Development of an innovative quasi-zero stiffness oscillation model using pneumatic artificial muscle

•An innovative quasi-zero stiffness oscillation model using pneumatic artificial muscle is proposed.•The restoring model of the pneumatic artificial muscle is analyzed and identified experimentally•The structure of the nonlinear oscillator is designed and analyzed to obtain quasi-zero stiffness in working region.•A prototype of the proposed model is manufactured and then an experimental apparatus is set up to assess the theoretical restoring force model The paper proposes an innovative nonlinear oscillation model having potential benefits in engineering application such as vibration isolation, vibration absorber and so forth. This model composes four offset slider-crank mechanism and four cam mechanism, whose main feature is to remain the quasi-zero stiffness value within the working region. Furthermore, instead of using conventional elastic elements such as coil spring, rubber air spring, etc. Another potential elastic element which is pneumatic artificial muscle (PAM) will be introduced in this work. Indeed, the PAM can work as a spring for supporting the load simultaneously it may also work as an actuator for creating active force. This means that the proposed model can be changed easily between two working modes such as passive and active one. First of all, the restoring model of a commercial PAM will be analyzed and identified experimentally. Based on these results, an offset slider-crank mechanism is then designed, next designing the cam mechanism will be presented. The constraint of this design is that vertical restoring force of the proposed oscillation model is always constant in working region, attaining the quasi-zero stiffness. The result is to obtain a set of equations describing the profile of the cam. From these equations, a 3D model of the cam mechanism will be built. Finally, a prototype of the proposed model will be fabricated and realized experimentally. The experimental result confirmed the agreement between the measured and simulated data, meaning that the proposed model can offer a constant force-displacement or quasi-zero stiffness curves in working region. This study will offer a useful insight into the dynamic analysis of this oscillation model.