Energy optimization of excavator swing drives through accumulator assisted dynamics and intelligent braking control

The hydraulic swing system of excavators suffers from substantial efficiency losses, primarily due to relief valve overflows during acceleration and deceleration phases. To mitigate these inefficiencies, this study proposes and validates a novel accumulator-assisted hydraulic swing drive (HSD) system that significantly enhances energy efficiency. The core innovation lies in two complementary strategies: (i) a Rule-based control strategy that dynamically manages accumulator charging and discharging cycles to maximize energy recovery, and (ii) an intelligent brake control mechanism utilizing the XGBoost machine learning model for precise swing angle regulation under variable operating conditions. A comprehensive dynamic model of the proposed HSD system is developed and simulated in MATLAB/Simulink ® , followed by experimental validation using a dedicated hardware test setup. Results reveal that the system achieves a 13.2% improvement in energy savings while limiting swing angle deviation to just 2.5%, highlighting its efficiency and motion precision. In addition, the system mitigates transient pressure spikes at the swing motor inlet and outlet, improving component reliability. The article further investigates the effects of critical parameters, including inertia load, accumulator size, and precharge pressure, on energy savings and regeneration efficiency. The results reveal that the energy-saving efficiency varies from 1.6% to 67%, with a peak regeneration efficiency of 97.5%, depending on inertia load, accumulator size, and precharge pressure. The findings further confirm that larger accumulator capacities and higher inertia loads promote superior energy recovery, while excessive precharge pressure can diminish efficiency.