Enhancing Existing Cranes by a Semi-Automatic Navigation System

Following previous feasibility studies on the subject, this paper presents the actual conversion of an existing full-scale 5-ton payload crane into a semi-automatic “Handling Robot”. Although performed in a laboratory setting, this crane- by its size, degrees of freedom, and mode of operation- resembles typical construction cranes, mainly tower cranes, and they can be enhanced in the same manner, similar components being used. The system allows operation of the crane in either a manual or a semi-automatic mode, and it can be taught to memorize up to 50 different benchmarks, i.e. particular points in the construction site, as well as safe routes among them. The major components of the system include: a programmable controller, three speed regulators, three encoders, several limit switches, a wireless remote control set, and a user-friendly M.M.I. (Man-Machine-Interface). Most of the components can be installed externally in the vicinity of the crane’s joints and inside the cabin, with minimal intervention in the original wiring. Following the physical retrofitting of the crane, a series of tests examined performance, accuracy, repeatability, and safety aspects. They demonstrated a 15%-50% shortening of typical work cycles, high accuracy and repeatability, and a general safer operation due to pre-tested paths and smoother movements with less sway and swing of the load.