Redundant Digital Hydraulic Actuators for Flight Control Surfaces

Abstract

The aircraft industry is continually driven to improve energy efficiency in response to environmental concerns and cost reduction. Among solutions available in the field, hydraulics is commonly chosen to deliver crucial functions for its known reliability, precise controllability, and high stiffness. Additionally, when compared to competing technologies in development, hydraulic systems are far less susceptible to jamming, heat rejection problems, and premature wear. In the current context, digital hydraulics emerges as a promising alternative to conventional hydraulics, greatly increasing energy efficiency while keeping the robustness of fluid power systems. Aiming to apply this technology to aircraft systems, this paper introduces enhancements for the digital hydraulic topologies developed at LASHIP/UFSC that allow them to be applied in critical tasks, such as flight control actuation, achieving reliability and performance criteria, beyond the increase in efficiency. These topologies were refined with segregation and independence principles, as is standard in aircraft. The solutions address both centralized (easier to adapt to existing aircraft designs) and distributed hydraulic systems (coherent with the More Electric Aircraft concept). Furthermore, to evaluate the feasibility of the systems, the study correlates industrial components and aeronautical systems through systematic analogy, resulting in an estimate of the size and weight of digital hydraulic systems if designed for the aeronautical industry. The resulting digital hydraulic systems adhere to the reliability practices and safety standards employed in aircraft flight control while showing similar sizes and weights to the current solutions.