A delayed-position feedback controller for cranes

摘要

We have designed and implemented a nonlinear controller, based on delayed-position feedback, that suppresses cargo pendulation on most common military and commercial cranes in the presence of noise, initial sway, and wind disturbances. The controller is designed to operate transparently to the crane operator, thereby eliminating any special training requirements for crane operators and furnishing smoother and faster transport operations. The system can be operated in both the automated and manual modes and is capable of handling an operator stop command at any random time. Neither the trajectory nor the end point of the transport maneuver needs to be predefined. The controller is insensitive to the system parameters and can handle base excitations, initial sways, and noise. Such a control can be achieved with the heavy equipment that is already part of existing cranes so that retrofitting them would require a small effort. Most large-scale mechanical drivers have inherent time delays: Instead of compensating for these time delays, the proposed feedback controller makes use of these time delays. The effectiveness of the controller has been demonstrated using fully nonlinear numerical simulations as well as on scaled models of ship-mounted, rotary, and container cranes. The numerical and experimental results demonstrate that pendulations can be significantly reduced, and therefore the rate of operation can be greatly increased and the range of sea conditions in which cargo-transfer operations can take place can be greatly expanded. Moreover, because the controller eliminates pendulations of the load, the power needed in the controlled case is guaranteed to be less than the power needed in the uncontrolled case