Influence of counterbalance valve parameters on stability of the crane lifting system
In this paper, a model of the large crane lifting system has been developed in the AMESim environment. The comparison between the simulation results and the experimental data shows good agreement in both time and frequency domains, indicating the correctness of the model. Furthermore, the causes of pressure pulsations of the lifting system are described by means of dynamic simulation and experimental research. The analysis result indicates that the pressure pulsation of the lifting system is closely related to dynamic characteristic of the counterbalance valve, and stability of the system can be improved by means of the flow area of counterbalance valve with linear small gradient.
Modeling and Characteristics Investigation on a Load Control Valve
In this work, a new solution of load control valve based on a hydraulic coupling two-stage principle is proposed. A detailed mathematical model of the valve has been developed. According the model, the steady-state and dynamic characteristics have been studied. The steady state study shows that the valve has an ideal piloted opening function which is not affected by the load pressure or back pressure alteration. Through an insightful analysis based on the linearized model, the dynamic study reveals that the main stage respond as a 1st order model which is smooth and fast enough compared to the pilot stage, while the pilot stage can be simplified as 2nd order model which may cause a problem of oscillation or overshot. The transition response of the valve is mainly decided by the pilot stage. Through the study of various parameters, the diameter of the orifice on the pilot piston shows its efficient influence in adjusting the poles in the pilot stage without affecting the steady state operation of the valve. An optimization based on root locus method is implemented and the poles have been deployed to the fastest points without oscillation.
Optimal control of a rotary crane
This paper is concerned with the optimal control of a rotary crane, which makes two kinds of motion (rotation and hoisting) at the same time. The optimal control which transfers a load to a desired place as fast as possible and minimizes the swing of the load during the transfer, as well as the swing at the end of transfer, is calculated on the basis of a dynamic model. A new computational technique is employed for computing the optimal control, and several numerical results are presented.