  Investigating the early-stage evolution of an erupting flux rope from the Sun
is important to understand the mechanisms of how it looses its stability and
its space weather impacts. Our aim is to develop an efficient scheme for
tracking the early dynamics of erupting solar flux ropes and use the algorithm
to analyse its early-stage properties. The algorithm is tested on a data-driven
simulation of an eruption that took place in active region AR12473. We
investigate the modelled flux rope's footpoint movement and magnetic flux
evolution and compare with observational data from the Solar Dynamics
Observatory's Atmospheric Imaging Assembly in the 211 $\unicode{x212B}$ and
1600 $\unicode{x212B}$ channels. To carry out our analysis, we use the
time-dependent data-driven magnetofrictional model (TMFM). We also perform
another modelling run, where we stop the driving of the TMFM midway through the
flux rope's rise through the simulation domain and evolve it instead with a
zero-beta magnetohydrodynamic (MHD) approach. The developed algorithm
successfully extracts a flux rope and its ascend through the simulation domain.
We find that the movement of the modelled flux rope footpoints showcases
similar trends in both TMFM and relaxation MHD run: they recede from their
respective central location as the eruption progresses and the positive
polarity footpoint region exhibits a more dynamic behaviour. The ultraviolet
brightenings and extreme ultraviolet dimmings agree well with the models in
terms of their dynamics. According to our modelling results, the toroidal
magnetic flux in the flux rope first rises and then decreases. In our
observational analysis, we capture the descending phase of toroidal flux. In
conclusion, the extraction algorithm enables us to effectively study the flux
rope's early dynamics and derive some of its key properties such as footpoint
movement and toroidal magnetic flux.
