The following is a review of the current status and future plans of the research concerning tower crane operations, carried out by the Technical Research Centre of Finland (VTT). Firstly, an empirical time-motion study of crane operations on building sites is described. The results can be used for creating a crane selection guideline in a textual or knowledge based form and in crane automation ideas evaluation. Secondly, the current crane automation research results carried out by VTT are summarized and possible applications to a tower crane are characterized. Thirdly, some of the future activities in crane automation research in VTT are discussed. In those studies an integrated approach to crane automation problems will be applied, where development of the site's overall order, systematic construction management methods, knowledge or simulation based crane selection methods, adaptation of building components and crane automation will be gradually combined on the way to the long term goal: a highly automated building frame erection system.
Most of the positioning and navigation systems developed for construction machines have been focused on satisfying 2D navigation requirements. In this paper, a system is proposed for continuous and accurate tracking of a bulldozer or corresponding moving machine. Tracking is based on 3D coordinate determination using a time -of-flight laser range finder and angle encoders as a measuring head and optical reflectors attached to the machine. Tracking is accomplished by illuminating the cooperative target with an infrared emitting diode (IRED) or laser diode and focusing the reflected light on a surface of a position sensitive detector (PSD). Preliminary tests of the technique have been performed in a bulldozer's real working environment at a cellulose mill and have been promising : an angle resolution of about 200 Arad is achievable in a measurement range of up to 100 -150 in using a spherical target constructed of highly reflective tape attached to the machine and a cw laser diode (8 mW) as the transmitter.
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