Requirements of high pointing accuracy for Earth observation missions have tightened the tolerable levels of onboard micro-disturbances. Active, passive, or hybrid active-passive mitigation techniques have been proposed, generally accommodated at a perturbation source. The GNC, AOCS and Pointing Division at ESTEC has carried out research in this field leading to a substantial progress over the past years. A hybrid micro-disturbance mitigation platform was designed to isolate perturbations at source level (reaction wheel). Robust linear parameter-varying (LPV) control was proposed in this framework. Contrary to this activity, the proposed PhD thesis intends to study adaptive regulation for active vibration isolation at payload level. The novelty is the use of adaptive LPV regulation schemes to isolate a sensitive instrument from multiple unknown perturbation sources simultaneously. Possible perturbation settings include multiple reaction wheel configurations with varying harmonic frequencies and single or multiple cryocoolers. The varying parameter in the LPV scheme are the estimated harmonic frequencies of the perturbations. Another parameter can be used to steer the control aggressiveness to avoid actuator saturation in case of unexpected abrupt variations. The focus lays on a real-time disturbance model identification which shall be optimised to increase the pointing performances (RPE) at system level. The end-to-end modelling i.e. from micro-disturbances to line-of-sight stabilisation is thereby a key element. An additional new element is the development of strategies for sensor and actuator placement optimisation while considering actuator failures. The controller shall be robust to a different actuator configuration in case of a failure. A further objective is the study of broadband isolation when perturbations are emitted by the payload itself. Strategies to isolate the payload in the presence of external and internal perturbation sources shall be investigated.
