Discrete-time command profile for simultaneous travel and hoist maneuvers of overhead cranes

A strategy for generating optimal shaped command-profile for the reduction of residual vibrations in rest-to-rest crane maneuvers is proposed. The technique used is based on generating discrete-time shaped acceleration profile. This profile accommodates simultaneous travel and hoist maneuvers in the presence of damping. The discrete-time acceleration profile is derived analytically using finite step segments. These segments are integrated into an input matrix coupled with a response matrix through a time varying equation of motion of the system. The input acceleration matrix is then optimized to satisfy specific rest-to-rest maneuver conditions. Several parameters are incorporated in the proposed strategy including maneuver time, time step, hoisting speed, damping, and maximum travel velocity and acceleration. Unlike traditional command shapers, the proposed strategy matches the discrete command signal steps to the machine minimum time step of the control hardware used. To achieve an optimum maneuvering time, the shaped command utilizes the full system acceleration and velocity capabilities. The resulting shaped command profile is capable of eliminating travel and residual oscillations. Successful performance of the proposed command shaping strategy is validated through numerical simulations and experiments on a scaled model of an overhead crane.