Non-Colocated path tracking in crane suspended loads

This paper proposes and validates experimentally a non-time based scheme for the non-colocated path tracking control of a crane suspended load. The controller is named Delayed Reference Non-Colocated Control (DRNC) and extends the idea of the Delayed Reference Control (DRC) schemes. The DRNC action is exerted by shaping the crane moving platform reference trajectory for making the load track the planned path. Such a goal is achieved by both shifting in time the trajectory execution and modifying the platform path with respect to the reference path defined for the load. DRNC schemes have two relevant advantages. On the one hand they provide accurate path tracking and also allow coping with unexpected obstacles: if an obstacle is hit, path execution is indefinitely delayed until the load is removed. On the other hand they necessitate a very simple software and hardware implementation, which is basically traced back to the closure of an additional feedback loop outside the crane native position controller.