Cranes belong to underactuated mechanical systems, an important subclass of nonlinear control systems typified by fewer control inputs than the degrees of freedom. The usual performance goal of a crane is to execute a desired motion of the load, specified by as many outputs as the control inputs. The challenging task of inverse simulation study, in which control of the underactuated system subject to execute the partly specified motion is determined, is usually formulated in independent variables. In this paper, a dependent variable formulation is motivated and developed. Compared to the independent variable formulation, the use of dependent variables leads to much simpler governing equations, and their effective number is reduced. The developed formulation is illustrated by a simulation model of an overhead crane executing a rest-to-rest maneuver of the load along a specified curvilinear trajectory.
In Nantes, the last shipyard closed in 1986 leaving the city in a desperate situation. The cranes, symbolizing the industrial activity, one by one stopped. Unemployment stroked. The question was between turning the page, tearing down the workshops and reinventing a new story or trying to preserve would appear to most of the population, a kind of modern bulky legacy. In the early 2000’s, the revitalization of Nantes’ former industrial area, led to developing a new way thinking. Instead of designing an urban map with major spots and rows of housing, A. Chemetoff thought better to draw an urban landscape where the past could mix with the future. The industrial heritage has been then preserved in two diff erent ways: construction halls have been reshaped preserving the original structure, everything should be reversed. The intangible heritage, meaning worker’s knowledge, has been reinvested in the cultural industry. This way, the image of the city, its brand, moved from industrial to cultural, attracting a new kind of business, mainly high-tech, students, in a new: “art de Vivre” (Art of living).
Crane selection is an important issue in assembly works planning. Tower and telescopic, stationary and mobile cranes used in construction have essentially different properties. Assembly planning begins in analyzing the possibilities of assembly with a given crane. This is called technical aspect of crane selection. Cranes that meet the technical criteria are then analyzed in terms of other criteria related to the effectiveness of their use on the construction site. The article presents the assessment of the selection criteria and the method of crane selection itself. Surveys conducted among construction managers and planners in Polish companies dealing with assembly works allowed to determine the significance of the selection criteria. For this purpose, an example using SAW (Simple Additive Weighting) and FSAW (Fuzzy Simple Additive Weighting) methods was presented. They also allowed to propose a technique for determining preferences in the use of selected construction cranes. The aim of the research was to increase the usability of computer applications supporting assembly planning by acquiring expert knowledge for the initial selection of organizational solutions.