Optimized Creep-Hysteresis Model to Improve Center-of-Pressure Detection in Pressure-Sensitive Mats

Pressure-sensitive mats (PSMs) have a wide variety of applications. They can be used to measure the center of pressure (CoP) when a person is standing. Measuring CoP is useful for several applications, such as human stability assessment or fall risk prediction. Low-cost PSMs can be manufactured using piezoresistive materials, such as Velostat, whose conductance depends on the pressure exerted. However, these low-cost materials often suffer from hysteresis and creep. These effects worsen CoP measurement. Therefore, correction of hysteresis and creep effects is required to improve it. In this study, a creep-hysteresis correction model is applied to quantify CoP displacements obtained with PSMs. The model to correct creep and hysteresis effects is optimized using the CoP measurements themselves. This is a novel approach to optimize the creep and hysteresis model for this application. This approach has been experimentally tested on three different PSMs, including a commercial mat. Several tests and comparisons with existing models were performed, resulting in an improvement in CoP measurement when the CoP-optimized creep-hysteresis correction model was applied.