Vibration isolator using pneumatic artificial muscle: theoretical modeling and experimental verification

Abstract

This paper addresses a comprehensive study about theoretical model and experimental evaluation of a vibration isolation model (named CFIM) using pneumatic artificial muscle (PAM) in which a cam profile is especially designed to obtain the constant-force behavior in working region. Firstly, the total vertical restoring force as a piecewise linear function will be established, the piecewise dynamic equation is then built in consideration of structure damping incurred by the nonlinearity of PAM. The analysis solution of dynamic response of the CFIM under the harmonic force excitation is realized by using the Average method. Simultaneously, the stability of the analysis solution is discussed. At the same time, the effects of the excited force, damping coefficient and the critical position for non-contact between roller and effective surface of cam will be analyzed. Additionally, the complex dynamic behavior of the CFIM is explored, which shows the bifurcation phenomenon between sinusoidal solution and multi-period solution, even chaos solution. Secondly, the ability of force transmissibility of the CFIM is analyzed and discussed, proving that the peak frequency and the initial frequency for isolation never exceed those of the equivalent linear model regardless of increase or decrease in excited force, critical position and damping coefficient, especially, ignoring the bending of vibration transmission curve. Finally, an experimental apparatus is set up for purpose to evaluate the theoretical model. The analysis and experimental results confirm that the developed model offers a good effectiveness of suppressing the force transmission from the load plate to the framework compared with the linear counterpart. This study will offer an insight into designing a vibration isolation system supported by PAMs.