This activity shall investigate, trade-off, and preliminary prototype a control system for the upcoming L3 mission, taking advantage of the results and lessons learnt from the Lisa Pathfinder mission. The study shall trade-off different control system architectures and design methodologies to satisfy the challenging requirements of this mission. Preliminary prototyping using a representative simulation environment shall also be implemented. This activity will allow to lower the development risk of this expensive and complex control system before phases A/B1.

It is expected that the control system for the L3 mission will need to control several degrees of freedom with different actuators at different frequencies, yielding a tightly coupled, multiple-input multiple-output system. Even though the Lisa Pathfinder (LPF) mission has proven some of the control system technologies required to achieve this, the architecture of the LPF Drag Free Attitude Control System (DFACS) has been designed to best fit the motion equations and requirements of LPF, which are less challenging than those for L3. For this reason, an in depth theoretical investigation of the possible control system architectures and control design methodologies for L3 is required. The drag free control architecture for this mission is key for its performance and therefore an in depth trade-off at mathematical-theory level, aided by simulations shall be prototyped.This activity is proposed as a briding phase between the activities executed for the design, development, and early operations of the control system of the LPF mission and those for L3. It will allow to gather the results and lessons learnt from LPF project and inject this knowledge quickly into the early phases of the design and development of the control system for the L3 mission.The software final product of the activity will serve as a framework for ESA to test case any changes in the evolution of requirements of the L3 mission during its early phases.Tasks:1) State of the art and definition of the elementary equations of motion for the L3 mission, including a de-coupling analysis to identify possible control system design simplifications. 2) Trade-off different control system architectures and advanced, robust control system design methodologies to preliminary prototype the drag free control system.3) Implement the different proposed options into a representative simulation environment and analyse the different proposed solutions to find the best candidate. 4) Provide conclusions a and identify way forward for phases A/B1.