Towards a new terrain perception for humanoid robots

In this work we tackle the problem of estimating the local compliance of tactile arrays exploiting global measurements from a single force and torque sensor. Experiments have been conducted on the feet of the iCub robot [1], sensorized with a single force/torque sensor, an inertial unit and a tactile array of 250 tactile elements (taxels) on the foot sole. Results show that a simple calibration procedure can be employed to estimate the stiffness parameters of virtual springs over a tactile array and to use this model to predict normal forces exerted on the array, based only on the tactile feedback. This prediction is further exploited to improve the estimation of the total feet state by fusing it with inertial and force/torque measurements in an Extended Kalman Filter. This multimodal sensor fusion is relevant when implementing whole-body controllers for robots in non-rigid non-coplanar contacts.