Design and Development of a Pressure-Sensitive Shoe Platform for Nao H25

This paper introduces a smart pressure-sensitive platform designed in a modular manner similar to the shape of the foot of the Nao H25 V5 humanoid robot; hence, any H25 Nao can easily wear it like a shoe. The main purpose of the developed shoe system is to accurately estimate and monitor ground reactive forces and the plantar pressure distribution of the foot of the Nao in real-time. In order to measure these forces, a unique pressure sensing element was designed and developed and four sensing elements have been placed at the bottom of the shoe. Since the sensing element should be in direct contact with the ground, a soft pressure sensing element should be utilized it should be flexible enough and also can withstand the weight of the robot. The presented sensing element consists of a barometric pressure sensor and a silicone coating. It has been designed in a way that can withstand extreme burst pressures without being damaged, and it has a linearity of up to 300 N. All the necessary electrical components such as battery and wireless module are built-in inside the shoe in order to make a standalone wireless-enabled platform that seamlessly integrates with Nao without any complications. The presented shoe platform can measure the center of pressure across the plantar surface of the foot in real-time. These parameters can help form a comprehensive balance controller for Nao which can have significant value in a variety of applications. The calculated parameters and sensor readings have been preliminarily validated, and the estimated center of pressure is comparable with similar studies.