Sensing with a 3-toe foot for a mini-biped robot

This thesis describes the implementation of a 3-toe foot for biped robots. The objective is to provide a reliable and low-cost solution for the problem of sensing the center of pressure when stepping over uneven surfaces. To accomplish this goal, a new method for measuring force based on the degree of deflection of a flexural plastic toe is presented. Empirical results confirm that it is possible to obtain the same level of accuracy using this new method than using standard force sensing resistors (FSR).;In order to measure the level of deflection of the plastic toe, a small magnet has been inserted in each toe tip. An arrangement of Hall effect sensors measure the magnetic field generated by the magnet. With the information obtained from the hall effect sensors it is possible to estimate the torques acting on the foot.;In order to obtain a quantitative measurement of the behavior of the system, a set of experiments has been executed. In these experiments, an initial load is applied to the foot, and subsequent variations of extra loads are then applied to modify the location of the center of pressure and the level of torque. The information obtained from the foot is then contrasted with an industrial load cell installed in the ankle of the robot, which provides accurate information regarding the real location of the forces and torques (ground truth). The same experiment has been conducted using a standard commercial FSR foot from Robotis. The results show that the model implemented provides more information, while showing similar accuracy to the commercial model.