A Novel Dual-Modeling Framework for Precision Control of Servovalve Electrohydraulic Actuators

Electrohydraulic actuators (EHAs) are increasingly used in robotics because of their superior power density, bandwidth, and force control. However, accurately modeling their behavior is challenging due to the complex internal dynamics of the servovalve. This paper presents a dualmodelling methodology for a symmetric double-acting cylinder. First is a nonlinear mathematical model derived from fluid continuity, orifice flow, and Newton's motion equations (including a hard-stop spring-damper to emulate end caps). The second is a component-level simscape implementation that mirrors the hardware architecture. The initial parameters were obtained from direct measurements of a dismantled servovalve and manufacturer datasheets. The remaining eleven unknowns were identified via nonlinear least-squares optimization using the Trust-Region Reflective algorithm against experimental sinusoidal displacement data. Beyond regular validation with piston displacement, multi-metric validation of both models behavior verified their ability to track sinusoidal inputs in displacement, and also the expected chamber pressure dynamics. This rigorously validated dual-model framework provides analytical clarity and high-fidelity simulation for designing precise position, force, and compliant controllers for EHAs, enabling safe human-robot interaction.