Modeling And Control Simulation For Loading System Of Six-degree Of Freedom

The six-DOF parallel loading system, which is designed by using electro- hydraulic pressure as the driving load in this paper, is competent for the test of tied degree and life-span of industry product in versatile situation. A typical cement pump truck is taken as the force analysis object in the simulation.Based on the outstanding engineering simulation tools: ADAMS, Simulink and AMESim, this study designs the models for the two aspects of this parallel system separately: the mechanical part and the hydraulic part. During the co-simulation, the subroutine for driving force moment, which is written in simulink, will be exported to AMESim as a sub-model by invoking the interface of these tools. To improve the accuracy of simulation, the co-simulation's model particularly take the detailed characters of real machine into account.In this paper, firstly, a model of single cylinder is built based on hydraulic pressure control system. Then, the range of workload stiffness can be known after the analysis for simulation under diverse workload stiffness in this system. These parameters can be useful for providing the range of workload stiffness which has good tracing performance, and giving the guidelines of system overall control plan. The load of platform and typical load pump part in the global model are analyzed with detail and a simplified plan is deduced for the system model. Finally, on the assumption that the pump truck has various stiffness performance, i.e., stiffness is divided into three parts: turret's centralized stiffness and stiffness distributed on four legs of pump truck and the impact on platform of jib force load. Based on the analysis result of simulation under various load characters, a conclusion for the impact on load property for six cylinders comes out: with the load stiffness becomes small, the steady state error of load force grows, the tracing performance gets worse. On the other hand, when object's stiffness spread around the center of parallel machine, the load character of six hydraulic cylinders turns to be coupled, and the smaller the stiffness is, the more serious the coupling degree is.