Segmented foot sensor with curved surface

This paper presents a new structure of foot force sensors for bipedal robots. The sensor has a property of passive compliance. Passive compliance is achieved with two kinds of elastic elements. The first is a metal plate and the second is a rubber elastic element. Sensing elements are reflex couplers. They measure the deformation of the rubber elastic element caused by forces acting on the foot. The sensor is segmented into three parts. One part consists of a metal plate attached to three rubber elastic elements and the corresponding displacement sensing elements. Unlike most present robot feet, having flat plates at the bottom of their feet, our metal plates are curved to a hyperboloid shape. This way the whole foot is a combination of flat and curved parts. Such composition of the foot can provide less energy consumption and easier control of bipedal walkers, ensuring a more human-like walk. An experiment was conducted in order to verify that the sensor measures ground reaction forces correctly.