Coordinated control of a planar dual crane non-fully restrained system

Abstract

In this dissertation a control scheme that provides motion compensation for a ship-based two-crane system suspending a single payload is developed. Historical experience during the conflict in Vietnam, along with the introduction of standard containerized packaging have steered military sustainment logistics towards a reliance on commercially developed cranes for discharge of containers - even for instream lightering operations. With the inclusion of Seabasing as one of the Navys pillars, there has been a resurgence in interest in cargo transfer technology. While several approaches to the movement of individual containers have been pursued, there has not been a similar focus on the handling of outsize cargo in the military logistics-overthe- shore (LOTS) operating environment. In the body of this work is an algorithm for the coordinated control of two cranes to facilitate the movement of cargo. The use of multiple cranes may be required by either the geometric extent or the weight of the cargo. The kinematic chain is developed for the incompletely-restrained cablesuspended system that describes this system. With the inclusion of the dynamics of the system to fully describe the force and moment constraints, the equations of motion can be inverted to yield expressions that relate desired payload motion to crane control inputs. The presence of seaway induced motions on the ship platform introduces disturbances that must be accounted for in the kinematics of the ship-attached crane reference frame and be compensated for by the dual-crane system. Without this motion compensation, the operational capability is limited by the environment. With this system the payload is isolated from the ship motion and held fixed in inertial space. The weighted-norm method used to derive the solution allows for distribution of the actuation effort of the system, which could be useful in actual operations of the cranes onboard a vessel and provides an opportunity for optimization by judicious selection of the weighting matrix. Future development of coordinated control for dual-crane systems may also employ trajectory planning to automate the movement of large payloads. Results from a MATLAB/Simulink simulation and selected results from a 1/32nd-scale model are presented to illustrate the concepts developed.