Measuring of foot plantar pressure—possible applications in quantitative analysis of human body mobility

Abstract

The paper presents an evaluation of human mobility by gait analysis, carried out in natural conditions (outside of the laboratory). Foot plantar pressure is measured using a shoe insole with 8 sensors placed in different anatomical zones of the foot, and placed inside a sports shoe. Polarized polyvinylidene fluoride (PVDF) foil is used as a sensor material. A wireless transmission system is used to transmit voltage values to the computer. Miniaturization was the priority during the design of the system. Due to the linear relationship between force and transducer voltage, energy and power released during walking in arbitrary units can be calculated as an integral of the square of the transducer voltage over time. Gait measurements were carried out over several days on healthy persons during normal walking and slow walking. The performed measurements allowed for the determination of walking speed (number of steps per second), gait rhythm and manner of walking (applying force to inside versus outside part of the sole). It was found that switching from normal to slow walk increases gait energy by 25% while the pressure distribution across the anatomical regions of the foot remains unchanged. The results will be used to develop a programme for the evaluation of patients with orthopedic diseases or even with cardiac failures, for an estimation of the results of health recovery and training efficiency in many sports activities.