Design and construction of step counters for disable people: preliminary experience at the Italian Institute of Health.

Step counting is an important index of motion One of the most diffused wearable systems, designed for this purpose, is the pedometer. The accuracy of commercial pedometers has been tested in literature. Several limits have been found in many commercial systems both in healthy subjects and in disable people. Furthermore, commercial pedometers lack in interoperability. A new wearable system for the step counting has been introduced in this paper. The wearable system is based on a wearable device with a force sensing resistor and a band; it is affixed at the calf gastrocnemius level for the monitoring of the muscular expansion correlated to the gait. The proposed gastrocnemius expansion measurement unit (GEMU) was tested on a three subjects with the Parkinson' s disease at the Level 2 of the Tinetti test of unbalance who performed five repetition of 200 steps with three different instructions (fast, slow). The mean error was lower than 0.5%. Results also showed that GEMU performed better than an accelerometer unit (considered in literature the best solution for this disability). The study showed that GEMU had a high performance in a subject with a pathology (the Parkinson' s disease) causing a high degree of unbalance confounding the motion style and thus pedometers. The next phase will be the optimization of GEMU for long term medical applications at patients' home with the special care to the material and with a comparison to a golden standard.