A Fully Analog Intelligent Servo-valve Amplifier Enabling Wide-band Pressure Control of Pneumatic Actuators

Pneumatic actuators are widely used in precision manufacturing, robotics, and compliant actuation due to their simplicity and high power density. However, nonlinearities from air compressibility and valve flow dynamics fundamentally limit control bandwidth and precision. Although digital pressure control can reduce these limitations, its dependence on high-speed sampling and complex computation introduces latency, cost, and architectural constraints. This paper proposes a fully analog intelligent servo-valve amplifier for broadband pneumatic pressure control by preserving the structure of a robust digital pressure controller. A mathematical model of a nozzle-flapper servo-valve pneumatic actuator is developed and identified through frequency response analysis. A robust control architecture, consisting of a current amplifier, two-degree-of-freedom pressure controller, and disturbance observer (DOB), is systematically implemented as an integrated analog circuit, eliminating sampling and computational delays. Simulations verify stability and performance equivalence between analog and digital implementations. Experimental validation in an active vibration isolation system demonstrates a 30 Hz pressure control bandwidth (-3 dB) with performance closely matching the digital controller. The proposed amplifier provides a low-latency, generalizable platform for broadband pneumatic systems, with applications in precision vibration isolation and compliant actuators such as pneumatic artificial muscles.