Degradation-aware redundancy allocation in multi-redundant electro-hydrostatic actuator

Redundancy allocation in multi-redundant electro-hydrostatic actuator (MREHA) systems is critical for distributing the actuation demand among multiple motor-pump units to ensure system performance and reliability. However, in safety-critical applications, intrinsic redundancy together with multi-source coupling introduces significant challenges for redundancy allocation, particularly when individual drive units experience different levels of degradation associated with leakage, thermal effects, and reduced available power capability. Conventional equal or fixed strategies often lead to power allocation inconsistent with unit capabilities, accelerating degradation of weaker units. To address these issues, this paper investigates modeling and redundancy allocation from a degradation-aware system-level perspective. A redundancy allocation cooperative control (RACC) framework is established, in which system-level actuation demand is distributed among drive units through a hierarchical structure. Within this framework, two allocation strategies are developed. The health-aware flow allocation (HAFA) strategy adjusts flow distribution based on degradation indicators to reduce overload of degraded units. The power-constrained optimal flow allocation (PCOFA) strategy formulates the problem as a constrained convex optimization model to ensure balanced and feasible power utilization. The proposed framework provides a systematic approach for degradation-aware redundancy management, enhancing operational safety and fault tolerance in multi-drive actuation systems.