Critical Technique For Crane's Fast Contraposition Based On Load's Anti-Sway Control

Generally, the trolley of overhead cranes or gantry cranes and the load are connected by the flexible wire rope. The operation of the trolley or the crane causes the load's sway because of the inertia of the trolley, crane and load. Load's sway is not favorable to the crane's fast contraposition. Passive control of the load's anti-sway is often easier than the active control. The kinds of the load's anti-sway usually include mechanical system, hydraulic system, wire rope system, mechanical electronic system and intelligent electronic system. Research emphasis of this thesis is on the hydraulic and the intelligent electronic anti-sway system. Dynamic analysis for the crane-load or the trolley-load system is the foundation for solving the problem of the crane's fast contraposition. The crane-load system's dynamic equations were constructed for the overhead cranes, and the two-degree-of-freedom angle model was derived based on linear simplification for the system's dynamic equations. Dynamic simulation results show that load's hoist rope length and the acceleration of the crane or the trolley are the main influencing factors for the load's swing angle, and the acceleration has greater effect on the swing angle than the rope length, and the effect of the crane's running and the effect of the trolley's running on the load's swing angle are identical.Hydraulic anti-sway system has extensive application in the container cranes. In order to provide theoretic foundation and guidance for the engineering design of the hydraulic anti-sway system, in this thesis, the dynamic equations were constructed in the field of engineering application on the base of the characteristic of the anti-sway system's structure and the trolley-load system's dynamics. Then dynamic characteristic was analyzed for the hydraulic anti-sway system. Dynamic simulation according to the container cranes shows that the load's swing angle may be attenuated to zero according to the index form, and the anti-sway system's structure parameter, hoist load mass, hoist rope length and hoist velocity can affect the anti-sway effect. For the concrete hydraulic anti-sway system, there exists better anti-sway effect when the anti-sway system has the matching hoist load or the optimal ratio range of the structure parameter to the hoist load.The state variables information including the trolley's position and velocity, the load's swing angle and swing angle velocity and the trolley's driving force are often collected by corresponding sensors, then these information is provided to the anti-sway control system .But considering the difficulty and cost of site measurement for variables such as the load's swing angle, in this thesis, for the trolley-load's dynamic system drove by the DC motor, the corresponding variables can be observed through setting a full-state observer or a reduced dimension observer, and that is to reconstruct the state variable space. Then corresponding variables' estimated information may be provided to the anti-sway control system. The full-state observer was designed to observe all variables including the trolley's position through collecting the trolley's position information. The reduced dimension observer was designed to observe the load's swing angle, swing angle velocity and driving force through collecting the trolley's position and velocity information. The dynamic parameters of the trolley-load's system, the observer's pole location and the initial value of the corresponding state variable can affect the corresponding state variable's observation time. The curves of observation time vs. observer's pole location can be plotted when the system's dynamic parameters and the corresponding state variable's initial value are determinate. In order to reconstruct the state variables precisely, the observer's pole is placed on the negative real-axis in the complex plane and in the flat range on the curves.The trolley-load open-loop system is unstable according to the dynamic characteristic of the trolley-load open-loop system and the open-loop system's pole location in the complex plane, the closed-loop control system is constructed through introducing the state feedback gain regulator. The state variables information is offered through collecting with site sensors and observing with the observer. Considering a pair of closed-loop dominant poles in this control system's complex plan, the other poles of this control system may be distantly placed in the left side of the dominant poles based on pole placement (pole displacement) method. The gain adjusting parameter of the feedback controller is achieved with the analysis way of similar 2nd-order system. The feedback control system's poles expected are placed with the adjusting parameter, and the load's swing may be attenuated to zero at the target position and the expected adjusting time. When the state observer is introduced into the feedback control system, the observer's observing state variables must be faster than the feedback controller's adjusting state variables. In this thesis, the observer and feedback controller were designed. Simulation results show that the load's swing angle may be attenuated to zero at the trolley's expected position and adjusting time in the adjusting error range, and the anti-sway control system has favorable stability and dynamic characteristic. So the design of the observer and feedback controller is reasonable and effective.Physical realization of the cranes' modern intelligent electronic anti-sway control system must be based on the modern design of electronic circuit. In this thesis, the DSP anti-sway control system based on CAN bus structure was reasonably designed, and the concrete implementation scheme for the load's swing angle's measurement with triangle method was expounded. These key technologies's solving are the preparatory work on the physical implementations for these anti-sway control theory and method.