Virtual indoor-GPS for measurement uncertainty determination in reconfigurable environments

Christoph Nicksch,Mielad Sabzehi,Robert H Schmitt

doi:10.1007/s11740-022-01111-4

Christoph Nicksch, Mielad Sabzehi + Show 1 more

Open Access

https://doi.org/10.1007/s11740-022-01111-4

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Abstract

In Line-less Mobile Assembly Systems, the mobilization of assembly resources and products enables rapid physical system reconfigurations to increase flexibility and adaptability. The clean floor approach discards fixed anchor points, so that assembly resources such as mobile robots and automated guided vehicles transporting products can adapt to new products and form new processes. Associated challenges are accurate spatial referencing between mobile resources to meet assembly tolerance requirements. There is a need for more accurate positioning data to locate and navigate mobile assembly resources. An indoor-GPS, as a distributed large-scale metrology system, is able to cover a wide shop floor area and to obtain positioning data with uncertainties in the submillimeter range. The measurement uncertainty of such a system depends on the spatial distribution of the transmitters and the receiver positions. To be able to validate positioning tolerance requirements of an assembly process, measurement uncertainties must be determined. Virtual measurements simulate measurement processes and model dependencies between the environment and the metrology system. This work presents a novel approach for a virtual indoor-GPS to determine measurement uncertainties during a process and to evaluate the measurement process capability. Experiments show the validity of the virtual indoor-GPS which can be used as a planning tool for metrology system setups within Line-less Mobile Assembly Systems.

Highlights

The assembly of large-scale products is characterized by a high level of effort in terms of logistics and the set-up processes [5]
Nicksch et al [31] reviewed current large-scale metrology (LSM) systems to be used within a Global Reference System (GRS)
Afterwards, we review the state of the art regarding existing approaches for iGPS measurement uncertainty determination to derive requirements for the development of the proposed virtual iGPS

Summary

Introduction

The assembly of large-scale products is characterized by a high level of effort in terms of logistics and the set-up processes [5]. This results in a high depth of added value, which in turn leads to the requirement to produce large components “First-Time-Right” e.g. by applying the concept. Production Engineering referencing on the entire shop floor [7] Following this idea, Demeester [8] defined a Global Reference System (GRS) as a system covering the measuring volume of an entire shop floor and enabling measurements at many points simultaneously. Implementing a GRS requires a distributed metrology system that is scalable across the assembly environment and can simultaneously measure multiple objects in all six degrees of freedom. The iGPS measurement uncertainty depends on the spatial distribution of transmitters (called configuration in this work) which affects minimum tolerances to be checked and the measurement process capability [10]

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