Dynamic model of air spring based McKibben pneumatic artificial muscle

• Proposing a dynamic model of the pneumatic artificial muscle based on McKibben structure (PAM). • Identifying experimentally the parameters of the model. • Evaluating experimentally the proposed model. It is necessary to have an accurate nonlinear dynamic model for purpose of design of optimization of systems constructed by pneumatic artificial muscles (PAM) based on McKibben structure. Hence, this paper will develop an accurate dynamic model of PAM. As known, PAM tube is made of the rubber and it is also reinforced by metal fibers wrapping around the tube. In order to study comprehensively, the prediction model will consider the effects of the thermodynamic of air inside PAM, simultaneously the effects of friction between fibers and rubber, and viscoelasticity of the PAM tube material are taken account into. Firstly, the structure parameters of the proposed model comprising the effectiveness volume and its rates will be attained through geometrical analysis and experimental evaluation. Then, the effects of friction and viscoelasticity of the PAM tube on the hysteresis dynamic response of PAM will be also taken into account through proposing the hysteresis dynamic model including a fractional Maxwell model parallel with smooth friction model. From dynamic analysis, the dynamic stiffness model is attained and analyzed in domain frequency comprising the storage stiffness and loss stiffness. Finally, comparison between the proposed model and experimental results is realized subjected to harmonic displacement excitation. The results proved the effectiveness of the proposed model. The studied finding is useful insight into applications of PAM in vibration isolator as well as other engineering purposes.