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.
Energy-saving control for electro-hydraulic systems under time-varying negative loads
In a hydraulic system, employment of counterbalance valve introduces sizable energy consumption. In addition, a pressure-feedback control architecture with inflexible parameters causes instability under time-varying negative loads. As an alternative, an adjustable meter-out orifice was adopted, and a stable controller was proposed in this study. By combining inlet pressure and velocity, the concept of a flow rate follower was developed. Mathematical analysis of dynamic model illustrated that both the inlet pressure and velocity converged to a range related to the flow rate follower bounds. Feedback linearization with robust control was utilized such that flow rate follower converged in the presence of parametric uncertainties; meanwhile, a high-gain load observer was constructed for disturbance compensation. The effectiveness of the controller was verified by experiments and its performance discussed. As a result, the inlet pressure was held near a specified low value, thus significantly reducing energy consumption. Also, the velocity matched the supply flow rate, and the oscillations were acceptable in applications.
Cranes and Derricks
Basic concepts and components crane and derrick configuration loads and forces stability against overturning mobile crane installations tower crane installations derrick installations safety and liability.