Actuation dynamic modeling and characterization of an electrohydraulic system

Abstract

The physical model of an electrohydraulic actuation system with pressure-reducing cylinder end cushioning has been obtained. In order to arrive at the closure of the model, experimental models for actuator friction and the characteristics of the relief, non-return and proportional valves have been constructed. The variation in discharge through the proportional valve with both pressure and command signal has been modeled by training a neural network with experimental data. For the characterization of the discharge through the proportional valve, besides square root of the pressure drop in each metered orifice, polynomial forms of command signal for the discharge coefficients have been used. Such a direct characterization of the discharge with the command signal eliminates the orifice opening as an intermediate variable. A simple friction model that retains all the features of the existing complex models has been developed. Parameters such as maximum dynamic friction and the corresponding velocity have been introduced for this purpose. All these nonlinear subsystem models have been integrated together in MATLAB/Simulink frame to predict the actuation dynamics. The variations in the predicted and experimental displacements of the piston against different command signals have been found to be quite close to each other.

Accurate model identification of the inertial mass dynamic of hydraulic cylinder with model uncertainty

“…The specific method can be found by many existing studies. 5,8 It will not be described here for simplicity. As shown in Figure 9, DLN can still achieve accurate and stable parameter estimation in the identification of real system.…”

“…4 Several optimization criteria were adopted to solve the parameters, such as least square error and mean squared error criterion. 3–5 Also some global optimization methods were used, such as differential evolution (DE), genetic algorithm (GA). 6,7 The gray-box methods can generate compact identification result and the obtained parameters have clear physical meanings.…”

“…In order to get a model that matches the actual system, a lot of time was taken to find accurate and suitable models. 5–8 This reduces the identification efficiency of the gray-box method.…”

Experimental Study of 3D Movement in Cushioning of Hydraulic Cylinder

“…In industrial applications, a usual solution is applying some external control by means of valves installed in the hydraulic circuit; in mobile machinery, this control configuration and construction is usually difficult and dependent of several mechanical and hydraulic factors [1,2]. On the other hand, for mobile applications an end-stroke internal cushioning device is usually used.…”

Pressure-Drop Coefficients for Cushioning System of Hydraulic Cylinder With Grooved Piston: A Computational Fluid Dynamic Simulation

“…Cushioning can be done with external control, but for mobile applications, this is not generally appropriate, as it requires a complex set-up of mechanical and hydraulic components [2,3]. Alternatively, in this case of mobile applications, internal end-stroke cushioning systems are preferably used.…”