A method of estimating motion of an object during a magnetic resonance (MR) imaging scan of the object, wherein a main magnetic field is generated in the object by a main magnet and wherein superimposed magnetic fields and radiofrequency fields are generated according to an MR sequence for forming images, - the MR sequence comprising a train of sequence modules, - each sequence module comprising a radiofrequency (RF) excitation segment and an image encoding gradient segment, - said MR sequence further comprising a plurality of navigator gradient segments, in which method - object signal is acquired with an RF receive coil or coil array during a measurement segment of each sequence module, - navigator signal is acquired with said RF receive coil or coil array during each one of said navigator gradient segments, - said navigator signal is acquired along a trajectory k ( t ) in k-space - said navigator signal in a given sequence module is expressed as a discrete time series comprising a predefined number N of complex-valued signal datapoints s k t i , wherein i = 1 to N, characterized in that : - a transformation matrix M which relates rotation angles and translational shifts to corresponding changes in navigator signal in a first order approximation is calculated from the navigator signal s ( k ( t i )) acquired in a first sequence module, optionally including the navigator signal s j ( k ( t i )) acquired in at least one further sequence module, - the navigator signal s̃ ( k ( t i )) acquired in a subsequent sequence module is used to estimate object motion in terms of a translational displacement Δ x and a rotational displacement θ of the object between said first sequence module and said subsequent sequence module by solving the following linear least-squares estimation problem: min Δ x 1 , Δ x 2 , Δ x 3 , θ 1 , θ 2 , θ 3 s ̃ − s − M Δ x 1 Δ x 2 Δ x 3 θ 1 θ 2 θ 3 2 2 - the MR sequence comprising a train of sequence modules, - each sequence module comprising a radiofrequency (RF) excitation segment and an image encoding gradient segment, - said MR sequence further comprising a plurality of navigator gradient segments, - object signal is acquired with an RF receive coil or coil array during a measurement segment of each sequence module, - navigator signal is acquired with said RF receive coil or coil array during each one of said navigator gradient segments, - said navigator signal is acquired along a trajectory k ( t ) in k-space - said navigator signal in a given sequence module is expressed as a discrete time series comprising a predefined number N of complex-valued signal datapoints s k t i , wherein i = 1 to N, - a transformation matrix M which relates rotation angles and translational shifts to corresponding changes in navigator signal in a first order approximation is calculated from the navigator signal s ( k ( t i )) acquired in a first sequence module, optionally including the navigator signal s j ( k ( t i )) acquired in at least one further sequence module, - the navigator signal s̃ ( k ( t i )) acquired in a subsequent sequence module is used to estimate object motion in terms of a translational displacement Δ x and a rotational displacement θ of the object between said first sequence module and said subsequent sequence module by solving the following linear least-squares estimation problem: min Δ x 1 , Δ x 2 , Δ x 3 , θ 1 , θ 2 , θ 3 s ̃ − s − M Δ x 1 Δ x 2 Δ x 3 θ 1 θ 2 θ 3 2 2 <EOS>