Modeling and Verification of an Innovative Active Pneumatic Vibration Isolation System

This paper presents a novel concept in active pneumatic vibration isolation. The novelty in the concept is in utilizing an air-spring-orifice-accumulator combination to vary the natural frequency as well as inject damping into the system per requirement, thereby eliminating the need for a hydraulic cylinder or a magnetorheological damper. This continuously variable natural frequency and damping (CVNFD) technology is aimed at achieving active vibration isolation. For analysis purposes, a particular application in the form of pneumatic seat suspension for off-road vehicles is chosen. A mathematical model representing the system is derived rigorously from inertial dynamics and first principles in thermodynamics. Empirical corelations are also used to include nonlinearities such as friction that cannot be accounted for in the thermodynamic equations. An exhaustive computational study is undertaken to help understand the physics of the system. The computational study clearly depicts the CVNFD capability of the vibration isolation system. An experimental test rig is built to experimentally validate analytical and simulation modeling of the system. Experimental verification corroborated the variable natural frequency and damping characteristic of the system observed through computational simulations.