Abstract
Abstract. In this paper a localization system of a passive 3-D coil is proposed and signal uncertainties due to the 3-D coil's arbitrary orientation are analyzed. The 3-D coil is excited by an alternating primary magnetic field. Geometrically distributed pick-up coils measure the 3-D coil's secondary field. By means of a simulated look-up table that assigns expected voltages from the pick-up coils to the positions of the 3-D coil, the position of the 3-D coil is deduced by a least-squares approach. A basic assumption is that the secondary field is invariant to the orientation of the 3-D coil. This allows a reduction of the computational effort for the look-up table generation and the table search during the localization phase since for each position the field distribution for only one orientation has to be calculated. However, the assumption of invariance to rotation is only valid for a dipole model. In this paper we investigate the localization error introduced by this assumption when using 3-D coils with a geometric extent in an inhomogeneous primary field. Optimized localization methods that decrease the statistical error are proposed. The theoretical results are verified with measurements conducted on a laboratory system.
Highlights
Every modern producing industry has a storage solution within their logistics process
In this paper we investigate the localization error introduced by this assumption when using 3-D coils with a geometric extent in an inhomogeneous primary field
The reduced-complexity method described in Sect. 2.2 relies on the assumption that the secondary field of the 3-D coil system does not depend on its orientation
Summary
Every modern producing industry has a storage solution within their logistics process. As an alternative or extension, camera-based systems can provide important feedback to the operator in case of a wrongly picked item (KBS, 2018b) Such solutions, require a line of sight. In this paper we propose a magnetic-field-based approach for the localization of an operator’s hand in a shelf. The estimation of the position and the orientation of a magnetic source based on measured field values is a classic inverse problem. Several methods exist for the estimation of the position and the orientation of a magnetic field source. An advantage of using an optimizationbased approach is that not all possible combinations of positions and orientations of the magnet need to be calculated This comes with the risk of sticking to local solutions or even divergence of the estimate (Brauer et al, 2006).
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