implementation of a reliable launch locking system, the design of a flexible structure mechanism compatible with harsh mechanical environment. The present article describes each of the above problematics and the investigation carried by CSEM to find solutions meeting the mission needs and constrains.