(a) Acquired SPR signals (blue line SPR1 on right hand, red line SPR2 on left hand) and output of the algorithm for motion artifact removal (black line) during a driving session; circles A, B and C represent some significant portions zoomed in the next sub-figures. (b) Zoom of the signals in the circle A; when hands are still, the three traces are identical and SPR pulses look with smooth shape. (c) Zoom of the signals in the circle B; it is evident a motion artifact in right hand, but the output is not affected remaining close to zero. (d) Zoom of the signals in the circle C; motion artifacts are evident in both hands in t ∈ [495, 515] s, but the output is not affected; at t = 520 s instead, an SPR pulse is properly recognized.