Variable-Gain Subdivision Pressure Control Algorithm for Digital Valve Braking Systems via Partially Open Mode

High-performance braking systems are critical for the safety and efficiency of the more-electric aircraft. Digital valve braking systems, employing highly reliable and robust on/off valves, offer a promising alternative to conventional electro-hydraulic servo valves, which are prone to contamination. However, the discrete switching characteristics of on/off valves often cause undesirable pressure overshoot, fluctuations, and discontinuities. To overcome these limitations, this study proposes a novel variable-gain subdivision pressure control algorithm (VSPCA), which leverages the partially open mode of on/off valves to achieve near-continuous flow regulation. The VSPCA comprises three key components. The sliding window-based state identification module accurately identifies the braking stages to enable stage-adaptive control. The variable gain regulation module exploits the partially open mode of on/off valve to improve regulation precision. Furthermore, a low energy consumption driving strategy is combined with a subdivided execution period to enhance excitation time resolution and reduce energy consumption. Extensive experiments conducted on a digital brake valve performance test bench and a ground inertial test bench demonstrate the superior performance of the VSPCA. Compared with the conventional PNM+PWM strategy, the proposed VSPCA achieves a reduction of over 50% in the average tracking error and other key performance indicators under triangular wave commands. It delivers high-efficiency braking under both full-load and half-load conditions.