Tenders are invited for Advanced Techniques for Momentum Management with Thruster Orientation Mechanisms - Expro plus To improve the spacecraft momentum management with autonomous and optimal control of thrustorientation, enabling Reaction Wheel capacity reduction.DescriptionModern Telecom/GEO Satellites employ electric propulsion thrusters for both Orbit Raising phaseand Station Keeping. Gimbaled electric Thrusters via thruster orientation mechanisms (2 or 3 degree of freedom) are typically used both for orbital manoeuvres (e.g. North-South Position in Station Keeping) and concurrently management of the on-board momentum by unloading the reaction wheels. Conventional unloading strategies are often executed via controlled operations (e.g. sequence of programmed TOM angles along the orbit to ensure proper Thrust vectororientation). AOCS estimates the on board S/C momentum and controls the TOM angles in closed loop to limit the angular momentum storage due to both the thrust misalignment with respect to the S/C centre of gravity and the environmental disturbance torques, while satisfying multiple constraints such as TOM allowed angular range, TOM activation cycles, consumption, wheel capacity and collocation (if any). Large wheels are typically employed for this reason, thus increasing S/C overall mass.The activity consists of investigating advanced on-board optimization methods to control the TOM angles in optimal way and efficiently manage the on-board momentum, such to increase the onboardautonomy (less dependency on ground, autonomous generation of TOM angle profiles), minimize the maximum required wheel capacity while satisfying mechanisms constraints such as maximum number of activation cycles and minimising consumption.The activity is dedicated to GEO Telecom missions, taking into account their specifics in terms ofsensor and actuator architecture, as well as AOCS design drivers and mission/operations constraints. Gain on Reaction Wheel offloading need is expected to be in the range of 30%, on top on operational cost decrease thanks to autonomous TOM guidance during EOR.This activity encompasses the following tasks:- Existing application cases selection including performance requirements, sensors and actuators selection, AOCS subsystem /modes design, mission and system constraints for thrust control optimisation- Optimisation methods survey selection of the most promising one- Design analysis applied to the selected use cases - Implementation in simulator, including multi-body dynamics modelling- Validation test campaign- Assessment of autonomy, performance and mass gain vs heritage design and implementation way forward. Tender Link : https://esastar-publication-ext.sso.esa.int/ESATenderActions/filter/open
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