Geometric control for highly accurate construction machine guidance

Aims:

General investigation of closed-loop systems for machine guidance under geodetic aspects
Design of closed-loop systems for optimal integration of tracking tachymeters as position sensor
Investigation of geometric control tasks with an accuracy of a few millimeters.

Project description:

For threedimensional guidance of modern construction machines, such as slip-form pavers, graders, or dozers robot tachymeters or GPS-RTK are used. These have to be integrated, supplemented by further sensors, such as inclination sensors, as positioning sensors into the closed-loop system for machine control.

Due to the measuring accuracy only tachymeters can be used for high accurate guidance. Due to the fact that even modern robot tachymeters are, due to their relatively low scanning rate of up to 10 Hz and a time delay of up to several hundred millimetres, not well suited for the guidance task. Only slow machines may be guided geometrically with high accuracy.

The described dynamic behaviour of robot tachymeters results in determining the topical machine position in curves to late. The outcome of this are considerable deviations to the predetermined trajectory that have to be compensated by the control.

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 Figure 1: closed-loop system with anticipatory precontrol

 

If the human control behaviour in case of manual machine control is analysed, unfavourable dynamic characteristics similar to a tracking tachymeter can be realized. A human is able to integrate the future track of the desired trajectory into his manual control behaviour – he anticipates. Hence a precontrol is established, that leaves only small deviations for recontrol. Figure 1 schematically shows a closed-loop system with anticipatory precontrol.

This theoretical knowledge is to be realized experimentally and later in practice and its potential is to be investigated.

Experiment with model truck:
Experimental realization is effected with the model truck (scale 1:14), show in picture 2. The truck is automatically guided on a predetermined trajectory. A tachymeter (Leica TCP 1201) is integrated into the closed-loop system. The deviations should not exceed 5 mm. The mentioned control concept with anticipatory precontrol is realized in LabView®. A detailed experiment description can be found in (Gläser 2003).

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Figure 2: model truck as simulator (© iigs)

First results:

Figure 3 shows as a first result the deviation of the model truck to a reference trajectory. The deviations of automatic control with and without precontrol are compared. The speed was increased to 20cm/s, contrary to the speed of 1-2 cm/s used in practice (e.g. slip-form pavers). It can easily be recognized that the anticipatory precontrol increases the quality of automatic guidance considerable, and the aim of a maximum deviation of 5 mm can be reached despite a speed of 20 cm/s.

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 Figure 3: Deviation of the truck to the given trajectory

 

Publications:

  • Beetz, A., Schwieger, V.: (2008) Integration of Controllers and Filter Algorithms for Construction Machine Guidance. 1st International Conference on Machine Control and Guidance, Zürich, Schweiz, 24.-26-06.2008.
  • Schwieger, V., Beetz, A.: (2007) Optimierung von Regelalgorithmen zur Baumaschinensteuerung am Beispiel eines Simulators. Beiträge zum 15. Internationalen Ingenieurvermessungskurs, Graz, Herbert Wichmann Verlag, Heidelberg, 17.20.04.2007.
  • Gläser, A.(2005): A Modular System for Guidance and Control Applications for Construction Machines. In: Grün, Kahmen (Eds.): 7th Conference on Optical 3-D Measurement Techniques, Volume I, pp. 307-316, Vienna. (Kurzfassung)
  • Gläser, A., Schollmeyer, R. (2004): Messwerterfassung und –synchronisation in Multisensorsystemen. In: Beiträge zum 58. DVW-Seminar, Kinematische Messmethoden – Vermessung in Bewegung, Wißner Verlag, Augsburg.
  • Gläser, A. (2003): Steuerung autonomer Baumaschinen - Ein Simulator. In: Virtuelle Instrumente in der Praxis, National Instruments-VIP2003, Hüthig Verlag, München.

Diplomarbeiten:

  • Beetz, A. (2003): Entwicklung ausgewählter Komponenten eines Regelkreises zur Fahrzeugsteuerung und deren Realisierung in einem Testsystem. Diplomarbeit am IAGB, unveröffentlicht.

Contact:

Dipl.-Ing. Alexander Beetz
Prof. Dr.-Ing. habil. Volker Schwieger