A forward-inverse dynamic model for the hydraulic damping(magnetorheological) actuator based on cyclic stress–strain

Magnetorheological dampers (MRDs) are applied to hydraulic systems, which not only improve the underdamped characteristics of valve-controlled cylinder systems, but also help hydraulic actuators to resist high load impact. However, the high power density leads to the complexity of the internal flow channel of the damper, which seriously affects the output accuracy of the damping force. It can lead to the fact that existing dynamics models cannot accurately describe the hysteresis characteristics of the MRD. Therefore, this study proposes a simple and general dynamic model of MRD, which solves the problem that existing models are complex and difficult to invert. Firstly, the hydraulic damping actuator with the series MRD is taken as the research object. Based on the stress–strain hysteresis characteristics under the cyclic constitutive model, the hyperbolic tangent curve is reorganized and normalized. It can accurately describe the yield formation and yield dissipation stages of the hysteresis loop. Secondly, the relationship between the parameters of the dynamic model and the current is obtained according to the mechanical experimental data. Then the inverse model of the MRD is established by using the method of section-backstepping. Finally, in the static experiment, the mean absolute percentage error (MAPE) of the force at different velocity is less than 7.5%; in the dynamic experimental test, the MAPE of the force is 9.7%. The inverse dynamics model is verified to have high tracking performance under both static and dynamic forces. And it also indirectly confirms the effectiveness of the forward model.