Fig. 1

Responses of the monitoring methods to simulated input pressure signals. Parameter settings include sampling time, 0.1 s and relief time (tr), as shown in the figure. Pressure magnitude was set to 10 kPa in a), 20 kPa in b), 20 kPa amplitude at a frequency of 0.00333 Hz in c), and varied between 20 and 120 kPa with a mean of 70 kPa in d). In all cases the none-damaging and excessive pressure magnitude were 9 kPa and 32 kPa respectively according the pressure–time injury threshold. The arrow in the last row of a) indicate the impulse time. Avg, Averaging filter method; Fixed, Fixed decay with integrator method; Inverse, Inverse time decay with integrator method; Linear, proposed monitoring approach with linear decay; Exp, proposed monitoring approach with exponential decay