Projections for measurements of Higgs boson signal strengths and coupling parameters with the ATLAS detector at a HL-LHC

A study is presented on the ATLAS experimental prospects for measuring Higgs boson signal strengths, and determining couplings to individual fermions and bosons, using 14 TeV proton-proton collisions at the LHC with 300 fb$^{-1}$ and at the HL-LHC with 3000 fb$^{-1}$. This document is released coincident with the 2014 ECFA HL-LHC workshop and contains updates since the 2013 workshop for the $H\to Z\gamma$ and $VH/ttH\to\gamma\gamma$ channels. In addition, the prospects for the $VH\to b\bar{b}$ channel have now been included in the combination of channels.